Class: Oj::Doc

Inherits:
Object
  • Object
show all
Defined in:
ext/oj/fast.c,
ext/oj/fast.c

Overview

The Doc class is used to parse and navigate a JSON document. The model it employs is that of a document that while open can be navigated and values extracted. Once the document is closed the document can not longer be accessed. This allows the parsing and data extraction to be extremely fast compared to other JSON parses.

An Oj::Doc class is not created directly but the _open()_ class method is used to open a document and the yield parameter to the block of the #open() call is the Doc instance. The Doc instance can be moved across, up, and down the JSON document. At each element the data associated with the element can be extracted. It is also possible to just provide a path to the data to be extracted and retrieve the data in that manner.

For many of the methods a path is used to describe the location of an element. Paths follow a subset of the XPath syntax. The slash (‘/’) character is the separator. Each step in the path identifies the next branch to take through the document. A JSON object will expect a key string while an array will expect a positive index. A .. step indicates a move up the JSON document.

Examples:

json = %{[
  {
    "one"   : 1,
    "two"   : 2
  },
  {
    "three" : 3,
    "four"  : 4
  }
]}
# move and get value
Oj::Doc.open(json) do |doc|
  doc.move('/1/two')
  # doc location is now at the 'two' element of the hash that is the first element of the array.
  doc.fetch()
end
#=> 2

# Now try again using a path to Oj::Doc.fetch() directly and not using a block.
doc = Oj::Doc.open(json)
doc.fetch('/2/three')  #=> 3
doc.close()

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.open(json) ⇒ Object

Parses a JSON document String and then yields to the provided block if one is given with an instance of the Oj::Doc as the single yield parameter. If a block is not given then an Oj::Doc instance is returned and must be closed with a call to the #close() method when no longer needed.

@param [String] json JSON document string

Examples:

Oj::Doc.open('[1,2,3]') { |doc| doc.size() }  #=> 4
# or as an alternative
doc = Oj::Doc.open('[1,2,3]')
doc.size()  #=> 4
doc.close()

Yield Parameters:

  • doc (Oj::Doc) —

    parsed JSON document

Yield Returns:

  • (Object) —

    returns the result of the yield as the result of the method call



1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
 
# File 'ext/oj/fast.c', line 1119

static VALUE
doc_open(VALUE clas, VALUE str) {
    char	*json;
    size_t	len;
    VALUE	obj;
    int		given = rb_block_given_p();
    int		allocate;

    Check_Type(str, T_STRING);
    len = RSTRING_LEN(str) + 1;
    allocate = (SMALL_XML < len || !given);
    if (allocate) {
	json = ALLOC_N(char, len);
    } else {
	json = ALLOCA_N(char, len);
    }
    memcpy(json, StringValuePtr(str), len);
    obj = parse_json(clas, json, given, allocate);
    if (given && allocate) {
	xfree(json);
    }
    return obj;
}

.open_file(filename) ⇒ Object

Parses a JSON document from a file and then yields to the provided block if one is given with an instance of the Oj::Doc as the single yield parameter. If a block is not given then an Oj::Doc instance is returned and must be closed with a call to the #close() method when no longer needed.

@param [String] filename name of file that contains a JSON document

Examples:

File.open('array.json', 'w') { |f| f.write('[1,2,3]') }
Oj::Doc.open_file(filename) { |doc| doc.size() }  #=> 4
# or as an alternative
doc = Oj::Doc.open_file(filename)
doc.size()  #=> 4
doc.close()

Yield Parameters:

  • doc (Oj::Doc) —

    parsed JSON document

Yield Returns:

  • (Object) —

    returns the result of the yield as the result of the method call



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
 
# File 'ext/oj/fast.c', line 1161

static VALUE
doc_open_file(VALUE clas, VALUE filename) {
    char	*path;
    char	*json;
    FILE	*f;
    size_t	len;
    VALUE	obj;
    int		given = rb_block_given_p();
    int		allocate;

    Check_Type(filename, T_STRING);
    path = StringValuePtr(filename);
    if (0 == (f = fopen(path, "r"))) {
	rb_raise(rb_eIOError, "%s", strerror(errno));
    }
    fseek(f, 0, SEEK_END);
    len = ftell(f);
    allocate = (SMALL_XML < len || !given);
    if (allocate) {
	json = ALLOC_N(char, len + 1);
    } else {
	json = ALLOCA_N(char, len + 1);
    }
    fseek(f, 0, SEEK_SET);
    if (len != fread(json, 1, len, f)) {
	fclose(f);
	rb_raise(rb_const_get_at(Oj, rb_intern("LoadError")), 
		 "Failed to read %lu bytes from %s.", (unsigned long)len, path);
    }
    fclose(f);
    json[len] = '\0';
    obj = parse_json(clas, json, given, allocate);
    if (given && allocate) {
	xfree(json);
    }
    return obj;
}

.open(json) ⇒ Object

Parses a JSON document String and then yields to the provided block if one is given with an instance of the Oj::Doc as the single yield parameter. If a block is not given then an Oj::Doc instance is returned and must be closed with a call to the #close() method when no longer needed.

@param [String] json JSON document string

Examples:

Oj::Doc.open('[1,2,3]') { |doc| doc.size() }  #=> 4
# or as an alternative
doc = Oj::Doc.open('[1,2,3]')
doc.size()  #=> 4
doc.close()

Yield Parameters:

  • doc (Oj::Doc) —

    parsed JSON document

Yield Returns:

  • (Object) —

    returns the result of the yield as the result of the method call



1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
 
# File 'ext/oj/fast.c', line 1119

static VALUE
doc_open(VALUE clas, VALUE str) {
    char	*json;
    size_t	len;
    VALUE	obj;
    int		given = rb_block_given_p();
    int		allocate;

    Check_Type(str, T_STRING);
    len = RSTRING_LEN(str) + 1;
    allocate = (SMALL_XML < len || !given);
    if (allocate) {
	json = ALLOC_N(char, len);
    } else {
	json = ALLOCA_N(char, len);
    }
    memcpy(json, StringValuePtr(str), len);
    obj = parse_json(clas, json, given, allocate);
    if (given && allocate) {
	xfree(json);
    }
    return obj;
}

Instance Method Details

#clone ⇒ Object 



1653
1654
1655
1656
1657
 
# File 'ext/oj/fast.c', line 1653

static VALUE
doc_not_implemented(VALUE self) {
    rb_raise(rb_eNotImpError, "Not implemented.");
    return Qnil;
}

#close ⇒ Object

Closes an open document. No further calls to the document will be valid after closing.

Examples:

doc = Oj::Doc.open('[1,2,3]')
doc.size()  #=> 4
doc.close()


1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
 
# File 'ext/oj/fast.c', line 1635

static VALUE
doc_close(VALUE self) {
    Doc		doc = self_doc(self);

    rb_gc_unregister_address(&doc->self);
    DATA_PTR(doc->self) = 0;
    if (0 != doc) {
	xfree(doc->json);
	doc_free(doc);
	xfree(doc);
    }
    return Qnil;
}

#dump(path, filename) ⇒ Object

Dumps the document or nodes to a new JSON document. It uses the default options for generating the JSON.

@param path [String] if provided it identified the top of the branch to dump to JSON
@param filename [String] if provided it is the filename to write the output to

Examples:

Oj::Doc.open('[3,[2,1]]') { |doc|
    doc.dump('/2')
}
#=> "[2,1]"


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
 
# File 'ext/oj/fast.c', line 1571

static VALUE
doc_dump(int argc, VALUE *argv, VALUE self) {
    Doc		doc = self_doc(self);
    Leaf	leaf;
    const char	*path = 0;
    const char	*filename = 0;

    if (1 <= argc) {
	if (Qnil != *argv) {
	    Check_Type(*argv, T_STRING);
	    path = StringValuePtr(*argv);
	}
	if (2 <= argc) {
	    Check_Type(argv[1], T_STRING);
	    filename = StringValuePtr(argv[1]);
	}
    }
    if (0 != (leaf = get_doc_leaf(doc, path))) {
	VALUE	rjson;

	if (0 == filename) {
	    char	buf[4096];
	    struct _Out out;

	    out.buf = buf;
	    out.end = buf + sizeof(buf) - 10;
	    out.allocated = 0;
	    out.omit_nil = oj_default_options.dump_opts.omit_nil;
	    oj_dump_leaf_to_json(leaf, &oj_default_options, &out);
	    rjson = rb_str_new2(out.buf);
	    if (out.allocated) {
		xfree(out.buf);
	    }
	} else {
	    oj_write_leaf_to_file(leaf, filename, &oj_default_options);
	    rjson = Qnil;
	}
	return rjson;
    }
    return Qnil;
}

#dup ⇒ Object 



1653
1654
1655
1656
1657
 
# File 'ext/oj/fast.c', line 1653

static VALUE
doc_not_implemented(VALUE self) {
    rb_raise(rb_eNotImpError, "Not implemented.");
    return Qnil;
}

#each_child(path = nil) ⇒ Object

Yields to the provided block for each immediate child node with the identified location of the JSON document as the root. The parameter passed to the block on yield is the Doc instance after moving to the child location.

@param [String] path if provided it identified the top of the branch to process the chilren of

Examples:

Oj::Doc.open('[3,[2,1]]') { |doc|
    result = []
    doc.each_value('/2') { |doc| result << doc.where? }
    result
}
#=> ["/2/1", "/2/2"]

Yield Parameters:

  • Doc (Doc) —

    at the child location



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
 
# File 'ext/oj/fast.c', line 1474

static VALUE
doc_each_child(int argc, VALUE *argv, VALUE self) {
    if (rb_block_given_p()) {
	Leaf		save_path[MAX_STACK];
	Doc		doc = self_doc(self);
	const char	*path = 0;
	size_t		wlen;

	wlen = doc->where - doc->where_path;
	if (0 < wlen) {
	    memcpy(save_path, doc->where_path, sizeof(Leaf) * (wlen + 1));
	}
	if (1 <= argc) {
	    Check_Type(*argv, T_STRING);
	    path = StringValuePtr(*argv);
	    if ('/' == *path) {
		doc->where = doc->where_path;
		path++;
	    }
	    if (0 != move_step(doc, path, 1)) {
		if (0 < wlen) {
		    memcpy(doc->where_path, save_path, sizeof(Leaf) * (wlen + 1));
		}
		return Qnil;
	    }
	}
	if (COL_VAL == (*doc->where)->value_type && 0 != (*doc->where)->elements) {
	    Leaf	first = (*doc->where)->elements->next;
	    Leaf	e = first;

	    doc->where++;
	    do {
		*doc->where = e;
		rb_yield(self);
		e = e->next;
	    } while (e != first);
	}
	if (0 < wlen) {
	    memcpy(doc->where_path, save_path, sizeof(Leaf) * (wlen + 1));
	}
    }
    return Qnil;
}

#each_leaf(path = nil) ⇒ Object

Yields to the provided block for each leaf node with the identified location of the JSON document as the root. The parameter passed to the block on yield is the Doc instance after moving to the child location.

@param [String] path if provided it identified the top of the branch to process the leaves of

Examples:

Oj::Doc.open('[3,[2,1]]') { |doc|
    result = {}
    doc.each_leaf() { |d| result[d.where?] = d.fetch() }
    result
}
#=> ["/1" => 3, "/2/1" => 2, "/2/2" => 1]

Yield Parameters:

  • Doc (Doc) —

    at the child location



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
 
# File 'ext/oj/fast.c', line 1398

static VALUE
doc_each_leaf(int argc, VALUE *argv, VALUE self) {
    if (rb_block_given_p()) {
	Leaf		save_path[MAX_STACK];
	Doc		doc = self_doc(self);
	const char	*path = 0;
	size_t		wlen;

	wlen = doc->where - doc->where_path;
	if (0 < wlen) {
	    memcpy(save_path, doc->where_path, sizeof(Leaf) * (wlen + 1));
	}
	if (1 <= argc) {
	    Check_Type(*argv, T_STRING);
	    path = StringValuePtr(*argv);
	    if ('/' == *path) {
		doc->where = doc->where_path;
		path++;
	    }
	    if (0 != move_step(doc, path, 1)) {
		if (0 < wlen) {
		    memcpy(doc->where_path, save_path, sizeof(Leaf) * (wlen + 1));
		}
		return Qnil;
	    }
	}
	each_leaf(doc, self);
	if (0 < wlen) {
	    memcpy(doc->where_path, save_path, sizeof(Leaf) * (wlen + 1));
	}
    }
    return Qnil;
}

#each_value(path = nil) ⇒ Object

Yields to the provided block for each leaf value in the identified location of the JSON document. The parameter passed to the block on yield is the value of the leaf. Only those leaves below the element specified by the path parameter are processed.

@param [String] path if provided it identified the top of the branch to process the leaf values of

Examples:

Oj::Doc.open('[3,[2,1]]') { |doc|
    result = []
    doc.each_value() { |v| result << v }
    result
}
#=> [3, 2, 1]

Oj::Doc.open('[3,[2,1]]') { |doc|
    result = []
    doc.each_value('/2') { |v| result << v }
    result
}
#=> [2, 1]

Yield Parameters:

  • val (Object) —

    each leaf value



1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
 
# File 'ext/oj/fast.c', line 1541

static VALUE
doc_each_value(int argc, VALUE *argv, VALUE self) {
    if (rb_block_given_p()) {
	Doc		doc = self_doc(self);
	const char	*path = 0;
	Leaf		leaf;

	if (1 <= argc) {
	    Check_Type(*argv, T_STRING);
	    path = StringValuePtr(*argv);
	}
	if (0 != (leaf = get_doc_leaf(doc, path))) {
	    each_value(doc, leaf);
	}
    }
    return Qnil;
}

#fetch(path = nil) ⇒ Object

Returns the value at the location identified by the path or the current location if the path is nil or not provided. This method will create and return an Array or Hash if that is the type of Object at the location specified. This is more expensive than navigating to the leaves of the JSON document.

@param [String] path path to the location to get the type of if provided

Examples:

Oj::Doc.open('[1,2]') { |doc| doc.fetch() }      #=> [1, 2]
Oj::Doc.open('[1,2]') { |doc| doc.fetch('/1') }  #=> 1


1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
 
# File 'ext/oj/fast.c', line 1362

static VALUE
doc_fetch(int argc, VALUE *argv, VALUE self) {
    Doc		doc;
    Leaf	leaf;
    VALUE	val = Qnil;
    const char	*path = 0;

    doc = self_doc(self);
    if (1 <= argc) {
	Check_Type(*argv, T_STRING);
	path = StringValuePtr(*argv);
	if (2 == argc) {
	    val = argv[1];
	}
    }
    if (0 != (leaf = get_doc_leaf(doc, path))) {
	val = leaf_value(doc, leaf);
    }
    return val;
}

#home ⇒ Object

Moves the document marker or location to the hoot or home position. The same operation can be performed with a Oj::Doc.move(‘/’).

Examples:

Oj::Doc.open('[1,2,3]') { |doc| doc.move('/2'); doc.home(); doc.where? }  #=> '/'


1298
1299
1300
1301
1302
1303
1304
1305
1306
 
# File 'ext/oj/fast.c', line 1298

static VALUE
doc_home(VALUE self) {
    Doc	doc = self_doc(self);

    *doc->where_path = doc->data;
    doc->where = doc->where_path;

    return oj_slash_string;
}

#local_key ⇒ Object

Returns the final key to the current location.

Examples:

Oj::Doc.open('[1,2,3]') { |doc| doc.move('/2'); doc.local_key() }	    #=> 2
Oj::Doc.open('{"one":3}') { |doc| doc.move('/one'); doc.local_key() }  #=> "one"
Oj::Doc.open('[1,2,3]') { |doc| doc.local_key() }			    #=> nil


1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
 
# File 'ext/oj/fast.c', line 1276

static VALUE
doc_local_key(VALUE self) {
    Doc		doc = self_doc(self);
    Leaf	leaf = *doc->where;
    VALUE	key = Qnil;

    if (T_HASH == leaf->parent_type) {
	key = rb_str_new2(leaf->key);
	key = oj_encode(key);
    } else if (T_ARRAY == leaf->parent_type) {
	key = LONG2NUM(leaf->index);
    }
    return key;
}

#move(path) ⇒ Object

Moves the document marker to the path specified. The path can an absolute path or a relative path.

@param [String] path path to the location to move to

Examples:

Oj::Doc.open('{"one":[1,2]') { |doc| doc.move('/one/2'); doc.where? }  #=> "/one/2"


1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
 
# File 'ext/oj/fast.c', line 1440

static VALUE
doc_move(VALUE self, VALUE str) {
    Doc		doc = self_doc(self);
    const char	*path;
    int		loc;

    Check_Type(str, T_STRING);
    path = StringValuePtr(str);
    if ('/' == *path) {
	doc->where = doc->where_path;
	path++;
    }
    if (0 != (loc = move_step(doc, path, 1))) {
	rb_raise(rb_eArgError, "Failed to locate element %d of the path %s.", loc, path);
    }
    return Qnil;
}

#size ⇒ Object

Returns the number of nodes in the JSON document where a node is any one of the basic JSON components.

Examples:

Oj::Doc.open('[1,2,3]') { |doc| doc.size() }  #=> 4

Returns:

  • Returns the size of the JSON document.



1621
1622
1623
1624
 
# File 'ext/oj/fast.c', line 1621

static VALUE
doc_size(VALUE self) {
    return ULONG2NUM(((Doc)DATA_PTR(self))->size);
}

#type(path = nil) ⇒ Object

Returns the Class of the data value at the location identified by the path or the current location if the path is nil or not provided. This method does not create the Ruby Object at the location specified so the overhead is low.

@param [String] path path to the location to get the type of if provided

Examples:

Oj::Doc.open('[1,2]') { |doc| doc.type() }	     #=> Array
Oj::Doc.open('[1,2]') { |doc| doc.type('/1') }  #=> Fixnum


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
 
# File 'ext/oj/fast.c', line 1319

static VALUE
doc_type(int argc, VALUE *argv, VALUE self) {
    Doc		doc = self_doc(self);
    Leaf	leaf;
    const char	*path = 0;
    VALUE	type = Qnil;

    if (1 <= argc) {
	Check_Type(*argv, T_STRING);
	path = StringValuePtr(*argv);
    }
    if (0 != (leaf = get_doc_leaf(doc, path))) {
	switch (leaf->rtype) {
	case T_NIL:	type = rb_cNilClass;	break;
	case T_TRUE:	type = rb_cTrueClass;	break;
	case T_FALSE:	type = rb_cFalseClass;	break;
	case T_STRING:	type = rb_cString;	break;
#ifdef RUBY_INTEGER_UNIFICATION
	case T_FIXNUM:	type = rb_cInteger;	break;
#else
	case T_FIXNUM:	type = rb_cFixnum;	break;
#endif
	case T_FLOAT:	type = rb_cFloat;	break;
	case T_ARRAY:	type = rb_cArray;	break;
	case T_HASH:	type = rb_cHash;	break;
	default:				break;
	}
    }
    return type;
}

#where? ⇒ Boolean

Returns a String that describes the absolute path to the current location in the JSON document.

Returns:

  • (Boolean) 


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
 
# File 'ext/oj/fast.c', line 1231

static VALUE
doc_where(VALUE self) {
    Doc	doc = self_doc(self);

    if (0 == *doc->where_path || doc->where == doc->where_path) {
	return oj_slash_string;
    } else {
	Leaf	*lp;
	Leaf	leaf;
	size_t	size = 3; // leading / and terminating \0
	char	*path;
	char	*p;

	for (lp = doc->where_path; lp <= doc->where; lp++) {
	    leaf = *lp;
	    if (T_HASH == leaf->parent_type) {
		size += esc_strlen((*lp)->key) + 1;
	    } else if (T_ARRAY == leaf->parent_type) {
		size += ((*lp)->index < 100) ? 3 : 11;
	    }
	}
	path = ALLOCA_N(char, size);
	p = path;
	for (lp = doc->where_path; lp <= doc->where; lp++) {
	    leaf = *lp;
	    if (T_HASH == leaf->parent_type) {
		p = append_key(p, (*lp)->key);
	    } else if (T_ARRAY == leaf->parent_type) {
		p = ulong_fill(p, (*lp)->index);
	    }
	    *p++ = '/';
	}
	*--p = '\0';
	return rb_str_new(path, p - path);
    }
}