This file is indexed.

/usr/share/perl5/JSON/backportPP.pm is in libjson-perl 2.97001-1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
package # This is JSON::backportPP
    JSON::PP;

# JSON-2.0

use 5.005;
use strict;

use Exporter ();
BEGIN { @JSON::backportPP::ISA = ('Exporter') }

use overload ();
use JSON::backportPP::Boolean;

use Carp ();
#use Devel::Peek;

$JSON::backportPP::VERSION = '2.97001';

@JSON::PP::EXPORT = qw(encode_json decode_json from_json to_json);

# instead of hash-access, i tried index-access for speed.
# but this method is not faster than what i expected. so it will be changed.

use constant P_ASCII                => 0;
use constant P_LATIN1               => 1;
use constant P_UTF8                 => 2;
use constant P_INDENT               => 3;
use constant P_CANONICAL            => 4;
use constant P_SPACE_BEFORE         => 5;
use constant P_SPACE_AFTER          => 6;
use constant P_ALLOW_NONREF         => 7;
use constant P_SHRINK               => 8;
use constant P_ALLOW_BLESSED        => 9;
use constant P_CONVERT_BLESSED      => 10;
use constant P_RELAXED              => 11;

use constant P_LOOSE                => 12;
use constant P_ALLOW_BIGNUM         => 13;
use constant P_ALLOW_BAREKEY        => 14;
use constant P_ALLOW_SINGLEQUOTE    => 15;
use constant P_ESCAPE_SLASH         => 16;
use constant P_AS_NONBLESSED        => 17;

use constant P_ALLOW_UNKNOWN        => 18;

use constant OLD_PERL => $] < 5.008 ? 1 : 0;
use constant USE_B => 0;

BEGIN {
if (USE_B) {
    require B;
}
}

BEGIN {
    my @xs_compati_bit_properties = qw(
            latin1 ascii utf8 indent canonical space_before space_after allow_nonref shrink
            allow_blessed convert_blessed relaxed allow_unknown
    );
    my @pp_bit_properties = qw(
            allow_singlequote allow_bignum loose
            allow_barekey escape_slash as_nonblessed
    );

    # Perl version check, Unicode handling is enabled?
    # Helper module sets @JSON::PP::_properties.
    if ( OLD_PERL ) {
        my $helper = $] >= 5.006 ? 'JSON::backportPP::Compat5006' : 'JSON::backportPP::Compat5005';
        eval qq| require $helper |;
        if ($@) { Carp::croak $@; }
    }

    for my $name (@xs_compati_bit_properties, @pp_bit_properties) {
        my $property_id = 'P_' . uc($name);

        eval qq/
            sub $name {
                my \$enable = defined \$_[1] ? \$_[1] : 1;

                if (\$enable) {
                    \$_[0]->{PROPS}->[$property_id] = 1;
                }
                else {
                    \$_[0]->{PROPS}->[$property_id] = 0;
                }

                \$_[0];
            }

            sub get_$name {
                \$_[0]->{PROPS}->[$property_id] ? 1 : '';
            }
        /;
    }

}



# Functions

my $JSON; # cache

sub encode_json ($) { # encode
    ($JSON ||= __PACKAGE__->new->utf8)->encode(@_);
}


sub decode_json { # decode
    ($JSON ||= __PACKAGE__->new->utf8)->decode(@_);
}

# Obsoleted

sub to_json($) {
   Carp::croak ("JSON::PP::to_json has been renamed to encode_json.");
}


sub from_json($) {
   Carp::croak ("JSON::PP::from_json has been renamed to decode_json.");
}


# Methods

sub new {
    my $class = shift;
    my $self  = {
        max_depth   => 512,
        max_size    => 0,
        indent_length => 3,
    };

    bless $self, $class;
}


sub encode {
    return $_[0]->PP_encode_json($_[1]);
}


sub decode {
    return $_[0]->PP_decode_json($_[1], 0x00000000);
}


sub decode_prefix {
    return $_[0]->PP_decode_json($_[1], 0x00000001);
}


# accessor


# pretty printing

sub pretty {
    my ($self, $v) = @_;
    my $enable = defined $v ? $v : 1;

    if ($enable) { # indent_length(3) for JSON::XS compatibility
        $self->indent(1)->space_before(1)->space_after(1);
    }
    else {
        $self->indent(0)->space_before(0)->space_after(0);
    }

    $self;
}

# etc

sub max_depth {
    my $max  = defined $_[1] ? $_[1] : 0x80000000;
    $_[0]->{max_depth} = $max;
    $_[0];
}


sub get_max_depth { $_[0]->{max_depth}; }


sub max_size {
    my $max  = defined $_[1] ? $_[1] : 0;
    $_[0]->{max_size} = $max;
    $_[0];
}


sub get_max_size { $_[0]->{max_size}; }


sub filter_json_object {
    if (defined $_[1] and ref $_[1] eq 'CODE') {
        $_[0]->{cb_object} = $_[1];
    } else {
        delete $_[0]->{cb_object};
    }
    $_[0]->{F_HOOK} = ($_[0]->{cb_object} or $_[0]->{cb_sk_object}) ? 1 : 0;
    $_[0];
}

sub filter_json_single_key_object {
    if (@_ == 1 or @_ > 3) {
        Carp::croak("Usage: JSON::PP::filter_json_single_key_object(self, key, callback = undef)");
    }
    if (defined $_[2] and ref $_[2] eq 'CODE') {
        $_[0]->{cb_sk_object}->{$_[1]} = $_[2];
    } else {
        delete $_[0]->{cb_sk_object}->{$_[1]};
        delete $_[0]->{cb_sk_object} unless %{$_[0]->{cb_sk_object} || {}};
    }
    $_[0]->{F_HOOK} = ($_[0]->{cb_object} or $_[0]->{cb_sk_object}) ? 1 : 0;
    $_[0];
}

sub indent_length {
    if (!defined $_[1] or $_[1] > 15 or $_[1] < 0) {
        Carp::carp "The acceptable range of indent_length() is 0 to 15.";
    }
    else {
        $_[0]->{indent_length} = $_[1];
    }
    $_[0];
}

sub get_indent_length {
    $_[0]->{indent_length};
}

sub sort_by {
    $_[0]->{sort_by} = defined $_[1] ? $_[1] : 1;
    $_[0];
}

sub allow_bigint {
    Carp::carp("allow_bigint() is obsoleted. use allow_bignum() instead.");
    $_[0]->allow_bignum;
}

###############################

###
### Perl => JSON
###


{ # Convert

    my $max_depth;
    my $indent;
    my $ascii;
    my $latin1;
    my $utf8;
    my $space_before;
    my $space_after;
    my $canonical;
    my $allow_blessed;
    my $convert_blessed;

    my $indent_length;
    my $escape_slash;
    my $bignum;
    my $as_nonblessed;

    my $depth;
    my $indent_count;
    my $keysort;


    sub PP_encode_json {
        my $self = shift;
        my $obj  = shift;

        $indent_count = 0;
        $depth        = 0;

        my $props = $self->{PROPS};

        ($ascii, $latin1, $utf8, $indent, $canonical, $space_before, $space_after, $allow_blessed,
            $convert_blessed, $escape_slash, $bignum, $as_nonblessed)
         = @{$props}[P_ASCII .. P_SPACE_AFTER, P_ALLOW_BLESSED, P_CONVERT_BLESSED,
                    P_ESCAPE_SLASH, P_ALLOW_BIGNUM, P_AS_NONBLESSED];

        ($max_depth, $indent_length) = @{$self}{qw/max_depth indent_length/};

        $keysort = $canonical ? sub { $a cmp $b } : undef;

        if ($self->{sort_by}) {
            $keysort = ref($self->{sort_by}) eq 'CODE' ? $self->{sort_by}
                     : $self->{sort_by} =~ /\D+/       ? $self->{sort_by}
                     : sub { $a cmp $b };
        }

        encode_error("hash- or arrayref expected (not a simple scalar, use allow_nonref to allow this)")
             if(!ref $obj and !$props->[ P_ALLOW_NONREF ]);

        my $str  = $self->object_to_json($obj);

        $str .= "\n" if ( $indent ); # JSON::XS 2.26 compatible

        unless ($ascii or $latin1 or $utf8) {
            utf8::upgrade($str);
        }

        if ($props->[ P_SHRINK ]) {
            utf8::downgrade($str, 1);
        }

        return $str;
    }


    sub object_to_json {
        my ($self, $obj) = @_;
        my $type = ref($obj);

        if($type eq 'HASH'){
            return $self->hash_to_json($obj);
        }
        elsif($type eq 'ARRAY'){
            return $self->array_to_json($obj);
        }
        elsif ($type) { # blessed object?
            if (blessed($obj)) {

                return $self->value_to_json($obj) if ( $obj->isa('JSON::PP::Boolean') );

                if ( $convert_blessed and $obj->can('TO_JSON') ) {
                    my $result = $obj->TO_JSON();
                    if ( defined $result and ref( $result ) ) {
                        if ( refaddr( $obj ) eq refaddr( $result ) ) {
                            encode_error( sprintf(
                                "%s::TO_JSON method returned same object as was passed instead of a new one",
                                ref $obj
                            ) );
                        }
                    }

                    return $self->object_to_json( $result );
                }

                return "$obj" if ( $bignum and _is_bignum($obj) );

                if ($allow_blessed) {
                    return $self->blessed_to_json($obj) if ($as_nonblessed); # will be removed.
                    return 'null';
                }
                encode_error( sprintf("encountered object '%s', but neither allow_blessed "
                    . "nor convert_blessed settings are enabled", $obj)
                );
            }
            else {
                return $self->value_to_json($obj);
            }
        }
        else{
            return $self->value_to_json($obj);
        }
    }


    sub hash_to_json {
        my ($self, $obj) = @_;
        my @res;

        encode_error("json text or perl structure exceeds maximum nesting level (max_depth set too low?)")
                                         if (++$depth > $max_depth);

        my ($pre, $post) = $indent ? $self->_up_indent() : ('', '');
        my $del = ($space_before ? ' ' : '') . ':' . ($space_after ? ' ' : '');

        for my $k ( _sort( $obj ) ) {
            if ( OLD_PERL ) { utf8::decode($k) } # key for Perl 5.6 / be optimized
            push @res, $self->string_to_json( $k )
                          .  $del
                          . ( ref $obj->{$k} ? $self->object_to_json( $obj->{$k} ) : $self->value_to_json( $obj->{$k} ) );
        }

        --$depth;
        $self->_down_indent() if ($indent);

        return '{}' unless @res;
        return '{' . $pre . join( ",$pre", @res ) . $post . '}';
    }


    sub array_to_json {
        my ($self, $obj) = @_;
        my @res;

        encode_error("json text or perl structure exceeds maximum nesting level (max_depth set too low?)")
                                         if (++$depth > $max_depth);

        my ($pre, $post) = $indent ? $self->_up_indent() : ('', '');

        for my $v (@$obj){
            push @res, ref($v) ? $self->object_to_json($v) : $self->value_to_json($v);
        }

        --$depth;
        $self->_down_indent() if ($indent);

        return '[]' unless @res;
        return '[' . $pre . join( ",$pre", @res ) . $post . ']';
    }

    sub _looks_like_number {
        my $value = shift;
        if (USE_B) {
            my $b_obj = B::svref_2object(\$value);
            my $flags = $b_obj->FLAGS;
            return 1 if $flags & ( B::SVp_IOK() | B::SVp_NOK() ) and !( $flags & B::SVp_POK() );
            return;
        } else {
            no warnings 'numeric';
            # if the utf8 flag is on, it almost certainly started as a string
            return if utf8::is_utf8($value);
            # detect numbers
            # string & "" -> ""
            # number & "" -> 0 (with warning)
            # nan and inf can detect as numbers, so check with * 0
            return unless length((my $dummy = "") & $value);
            return unless 0 + $value eq $value;
            return 1 if $value * 0 == 0;
            return -1; # inf/nan
        }
    }

    sub value_to_json {
        my ($self, $value) = @_;

        return 'null' if(!defined $value);

        my $type = ref($value);

        if (!$type) {
            if (_looks_like_number($value)) {
                return $value;
            }
            return $self->string_to_json($value);
        }
        elsif( blessed($value) and  $value->isa('JSON::PP::Boolean') ){
            return $$value == 1 ? 'true' : 'false';
        }
        else {
            if ((overload::StrVal($value) =~ /=(\w+)/)[0]) {
                return $self->value_to_json("$value");
            }

            if ($type eq 'SCALAR' and defined $$value) {
                return   $$value eq '1' ? 'true'
                       : $$value eq '0' ? 'false'
                       : $self->{PROPS}->[ P_ALLOW_UNKNOWN ] ? 'null'
                       : encode_error("cannot encode reference to scalar");
            }

            if ( $self->{PROPS}->[ P_ALLOW_UNKNOWN ] ) {
                return 'null';
            }
            else {
                if ( $type eq 'SCALAR' or $type eq 'REF' ) {
                    encode_error("cannot encode reference to scalar");
                }
                else {
                    encode_error("encountered $value, but JSON can only represent references to arrays or hashes");
                }
            }

        }
    }


    my %esc = (
        "\n" => '\n',
        "\r" => '\r',
        "\t" => '\t',
        "\f" => '\f',
        "\b" => '\b',
        "\"" => '\"',
        "\\" => '\\\\',
        "\'" => '\\\'',
    );


    sub string_to_json {
        my ($self, $arg) = @_;

        $arg =~ s/([\x22\x5c\n\r\t\f\b])/$esc{$1}/g;
        $arg =~ s/\//\\\//g if ($escape_slash);
        $arg =~ s/([\x00-\x08\x0b\x0e-\x1f])/'\\u00' . unpack('H2', $1)/eg;

        if ($ascii) {
            $arg = JSON_PP_encode_ascii($arg);
        }

        if ($latin1) {
            $arg = JSON_PP_encode_latin1($arg);
        }

        if ($utf8) {
            utf8::encode($arg);
        }

        return '"' . $arg . '"';
    }


    sub blessed_to_json {
        my $reftype = reftype($_[1]) || '';
        if ($reftype eq 'HASH') {
            return $_[0]->hash_to_json($_[1]);
        }
        elsif ($reftype eq 'ARRAY') {
            return $_[0]->array_to_json($_[1]);
        }
        else {
            return 'null';
        }
    }


    sub encode_error {
        my $error  = shift;
        Carp::croak "$error";
    }


    sub _sort {
        defined $keysort ? (sort $keysort (keys %{$_[0]})) : keys %{$_[0]};
    }


    sub _up_indent {
        my $self  = shift;
        my $space = ' ' x $indent_length;

        my ($pre,$post) = ('','');

        $post = "\n" . $space x $indent_count;

        $indent_count++;

        $pre = "\n" . $space x $indent_count;

        return ($pre,$post);
    }


    sub _down_indent { $indent_count--; }


    sub PP_encode_box {
        {
            depth        => $depth,
            indent_count => $indent_count,
        };
    }

} # Convert


sub _encode_ascii {
    join('',
        map {
            $_ <= 127 ?
                chr($_) :
            $_ <= 65535 ?
                sprintf('\u%04x', $_) : sprintf('\u%x\u%x', _encode_surrogates($_));
        } unpack('U*', $_[0])
    );
}


sub _encode_latin1 {
    join('',
        map {
            $_ <= 255 ?
                chr($_) :
            $_ <= 65535 ?
                sprintf('\u%04x', $_) : sprintf('\u%x\u%x', _encode_surrogates($_));
        } unpack('U*', $_[0])
    );
}


sub _encode_surrogates { # from perlunicode
    my $uni = $_[0] - 0x10000;
    return ($uni / 0x400 + 0xD800, $uni % 0x400 + 0xDC00);
}


sub _is_bignum {
    $_[0]->isa('Math::BigInt') or $_[0]->isa('Math::BigFloat');
}



#
# JSON => Perl
#

my $max_intsize;

BEGIN {
    my $checkint = 1111;
    for my $d (5..64) {
        $checkint .= 1;
        my $int   = eval qq| $checkint |;
        if ($int =~ /[eE]/) {
            $max_intsize = $d - 1;
            last;
        }
    }
}

{ # PARSE 

    my %escapes = ( #  by Jeremy Muhlich <jmuhlich [at] bitflood.org>
        b    => "\x8",
        t    => "\x9",
        n    => "\xA",
        f    => "\xC",
        r    => "\xD",
        '\\' => '\\',
        '"'  => '"',
        '/'  => '/',
    );

    my $text; # json data
    my $at;   # offset
    my $ch;   # first character
    my $len;  # text length (changed according to UTF8 or NON UTF8)
    # INTERNAL
    my $depth;          # nest counter
    my $encoding;       # json text encoding
    my $is_valid_utf8;  # temp variable
    my $utf8_len;       # utf8 byte length
    # FLAGS
    my $utf8;           # must be utf8
    my $max_depth;      # max nest number of objects and arrays
    my $max_size;
    my $relaxed;
    my $cb_object;
    my $cb_sk_object;

    my $F_HOOK;

    my $allow_bignum;   # using Math::BigInt/BigFloat
    my $singlequote;    # loosely quoting
    my $loose;          # 
    my $allow_barekey;  # bareKey

    sub _detect_utf_encoding {
        my $text = shift;
        my @octets = unpack('C4', $text);
        return 'unknown' unless defined $octets[3];
        return ( $octets[0] and  $octets[1]) ? 'UTF-8'
             : (!$octets[0] and  $octets[1]) ? 'UTF-16BE'
             : (!$octets[0] and !$octets[1]) ? 'UTF-32BE'
             : ( $octets[2]                ) ? 'UTF-16LE'
             : (!$octets[2]                ) ? 'UTF-32LE'
             : 'unknown';
    }

    sub PP_decode_json {
        my ($self, $want_offset);

        ($self, $text, $want_offset) = @_;

        ($at, $ch, $depth) = (0, '', 0);

        if ( !defined $text or ref $text ) {
            decode_error("malformed JSON string, neither array, object, number, string or atom");
        }

        my $props = $self->{PROPS};

        ($utf8, $relaxed, $loose, $allow_bignum, $allow_barekey, $singlequote)
            = @{$props}[P_UTF8, P_RELAXED, P_LOOSE .. P_ALLOW_SINGLEQUOTE];

        if ( $utf8 ) {
            $encoding = _detect_utf_encoding($text);
            if ($encoding ne 'UTF-8' and $encoding ne 'unknown') {
                require Encode;
                Encode::from_to($text, $encoding, 'utf-8');
            } else {
                utf8::downgrade( $text, 1 ) or Carp::croak("Wide character in subroutine entry");
            }
        }
        else {
            utf8::upgrade( $text );
            utf8::encode( $text );
        }

        $len = length $text;

        ($max_depth, $max_size, $cb_object, $cb_sk_object, $F_HOOK)
             = @{$self}{qw/max_depth  max_size cb_object cb_sk_object F_HOOK/};

        if ($max_size > 1) {
            use bytes;
            my $bytes = length $text;
            decode_error(
                sprintf("attempted decode of JSON text of %s bytes size, but max_size is set to %s"
                    , $bytes, $max_size), 1
            ) if ($bytes > $max_size);
        }

        white(); # remove head white space

        decode_error("malformed JSON string, neither array, object, number, string or atom") unless defined $ch; # Is there a first character for JSON structure?

        my $result = value();

        if ( !$props->[ P_ALLOW_NONREF ] and !ref $result ) {
                decode_error(
                'JSON text must be an object or array (but found number, string, true, false or null,'
                       . ' use allow_nonref to allow this)', 1);
        }

        Carp::croak('something wrong.') if $len < $at; # we won't arrive here.

        my $consumed = defined $ch ? $at - 1 : $at; # consumed JSON text length

        white(); # remove tail white space

        return ( $result, $consumed ) if $want_offset; # all right if decode_prefix

        decode_error("garbage after JSON object") if defined $ch;

        $result;
    }


    sub next_chr {
        return $ch = undef if($at >= $len);
        $ch = substr($text, $at++, 1);
    }


    sub value {
        white();
        return          if(!defined $ch);
        return object() if($ch eq '{');
        return array()  if($ch eq '[');
        return string() if($ch eq '"' or ($singlequote and $ch eq "'"));
        return number() if($ch =~ /[0-9]/ or $ch eq '-');
        return word();
    }

    sub string {
        my $utf16;
        my $is_utf8;

        ($is_valid_utf8, $utf8_len) = ('', 0);

        my $s = ''; # basically UTF8 flag on

        if($ch eq '"' or ($singlequote and $ch eq "'")){
            my $boundChar = $ch;

            OUTER: while( defined(next_chr()) ){

                if($ch eq $boundChar){
                    next_chr();

                    if ($utf16) {
                        decode_error("missing low surrogate character in surrogate pair");
                    }

                    utf8::decode($s) if($is_utf8);

                    return $s;
                }
                elsif($ch eq '\\'){
                    next_chr();
                    if(exists $escapes{$ch}){
                        $s .= $escapes{$ch};
                    }
                    elsif($ch eq 'u'){ # UNICODE handling
                        my $u = '';

                        for(1..4){
                            $ch = next_chr();
                            last OUTER if($ch !~ /[0-9a-fA-F]/);
                            $u .= $ch;
                        }

                        # U+D800 - U+DBFF
                        if ($u =~ /^[dD][89abAB][0-9a-fA-F]{2}/) { # UTF-16 high surrogate?
                            $utf16 = $u;
                        }
                        # U+DC00 - U+DFFF
                        elsif ($u =~ /^[dD][c-fC-F][0-9a-fA-F]{2}/) { # UTF-16 low surrogate?
                            unless (defined $utf16) {
                                decode_error("missing high surrogate character in surrogate pair");
                            }
                            $is_utf8 = 1;
                            $s .= JSON_PP_decode_surrogates($utf16, $u) || next;
                            $utf16 = undef;
                        }
                        else {
                            if (defined $utf16) {
                                decode_error("surrogate pair expected");
                            }

                            if ( ( my $hex = hex( $u ) ) > 127 ) {
                                $is_utf8 = 1;
                                $s .= JSON_PP_decode_unicode($u) || next;
                            }
                            else {
                                $s .= chr $hex;
                            }
                        }

                    }
                    else{
                        unless ($loose) {
                            $at -= 2;
                            decode_error('illegal backslash escape sequence in string');
                        }
                        $s .= $ch;
                    }
                }
                else{

                    if ( ord $ch  > 127 ) {
                        unless( $ch = is_valid_utf8($ch) ) {
                            $at -= 1;
                            decode_error("malformed UTF-8 character in JSON string");
                        }
                        else {
                            $at += $utf8_len - 1;
                        }

                        $is_utf8 = 1;
                    }

                    if (!$loose) {
                        if ($ch =~ /[\x00-\x1f\x22\x5c]/)  { # '/' ok
                            $at--;
                            decode_error('invalid character encountered while parsing JSON string');
                        }
                    }

                    $s .= $ch;
                }
            }
        }

        decode_error("unexpected end of string while parsing JSON string");
    }


    sub white {
        while( defined $ch  ){
            if($ch eq '' or $ch =~ /\A[ \t\r\n]\z/){
                next_chr();
            }
            elsif($relaxed and $ch eq '/'){
                next_chr();
                if(defined $ch and $ch eq '/'){
                    1 while(defined(next_chr()) and $ch ne "\n" and $ch ne "\r");
                }
                elsif(defined $ch and $ch eq '*'){
                    next_chr();
                    while(1){
                        if(defined $ch){
                            if($ch eq '*'){
                                if(defined(next_chr()) and $ch eq '/'){
                                    next_chr();
                                    last;
                                }
                            }
                            else{
                                next_chr();
                            }
                        }
                        else{
                            decode_error("Unterminated comment");
                        }
                    }
                    next;
                }
                else{
                    $at--;
                    decode_error("malformed JSON string, neither array, object, number, string or atom");
                }
            }
            else{
                if ($relaxed and $ch eq '#') { # correctly?
                    pos($text) = $at;
                    $text =~ /\G([^\n]*(?:\r\n|\r|\n|$))/g;
                    $at = pos($text);
                    next_chr;
                    next;
                }

                last;
            }
        }
    }


    sub array {
        my $a  = $_[0] || []; # you can use this code to use another array ref object.

        decode_error('json text or perl structure exceeds maximum nesting level (max_depth set too low?)')
                                                    if (++$depth > $max_depth);

        next_chr();
        white();

        if(defined $ch and $ch eq ']'){
            --$depth;
            next_chr();
            return $a;
        }
        else {
            while(defined($ch)){
                push @$a, value();

                white();

                if (!defined $ch) {
                    last;
                }

                if($ch eq ']'){
                    --$depth;
                    next_chr();
                    return $a;
                }

                if($ch ne ','){
                    last;
                }

                next_chr();
                white();

                if ($relaxed and $ch eq ']') {
                    --$depth;
                    next_chr();
                    return $a;
                }

            }
        }

        $at-- if defined $ch and $ch ne '';
        decode_error(", or ] expected while parsing array");
    }


    sub object {
        my $o = $_[0] || {}; # you can use this code to use another hash ref object.
        my $k;

        decode_error('json text or perl structure exceeds maximum nesting level (max_depth set too low?)')
                                                if (++$depth > $max_depth);
        next_chr();
        white();

        if(defined $ch and $ch eq '}'){
            --$depth;
            next_chr();
            if ($F_HOOK) {
                return _json_object_hook($o);
            }
            return $o;
        }
        else {
            while (defined $ch) {
                $k = ($allow_barekey and $ch ne '"' and $ch ne "'") ? bareKey() : string();
                white();

                if(!defined $ch or $ch ne ':'){
                    $at--;
                    decode_error("':' expected");
                }

                next_chr();
                $o->{$k} = value();
                white();

                last if (!defined $ch);

                if($ch eq '}'){
                    --$depth;
                    next_chr();
                    if ($F_HOOK) {
                        return _json_object_hook($o);
                    }
                    return $o;
                }

                if($ch ne ','){
                    last;
                }

                next_chr();
                white();

                if ($relaxed and $ch eq '}') {
                    --$depth;
                    next_chr();
                    if ($F_HOOK) {
                        return _json_object_hook($o);
                    }
                    return $o;
                }

            }

        }

        $at-- if defined $ch and $ch ne '';
        decode_error(", or } expected while parsing object/hash");
    }


    sub bareKey { # doesn't strictly follow Standard ECMA-262 3rd Edition
        my $key;
        while($ch =~ /[^\x00-\x23\x25-\x2F\x3A-\x40\x5B-\x5E\x60\x7B-\x7F]/){
            $key .= $ch;
            next_chr();
        }
        return $key;
    }


    sub word {
        my $word =  substr($text,$at-1,4);

        if($word eq 'true'){
            $at += 3;
            next_chr;
            return $JSON::PP::true;
        }
        elsif($word eq 'null'){
            $at += 3;
            next_chr;
            return undef;
        }
        elsif($word eq 'fals'){
            $at += 3;
            if(substr($text,$at,1) eq 'e'){
                $at++;
                next_chr;
                return $JSON::PP::false;
            }
        }

        $at--; # for decode_error report

        decode_error("'null' expected")  if ($word =~ /^n/);
        decode_error("'true' expected")  if ($word =~ /^t/);
        decode_error("'false' expected") if ($word =~ /^f/);
        decode_error("malformed JSON string, neither array, object, number, string or atom");
    }


    sub number {
        my $n    = '';
        my $v;
        my $is_dec;
        my $is_exp;

        if($ch eq '-'){
            $n = '-';
            next_chr;
            if (!defined $ch or $ch !~ /\d/) {
                decode_error("malformed number (no digits after initial minus)");
            }
        }

        # According to RFC4627, hex or oct digits are invalid.
        if($ch eq '0'){
            my $peek = substr($text,$at,1);
            if($peek =~ /^[0-9a-dfA-DF]/){ # e may be valid (exponential)
                decode_error("malformed number (leading zero must not be followed by another digit)");
            }
            $n .= $ch;
            next_chr;
        }

        while(defined $ch and $ch =~ /\d/){
            $n .= $ch;
            next_chr;
        }

        if(defined $ch and $ch eq '.'){
            $n .= '.';
            $is_dec = 1;

            next_chr;
            if (!defined $ch or $ch !~ /\d/) {
                decode_error("malformed number (no digits after decimal point)");
            }
            else {
                $n .= $ch;
            }

            while(defined(next_chr) and $ch =~ /\d/){
                $n .= $ch;
            }
        }

        if(defined $ch and ($ch eq 'e' or $ch eq 'E')){
            $n .= $ch;
            $is_exp = 1;
            next_chr;

            if(defined($ch) and ($ch eq '+' or $ch eq '-')){
                $n .= $ch;
                next_chr;
                if (!defined $ch or $ch =~ /\D/) {
                    decode_error("malformed number (no digits after exp sign)");
                }
                $n .= $ch;
            }
            elsif(defined($ch) and $ch =~ /\d/){
                $n .= $ch;
            }
            else {
                decode_error("malformed number (no digits after exp sign)");
            }

            while(defined(next_chr) and $ch =~ /\d/){
                $n .= $ch;
            }

        }

        $v .= $n;

        if ($is_dec or $is_exp) {
            if ($allow_bignum) {
                require Math::BigFloat;
                return Math::BigFloat->new($v);
            }
        } else {
            if (length $v > $max_intsize) {
                if ($allow_bignum) { # from Adam Sussman
                    require Math::BigInt;
                    return Math::BigInt->new($v);
                }
                else {
                    return "$v";
                }
            }
        }

        return $is_dec ? $v/1.0 : 0+$v;
    }


    sub is_valid_utf8 {

        $utf8_len = $_[0] =~ /[\x00-\x7F]/  ? 1
                  : $_[0] =~ /[\xC2-\xDF]/  ? 2
                  : $_[0] =~ /[\xE0-\xEF]/  ? 3
                  : $_[0] =~ /[\xF0-\xF4]/  ? 4
                  : 0
                  ;

        return unless $utf8_len;

        my $is_valid_utf8 = substr($text, $at - 1, $utf8_len);

        return ( $is_valid_utf8 =~ /^(?:
             [\x00-\x7F]
            |[\xC2-\xDF][\x80-\xBF]
            |[\xE0][\xA0-\xBF][\x80-\xBF]
            |[\xE1-\xEC][\x80-\xBF][\x80-\xBF]
            |[\xED][\x80-\x9F][\x80-\xBF]
            |[\xEE-\xEF][\x80-\xBF][\x80-\xBF]
            |[\xF0][\x90-\xBF][\x80-\xBF][\x80-\xBF]
            |[\xF1-\xF3][\x80-\xBF][\x80-\xBF][\x80-\xBF]
            |[\xF4][\x80-\x8F][\x80-\xBF][\x80-\xBF]
        )$/x )  ? $is_valid_utf8 : '';
    }


    sub decode_error {
        my $error  = shift;
        my $no_rep = shift;
        my $str    = defined $text ? substr($text, $at) : '';
        my $mess   = '';
        my $type   = 'U*';

        if ( OLD_PERL ) {
            my $type   =  $] <  5.006           ? 'C*'
                        : utf8::is_utf8( $str ) ? 'U*' # 5.6
                        : 'C*'
                        ;
        }

        for my $c ( unpack( $type, $str ) ) { # emulate pv_uni_display() ?
            $mess .=  $c == 0x07 ? '\a'
                    : $c == 0x09 ? '\t'
                    : $c == 0x0a ? '\n'
                    : $c == 0x0d ? '\r'
                    : $c == 0x0c ? '\f'
                    : $c <  0x20 ? sprintf('\x{%x}', $c)
                    : $c == 0x5c ? '\\\\'
                    : $c <  0x80 ? chr($c)
                    : sprintf('\x{%x}', $c)
                    ;
            if ( length $mess >= 20 ) {
                $mess .= '...';
                last;
            }
        }

        unless ( length $mess ) {
            $mess = '(end of string)';
        }

        Carp::croak (
            $no_rep ? "$error" : "$error, at character offset $at (before \"$mess\")"
        );

    }


    sub _json_object_hook {
        my $o    = $_[0];
        my @ks = keys %{$o};

        if ( $cb_sk_object and @ks == 1 and exists $cb_sk_object->{ $ks[0] } and ref $cb_sk_object->{ $ks[0] } ) {
            my @val = $cb_sk_object->{ $ks[0] }->( $o->{$ks[0]} );
            if (@val == 1) {
                return $val[0];
            }
        }

        my @val = $cb_object->($o) if ($cb_object);
        if (@val == 0 or @val > 1) {
            return $o;
        }
        else {
            return $val[0];
        }
    }


    sub PP_decode_box {
        {
            text    => $text,
            at      => $at,
            ch      => $ch,
            len     => $len,
            depth   => $depth,
            encoding      => $encoding,
            is_valid_utf8 => $is_valid_utf8,
        };
    }

} # PARSE


sub _decode_surrogates { # from perlunicode
    my $uni = 0x10000 + (hex($_[0]) - 0xD800) * 0x400 + (hex($_[1]) - 0xDC00);
    my $un  = pack('U*', $uni);
    utf8::encode( $un );
    return $un;
}


sub _decode_unicode {
    my $un = pack('U', hex shift);
    utf8::encode( $un );
    return $un;
}

#
# Setup for various Perl versions (the code from JSON::PP58)
#

BEGIN {

    unless ( defined &utf8::is_utf8 ) {
       require Encode;
       *utf8::is_utf8 = *Encode::is_utf8;
    }

    if ( !OLD_PERL ) {
        *JSON::PP::JSON_PP_encode_ascii      = \&_encode_ascii;
        *JSON::PP::JSON_PP_encode_latin1     = \&_encode_latin1;
        *JSON::PP::JSON_PP_decode_surrogates = \&_decode_surrogates;
        *JSON::PP::JSON_PP_decode_unicode    = \&_decode_unicode;

        if ($] < 5.008003) { # join() in 5.8.0 - 5.8.2 is broken.
            package # hide from PAUSE
              JSON::PP;
            require subs;
            subs->import('join');
            eval q|
                sub join {
                    return '' if (@_ < 2);
                    my $j   = shift;
                    my $str = shift;
                    for (@_) { $str .= $j . $_; }
                    return $str;
                }
            |;
        }
    }


    sub JSON::PP::incr_parse {
        local $Carp::CarpLevel = 1;
        ( $_[0]->{_incr_parser} ||= JSON::PP::IncrParser->new )->incr_parse( @_ );
    }


    sub JSON::PP::incr_skip {
        ( $_[0]->{_incr_parser} ||= JSON::PP::IncrParser->new )->incr_skip;
    }


    sub JSON::PP::incr_reset {
        ( $_[0]->{_incr_parser} ||= JSON::PP::IncrParser->new )->incr_reset;
    }

    eval q{
        sub JSON::PP::incr_text : lvalue {
            $_[0]->{_incr_parser} ||= JSON::PP::IncrParser->new;

            if ( $_[0]->{_incr_parser}->{incr_pos} ) {
                Carp::croak("incr_text cannot be called when the incremental parser already started parsing");
            }
            $_[0]->{_incr_parser}->{incr_text};
        }
    } if ( $] >= 5.006 );

} # Setup for various Perl versions (the code from JSON::PP58)


###############################
# Utilities
#

BEGIN {
    eval 'require Scalar::Util';
    unless($@){
        *JSON::PP::blessed = \&Scalar::Util::blessed;
        *JSON::PP::reftype = \&Scalar::Util::reftype;
        *JSON::PP::refaddr = \&Scalar::Util::refaddr;
    }
    else{ # This code is from Scalar::Util.
        # warn $@;
        eval 'sub UNIVERSAL::a_sub_not_likely_to_be_here { ref($_[0]) }';
        *JSON::PP::blessed = sub {
            local($@, $SIG{__DIE__}, $SIG{__WARN__});
            ref($_[0]) ? eval { $_[0]->a_sub_not_likely_to_be_here } : undef;
        };
        require B;
        my %tmap = qw(
            B::NULL   SCALAR
            B::HV     HASH
            B::AV     ARRAY
            B::CV     CODE
            B::IO     IO
            B::GV     GLOB
            B::REGEXP REGEXP
        );
        *JSON::PP::reftype = sub {
            my $r = shift;

            return undef unless length(ref($r));

            my $t = ref(B::svref_2object($r));

            return
                exists $tmap{$t} ? $tmap{$t}
              : length(ref($$r)) ? 'REF'
              :                    'SCALAR';
        };
        *JSON::PP::refaddr = sub {
          return undef unless length(ref($_[0]));

          my $addr;
          if(defined(my $pkg = blessed($_[0]))) {
            $addr .= bless $_[0], 'Scalar::Util::Fake';
            bless $_[0], $pkg;
          }
          else {
            $addr .= $_[0]
          }

          $addr =~ /0x(\w+)/;
          local $^W;
          #no warnings 'portable';
          hex($1);
        }
    }
}


# shamelessly copied and modified from JSON::XS code.

$JSON::PP::true  = do { bless \(my $dummy = 1), "JSON::PP::Boolean" };
$JSON::PP::false = do { bless \(my $dummy = 0), "JSON::PP::Boolean" };

sub is_bool { blessed $_[0] and $_[0]->isa("JSON::PP::Boolean"); }

sub true  { $JSON::PP::true  }
sub false { $JSON::PP::false }
sub null  { undef; }

###############################

package # hide from PAUSE
  JSON::PP::IncrParser;

use strict;

use constant INCR_M_WS   => 0; # initial whitespace skipping
use constant INCR_M_STR  => 1; # inside string
use constant INCR_M_BS   => 2; # inside backslash
use constant INCR_M_JSON => 3; # outside anything, count nesting
use constant INCR_M_C0   => 4;
use constant INCR_M_C1   => 5;

$JSON::backportPP::IncrParser::VERSION = '1.01';

sub new {
    my ( $class ) = @_;

    bless {
        incr_nest    => 0,
        incr_text    => undef,
        incr_pos     => 0,
        incr_mode    => 0,
    }, $class;
}


sub incr_parse {
    my ( $self, $coder, $text ) = @_;

    $self->{incr_text} = '' unless ( defined $self->{incr_text} );

    if ( defined $text ) {
        if ( utf8::is_utf8( $text ) and !utf8::is_utf8( $self->{incr_text} ) ) {
            utf8::upgrade( $self->{incr_text} ) ;
            utf8::decode( $self->{incr_text} ) ;
        }
        $self->{incr_text} .= $text;
    }

    if ( defined wantarray ) {
        my $max_size = $coder->get_max_size;
        my $p = $self->{incr_pos};
        my @ret;
        {
            do {
                unless ( $self->{incr_nest} <= 0 and $self->{incr_mode} == INCR_M_JSON ) {
                    $self->_incr_parse( $coder );

                    if ( $max_size and $self->{incr_pos} > $max_size ) {
                        Carp::croak("attempted decode of JSON text of $self->{incr_pos} bytes size, but max_size is set to $max_size");
                    }
                    unless ( $self->{incr_nest} <= 0 and $self->{incr_mode} == INCR_M_JSON ) {
                        # as an optimisation, do not accumulate white space in the incr buffer
                        if ( $self->{incr_mode} == INCR_M_WS and $self->{incr_pos} ) {
                            $self->{incr_pos} = 0;
                            $self->{incr_text} = '';
                        }
                        last;
                    }
                }

                my ($obj, $offset) = $coder->PP_decode_json( $self->{incr_text}, 0x00000001 );
                push @ret, $obj;
                use bytes;
                $self->{incr_text} = substr( $self->{incr_text}, $offset || 0 );
                $self->{incr_pos} = 0;
                $self->{incr_nest} = 0;
                $self->{incr_mode} = 0;
                last unless wantarray;
            } while ( wantarray );
        }

        if ( wantarray ) {
            return @ret;
        }
        else { # in scalar context
            return $ret[0] ? $ret[0] : undef;
        }
    }
}


sub _incr_parse {
    my ($self, $coder) = @_;
    my $text = $self->{incr_text};
    my $len = length $text;
    my $p = $self->{incr_pos};

INCR_PARSE:
    while ( $len > $p ) {
        my $s = substr( $text, $p, 1 );
        last INCR_PARSE unless defined $s;
        my $mode = $self->{incr_mode};

        if ( $mode == INCR_M_WS ) {
            while ( $len > $p ) {
                $s = substr( $text, $p, 1 );
                last INCR_PARSE unless defined $s;
                if ( ord($s) > 0x20 ) {
                    if ( $s eq '#' ) {
                        $self->{incr_mode} = INCR_M_C0;
                        redo INCR_PARSE;
                    } else {
                        $self->{incr_mode} = INCR_M_JSON;
                        redo INCR_PARSE;
                    }
                }
                $p++;
            }
        } elsif ( $mode == INCR_M_BS ) {
            $p++;
            $self->{incr_mode} = INCR_M_STR;
            redo INCR_PARSE;
        } elsif ( $mode == INCR_M_C0 or $mode == INCR_M_C1 ) {
            while ( $len > $p ) {
                $s = substr( $text, $p, 1 );
                last INCR_PARSE unless defined $s;
                if ( $s eq "\n" ) {
                    $self->{incr_mode} = $self->{incr_mode} == INCR_M_C0 ? INCR_M_WS : INCR_M_JSON;
                    last;
                }
                $p++;
            }
            next;
        } elsif ( $mode == INCR_M_STR ) {
            while ( $len > $p ) {
                $s = substr( $text, $p, 1 );
                last INCR_PARSE unless defined $s;
                if ( $s eq '"' ) {
                    $p++;
                    $self->{incr_mode} = INCR_M_JSON;

                    last INCR_PARSE unless $self->{incr_nest};
                    redo INCR_PARSE;
                }
                elsif ( $s eq '\\' ) {
                    $p++;
                    if ( !defined substr($text, $p, 1) ) {
                        $self->{incr_mode} = INCR_M_BS;
                        last INCR_PARSE;
                    }
                }
                $p++;
            }
        } elsif ( $mode == INCR_M_JSON ) {
            while ( $len > $p ) {
                $s = substr( $text, $p++, 1 );
                if ( $s eq "\x00" ) {
                    $p--;
                    last INCR_PARSE;
                } elsif ( $s eq "\x09" or $s eq "\x0a" or $s eq "\x0d" or $s eq "\x20" ) {
                    if ( !$self->{incr_nest} ) {
                        $p--; # do not eat the whitespace, let the next round do it
                        last INCR_PARSE;
                    }
                    next;
                } elsif ( $s eq '"' ) {
                    $self->{incr_mode} = INCR_M_STR;
                    redo INCR_PARSE;
                } elsif ( $s eq '[' or $s eq '{' ) {
                    if ( ++$self->{incr_nest} > $coder->get_max_depth ) {
                        Carp::croak('json text or perl structure exceeds maximum nesting level (max_depth set too low?)');
                    }
                    next;
                } elsif ( $s eq ']' or $s eq '}' ) {
                    if ( --$self->{incr_nest} <= 0 ) {
                        last INCR_PARSE;
                    }
                } elsif ( $s eq '#' ) {
                    $self->{incr_mode} = INCR_M_C1;
                    redo INCR_PARSE;
                }
            }
        }
    }

    $self->{incr_pos} = $p;
    $self->{incr_parsing} = $p ? 1 : 0; # for backward compatibility
}


sub incr_text {
    if ( $_[0]->{incr_pos} ) {
        Carp::croak("incr_text cannot be called when the incremental parser already started parsing");
    }
    $_[0]->{incr_text};
}


sub incr_skip {
    my $self  = shift;
    $self->{incr_text} = substr( $self->{incr_text}, $self->{incr_pos} );
    $self->{incr_pos}     = 0;
    $self->{incr_mode}    = 0;
    $self->{incr_nest}    = 0;
}


sub incr_reset {
    my $self = shift;
    $self->{incr_text}    = undef;
    $self->{incr_pos}     = 0;
    $self->{incr_mode}    = 0;
    $self->{incr_nest}    = 0;
}

###############################


1;
__END__
=pod

=head1 NAME

JSON::PP - JSON::XS compatible pure-Perl module.

=head1 SYNOPSIS

 use JSON::PP;

 # exported functions, they croak on error
 # and expect/generate UTF-8

 $utf8_encoded_json_text = encode_json $perl_hash_or_arrayref;
 $perl_hash_or_arrayref  = decode_json $utf8_encoded_json_text;

 # OO-interface

 $json = JSON::PP->new->ascii->pretty->allow_nonref;
 
 $pretty_printed_json_text = $json->encode( $perl_scalar );
 $perl_scalar = $json->decode( $json_text );
 
 # Note that JSON version 2.0 and above will automatically use
 # JSON::XS or JSON::PP, so you should be able to just:
 
 use JSON;


=head1 VERSION

    2.97001

=head1 DESCRIPTION

JSON::PP is a pure perl JSON decoder/encoder (as of RFC4627, which
we know is obsolete but we still stick to; see below for an option
to support part of RFC7159), and (almost) compatible to much
faster L<JSON::XS> written by Marc Lehmann in C. JSON::PP works as
a fallback module when you use L<JSON> module without having
installed JSON::XS.

Because of this fallback feature of JSON.pm, JSON::PP tries not to
be more JavaScript-friendly than JSON::XS (i.e. not to escape extra
characters such as U+2028 and U+2029 nor support RFC7159/ECMA-404),
in order for you not to lose such JavaScript-friendliness silently
when you use JSON.pm and install JSON::XS for speed or by accident.
If you need JavaScript-friendly RFC7159-compliant pure perl module,
try L<JSON::Tiny>, which is derived from L<Mojolicious> web
framework and is also smaller and faster than JSON::PP.

JSON::PP has been in the Perl core since Perl 5.14, mainly for
CPAN toolchain modules to parse META.json.

=head1 FUNCTIONAL INTERFACE

This section is taken from JSON::XS almost verbatim. C<encode_json>
and C<decode_json> are exported by default.

=head2 encode_json

    $json_text = encode_json $perl_scalar

Converts the given Perl data structure to a UTF-8 encoded, binary string
(that is, the string contains octets only). Croaks on error.

This function call is functionally identical to:

    $json_text = JSON::PP->new->utf8->encode($perl_scalar)

Except being faster.

=head2 decode_json

    $perl_scalar = decode_json $json_text

The opposite of C<encode_json>: expects an UTF-8 (binary) string and tries
to parse that as an UTF-8 encoded JSON text, returning the resulting
reference. Croaks on error.

This function call is functionally identical to:

    $perl_scalar = JSON::PP->new->utf8->decode($json_text)

Except being faster.

=head2 JSON::PP::is_bool

    $is_boolean = JSON::PP::is_bool($scalar)

Returns true if the passed scalar represents either JSON::PP::true or
JSON::PP::false, two constants that act like C<1> and C<0> respectively
and are also used to represent JSON C<true> and C<false> in Perl strings.

See L<MAPPING>, below, for more information on how JSON values are mapped to
Perl.

=head1 OBJECT-ORIENTED INTERFACE

This section is also taken from JSON::XS.

The object oriented interface lets you configure your own encoding or
decoding style, within the limits of supported formats.

=head2 new

    $json = JSON::PP->new

Creates a new JSON::PP object that can be used to de/encode JSON
strings. All boolean flags described below are by default I<disabled>.

The mutators for flags all return the JSON::PP object again and thus calls can
be chained:

   my $json = JSON::PP->new->utf8->space_after->encode({a => [1,2]})
   => {"a": [1, 2]}

=head2 ascii

    $json = $json->ascii([$enable])
    
    $enabled = $json->get_ascii

If C<$enable> is true (or missing), then the C<encode> method will not
generate characters outside the code range C<0..127> (which is ASCII). Any
Unicode characters outside that range will be escaped using either a
single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
as per RFC4627. The resulting encoded JSON text can be treated as a native
Unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
or any other superset of ASCII.

If C<$enable> is false, then the C<encode> method will not escape Unicode
characters unless required by the JSON syntax or other flags. This results
in a faster and more compact format.

See also the section I<ENCODING/CODESET FLAG NOTES> later in this document.

The main use for this flag is to produce JSON texts that can be
transmitted over a 7-bit channel, as the encoded JSON texts will not
contain any 8 bit characters.

  JSON::PP->new->ascii(1)->encode([chr 0x10401])
  => ["\ud801\udc01"]

=head2 latin1

    $json = $json->latin1([$enable])
    
    $enabled = $json->get_latin1

If C<$enable> is true (or missing), then the C<encode> method will encode
the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
outside the code range C<0..255>. The resulting string can be treated as a
latin1-encoded JSON text or a native Unicode string. The C<decode> method
will not be affected in any way by this flag, as C<decode> by default
expects Unicode, which is a strict superset of latin1.

If C<$enable> is false, then the C<encode> method will not escape Unicode
characters unless required by the JSON syntax or other flags.

See also the section I<ENCODING/CODESET FLAG NOTES> later in this document.

The main use for this flag is efficiently encoding binary data as JSON
text, as most octets will not be escaped, resulting in a smaller encoded
size. The disadvantage is that the resulting JSON text is encoded
in latin1 (and must correctly be treated as such when storing and
transferring), a rare encoding for JSON. It is therefore most useful when
you want to store data structures known to contain binary data efficiently
in files or databases, not when talking to other JSON encoders/decoders.

  JSON::PP->new->latin1->encode (["\x{89}\x{abc}"]
  => ["\x{89}\\u0abc"]    # (perl syntax, U+abc escaped, U+89 not)

=head2 utf8

    $json = $json->utf8([$enable])
    
    $enabled = $json->get_utf8

If C<$enable> is true (or missing), then the C<encode> method will encode
the JSON result into UTF-8, as required by many protocols, while the
C<decode> method expects to be handled an UTF-8-encoded string.  Please
note that UTF-8-encoded strings do not contain any characters outside the
range C<0..255>, they are thus useful for bytewise/binary I/O. In future
versions, enabling this option might enable autodetection of the UTF-16
and UTF-32 encoding families, as described in RFC4627.

If C<$enable> is false, then the C<encode> method will return the JSON
string as a (non-encoded) Unicode string, while C<decode> expects thus a
Unicode string.  Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs
to be done yourself, e.g. using the Encode module.

See also the section I<ENCODING/CODESET FLAG NOTES> later in this document.

Example, output UTF-16BE-encoded JSON:

  use Encode;
  $jsontext = encode "UTF-16BE", JSON::PP->new->encode ($object);

Example, decode UTF-32LE-encoded JSON:

  use Encode;
  $object = JSON::PP->new->decode (decode "UTF-32LE", $jsontext);

=head2 pretty

    $json = $json->pretty([$enable])

This enables (or disables) all of the C<indent>, C<space_before> and
C<space_after> (and in the future possibly more) flags in one call to
generate the most readable (or most compact) form possible.

=head2 indent

    $json = $json->indent([$enable])
    
    $enabled = $json->get_indent

If C<$enable> is true (or missing), then the C<encode> method will use a multiline
format as output, putting every array member or object/hash key-value pair
into its own line, indenting them properly.

If C<$enable> is false, no newlines or indenting will be produced, and the
resulting JSON text is guaranteed not to contain any C<newlines>.

This setting has no effect when decoding JSON texts.

The default indent space length is three.
You can use C<indent_length> to change the length.

=head2 space_before

    $json = $json->space_before([$enable])
    
    $enabled = $json->get_space_before

If C<$enable> is true (or missing), then the C<encode> method will add an extra
optional space before the C<:> separating keys from values in JSON objects.

If C<$enable> is false, then the C<encode> method will not add any extra
space at those places.

This setting has no effect when decoding JSON texts. You will also
most likely combine this setting with C<space_after>.

Example, space_before enabled, space_after and indent disabled:

   {"key" :"value"}

=head2 space_after

    $json = $json->space_after([$enable])
    
    $enabled = $json->get_space_after

If C<$enable> is true (or missing), then the C<encode> method will add an extra
optional space after the C<:> separating keys from values in JSON objects
and extra whitespace after the C<,> separating key-value pairs and array
members.

If C<$enable> is false, then the C<encode> method will not add any extra
space at those places.

This setting has no effect when decoding JSON texts.

Example, space_before and indent disabled, space_after enabled:

   {"key": "value"}

=head2 relaxed

    $json = $json->relaxed([$enable])
    
    $enabled = $json->get_relaxed

If C<$enable> is true (or missing), then C<decode> will accept some
extensions to normal JSON syntax (see below). C<encode> will not be
affected in anyway. I<Be aware that this option makes you accept invalid
JSON texts as if they were valid!>. I suggest only to use this option to
parse application-specific files written by humans (configuration files,
resource files etc.)

If C<$enable> is false (the default), then C<decode> will only accept
valid JSON texts.

Currently accepted extensions are:

=over 4

=item * list items can have an end-comma

JSON I<separates> array elements and key-value pairs with commas. This
can be annoying if you write JSON texts manually and want to be able to
quickly append elements, so this extension accepts comma at the end of
such items not just between them:

   [
      1,
      2, <- this comma not normally allowed
   ]
   {
      "k1": "v1",
      "k2": "v2", <- this comma not normally allowed
   }

=item * shell-style '#'-comments

Whenever JSON allows whitespace, shell-style comments are additionally
allowed. They are terminated by the first carriage-return or line-feed
character, after which more white-space and comments are allowed.

  [
     1, # this comment not allowed in JSON
        # neither this one...
  ]

=item * C-style multiple-line '/* */'-comments (JSON::PP only)

Whenever JSON allows whitespace, C-style multiple-line comments are additionally
allowed. Everything between C</*> and C<*/> is a comment, after which
more white-space and comments are allowed.

  [
     1, /* this comment not allowed in JSON */
        /* neither this one... */
  ]

=item * C++-style one-line '//'-comments (JSON::PP only)

Whenever JSON allows whitespace, C++-style one-line comments are additionally
allowed. They are terminated by the first carriage-return or line-feed
character, after which more white-space and comments are allowed.

  [
     1, // this comment not allowed in JSON
        // neither this one...
  ]

=back

=head2 canonical

    $json = $json->canonical([$enable])
    
    $enabled = $json->get_canonical

If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
by sorting their keys. This is adding a comparatively high overhead.

If C<$enable> is false, then the C<encode> method will output key-value
pairs in the order Perl stores them (which will likely change between runs
of the same script, and can change even within the same run from 5.18
onwards).

This option is useful if you want the same data structure to be encoded as
the same JSON text (given the same overall settings). If it is disabled,
the same hash might be encoded differently even if contains the same data,
as key-value pairs have no inherent ordering in Perl.

This setting has no effect when decoding JSON texts.

This setting has currently no effect on tied hashes.

=head2 allow_nonref

    $json = $json->allow_nonref([$enable])
    
    $enabled = $json->get_allow_nonref

If C<$enable> is true (or missing), then the C<encode> method can convert a
non-reference into its corresponding string, number or null JSON value,
which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
values instead of croaking.

If C<$enable> is false, then the C<encode> method will croak if it isn't
passed an arrayref or hashref, as JSON texts must either be an object
or array. Likewise, C<decode> will croak if given something that is not a
JSON object or array.

Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,
resulting in an invalid JSON text:

   JSON::PP->new->allow_nonref->encode ("Hello, World!")
   => "Hello, World!"

=head2 allow_unknown

    $json = $json->allow_unknown ([$enable])
    
    $enabled = $json->get_allow_unknown

If C<$enable> is true (or missing), then C<encode> will I<not> throw an
exception when it encounters values it cannot represent in JSON (for
example, filehandles) but instead will encode a JSON C<null> value. Note
that blessed objects are not included here and are handled separately by
c<allow_blessed>.

If C<$enable> is false (the default), then C<encode> will throw an
exception when it encounters anything it cannot encode as JSON.

This option does not affect C<decode> in any way, and it is recommended to
leave it off unless you know your communications partner.

=head2 allow_blessed

    $json = $json->allow_blessed([$enable])
    
    $enabled = $json->get_allow_blessed

See L<OBJECT SERIALISATION> for details.

If C<$enable> is true (or missing), then the C<encode> method will not
barf when it encounters a blessed reference that it cannot convert
otherwise. Instead, a JSON C<null> value is encoded instead of the object.

If C<$enable> is false (the default), then C<encode> will throw an
exception when it encounters a blessed object that it cannot convert
otherwise.

This setting has no effect on C<decode>.

=head2 convert_blessed

    $json = $json->convert_blessed([$enable])
    
    $enabled = $json->get_convert_blessed

See L<OBJECT SERIALISATION> for details.

If C<$enable> is true (or missing), then C<encode>, upon encountering a
blessed object, will check for the availability of the C<TO_JSON> method
on the object's class. If found, it will be called in scalar context and
the resulting scalar will be encoded instead of the object.

The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
returns other blessed objects, those will be handled in the same
way. C<TO_JSON> must take care of not causing an endless recursion cycle
(== crash) in this case. The name of C<TO_JSON> was chosen because other
methods called by the Perl core (== not by the user of the object) are
usually in upper case letters and to avoid collisions with any C<to_json>
function or method.

If C<$enable> is false (the default), then C<encode> will not consider
this type of conversion.

This setting has no effect on C<decode>.

=head2 filter_json_object

    $json = $json->filter_json_object([$coderef])

When C<$coderef> is specified, it will be called from C<decode> each
time it decodes a JSON object. The only argument is a reference to the
newly-created hash. If the code references returns a single scalar (which
need not be a reference), this value (i.e. a copy of that scalar to avoid
aliasing) is inserted into the deserialised data structure. If it returns
an empty list (NOTE: I<not> C<undef>, which is a valid scalar), the
original deserialised hash will be inserted. This setting can slow down
decoding considerably.

When C<$coderef> is omitted or undefined, any existing callback will
be removed and C<decode> will not change the deserialised hash in any
way.

Example, convert all JSON objects into the integer 5:

   my $js = JSON::PP->new->filter_json_object (sub { 5 });
   # returns [5]
   $js->decode ('[{}]'); # the given subroutine takes a hash reference.
   # throw an exception because allow_nonref is not enabled
   # so a lone 5 is not allowed.
   $js->decode ('{"a":1, "b":2}');

=head2 filter_json_single_key_object

    $json = $json->filter_json_single_key_object($key [=> $coderef])

Works remotely similar to C<filter_json_object>, but is only called for
JSON objects having a single key named C<$key>.

This C<$coderef> is called before the one specified via
C<filter_json_object>, if any. It gets passed the single value in the JSON
object. If it returns a single value, it will be inserted into the data
structure. If it returns nothing (not even C<undef> but the empty list),
the callback from C<filter_json_object> will be called next, as if no
single-key callback were specified.

If C<$coderef> is omitted or undefined, the corresponding callback will be
disabled. There can only ever be one callback for a given key.

As this callback gets called less often then the C<filter_json_object>
one, decoding speed will not usually suffer as much. Therefore, single-key
objects make excellent targets to serialise Perl objects into, especially
as single-key JSON objects are as close to the type-tagged value concept
as JSON gets (it's basically an ID/VALUE tuple). Of course, JSON does not
support this in any way, so you need to make sure your data never looks
like a serialised Perl hash.

Typical names for the single object key are C<__class_whatever__>, or
C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even
things like C<__class_md5sum(classname)__>, to reduce the risk of clashing
with real hashes.

Example, decode JSON objects of the form C<< { "__widget__" => <id> } >>
into the corresponding C<< $WIDGET{<id>} >> object:

   # return whatever is in $WIDGET{5}:
   JSON::PP
      ->new
      ->filter_json_single_key_object (__widget__ => sub {
            $WIDGET{ $_[0] }
         })
      ->decode ('{"__widget__": 5')

   # this can be used with a TO_JSON method in some "widget" class
   # for serialisation to json:
   sub WidgetBase::TO_JSON {
      my ($self) = @_;

      unless ($self->{id}) {
         $self->{id} = ..get..some..id..;
         $WIDGET{$self->{id}} = $self;
      }

      { __widget__ => $self->{id} }
   }

=head2 shrink

    $json = $json->shrink([$enable])
    
    $enabled = $json->get_shrink

If C<$enable> is true (or missing), the string returned by C<encode> will
be shrunk (i.e. downgraded if possible).

The actual definition of what shrink does might change in future versions,
but it will always try to save space at the expense of time.

If C<$enable> is false, then JSON::PP does nothing.

=head2 max_depth

    $json = $json->max_depth([$maximum_nesting_depth])
    
    $max_depth = $json->get_max_depth

Sets the maximum nesting level (default C<512>) accepted while encoding
or decoding. If a higher nesting level is detected in JSON text or a Perl
data structure, then the encoder and decoder will stop and croak at that
point.

Nesting level is defined by number of hash- or arrayrefs that the encoder
needs to traverse to reach a given point or the number of C<{> or C<[>
characters without their matching closing parenthesis crossed to reach a
given character in a string.

Setting the maximum depth to one disallows any nesting, so that ensures
that the object is only a single hash/object or array.

If no argument is given, the highest possible setting will be used, which
is rarely useful.

See L<JSON::XS/SECURITY CONSIDERATIONS> for more info on why this is useful.

=head2 max_size

    $json = $json->max_size([$maximum_string_size])
    
    $max_size = $json->get_max_size

Set the maximum length a JSON text may have (in bytes) where decoding is
being attempted. The default is C<0>, meaning no limit. When C<decode>
is called on a string that is longer then this many bytes, it will not
attempt to decode the string but throw an exception. This setting has no
effect on C<encode> (yet).

If no argument is given, the limit check will be deactivated (same as when
C<0> is specified).

See L<JSON::XS/SECURITY CONSIDERATIONS> for more info on why this is useful.

=head2 encode

    $json_text = $json->encode($perl_scalar)

Converts the given Perl value or data structure to its JSON
representation. Croaks on error.

=head2 decode

    $perl_scalar = $json->decode($json_text)

The opposite of C<encode>: expects a JSON text and tries to parse it,
returning the resulting simple scalar or reference. Croaks on error.

=head2 decode_prefix

    ($perl_scalar, $characters) = $json->decode_prefix($json_text)

This works like the C<decode> method, but instead of raising an exception
when there is trailing garbage after the first JSON object, it will
silently stop parsing there and return the number of characters consumed
so far.

This is useful if your JSON texts are not delimited by an outer protocol
and you need to know where the JSON text ends.

   JSON::PP->new->decode_prefix ("[1] the tail")
   => ([1], 3)

=head1 FLAGS FOR JSON::PP ONLY

The following flags and properties are for JSON::PP only. If you use
any of these, you can't make your application run faster by replacing
JSON::PP with JSON::XS. If you need these and also speed boost,
try L<Cpanel::JSON::XS>, a fork of JSON::XS by Reini Urban, which
supports some of these.

=head2 allow_singlequote

    $json = $json->allow_singlequote([$enable])
    $enabled = $json->get_allow_singlequote

If C<$enable> is true (or missing), then C<decode> will accept
invalid JSON texts that contain strings that begin and end with
single quotation marks. C<encode> will not be affected in anyway.
I<Be aware that this option makes you accept invalid JSON texts
as if they were valid!>. I suggest only to use this option to
parse application-specific files written by humans (configuration
files, resource files etc.)

If C<$enable> is false (the default), then C<decode> will only accept
valid JSON texts.

    $json->allow_singlequote->decode(qq|{"foo":'bar'}|);
    $json->allow_singlequote->decode(qq|{'foo':"bar"}|);
    $json->allow_singlequote->decode(qq|{'foo':'bar'}|);

=head2 allow_barekey

    $json = $json->allow_barekey([$enable])
    $enabled = $json->get_allow_barekey

If C<$enable> is true (or missing), then C<decode> will accept
invalid JSON texts that contain JSON objects whose names don't
begin and end with quotation marks. C<encode> will not be affected
in anyway. I<Be aware that this option makes you accept invalid JSON
texts as if they were valid!>. I suggest only to use this option to
parse application-specific files written by humans (configuration
files, resource files etc.)

If C<$enable> is false (the default), then C<decode> will only accept
valid JSON texts.

    $json->allow_barekey->decode(qq|{foo:"bar"}|);

=head2 allow_bignum

    $json = $json->allow_bignum([$enable])
    $enabled = $json->get_allow_bignum

If C<$enable> is true (or missing), then C<decode> will convert
big integers Perl cannot handle as integer into L<Math::BigInt>
objects and convert floating numbers into L<Math::BigFloat>
objects. C<encode> will convert C<Math::BigInt> and C<Math::BigFloat>
objects into JSON numbers.

   $json->allow_nonref->allow_bignum;
   $bigfloat = $json->decode('2.000000000000000000000000001');
   print $json->encode($bigfloat);
   # => 2.000000000000000000000000001

See also L<MAPPING>.

=head2 loose

    $json = $json->loose([$enable])
    $enabled = $json->get_loose

If C<$enable> is true (or missing), then C<decode> will accept
invalid JSON texts that contain unescaped [\x00-\x1f\x22\x5c]
characters. C<encode> will not be affected in anyway.
I<Be aware that this option makes you accept invalid JSON texts
as if they were valid!>. I suggest only to use this option to
parse application-specific files written by humans (configuration
files, resource files etc.)

If C<$enable> is false (the default), then C<decode> will only accept
valid JSON texts.

    $json->loose->decode(qq|["abc
                                   def"]|);

=head2 escape_slash

    $json = $json->escape_slash([$enable])
    $enabled = $json->get_escape_slash

If C<$enable> is true (or missing), then C<encode> will explicitly
escape I<slash> (solidus; C<U+002F>) characters to reduce the risk of
XSS (cross site scripting) that may be caused by C<< </script> >>
in a JSON text, with the cost of bloating the size of JSON texts.

This option may be useful when you embed JSON in HTML, but embedding
arbitrary JSON in HTML (by some HTML template toolkit or by string
interpolation) is risky in general. You must escape necessary
characters in correct order, depending on the context.

C<decode> will not be affected in anyway.

=head2 indent_length

    $json = $json->indent_length($number_of_spaces)
    $length = $json->get_indent_length

This option is only useful when you also enable C<indent> or C<pretty>.

JSON::XS indents with three spaces when you C<encode> (if requested
by C<indent> or C<pretty>), and the number cannot be changed.
JSON::PP allows you to change/get the number of indent spaces with these
mutator/accessor. The default number of spaces is three (the same as
JSON::XS), and the acceptable range is from C<0> (no indentation;
it'd be better to disable indentation by C<indent(0)>) to C<15>.

=head2 sort_by

    $json = $json->sort_by($code_ref)
    $json = $json->sort_by($subroutine_name)

If you just want to sort keys (names) in JSON objects when you
C<encode>, enable C<canonical> option (see above) that allows you to
sort object keys alphabetically.

If you do need to sort non-alphabetically for whatever reasons,
you can give a code reference (or a subroutine name) to C<sort_by>,
then the argument will be passed to Perl's C<sort> built-in function.

As the sorting is done in the JSON::PP scope, you usually need to
prepend C<JSON::PP::> to the subroutine name, and the special variables
C<$a> and C<$b> used in the subrontine used by C<sort> function.

Example:

   my %ORDER = (id => 1, class => 2, name => 3);
   $json->sort_by(sub {
       ($ORDER{$JSON::PP::a} // 999) <=> ($ORDER{$JSON::PP::b} // 999)
       or $JSON::PP::a cmp $JSON::PP::b
   });
   print $json->encode([
       {name => 'CPAN', id => 1, href => 'http://cpan.org'}
   ]);
   # [{"id":1,"name":"CPAN","href":"http://cpan.org"}]

Note that C<sort_by> affects all the plain hashes in the data structure.
If you need finer control, C<tie> necessary hashes with a module that
implements ordered hash (such as L<Hash::Ordered> and L<Tie::IxHash>).
C<canonical> and C<sort_by> don't affect the key order in C<tie>d
hashes.

   use Hash::Ordered;
   tie my %hash, 'Hash::Ordered',
       (name => 'CPAN', id => 1, href => 'http://cpan.org');
   print $json->encode([\%hash]);
   # [{"name":"CPAN","id":1,"href":"http://cpan.org"}] # order is kept

=head1 INCREMENTAL PARSING

This section is also taken from JSON::XS.

In some cases, there is the need for incremental parsing of JSON
texts. While this module always has to keep both JSON text and resulting
Perl data structure in memory at one time, it does allow you to parse a
JSON stream incrementally. It does so by accumulating text until it has
a full JSON object, which it then can decode. This process is similar to
using C<decode_prefix> to see if a full JSON object is available, but
is much more efficient (and can be implemented with a minimum of method
calls).

JSON::PP will only attempt to parse the JSON text once it is sure it
has enough text to get a decisive result, using a very simple but
truly incremental parser. This means that it sometimes won't stop as
early as the full parser, for example, it doesn't detect mismatched
parentheses. The only thing it guarantees is that it starts decoding as
soon as a syntactically valid JSON text has been seen. This means you need
to set resource limits (e.g. C<max_size>) to ensure the parser will stop
parsing in the presence if syntax errors.

The following methods implement this incremental parser.

=head2 incr_parse

    $json->incr_parse( [$string] ) # void context
    
    $obj_or_undef = $json->incr_parse( [$string] ) # scalar context
    
    @obj_or_empty = $json->incr_parse( [$string] ) # list context

This is the central parsing function. It can both append new text and
extract objects from the stream accumulated so far (both of these
functions are optional).

If C<$string> is given, then this string is appended to the already
existing JSON fragment stored in the C<$json> object.

After that, if the function is called in void context, it will simply
return without doing anything further. This can be used to add more text
in as many chunks as you want.

If the method is called in scalar context, then it will try to extract
exactly I<one> JSON object. If that is successful, it will return this
object, otherwise it will return C<undef>. If there is a parse error,
this method will croak just as C<decode> would do (one can then use
C<incr_skip> to skip the erroneous part). This is the most common way of
using the method.

And finally, in list context, it will try to extract as many objects
from the stream as it can find and return them, or the empty list
otherwise. For this to work, there must be no separators (other than
whitespace) between the JSON objects or arrays, instead they must be
concatenated back-to-back. If an error occurs, an exception will be
raised as in the scalar context case. Note that in this case, any
previously-parsed JSON texts will be lost.

Example: Parse some JSON arrays/objects in a given string and return
them.

    my @objs = JSON::PP->new->incr_parse ("[5][7][1,2]");

=head2 incr_text

    $lvalue_string = $json->incr_text

This method returns the currently stored JSON fragment as an lvalue, that
is, you can manipulate it. This I<only> works when a preceding call to
C<incr_parse> in I<scalar context> successfully returned an object. Under
all other circumstances you must not call this function (I mean it.
although in simple tests it might actually work, it I<will> fail under
real world conditions). As a special exception, you can also call this
method before having parsed anything.

That means you can only use this function to look at or manipulate text
before or after complete JSON objects, not while the parser is in the
middle of parsing a JSON object.

This function is useful in two cases: a) finding the trailing text after a
JSON object or b) parsing multiple JSON objects separated by non-JSON text
(such as commas).

=head2 incr_skip

    $json->incr_skip

This will reset the state of the incremental parser and will remove
the parsed text from the input buffer so far. This is useful after
C<incr_parse> died, in which case the input buffer and incremental parser
state is left unchanged, to skip the text parsed so far and to reset the
parse state.

The difference to C<incr_reset> is that only text until the parse error
occurred is removed.

=head2 incr_reset

    $json->incr_reset

This completely resets the incremental parser, that is, after this call,
it will be as if the parser had never parsed anything.

This is useful if you want to repeatedly parse JSON objects and want to
ignore any trailing data, which means you have to reset the parser after
each successful decode.

=head1 MAPPING

Most of this section is also taken from JSON::XS.

This section describes how JSON::PP maps Perl values to JSON values and
vice versa. These mappings are designed to "do the right thing" in most
circumstances automatically, preserving round-tripping characteristics
(what you put in comes out as something equivalent).

For the more enlightened: note that in the following descriptions,
lowercase I<perl> refers to the Perl interpreter, while uppercase I<Perl>
refers to the abstract Perl language itself.

=head2 JSON -> PERL

=over 4

=item object

A JSON object becomes a reference to a hash in Perl. No ordering of object
keys is preserved (JSON does not preserve object key ordering itself).

=item array

A JSON array becomes a reference to an array in Perl.

=item string

A JSON string becomes a string scalar in Perl - Unicode codepoints in JSON
are represented by the same codepoints in the Perl string, so no manual
decoding is necessary.

=item number

A JSON number becomes either an integer, numeric (floating point) or
string scalar in perl, depending on its range and any fractional parts. On
the Perl level, there is no difference between those as Perl handles all
the conversion details, but an integer may take slightly less memory and
might represent more values exactly than floating point numbers.

If the number consists of digits only, JSON::PP will try to represent
it as an integer value. If that fails, it will try to represent it as
a numeric (floating point) value if that is possible without loss of
precision. Otherwise it will preserve the number as a string value (in
which case you lose roundtripping ability, as the JSON number will be
re-encoded to a JSON string).

Numbers containing a fractional or exponential part will always be
represented as numeric (floating point) values, possibly at a loss of
precision (in which case you might lose perfect roundtripping ability, but
the JSON number will still be re-encoded as a JSON number).

Note that precision is not accuracy - binary floating point values cannot
represent most decimal fractions exactly, and when converting from and to
floating point, JSON::PP only guarantees precision up to but not including
the least significant bit.

When C<allow_bignum> is enabled, big integer values and any numeric
values will be converted into L<Math::BigInt> and L<Math::BigFloat>
objects respectively, without becoming string scalars or losing
precision.

=item true, false

These JSON atoms become C<JSON::PP::true> and C<JSON::PP::false>,
respectively. They are overloaded to act almost exactly like the numbers
C<1> and C<0>. You can check whether a scalar is a JSON boolean by using
the C<JSON::PP::is_bool> function.

=item null

A JSON null atom becomes C<undef> in Perl.

=item shell-style comments (C<< # I<text> >>)

As a nonstandard extension to the JSON syntax that is enabled by the
C<relaxed> setting, shell-style comments are allowed. They can start
anywhere outside strings and go till the end of the line.

=back


=head2 PERL -> JSON

The mapping from Perl to JSON is slightly more difficult, as Perl is a
truly typeless language, so we can only guess which JSON type is meant by
a Perl value.

=over 4

=item hash references

Perl hash references become JSON objects. As there is no inherent
ordering in hash keys (or JSON objects), they will usually be encoded
in a pseudo-random order. JSON::PP can optionally sort the hash keys
(determined by the I<canonical> flag and/or I<sort_by> property), so
the same data structure will serialise to the same JSON text (given
same settings and version of JSON::PP), but this incurs a runtime
overhead and is only rarely useful, e.g. when you want to compare some
JSON text against another for equality.

=item array references

Perl array references become JSON arrays.

=item other references

Other unblessed references are generally not allowed and will cause an
exception to be thrown, except for references to the integers C<0> and
C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
also use C<JSON::PP::false> and C<JSON::PP::true> to improve
readability.

   to_json [\0, JSON::PP::true]      # yields [false,true]

=item JSON::PP::true, JSON::PP::false

These special values become JSON true and JSON false values,
respectively. You can also use C<\1> and C<\0> directly if you want.

=item JSON::PP::null

This special value becomes JSON null.

=item blessed objects

Blessed objects are not directly representable in JSON, but C<JSON::PP>
allows various ways of handling objects. See L<OBJECT SERIALISATION>,
below, for details.

=item simple scalars

Simple Perl scalars (any scalar that is not a reference) are the most
difficult objects to encode: JSON::PP will encode undefined scalars as
JSON C<null> values, scalars that have last been used in a string context
before encoding as JSON strings, and anything else as number value:

   # dump as number
   encode_json [2]                      # yields [2]
   encode_json [-3.0e17]                # yields [-3e+17]
   my $value = 5; encode_json [$value]  # yields [5]

   # used as string, so dump as string
   print $value;
   encode_json [$value]                 # yields ["5"]

   # undef becomes null
   encode_json [undef]                  # yields [null]

You can force the type to be a string by stringifying it:

   my $x = 3.1; # some variable containing a number
   "$x";        # stringified
   $x .= "";    # another, more awkward way to stringify
   print $x;    # perl does it for you, too, quite often
                # (but for older perls)

You can force the type to be a number by numifying it:

   my $x = "3"; # some variable containing a string
   $x += 0;     # numify it, ensuring it will be dumped as a number
   $x *= 1;     # same thing, the choice is yours.

You cannot currently force the type in other, less obscure, ways.

Note that numerical precision has the same meaning as under Perl (so
binary to decimal conversion follows the same rules as in Perl, which
can differ to other languages). Also, your perl interpreter might expose
extensions to the floating point numbers of your platform, such as
infinities or NaN's - these cannot be represented in JSON, and it is an
error to pass those in.

JSON::PP (and JSON::XS) trusts what you pass to C<encode> method
(or C<encode_json> function) is a clean, validated data structure with
values that can be represented as valid JSON values only, because it's
not from an external data source (as opposed to JSON texts you pass to
C<decode> or C<decode_json>, which JSON::PP considers tainted and
doesn't trust). As JSON::PP doesn't know exactly what you and consumers
of your JSON texts want the unexpected values to be (you may want to
convert them into null, or to stringify them with or without
normalisation (string representation of infinities/NaN may vary
depending on platforms), or to croak without conversion), you're advised
to do what you and your consumers need before you encode, and also not
to numify values that may start with values that look like a number
(including infinities/NaN), without validating.

=back

=head2 OBJECT SERIALISATION

As for Perl objects, JSON::PP only supports a pure JSON representation (without the ability to deserialise the object automatically again).

=head3 SERIALISATION

What happens when C<JSON::PP> encounters a Perl object depends on the
C<allow_blessed>, C<convert_blessed> and C<allow_bignum> settings, which are
used in this order:

=over 4

=item 1. C<convert_blessed> is enabled and the object has a C<TO_JSON> method.

In this case, the C<TO_JSON> method of the object is invoked in scalar
context. It must return a single scalar that can be directly encoded into
JSON. This scalar replaces the object in the JSON text.

For example, the following C<TO_JSON> method will convert all L<URI>
objects to JSON strings when serialised. The fact that these values
originally were L<URI> objects is lost.

   sub URI::TO_JSON {
      my ($uri) = @_;
      $uri->as_string
   }

=item 2. C<allow_bignum> is enabled and the object is a C<Math::BigInt> or C<Math::BigFloat>.

The object will be serialised as a JSON number value.

=item 3. C<allow_blessed> is enabled.

The object will be serialised as a JSON null value.

=item 4. none of the above

If none of the settings are enabled or the respective methods are missing,
C<JSON::PP> throws an exception.

=back

=head1 ENCODING/CODESET FLAG NOTES

This section is taken from JSON::XS.

The interested reader might have seen a number of flags that signify
encodings or codesets - C<utf8>, C<latin1> and C<ascii>. There seems to be
some confusion on what these do, so here is a short comparison:

C<utf8> controls whether the JSON text created by C<encode> (and expected
by C<decode>) is UTF-8 encoded or not, while C<latin1> and C<ascii> only
control whether C<encode> escapes character values outside their respective
codeset range. Neither of these flags conflict with each other, although
some combinations make less sense than others.

Care has been taken to make all flags symmetrical with respect to
C<encode> and C<decode>, that is, texts encoded with any combination of
these flag values will be correctly decoded when the same flags are used
- in general, if you use different flag settings while encoding vs. when
decoding you likely have a bug somewhere.

Below comes a verbose discussion of these flags. Note that a "codeset" is
simply an abstract set of character-codepoint pairs, while an encoding
takes those codepoint numbers and I<encodes> them, in our case into
octets. Unicode is (among other things) a codeset, UTF-8 is an encoding,
and ISO-8859-1 (= latin 1) and ASCII are both codesets I<and> encodings at
the same time, which can be confusing.

=over 4

=item C<utf8> flag disabled

When C<utf8> is disabled (the default), then C<encode>/C<decode> generate
and expect Unicode strings, that is, characters with high ordinal Unicode
values (> 255) will be encoded as such characters, and likewise such
characters are decoded as-is, no changes to them will be done, except
"(re-)interpreting" them as Unicode codepoints or Unicode characters,
respectively (to Perl, these are the same thing in strings unless you do
funny/weird/dumb stuff).

This is useful when you want to do the encoding yourself (e.g. when you
want to have UTF-16 encoded JSON texts) or when some other layer does
the encoding for you (for example, when printing to a terminal using a
filehandle that transparently encodes to UTF-8 you certainly do NOT want
to UTF-8 encode your data first and have Perl encode it another time).

=item C<utf8> flag enabled

If the C<utf8>-flag is enabled, C<encode>/C<decode> will encode all
characters using the corresponding UTF-8 multi-byte sequence, and will
expect your input strings to be encoded as UTF-8, that is, no "character"
of the input string must have any value > 255, as UTF-8 does not allow
that.

The C<utf8> flag therefore switches between two modes: disabled means you
will get a Unicode string in Perl, enabled means you get an UTF-8 encoded
octet/binary string in Perl.

=item C<latin1> or C<ascii> flags enabled

With C<latin1> (or C<ascii>) enabled, C<encode> will escape characters
with ordinal values > 255 (> 127 with C<ascii>) and encode the remaining
characters as specified by the C<utf8> flag.

If C<utf8> is disabled, then the result is also correctly encoded in those
character sets (as both are proper subsets of Unicode, meaning that a
Unicode string with all character values < 256 is the same thing as a
ISO-8859-1 string, and a Unicode string with all character values < 128 is
the same thing as an ASCII string in Perl).

If C<utf8> is enabled, you still get a correct UTF-8-encoded string,
regardless of these flags, just some more characters will be escaped using
C<\uXXXX> then before.

Note that ISO-8859-1-I<encoded> strings are not compatible with UTF-8
encoding, while ASCII-encoded strings are. That is because the ISO-8859-1
encoding is NOT a subset of UTF-8 (despite the ISO-8859-1 I<codeset> being
a subset of Unicode), while ASCII is.

Surprisingly, C<decode> will ignore these flags and so treat all input
values as governed by the C<utf8> flag. If it is disabled, this allows you
to decode ISO-8859-1- and ASCII-encoded strings, as both strict subsets of
Unicode. If it is enabled, you can correctly decode UTF-8 encoded strings.

So neither C<latin1> nor C<ascii> are incompatible with the C<utf8> flag -
they only govern when the JSON output engine escapes a character or not.

The main use for C<latin1> is to relatively efficiently store binary data
as JSON, at the expense of breaking compatibility with most JSON decoders.

The main use for C<ascii> is to force the output to not contain characters
with values > 127, which means you can interpret the resulting string
as UTF-8, ISO-8859-1, ASCII, KOI8-R or most about any character set and
8-bit-encoding, and still get the same data structure back. This is useful
when your channel for JSON transfer is not 8-bit clean or the encoding
might be mangled in between (e.g. in mail), and works because ASCII is a
proper subset of most 8-bit and multibyte encodings in use in the world.

=back

=head1 SEE ALSO

The F<json_pp> command line utility for quick experiments.

L<JSON::XS>, L<Cpanel::JSON::XS>, and L<JSON::Tiny> for faster alternatives.
L<JSON> and L<JSON::MaybeXS> for easy migration.

L<JSON::backportPP::Compat5005> and L<JSON::backportPP::Compat5006> for older perl users.

RFC4627 (L<http://www.ietf.org/rfc/rfc4627.txt>)

=head1 AUTHOR

Makamaka Hannyaharamitu, E<lt>makamaka[at]cpan.orgE<gt>


=head1 COPYRIGHT AND LICENSE

Copyright 2007-2016 by Makamaka Hannyaharamitu

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself. 

=cut