Re: [PATCH v3 2/7] json-parser: replace with a push parser

[Markus Armbruster <armbru@redhat.com>]

Paolo Bonzini <pbonzini@redhat.com> writes:

> In order to avoid stashing all the tokens corresponding to a JSON value,
> embed the parsing stack and state machine in JSONParser.  This is more
> efficient and allows for more prompt error recovery; it also does not
> make the code substantially larger than the current recursive descent
> parser, though the state machine is probably a bit harder to follow.
>
> The stack consists of QLists and QDicts corresponding to open
> brackets and braces, plus optionally a QString with the current
> key on top of each QDict.
>
> After each value is parsed, it is added to the top array or dictionary
> or, if the stack is empty, json_parser_feed returns the complete
> QObject.
>
> For now, json-streamer.c keeps tracking the tokens up until braces
> and brackets are balanced, and then shoves the whole queue of tokens
> into the push parser.  The only logic change is that JSON_END_OF_INPUT
> always triggers the emptying of the queue; the parser takes notice and
> checks that there is nothing on the stack.  Not using brace_count
> and bracket_count for this is the first step towards improved separation
> of concerns between json-parser.c and json-streamer.c.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

[...]

> diff --git a/qobject/json-parser-int.h b/qobject/json-parser-int.h
> index 8c01f236276..1f435cb8eb2 100644
> --- a/qobject/json-parser-int.h
> +++ b/qobject/json-parser-int.h
> @@ -49,6 +49,9 @@ void json_message_process_token(JSONLexer *lexer, GString *input,
>  
>  /* json-parser.c */
>  JSONToken *json_token(JSONTokenType type, int x, int y, GString *tokstr);
> -QObject *json_parser_parse(GQueue *tokens, va_list *ap, Error **errp);
> +void json_parser_init(JSONParserContext *ctxt, va_list *ap);
> +void json_parser_reset(JSONParserContext *ctxt);
> +QObject *json_parser_feed(JSONParserContext *ctxt, const JSONToken *token, Error **errp);

checkpatch WARNING: line over 80 characters.  It's just a warning, but
the line is *really* easy to break.

> +void json_parser_destroy(JSONParserContext *ctxt);
>  
>  #endif

[...]