[OPEN-ILS-DEV] JSON: retire old parser?

[Scott McKellar]

The file osrf_json_parser.c implements a JSON parser that we don't use any more.  Is there any objection to getting rid of it?

The most important function in this file is jsonParseString(), which parses a JSON string and produces a jsonObject to represent its structure.  There are also two variants: jsonParseStringRaw() and jsonParseStringFmt(), and a number of other functions that are only used internally.

This parser is designed internally as an incremental parser, parsing a stream of JSON one chunk at a time.  In practice it has always been used to parse an entire JSON string at one go; its incremental aspect, so far as I know, has never been used.

We now use a different parser, based on recursive descent, implemented in osrf_parse_json.c.  The newer parser is faster, and much better at catching syntax errors.

We also have a separate parser in jsonpush.c for parsing incrementally.  So far we haven't had a need for it, but if (for example) we ever want to parse a large JSON file without loading it all into memory, we can do so.

For some months now, nothing outside of osrf_json_parser.c (the old parser) has made any calls to the old parser.  It's dead code.

Accordingly I propose to remove osrf_json_parser.c from the Makefiles, and remove its function prototypes from the relevant header files.  We don't need to remove it from the repository; we can keep it around as a historical relic, though we should probably add a prominent comment pointing out its defunctness.

Another question is one of timing: should we include these changes in v2.0?  I don't greatly care one way or the other, myself.  The old dead code is harmless enough, apart from the clutter and the potential for confusion.  I could understand a reluctance to make unnecessary changes just before a major release.

(Note: there is an even older parser in osrf_legacy_json.c, which parses a JSON-like format that includes comments.  It's used only in the gateway, and is not yet small enough to be drowned in the bathtub.  I mention it only to clarify that I'm not proposing to do anything to it.)

Scott McKellar