Initial commit

ArduinoJsonParser.h

@@ -0,0 +1,69 @@
+/*
+ * malloc-free JSON parser for Arduino
+ * Benoit Blanchon 2014
+ * MIT License
+ */
+
+#ifndef __ARDUINOJSONPARSER_H
+#define __ARDUINOJSONPARSER_H
+
+#include <Arduino.h>
+#include "utility/jsmn.h"
+
+template <int N>
+class ArduinoJsonParser
+{
+public:
+
+	ArduinoJsonParser()
+	{
+		jsmn_init(&parser);
+	}
+
+	boolean parse(char* jsonString)
+	{
+		buffer = jsonString;
+
+		int tokenCount = sizeof(tokens) / sizeof(tokens[0]);
+
+		if (JSMN_SUCCESS != jsmn_parse(&parser, jsonString, tokens, tokenCount))
+			return false;
+
+		// Add null termination to each token
+		for (int i = 0; i < tokenCount; i++)
+		{
+			buffer[tokens[i].end] = 0;
+		}
+
+		return true;
+	}
+
+	char* getValue(char* name)
+	{
+		// Scan each keys, every two other token
+		// (skip index 0, because it's the whole json object)
+		for (int i = 1; i < 2 * N; i += 2)
+		{
+			// Early break if we reach the last token
+			if (i >= parser.toknext) break;
+
+			// Get key token string
+			char* key = buffer + tokens[i].start;
+
+			// Compare with desired name, ignoring case
+			if (strcasecmp(name, key) == 0)
+			{
+				return buffer + tokens[i + 1].start;
+			}
+		}
+	}
+
+private:
+
+	char* buffer;
+	jsmn_parser parser;
+	jsmntok_t tokens[N * 2 + 1];
+};
+
+#endif
+

utility/jsmn.cpp

@@ -0,0 +1,255 @@
+#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, 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 jsmnerr_t jsmn_parse_primitive(jsmn_parser *parser, const char *js,
+		jsmntok_t *tokens, size_t num_tokens) {
+	jsmntok_t *token;
+	int start;
+
+	start = parser->pos;
+
+	for (; 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:
+	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;
+}
+
+/**
+ * Filsl next token with JSON string.
+ */
+static jsmnerr_t jsmn_parse_string(jsmn_parser *parser, const char *js,
+		jsmntok_t *tokens, size_t num_tokens) {
+	jsmntok_t *token;
+
+	int start = parser->pos;
+
+	parser->pos++;
+
+	/* Skip starting quote */
+	for (; 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++;
+			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, jsmntok_t *tokens, 
+		unsigned int num_tokens) {
+	jsmnerr_t r;
+	int i;
+	jsmntok_t *token;
+
+	for (; 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->toknext = 0;
+	parser->toksuper = -1;
+}
+

utility/jsmn.h

@@ -0,0 +1,67 @@
+#ifndef __JSMN_H_
+#define __JSMN_H_
+
+/**
+ * JSON type identifier. Basic types are:
+ * 	o Object
+ * 	o Array
+ * 	o String
+ * 	o Other primitive: number, boolean (true/false) or null
+ */
+typedef enum {
+	JSMN_PRIMITIVE = 0,
+	JSMN_OBJECT = 1,
+	JSMN_ARRAY = 2,
+	JSMN_STRING = 3
+} jsmntype_t;
+
+typedef enum {
+	/* Not enough tokens were provided */
+	JSMN_ERROR_NOMEM = -1,
+	/* Invalid character inside JSON string */
+	JSMN_ERROR_INVAL = -2,
+	/* The string is not a full JSON packet, more bytes expected */
+	JSMN_ERROR_PART = -3,
+	/* Everything was fine */
+	JSMN_SUCCESS = 0
+} jsmnerr_t;
+
+/**
+ * JSON token description.
+ * @param		type	type (object, array, string etc.)
+ * @param		start	start position in JSON data string
+ * @param		end		end position in JSON data string
+ */
+typedef struct {
+	jsmntype_t type;
+	int start;
+	int end;
+	int size;
+#ifdef JSMN_PARENT_LINKS
+	int parent;
+#endif
+} jsmntok_t;
+
+/**
+ * JSON parser. Contains an array of token blocks available. Also stores
+ * the string being parsed now and current position in that string
+ */
+typedef struct {
+	unsigned int pos; /* offset in the JSON string */
+	int toknext; /* next token to allocate */
+	int toksuper; /* superior token node, e.g parent object or array */
+} jsmn_parser;
+
+/**
+ * Create JSON parser over an array of tokens
+ */
+void jsmn_init(jsmn_parser *parser);
+
+/**
+ * Run JSON parser. It parses a JSON data string into and array of tokens, each describing
+ * a single JSON object.
+ */
+jsmnerr_t jsmn_parse(jsmn_parser *parser, const char *js, 
+		jsmntok_t *tokens, unsigned int num_tokens);
+
+#endif /* __JSMN_H_ */