Grammar & Language
Simple explanation
A grammar describes a language's structure (what an expression looks like); a language is that description packaged as data the parser can run. tree-sitter.zig never hard-codes any programming language — the same engine parses whatever tables you load.
Technical explanation
language/language.zig is the runtime-facing Language struct: metadata, symbol table, token matchers, extras, LR tables, fields, aliases, supertypes, and an optional external scanner. Grammar authors (or generators targeting this runtime) produce those tables; the parser only calls actionFor / gotoState and the matchers. Four table sets ship with the library: the 18-state expression grammar (expression_language, formerly also reachable as test_grammar.test_language), a 12-state s-expression grammar (sexp_language) demonstrating aliases, a 27-state JSON grammar (json_language) with key/value fields, and a 21-state indentation-sensitive outline grammar (outline_language) demonstrating external scanners. All are used by tests, examples, benchmarks, and the conformance corpus.