jsmn.c

/*
 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 "jsmn.h"

/**
 * Allocates a fresh unused token from the token pull.
 */
static jsmntok_t *jsmn_alloc_token(jsmn_parser *parser,
		jsmntok_t *tokens, size_t 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 int jsmn_parse_primitive(jsmn_parser *parser, const char *js,
		size_t len, jsmntok_t *tokens, size_t num_tokens) {
	jsmntok_t *token;
	int start;

	start = parser->pos;

	for (; parser->pos < len && 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;
		}
		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:
	if (tokens == NULL) {
		parser->pos--;
		return 0;
	}
	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 0;
}

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

	int start = parser->pos;

	parser->pos++;

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

		/* Quote: end of string */
		if (c == '\"') {
			if (tokens == NULL) {
				return 0;
			}
			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 0;
		}

		/* Backslash: Quoted symbol expected */
		if (c == '\\' && parser->pos + 1 < len) {
			int i;
			parser->pos++;
			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':
					parser->pos++;
					for(i = 0; i < 4 && parser->pos < len && js[parser->pos] != '\0'; i++) {
						/* If it isn't a hex character we have an error */
						if(!((js[parser->pos] >= 48 && js[parser->pos] <= 57) || /* 0-9 */
									(js[parser->pos] >= 65 && js[parser->pos] <= 70) || /* A-F */
									(js[parser->pos] >= 97 && js[parser->pos] <= 102))) { /* a-f */
							parser->pos = start;
							return JSMN_ERROR_INVAL;
						}
						parser->pos++;
					}
					parser->pos--;
					break;
				/* Unexpected symbol */
				default:
					parser->pos = start;
					return JSMN_ERROR_INVAL;
			}
		}
	}
	parser->pos = start;
	return JSMN_ERROR_PART;
}

/**
 * Parse JSON string and fill tokens.
 */
int jsmn_parse(jsmn_parser *parser, const char *js, size_t len,
		jsmntok_t *tokens, unsigned int num_tokens) {
	int r;
	int i;
	jsmntok_t *token;
	int count = parser->toknext;

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

		c = js[parser->pos];
		switch (c) {
			case '{': case '[':
				count++;
				if (tokens == NULL) {
					break;
				}
				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 ']':
				if (tokens == NULL)
					break;
				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, len, tokens, num_tokens);
				if (r < 0) return r;
				count++;
				if (parser->toksuper != -1 && tokens != NULL)
					tokens[parser->toksuper].size++;
				break;
			case '\t' : case '\r' : case '\n' : case ' ':
				break;
			case ':':
				parser->toksuper = parser->toknext - 1;
				break;
			case ',':
				if (tokens != NULL && parser->toksuper != -1 &&
						tokens[parser->toksuper].type != JSMN_ARRAY &&
						tokens[parser->toksuper].type != JSMN_OBJECT) {
#ifdef JSMN_PARENT_LINKS
					parser->toksuper = tokens[parser->toksuper].parent;
#else
					for (i = parser->toknext - 1; i >= 0; i--) {
						if (tokens[i].type == JSMN_ARRAY || tokens[i].type == JSMN_OBJECT) {
							if (tokens[i].start != -1 && tokens[i].end == -1) {
								parser->toksuper = i;
								break;
							}
						}
					}
#endif
				}
				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' :
				/* And they must not be keys of the object */
				if (tokens != NULL && parser->toksuper != -1) {
					jsmntok_t *t = &tokens[parser->toksuper];
					if (t->type == JSMN_OBJECT ||
							(t->type == JSMN_STRING && t->size != 0)) {
						return JSMN_ERROR_INVAL;
					}
				}
#else
			/* In non-strict mode every unquoted value is a primitive */
			default:
#endif
				r = jsmn_parse_primitive(parser, js, len, tokens, num_tokens);
				if (r < 0) return r;
				count++;
				if (parser->toksuper != -1 && tokens != NULL)
					tokens[parser->toksuper].size++;
				break;

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

	if (tokens != NULL) {
		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 count;
}

/**
 * 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->toknext = 0;
	parser->toksuper = -1;
}