support for comments

[yueswing07]

there is many situations need read configure file has annotation
i have test the code

char *s = "{//aa \n \"list\":[{\"name\":\"22xiao hong\",\"age\":10},{\"name\":\"33hua hua\",\"age\":\"11\"}]}";  
    cJSON *root = cJSON_Parse(s);

parse return NULL

[FSMaxB]

Yes, JSON is kind of bad for configuration files because of this. This is why I personally prefer YAML for that, although it requires a much more complex parser.

I can't currently support comments in cJSON, but once #177 is implemented, it could be added as a configuration option.

[nemo20000]

As comments are not part of the JSON standard, this must be optional.

And if we’re listing ‘favourite configuration format that isn’t JSON’, mine is PSON – PostScript Object Notation (which does support comments!).

[FSMaxB]

As comments are not part of the JSON standard, this must be optional.

This would not be enabled by default of course

[mateosss]

Has there been any update on this topic?

[Timmmm]

Here's some code to implement this. It's not configurable, and also not well tested, but you can probably use it if this ever happens (or if people want to patch a local copy).

/* Utility to jump whitespace and cr/lf */
static parse_buffer *buffer_skip_whitespace(parse_buffer * const buffer)
{
    if ((buffer == NULL) || (buffer->content == NULL))
    {
        return NULL;
    }

    enum State {
        Whitespace,
        SingleLineComment,
        MultiLineComment,
    } state = Whitespace;

    while (buffer->offset < buffer->length) {
        char c0 = buffer_at_offset(buffer)[0];
        char c1 = buffer->offset + 1 < buffer->length ? buffer_at_offset(buffer)[1] : '\0';
        switch (state) {
            case Whitespace:
                if (c0 == '/' && c1 == '/') {
                    ++buffer->offset;
                    state = SingleLineComment;
                } else if (c0 == '/' && c1 == '*') {
                    ++buffer->offset;
                    state = MultiLineComment;
                } else if (c0 > 32) {
                    // Not a whitespace character or the start of a comment.
                    goto done;
                }
                break;
            case SingleLineComment:
                if (c0 == '\n') {
                    state = Whitespace;
                }
                break;
            case MultiLineComment:
                if (c0 == '*' && c1 == '/') {
                    ++buffer->offset;
                    state = Whitespace;
                }
                break;
        }
        ++buffer->offset;
    }
done:

    if (buffer->offset == buffer->length)
    {
        buffer->offset--;
    }

    return buffer;
}

I left this last bit even though it looks highly suspect.

    if (buffer->offset == buffer->length)
    {
        buffer->offset--;
    }