jsmn.c

/*
 * jsmn.c
 * Simple JSON parser
 *
 * Copyright (c) 2010 Serge A. Zaitsev
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include <stdlib.h>

#include "jsmn.h"

/**
 * Allocates a fresh unused token from the token pull.
 */
static jsmntok_t *jsmn_alloc_token(jsmn_parser *parser,
		jsmntok_t *tokens, int num_tokens) {
	jsmntok_t *tok;
	if (parser->toknext >= num_tokens) {
		return NULL;
	}
	tok = &tokens[parser->toknext++];
	tok->start = tok->end = -1;
	tok->size = 0;
#ifdef JSMN_PARENT_LINKS
	tok->parent = -1;
#endif
	return tok;
}

/**
 * Fills token type and boundaries.
 */
static void jsmn_fill_token(jsmntok_t *token, jsmntype_t type,
                            int start, int end) {
	token->type = type;
	token->start = start;
	token->end = end;
	token->size = 0;
}

/**
 * Fills next available token with JSON primitive.
 */
static jsmnerr_t jsmn_parse_primitive(jsmn_parser *parser, const char *js,
		jsmntok_t *tokens, int num_tokens) {
	jsmntok_t *token;
	int start;

	start = parser->pos;

	for (; (parser->end > 0 && parser->pos < parser->end) && js[parser->pos] != '\0'; parser->pos++) {
		switch (js[parser->pos]) {
#ifndef JSMN_STRICT
			/* In strict mode primitive must be followed by "," or "}" or "]" */
			case ':':
#endif
			case '\t' : case '\r' : case '\n' : case ' ' :
			case ','  : case ']'  : case '}' :
				goto found;
			default:
				break;
		}
		if (js[parser->pos] < 32 || js[parser->pos] >= 127) {
			parser->pos = start;
			return JSMN_ERROR_INVAL;
		}
	}
#ifdef JSMN_STRICT
	/* In strict mode primitive must be followed by a comma/object/array */
	parser->pos = start;
	return JSMN_ERROR_PART;
#endif

found:
	token = jsmn_alloc_token(parser, tokens, num_tokens);
	if (token == NULL) {
		parser->pos = start;
		return JSMN_ERROR_NOMEM;
	}
	jsmn_fill_token(token, JSMN_PRIMITIVE, start, parser->pos);
#ifdef JSMN_PARENT_LINKS
	token->parent = parser->toksuper;
#endif
	parser->pos--;
	return JSMN_SUCCESS;
}

/**
 * Fills next token with JSON string.
 */
static jsmnerr_t jsmn_parse_string(jsmn_parser *parser, const char *js,
		jsmntok_t *tokens, int num_tokens) {
	jsmntok_t *token;

	int start = parser->pos;

	parser->pos++;

	/* Skip starting quote */
	for (; (parser->end > 0 && parser->pos < parser->end) && js[parser->pos] != '\0'; parser->pos++) {
		char c = js[parser->pos];

		/* Quote: end of string */
		if (c == '\"') {
			token = jsmn_alloc_token(parser, tokens, num_tokens);
			if (token == NULL) {
				parser->pos = start;
				return JSMN_ERROR_NOMEM;
			}
			jsmn_fill_token(token, JSMN_STRING, start+1, parser->pos);
#ifdef JSMN_PARENT_LINKS
			token->parent = parser->toksuper;
#endif
			return JSMN_SUCCESS;
		}

		/* Backslash: Quoted symbol expected */
		if (c == '\\') {
			parser->pos++;
			if (parser->end > 0 && parser->pos >= parser->end) {
				parser->pos = start;
				return JSMN_ERROR_INVAL;
			}
			switch (js[parser->pos]) {
				/* Allowed escaped symbols */
				case '\"': case '/' : case '\\' : case 'b' :
				case 'f' : case 'r' : case 'n'  : case 't' :
					break;
				/* Allows escaped symbol \uXXXX */
				case 'u':
					/* TODO */
					break;
				/* Unexpected symbol */
				default:
					parser->pos = start;
					return JSMN_ERROR_INVAL;
			}
		}
	}
	parser->pos = start;
	return JSMN_ERROR_PART;
}

/**
 * Parse JSON string and fill tokens.
 */
jsmnerr_t jsmn_parse(jsmn_parser *parser, const char *js, unsigned int length, jsmntok_t *tokens,
		unsigned int num_tokens) {
	jsmnerr_t r;
	int i;
	jsmntok_t *token;

	parser->end = length;

	for (; (parser->end > 0 && parser->pos < parser->end) && js[parser->pos] != '\0'; parser->pos++) {
		char c;
		jsmntype_t type;

		c = js[parser->pos];
		switch (c) {
			case '{': case '[':
				token = jsmn_alloc_token(parser, tokens, num_tokens);
				if (token == NULL)
					return JSMN_ERROR_NOMEM;
				if (parser->toksuper != -1) {
					tokens[parser->toksuper].size++;
#ifdef JSMN_PARENT_LINKS
					token->parent = parser->toksuper;
#endif
				}
				token->type = (c == '{' ? JSMN_OBJECT : JSMN_ARRAY);
				token->start = parser->pos;
				parser->toksuper = parser->toknext - 1;
				break;
			case '}': case ']':
				type = (c == '}' ? JSMN_OBJECT : JSMN_ARRAY);
#ifdef JSMN_PARENT_LINKS
				if (parser->toknext < 1) {
					return JSMN_ERROR_INVAL;
				}
				token = &tokens[parser->toknext - 1];
				for (;;) {
					if (token->start != -1 && token->end == -1) {
						if (token->type != type) {
							return JSMN_ERROR_INVAL;
						}
						token->end = parser->pos + 1;
						parser->toksuper = token->parent;
						break;
					}
					if (token->parent == -1) {
						break;
					}
					token = &tokens[token->parent];
				}
#else
				for (i = parser->toknext - 1; i >= 0; i--) {
					token = &tokens[i];
					if (token->start != -1 && token->end == -1) {
						if (token->type != type) {
							return JSMN_ERROR_INVAL;
						}
						parser->toksuper = -1;
						token->end = parser->pos + 1;
						break;
					}
				}
				/* Error if unmatched closing bracket */
				if (i == -1) return JSMN_ERROR_INVAL;
				for (; i >= 0; i--) {
					token = &tokens[i];
					if (token->start != -1 && token->end == -1) {
						parser->toksuper = i;
						break;
					}
				}
#endif
				break;
			case '\"':
				r = jsmn_parse_string(parser, js, tokens, num_tokens);
				if (r < 0) return r;
				if (parser->toksuper != -1)
					tokens[parser->toksuper].size++;
				break;
			case '\t' : case '\r' : case '\n' : case ':' : case ',': case ' ':
				break;
#ifdef JSMN_STRICT
			/* In strict mode primitives are: numbers and booleans */
			case '-': case '0': case '1' : case '2': case '3' : case '4':
			case '5': case '6': case '7' : case '8': case '9':
			case 't': case 'f': case 'n' :
#else
			/* In non-strict mode every unquoted value is a primitive */
			default:
#endif
				r = jsmn_parse_primitive(parser, js, tokens, num_tokens);
				if (r < 0) return r;
				if (parser->toksuper != -1)
					tokens[parser->toksuper].size++;
				break;

#ifdef JSMN_STRICT
			/* Unexpected char in strict mode */
			default:
				return JSMN_ERROR_INVAL;
#endif

		}
	}

	for (i = parser->toknext - 1; i >= 0; i--) {
		/* Unmatched opened object or array */
		if (tokens[i].start != -1 && tokens[i].end == -1) {
			return JSMN_ERROR_PART;
		}
	}

	return JSMN_SUCCESS;
}

/**
 * Creates a new parser based over a given  buffer with an array of tokens
 * available.
 */
void jsmn_init(jsmn_parser *parser) {
	parser->pos = 0;
	parser->end = 0;
	parser->toknext = 0;
	parser->toksuper = -1;
}