SLQ Grammar

The query language used by sq is formally known as SLQ. The grammar is defined in SLQ.g4, which is an ANTLR4 grammar.

There's a bunch of valid sample input in the testdata dir.

The antlr4 tool generates the parser / lexer files from the grammar. Being that antlr4 is Java-based, Java must be installed to regenerate from the grammar. The process is encapsulated in generate.sh (or execute go generate ./...).

The generated .go files ultimately end up in package libsq/ast/internal/slq. Files in this directory should not be directly edited.

The libsq/ast.Parse function takes a SLQ input string and returns an *ast.AST. The entrypoint that accepts the SLQ string is libsq.ExecuteSLQ, which ultimately invokes ast.Parse.

Working with the grammar

You probably should install the antlr tools.

pip install antlr4-tools

You may also find antlr4ts useful.

npm install antlr4ts

And there are various IDE plugins available.

In particular, note the VS Code extension.