JSONPath.c

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/*
 * Objectively: Ultra-lightweight object oriented framework for GNU C.
 * Copyright (C) 2014 Jay Dolan <jay@jaydolan.com>
 *
 * This software is provided 'as-is', without any express or implied
 * warranty. In no event will the authors be held liable for any damages
 * arising from the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 * claim that you wrote the original software. If you use this software
 * in a product, an acknowledgment in the product documentation would be
 * appreciated but is not required.
 *
 * 2. Altered source versions must be plainly marked as such, and must not be
 * misrepresented as being the original software.
 *
 * 3. This notice may not be removed or altered from any source distribution.
 */
 
#include <assert.h>
#include <stdlib.h>
 
#include "Array.h"
#include "Boole.h"
#include "Dictionary.h"
#include "JSONPath.h"
#include "Number.h"
#include "Regexp.h"
#include "String.h"
 
#define _Class _JSONPath
 
#pragma mark - JSONPath
 
static Regexp *_re;
 
static ident objectForKeyPath(const ident root, const char *path) {
 
    assert(root);
    assert(path);
 
    assert(*path == '$');
    const char *c = path;
 
    ident obj = root;
    while (obj) {
 
        Range *matches;
        if ($(_re, matchesCharacters, c, 0, &matches) == false) {
            break;
        }
 
        const uint8_t *bytes = (uint8_t *) c + matches[1].location;
        const size_t length = matches[1].length;
 
        String *segment = $$(String, stringWithBytes, bytes, length, STRING_ENCODING_UTF8);
        if (*segment->chars == '.') {
 
            const Dictionary *dictionary = cast(Dictionary, obj);
            const Range range = { .location = 1, .length = segment->length - 1 };
 
            String *key = $(segment, substring, range);
 
            obj = $(dictionary, objectForKey, key);
 
            release(key);
 
        } else if (*segment->chars == '[') {
 
            const Array *array = cast(Array, obj);
            const unsigned long index = strtoul(segment->chars + 1, NULL, 10);
            if (index < array->count) {
                obj = $(array, objectAtIndex, index);
            } else {
                obj = NULL;
            }
        }
        release(segment);
 
        c += length;
    }
 
    return obj;
}
 
#pragma mark - Class lifecycle
 
static void initialize(Class *clazz) {
 
    ((JSONPathInterface *) clazz->interface)->objectForKeyPath = objectForKeyPath;
 
    _re = re("(.[^.\\[]+|\\[[0-9]+\\])", 0);
}
 
static void destroy(Class *clazz) {
 
    release(_re);
}
 
Class *_JSONPath(void) {
    static Class *clazz;
    static Once once;
 
    do_once(&once, {
        clazz = _initialize(&(const ClassDef) {
            .name = "JSONPath",
            .superclass = _Object(),
            .instanceSize = sizeof(JSONPath),
            .interfaceOffset = offsetof(JSONPath, interface),
            .interfaceSize = sizeof(JSONPathInterface),
            .initialize = initialize,
            .destroy = destroy,
        });
    });
 
    return clazz;
}
 
#undef _Class