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Benoit Blanchon
2014-01-10 16:55:12 +01:00
commit 49f5843788
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69
ArduinoJsonParser.h Normal file
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/*
* 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

255
utility/jsmn.cpp Normal file
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#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;
}

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utility/jsmn.h Normal file
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#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_ */