ArduinoJson/src/Internals/JsonParser.cpp

#include "ArduinoJson/Internals/JsonParser.hpp"

#include <stdlib.h> // for strtol, strtod
#include <ctype.h>

#include "ArduinoJson/JsonBuffer.hpp"
#include "ArduinoJson/Internals/QuotedString.hpp"

using namespace ArduinoJson::Internals;

void JsonParser::skipSpaces()
{
    while(isspace(*_ptr)) _ptr++;
}

bool JsonParser::skip(char charToSkip)
{
    skipSpaces();
    if (*_ptr != charToSkip) return false;
    _ptr++;
    skipSpaces();
    return true;
}

JsonNode* JsonParser::parseAnything()
{
    skipSpaces();

    switch(*_ptr)
    {
        case '[':
            return parseArray();

        case 't':
        case 'f':
            return parseBoolean();

        case '-':
        case '.':
        case '0':
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
        case '8':
        case '9':
            return parseNumber();

        case 'n':
            return parseNull();

        case '{':
            return parseObject();

        case '\'':
        case '\"':
            return parseString();

        default:
            return NULL; // invalid JSON
    }
}

JsonNode* JsonParser::parseArray()
{
    JsonNode* node = _buffer->createArrayNode();

    skip('[');

    if (isEnd())
        return 0;

    if (skip(']'))
        return node; // empty array

    for(;;)
    {
        JsonNode* child = parseAnything();

        if (!child)
            return 0; // child parsing failed

        node->addChild(child);

        if (skip(']'))
            return node; // end of the array

        if (!skip(','))
            return 0; // comma is missing
    }
}

JsonNode *JsonParser::parseBoolean()
{
    bool value = *_ptr == 't';

    _ptr += value ? 4 : 5;
    // 4 = strlen("true")
    // 5 = strlen("false");

    return _buffer->createBoolNode(value);
}

JsonNode* JsonParser::parseNumber()
{
    char* endOfLong;
    long longValue = strtol(_ptr, &endOfLong, 10);

    if (*endOfLong == '.') // stopped on a decimal separator
    {
        double value = strtod(_ptr, &_ptr);
        int decimals = _ptr - endOfLong - 1;
        return _buffer->createDoubleNode(value, decimals);
    }
    else
    {
        _ptr = endOfLong;
        return _buffer->createLongNode(longValue);
    }
}

JsonNode* JsonParser::parseNull()
{
    _ptr += 4; // strlen("null")

    return _buffer->createStringNode(0);
}

JsonNode* JsonParser::parseObject()
{
    JsonNode* node = _buffer->createObjectNode();

    skip('{');

    if (isEnd())
        return 0; // premature ending

    if (skip('}'))
        return node; // empty object

    for(;;)
    {
        JsonNode* child = parseObjectKeyValue();

        if (!child)
            return 0; // child parsing failed

        node->addChild(child);

        if (skip('}'))
            return node; // end of the object

        if (!skip(','))
            return 0; // comma is missing
    }
}

JsonNode* JsonParser::parseObjectKeyValue()
{
    const char* key = QuotedString::extractFrom(_ptr, &_ptr);

    if (!key)
        return 0; // failed to extract key

    if (!skip(':'))
        return 0; // colon is missing

    JsonNode* value = parseAnything();

    if (!value)
        return 0; // value parsing failed

    return _buffer->createObjectKeyValueNode(key, value);
}

JsonNode* JsonParser::parseString()
{
    const char* s = QuotedString::extractFrom(_ptr, &_ptr);
    return _buffer->createStringNode(s);
}