path: root/json.c

/*-------------------------------------------------------------------------
 *
 * json.c
 *	  Core JSON manipulation routines used by JSON data type support.
 *
 * Copyright (c) 2010, PostgreSQL Global Development Group
 * Written by Joey Adams <[email protected]>.
 *
 *-------------------------------------------------------------------------
 */

#include "json.h"
#include "util.h"

#include <ctype.h>

#include "mb/pg_wchar.h"

#define is_internal(node) ((node)->type == JSON_ARRAY || (node)->type == JSON_OBJECT)

/* We can't use isspace() because it also accepts \v and \f, which
   aren't legal whitespace characters in strict JSON. */
#define is_whitespace(c) ((c)==' ' || (c)=='\t' || (c)=='\n' || (c)=='\r')

static void
skip_whitespace(const char **sp)
{
	const char *s = *sp;

	while (is_whitespace(*s))
		s++;
	*sp = s;
}

static char
end_parenthesis(JSON * node)
{
	Assert(node != NULL);

	switch (node->type)
	{
		case JSON_ARRAY:
			return ']';
		case JSON_OBJECT:
			return '}';
		default:
			Assert(false);
			return '\0';
	}
}

/*
 * Reads exactly 4 hex characters (capital or lowercase).
 * Writes the result to *out .
 * Returns true on success, false if any input chars are not [0-9A-Fa-f] .
 */
static bool
read_hex16(const char *in, unsigned int *out)
{
	unsigned int i;
	unsigned int tmp;
	char		c;

	*out = 0;

	for (i = 0; i < 4; i++)
	{
		c = *in++;
		if (c >= '0' && c <= '9')
			tmp = c - '0';
		else if (c >= 'A' && c <= 'F')
			tmp = c - 'A' + 10;
		else if (c >= 'a' && c <= 'f')
			tmp = c - 'a' + 10;
		else
			return false;

		*out <<= 4;
		*out += tmp;
	}

	return true;
}

/*
 * Encodes a 16-bit number into hexadecimal,
 * writing exactly 4 hex chars.
 */
static void
write_hex16(char *out, unsigned int val)
{
	const char *hex = "0123456789ABCDEF";

	*out++ = hex[(val >> 12) & 0xF];
	*out++ = hex[(val >> 8) & 0xF];
	*out++ = hex[(val >> 4) & 0xF];
	*out++ = hex[val & 0xF];
}


/*********** JSON creation, manipulation, and deletion **********/

JSON *
json_mknode(json_type type)
{
	JSON	   *node = palloc(sizeof(*node));

	memset(node, 0, sizeof(*node));
	node->type = type;
	return node;
}

JSON *
json_mkbool(bool v_bool)
{
	JSON	   *node = json_mknode(JSON_BOOL);

	node->v.v_bool = v_bool;
	return node;
}

JSON *
json_mkstring(const char *str, size_t length)
{
	JSON	   *node = json_mknode(JSON_STRING);

	if (str)
	{
		node->v.string.str = pnstrdup(str, length);
		node->v.string.length = length;
	}
	return node;
}

JSON *
json_mknumber(const char *number, size_t length)
{
	JSON	   *node = json_mknode(JSON_NUMBER);

	if (number)
		node->v.number = pnstrdup(number, length);
	return node;
}

/*
 * Indicate that the node's value has changed,
 * marking ancestors as necessary.
 *
 * Call json_touch_value so that json_encode(..., JSONOPT_ORIG)
 * will encode the new value rather than using original text.
 */
void
json_touch_value(JSON * node)
{
	while (node && node->orig.value.start)
	{
		node->orig.value.start = NULL;
		node = node->parent;
	}
}

/*
 * Add child to parent, but don't clear orig pointers of ancestors.
 *
 * This is used by json_decode to ensure that original text segments
 * are preserved while building the JSON tree.
 */
static void
json_append_notouch(JSON * parent, JSON * child)
{
	Assert(parent->type == JSON_ARRAY || parent->type == JSON_OBJECT);
	Assert(child->parent == NULL);

	parent->v.children.count++;
	child->parent = parent;
	child->prev = parent->v.children.tail;
	child->next = NULL;

	if (parent->v.children.tail)
	{
		parent->v.children.tail->next = child;
		parent->v.children.tail = child;
	}
	else
	{
		parent->v.children.head = parent->v.children.tail = child;
	}
}

/*
 * json_append
 *	  Add child to parent, putting it at the end of its child list.
 *
 *	  Child must not already have another parent.
 */
void
json_append(JSON * parent, JSON * child)
{
	json_append_notouch(parent, child);
	json_touch_value(parent);
}

/*
 * json_remove
 *	  Remove node from its parent, but do not delete it.
 */
void
json_remove(JSON * node)
{
	JSON	   *parent = node->parent;

	if (parent == NULL)
		return;
	Assert(parent->type == JSON_ARRAY || parent->type == JSON_OBJECT);
	Assert(parent->v.children.count > 0);

	if (node->prev)
		node->prev->next = node->next;
	else
		parent->v.children.head = node->next;
	if (node->next)
		node->next->prev = node->prev;
	else
		parent->v.children.tail = node->prev;

	parent->v.children.count--;
	node->parent = NULL;
	node->prev = NULL;
	node->next = NULL;

	json_touch_value(parent);
}

/*
 * Update the value of a node, preserving position and key information.
 *
 * Note well: If replacement is an array or object with children, the parent
 *			  pointers of those children will be incorrect
 *			  (they'll still refer to their original parent).
 *
 *			  Untrustworthy parent pointers is the price to pay for
 *			  being able to copy JSON values by reference.
 */
void
json_replace_value(JSON * node, JSON * replacement)
{
	node->type = replacement->type;
	node->v = replacement->v;
	node->orig.value = replacement->orig.value;

	if (node->parent)
		json_touch_value(node->parent);
}

const char *
json_get_string(JSON * node, size_t *length_out)
{
	Assert(node->type == JSON_STRING);
	if (length_out)
		*length_out = node->v.string.length;
	return node->v.string.str;
}

void
json_set_string(JSON * node, const char *str, size_t length)
{
	Assert(node->type == JSON_STRING);
	if (node->v.string.str)
		pfree(node->v.string.str);
	if (str)
	{
		node->v.string.str = pnstrdup(str, length);
		node->v.string.length = length;
	}
	else
	{
		node->v.string.str = NULL;
		node->v.string.length = 0;
	}
	json_touch_value(node);
}

const char *
json_get_number(JSON * node)
{
	Assert(node->type == JSON_NUMBER);
	return node->v.number;
}

void
json_set_number(JSON * node, const char *number, size_t length)
{
	Assert(node->type == JSON_NUMBER);
	if (node->v.number)
		pfree(node->v.number);
	if (number)
		node->v.number = pnstrdup(number, length);
	else
		node->v.number = NULL;
	json_touch_value(node);
}

/* Non-recursively free a node */
static void
free_node(JSON * node)
{
	if (node->type == JSON_STRING)
	{
		if (node->v.string.str)
			pfree(node->v.string.str);
	}
	else if (node->type == JSON_NUMBER)
	{
		if (node->v.number)
			pfree(node->v.number);
	}

	if (node->key)
		pfree(node->key);

	pfree(node);
}

/*
 * Free a JSON node and all its descendants.
 *
 * Do not use this function if you have performed json_replace_value on
 * a descendant, as this function relies on each node's ->parent field
 * being trustworthy.
 */
static void
json_delete(JSON * node)
{
	JSON	   *parent,
			   *next;

	if (node == NULL)
		return;

	/* Remove node from parent (if it has one). */
	json_remove(node);

descend:
	while (is_internal(node) && node->v.children.head)
		node = node->v.children.head;

advance:
	parent = node->parent;
	next = node->next;
	free_node(node);
	node = next;

	if (node != NULL)
	{
		goto descend;
	}
	else
	{
		node = parent;
		if (node != NULL)
			goto advance;
		else
			return;
	}
}


/*********************** Parsing and validation **********************/

static JSON *decode_leaf(const char **sp);
static JSON *decode_number(const char **sp);

/*
 * json_decode_string has a different signature than its friends
 * because it's also used to parse object member keys.
 * It's also useful outside of json.c, such as in jsonpath.c .
 */
char	   *json_decode_string(const char **sp, size_t *length, bool strict);

/*
 * json_validate
 *	  Make sure the given UTF-8 string is valid JSON.
 *
 * TODO: Consider making a dedicated function for this so we don't have to
 *		 convert to UTF-8, build a JSON node, then free both
 *		 whenever we need to validate (such as in json_in and json_recv).
 */
bool
json_validate(const char *str)
{
	JSON	   *node = json_decode(str);

	if (node == NULL)
		return false;
	json_delete(node);
	return true;
}

/*
 * json_validate_server_encoded
 *	  Variant of json_validate that takes a server-encoded string
 *	  rather than a UTF-8 string.
 *
 *	  Note that a dedicated json_validate (described in the TODO above)
 *	  would be able to handle both encodings natively, since both are
 *	  ASCII-compatible.
 */
bool
json_validate_server_encoded(const char *str)
{
	char	   *str_utf8 = server_to_utf8(str, strlen(str));
	bool		result = json_validate(str_utf8);

	if (str_utf8 != str)
		pfree(str_utf8);

	return result;
}

/*
 * json_decode
 *	  Convert a JSON-encoded string to a JSON node.
 *	  @str must be valid UTF-8.
 */
JSON *
json_decode(const char *str)
{
	JSON	   *root = NULL,
			   *parent = NULL,
			   *node = NULL;
	const char *s = str;
	char	   *key;
	size_t		key_length;
	struct json_orig orig;
	bool		expect_endp;

	if (str == NULL)
		return NULL;

	Assert(utf8_validate(str, strlen(str)));

	expect_endp = false;
	goto item;

item:							/* Expect a value (set expect_endp before goto
								 * item; ) */
	key = NULL;
	key_length = 0;
	memset(&orig, 0, sizeof(orig));

	orig.key_left_space.start = s;
	orig.left_space.start = s;

	skip_whitespace(&s);

	if (expect_endp)
	{
		if (*s == ']' || *s == '}')
			goto endp;
	}

	if (parent != NULL && parent->type == JSON_OBJECT)
	{
		/* Parse member key string. */
		orig.key_left_space.end = s;
		orig.key.start = s;

		key = json_decode_string(&s, &key_length, true);
		if (key == NULL)
			goto failed;

		orig.key.end = s;
		orig.key_right_space.start = s;

		/* Eat the " : " */
		skip_whitespace(&s);
		if (*s != ':')
			goto failed;

		orig.key_right_space.end = s;
		s++;
		orig.left_space.start = s;

		skip_whitespace(&s);
	}

	/*
	 * The way orig.value and company are initialized is a bit funky. If this
	 * node has children, we have to finish parsing the node's children before
	 * we know where it ends.  Hence, initialization of orig.value_end and
	 * after will be deferred if this node has children.
	 */

	orig.left_space.end = s;
	orig.value.start = s;

	node = decode_leaf(&s);
	if (node == NULL)
	{
		if (*s == '[')
			node = json_mknode(JSON_ARRAY);
		else if (*s == '{')
			node = json_mknode(JSON_OBJECT);
		else
			goto failed;
		s++;

		/*
		 * orig.value.end and later are dangling (actually NULL) for now, but
		 * will be initialized when we get to state 'endp' .
		 */
	}
	else
	{
		orig.value.end = s;
		orig.right_space.start = s;

		skip_whitespace(&s);

		orig.right_space.end = s;
	}

	node->key = key;
	node->key_length = key_length;

	/*
	 * The key now belongs to the node.  This prevents a double free on
	 * failure (see the failed: label).
	 */
	key = NULL;

	node->orig = orig;

	if (parent != NULL)
		json_append_notouch(parent, node);
	else
		root = node;

	if (is_internal(node))
	{
		/*
		 * "push" node onto the "stack".  Nodes point up to their parents,
		 * which is why this function doesn't need a "stack" per se.
		 */
		parent = node;

		expect_endp = true;
		goto item;
	}

	if (parent != NULL)
		goto comma_endp;
	else
		goto end;

comma_endp:						/* Expect a comma or end bracket/brace */
	if (*s == ',')
	{
		s++;

		expect_endp = false;
		goto item;
	}
	if (*s == ']' || *s == '}')
		goto endp;

	goto failed;

endp:							/* Handle an end bracket/brace */
	if (*s != end_parenthesis(parent))
		goto failed;
	s++;

	/* "pop" a node from the "stack" */
	node = parent;
	parent = parent->parent;

	/*
	 * The other pointers were set when we started parsing this node in the
	 * 'item' state.
	 */
	node->orig.value.end = s;
	node->orig.right_space.start = s;

	skip_whitespace(&s);

	node->orig.right_space.end = s;

	if (parent != NULL)
		goto comma_endp;
	else
		goto end;

end:							/* Expect end of text */
	if (*s != '\0')
		goto failed;
	return node;

failed:					/* Handle failure */
	if (key != NULL)
		pfree(key);
	json_delete(root);
	return NULL;
}

/*
 * Decode and skip a node that does not have children.
 * Whitespace is not skipped first (it is done in the primary decode loop).
 *
 * Returns NULL if next character is '[', '{', or invalid.
 */
static JSON *
decode_leaf(const char **sp)
{
	char		c = **sp;

	if (c == '"')
	{
		size_t		length;
		char	   *str = json_decode_string(sp, &length, true);

		if (str != NULL)
		{
			JSON	   *node = json_mknode(JSON_STRING);

			node->v.string.str = str;
			node->v.string.length = length;
			return node;
		}

		return NULL;
	}
	if ((c >= '0' && c <= '9') || c == '-')
		return decode_number(sp);
	if (strncmp(*sp, "true", 4) == 0)
	{
		(*sp) += 4;
		return json_mkbool(true);
	}
	if (strncmp(*sp, "false", 5) == 0)
	{
		(*sp) += 5;
		return json_mkbool(false);
	}
	if (strncmp(*sp, "null", 4) == 0)
	{
		(*sp) += 4;
		return json_mknode(JSON_NULL);
	}

	return NULL;
}

/*
 * The JSON spec says that a number shall follow this precise pattern
 * (spaces and quotes added for readability):
 *	 '-'? (0 | [1-9][0-9]*) ('.' [0-9]+)? ([Ee] [+-]? [0-9]+)?
 *
 * However, some JSON parsers are more liberal.  For instance, PHP accepts
 * '.5' and '1.'.  JSON.parse accepts '+3'.
 *
 * This function takes the strict approach.
 */
static bool
validate_number(const char **sp)
{
	const char *s = *sp;

	/* '-'? */
	if (*s == '-')
		s++;

	/* (0 | [1-9][0-9]*) */
	if (*s == '0')
	{
		s++;
	}
	else
	{
		if (!isdigit(*s))
			return false;
		do
			s++;
		while (isdigit(*s));
	}

	/* ('.' [0-9]+)? */
	if (*s == '.')
	{
		s++;
		if (!isdigit(*s))
			return false;
		do
			s++;
		while (isdigit(*s));
	}

	/* ([Ee] [+-]? [0-9]+)? */
	if (*s == 'E' || *s == 'e')
	{
		s++;
		if (*s == '+' || *s == '-')
			s++;
		if (!isdigit(*s))
			return false;
		do
			s++;
		while (isdigit(*s));
	}

	*sp = s;
	return true;
}

static JSON *
decode_number(const char **sp)
{
	const char *start,
			   *end;

	start = *sp;
	if (!validate_number(sp))
		return NULL;
	end = *sp;

	return json_mknumber(start, end - start);
}

/*
 * json_decode_string
 *	  If you're interested in the decoding JSON in general, see json_decode.
 *
 *	  Decodes a JSON string literal (e.g. "\"hello\"").
 *
 *	  If strict is true, string must be double-quoted,
 *	  as is required by the JSON RFC.
 *	  Otherwise (e.g. if parsing something JSON-like, such as JSONPath),
 *	  the string may be single- or double-quoted.
 *
 *	  Also, no whitespace skipping is done, so the caller should only
 *	  call this function when it expects **sp to be either " or '
 *
 *	  On success, returns the decoded string, passes the decoded string's
 *	  length through *length (which must not be NULL), and advances *sp to point
 *	  to the end of string literal (after the closing quote character).
 *
 *	  On failure (parse error), returns NULL and
 *	  leaves *length and *sp untouched.
 */
char *
json_decode_string(const char **sp, size_t *length, bool strict)
{
	const char *s = *sp;
	StringInfoData ret;
	char		buf[4];
	int			len;
	char		quote;

	Assert(length != NULL);

	initStringInfo(&ret);

	quote = *s++;
	if (strict)
	{
		if (quote != '"')
			return NULL;
	}
	else
	{
		if (quote != '"' && quote != '\'')
			return NULL;
	}

	while (*s != '\0' && *s != quote)
	{
		unsigned char c = *s++;
		unsigned int uc;
		unsigned int lc;

		if (c == '\\')
		{
			c = *s++;
			switch (c)
			{
				case '\\':
				case '/':
					break;
				case 'b':
					c = '\b';
					break;
				case 'f':
					c = '\f';
					break;
				case 'n':
					c = '\n';
					break;
				case 'r':
					c = '\r';
					break;
				case 't':
					c = '\t';
					break;
				case 'u':
					if (!read_hex16(s, &uc))
						goto failed;
					s += 4;

					if (uc >= 0xD800 && uc <= 0xDFFF)
					{
						/* Handle UTF-16 surrogate pair. */

						if (uc >= 0xDC00)
							goto failed;		/* Second surrogate not
												 * preceded by first
												 * surrogate. */

						if (s[0] != '\\' || s[1] != 'u'
							|| !read_hex16(s + 2, &lc)
							|| !(lc >= 0xDC00 && lc <= 0xDFFF))
							goto failed;		/* First surrogate not
												 * followed by second
												 * surrogate. */

						s += 6;

						uc = 0x10000 + (((uc & 0x3FF) << 10) | (lc & 0x3FF));
					}

					unicode_to_utf8(uc, (unsigned char *) buf);
					len = pg_utf_mblen((unsigned char *) buf);

					Assert(len > 0);

					appendBinaryStringInfo(&ret, buf, len);

					continue;	/* Continue the enclosing while loop to skip
								 * the str_append below. */
				default:		/* Invalid escape */
					if (c == quote)
						break;
					if (!strict && (c == '"' || c == '\''))
						break;
					goto failed;	/* Invalid escape */
			}
		}
		else if (c <= 0x1F)
		{
			/* Control characters not allowed in string literals. */
			goto failed;
		}
		appendStringInfoChar(&ret, c);
	}

	if (*s++ != quote)
		goto failed;

	*length = ret.len;
	*sp = s;
	return ret.data;

failed:
	pfree(ret.data);
	return NULL;
}

/*
 * json_text_type
 *	  Determines the type of a JSON string without fully decoding it.
 *	  Expects the given string to be valid JSON.
 *	  Might return JSON_INVALID if something is wrong with the input.
 */
json_type
json_text_type(const char *str, size_t nbytes)
{
	const char *s = str;
	const char *e = str + nbytes;
	char		c;

	/* Skip whitespace characters. */
	while (s < e && is_whitespace(*s))
		s++;

	/* Get first non-white character, making sure it's in bounds. */
	if (s >= e)
		return JSON_INVALID;
	c = *s;

	switch (c)
	{
		case 'n':
			return JSON_NULL;
		case '"':
			return JSON_STRING;
		case 't':
		case 'f':
			return JSON_BOOL;
		case '{':
			return JSON_OBJECT;
		case '[':
			return JSON_ARRAY;
		default:
			if (c == '-' || (c >= '0' && c <= '9'))
				return JSON_NUMBER;
			return JSON_INVALID;
	}
}


/****************************** Encoding *****************************/

/*
 * encode_string
 *	  Variant of json_encode_string that writes its output to a StringInfo.
 */
static void
encode_string(StringInfo out, const char *string, size_t length, char quote,
			  bool escape_unicode)
{
	const char *s = string;
	const char *e = s + length;

	Assert(quote != '\\');
	if (escape_unicode)
		Assert(utf8_validate(string, length));

	appendStringInfoChar(out, quote);

	while (s < e)
	{
		unsigned char c = *s++;
		unsigned char endchar;

		switch (c)
		{
			case '\\':
				endchar = '\\';
				break;
			case '\b':
				endchar = 'b';
				break;
			case '\f':
				endchar = 'f';
				break;
			case '\n':
				endchar = 'n';
				break;
			case '\r':
				endchar = 'r';
				break;
			case '\t':
				endchar = 't';
				break;
			default:
				{
					if (c == quote)
					{
						endchar = quote;
						break;
					}
					if (c < 0x1F || (c >= 0x80 && escape_unicode))
					{
						/* Encode using \u.... */
						pg_wchar	uc;
						unsigned int lc;
						char		txt[13];

						s--;
						uc = utf8_decode_char(&s);

						txt[0] = '\\';
						txt[1] = 'u';
						txt[6] = '\\';
						txt[7] = 'u';
						if (uc <= 0xFFFF)
						{
							write_hex16(txt + 2, uc);
							txt[6] = '\0';
						}
						else
						{
							uc -= 0x10000;
							lc = uc & 0x3FF;
							uc = uc >> 10;
							uc |= 0xD800;
							lc |= 0xDC00;
							write_hex16(txt + 2, uc);
							write_hex16(txt + 8, lc);
							txt[12] = '\0';
						}

						appendStringInfoString(out, txt);
						continue;		/* Skip backslash-encoding code below. */
					}
					endchar = '\0';
				}
		}

		appendStringInfoChar(out, endchar ? '\\' : c);
		if (endchar != '\0')
			appendStringInfoChar(out, endchar);
	}

	appendStringInfoChar(out, quote);
}

static bool
encode_number(StringInfo out, const char *string)
{
	const char *s = string;
	const char *start,
			   *end;

	if (string == NULL)
		return false;

	/* Validate number, trimming whitespace. */
	skip_whitespace(&s);
	start = s;
	if (!validate_number(&s))
		return false;
	end = s;
	skip_whitespace(&s);
	if (*s != '\0')
		return false;

	/* Append number to out */
	appendBinaryStringInfo(out, start, end - start);

	return true;
}

typedef struct
{
	StringInfoData str;
	bool		use_orig;
	bool		escape_unicode;
	bool		trim;
}	json_encode_ctx;

static bool json_encode_recurse(JSON * node, json_encode_ctx * ctx);

/*
 * json_encode
 *	  Encode a JSON node.
 *
 *	  The JSONOPT_ESCAPE_UNICODE option may only be used
 *	  if the strings in the JSON tree are UTF-8-encoded.
 */
char *
json_encode(JSON * node, int options)
{
	json_encode_ctx ctx;

	initStringInfo(&ctx.str);
	ctx.use_orig = !!(options & JSONOPT_USE_ORIG);
	ctx.escape_unicode = !!(options & JSONOPT_ESCAPE_UNICODE);
	ctx.trim = !(options & JSONOPT_NO_TRIM);

	if (!json_encode_recurse(node, &ctx))
	{
		pfree(ctx.str.data);
		return NULL;
	}

	return ctx.str.data;
}

static bool
json_encode_recurse(JSON * node, json_encode_ctx * ctx)
{
#define has_orig(field) \
		(use_orig && node->orig.field.start)
#define push_orig(field) \
		appendBinaryStringInfo(&ctx->str, node->orig.field.start, \
							node->orig.field.end - node->orig.field.start)

	bool		use_orig = ctx->use_orig;
	bool		trim = ctx->trim;

	ctx->trim = false;			/* Don't trim internal nodes, just the root
								 * node. */

	if (!trim && has_orig(left_space))
		push_orig(left_space);

	if (has_orig(value))
	{
		push_orig(value);
	}
	else
	{
		const char *txt = NULL;
		JSON	   *child;

		switch (node->type)
		{
			case JSON_NULL:
				txt = "null";
				break;
			case JSON_BOOL:
				if (node->v.v_bool)
					txt = "true";
				else
					txt = "false";
				break;
			case JSON_STRING:
				encode_string(&ctx->str,
							  node->v.string.str, node->v.string.length,
							  '"', ctx->escape_unicode);
				break;
			case JSON_NUMBER:
				if (!encode_number(&ctx->str, node->v.number))
					return false;
				break;
			case JSON_ARRAY:
				appendStringInfoChar(&ctx->str, '[');

				json_foreach(child, node)
				{
					json_encode_recurse(child, ctx);
					if (child->next != NULL)
						appendStringInfoChar(&ctx->str, ',');
				}

				appendStringInfoChar(&ctx->str, ']');
				break;
			case JSON_OBJECT:
				appendStringInfoChar(&ctx->str, '{');

				json_foreach(child, node)
				{
					/*
					 * Shadows the parent node (assigned to the variable
					 * @node) so we can use our macros on the child node
					 * instead. Hurray for lexical scoping!
					 */
					JSON	   *node = child;

					if (has_orig(key_left_space))
						push_orig(key_left_space);

					if (has_orig(key))
						push_orig(key);
					else
						encode_string(&ctx->str, node->key, node->key_length,
									  '"', ctx->escape_unicode);

					if (has_orig(key_right_space))
						push_orig(key_right_space);

					appendStringInfoChar(&ctx->str, ':');

					json_encode_recurse(node, ctx);

					if (node->next != NULL)
						appendStringInfoChar(&ctx->str, ',');
				}

				appendStringInfoChar(&ctx->str, '}');
				break;
			default:
				return false;
		}

		if (txt != NULL)
			appendStringInfoString(&ctx->str, txt);
	}

	if (!trim && has_orig(right_space))
		push_orig(right_space);

	return true;

#undef has_orig
#undef push_orig
}

/*
 * json_encode_string
 *	  If you're interested in encoding JSON in general, see json_encode .
 *
 *	  Encodes a string literal JSON-style using the given quote character.
 *	  Note that using anything but '"' as the quote character will result
 *	  in invalid JSON.
 *
 *	  If escape_unicode is true, str must be valid UTF-8.
 *	  In any case, str may contain null characters (hence the length argument).
 *
 *	  quote must not be a backslash.
 */
char *
json_encode_string(const char *str, size_t length, char quote,
				   bool escape_unicode)
{
	StringInfoData ret;

	initStringInfo(&ret);
	encode_string(&ret, str, length, quote, escape_unicode);

	return ret.data;
}