Zua

An attempt at a Lua 5.1 implementation in Zig.

Goals, in order of priority:

1. Learn more about Lua internals
2. Learn more about Zig
3. Anything else

Status

• Lexer (llex.c/.h) -> lex.zig
  • Keywords
  • Identifiers
  • .., ...
  • ==, >=, <=, ~=
  • String literals (single/double quoted and multi-line ([[))
  • Comments (-- and --[[)
  • Numbers
  • Improve tests, perhaps use fuzz testing
    • See Fuzzing As a Test Case Generator and squeek502/fuzzing-lua
  • Cleanup implementation
• String parsing (in Lua this was done at lex-time) -> parse_literal.zig (see 4324bd0 for more details)
• Number parsing (in Lua this was done at lex-time) -> parse_literal.zig
  • Basic number parsing
  • Proper strtod-compatible number parsing implementation
• Parser (lparser.c/.h) (in Lua this was done as one step with no AST intermediate)
  • Parsing tokens into an AST -> parse.zig (mostly done, needs some more testing/cleanup)
  • Compiling the AST into bytecode -> compiler.zig
• …

Why Lua 5.1?

It’s what I’m most familiar with, and I’m also assuming that 5.1 is simpler internally than more recent Lua versions.

Building / running

• zig build to build zua.exe
• zig build test to build & run the main test suite
• zig build run to build & run zua.exe (does nothing right now)
• zig build lua51_tests to run tests on the PUC Lua 5.1 test files (currently it just tests parsing them)
• zig build fuzzed_lex to run lexer tests on a large set of inputs/outputs generated by fuzzing-lua
• zig build bench_lex to run a benchmark of the lexer (this benchmark needs improvement)
• zig build fuzzed_strings to run string parsing tests on a set of inputs/outputs generated by fuzzing-lua