Yet another XML Parser

This parser was built with two main goals:

• binary parsing

• Namespace specific parsing

It uses the parser_pt parse transform (aka don't write these) for writing the actual parser.

Components

• src/parser_pt.erl Will generate simple parsers from a specification embedded in the erlang code.

• src/exemell.erl The main XML Parser, the parser is strickly whitespace preserving.

• src/exemellp.erl Xml output, no pretty printing, and behaviour for xml serializable things. Defines Module:xml(exemellp:state(),Module()) -> iolist(), and provides xml(tag(),[{tag(),iolist()}],[child()],exemellp:state()) -> iolist() as the preferred way of implementing the callback.

• src/exemell_parser.erl behaviour for parser callback modules (and default implementation)

• src/exemell_namespace.erl behaviour for namespace callback and implementation of the none namespace.

• src/exemell_namespace_xml.erl implementation of the xml: namespace.

• src/exemell_block.erl and src/exemell_blob.erl callbacks (and default implementations) for the block creation.

• include/xml.hrl Defines the record generated by the parser when reverting to pseudo DOM mode.

• include/exemell.hrl Exposes the internal state of full parser, useful if you wish to set your own entity handling, meta handling or p.i. handling (or even to rewire the namespace handling).

• src/parser.hrl The actual XML parser used by exemell.erl. The parser is not for the faint of heart but should make it obvious how to use parser_pt.erl.

Performance

It's not the fastest parser out there, but its reasonably fast a very rough test places the parser at about:

• ~10% slower then erlsom
• twice as fast as xmerl As with any performance rating, take them with a lot of salt, and do your own measurements.

Caviats

• No validation other then basic wellformedness is done (the parser will silently ignore missing close tags)
• The parser is hard coded to UTF8 encoding
• Other than sanity checking there's no testing done.
• Not all features are implemented yet (particularly skip and blob are not implemented).
• There is an unavoidable warning about an undefined behaviour exemell (erlc is not favourable to self referentiality).

Todos

• Proper test cases, the modules are type annotated and dialyzer seems happy enough.
• Figure out how to make dialyzer like a polymorphic version of the module.

Benchmark

A simple parsing benchmark is included, though its results are likely meaningless for practical purposes. Enter the path(s)s to your favourite example XML in to test/exemell_bennchmar.erl and then make benchmark. To include erlsom in the benchmark uncomment the dependency in rebar.config and make dependencies; make all.