wa_parser

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A WebAssembly binary format parser for the Erlang ecosystem, written in Erlang. It parses a .wasm binary into a flat sequence of parse events — no dependencies beyond kernel and stdlib.

This is the Erlang package. Elixir projects can depend on it directly, or use the companion wa_parser_ex package for an idiomatic Elixir API.

Installation (rebar3)

%% rebar.config
{deps, [{wa_parser, "~> 0.1"}]}.

Usage

{ok, Bin} = file:read_file("module.wasm"),
Events = wa_parser:events(Bin).

events/1 returns the full list of parse events. Each event is one of:

  • {magic, Bin} / {version, Bin} — the 8-byte header
  • {section_id, Id} / {section_type, Type} / {section_length, Len}
  • {section_body, Body} — the decoded section contents

For incremental parsing, parse/1 returns {ok, {Event, Rest, NextFun}} — the continuation the event list is built on.

Malformed input raises erlang:error({parse_error, Reason, DetailBin}), where Reason is a stable atom for programmatic matching (bad_magic, bad_version, unknown_section, unknown_opcode, truncated, non_canonical, section_truncated, unconsumed_section_bytes, unknown_type) and DetailBin is human-readable context.

Supported features

Parses all standard WASM sections (type, import, function, table, memory, global, export, start, element, code, data, data_count, tag, custom including the name subsection) and the full instruction set: control flow, locals/globals, direct/indirect/tail calls, i32/i64/f32/f64 numerics, memory load/store, reference types, SIMD (0xFD), GC (0xFB), atomics/threads (0xFE), bulk memory (0xFC), and exception handling (try_table, throw, throw_ref).

License

Released into the public domain under the Unlicense.