gdck-syntax

A lossless lexer and parser for GDScript.

Part of gdck, but usable on its own.

What "lossless" means here

Every byte of the source lives in exactly one token, and every token lives in the tree. The input is always exactly recoverable:

let tree = gdck_syntax::parse(source);
assert_eq!(tree.text(), source);

That holds for whitespace, comments and blank lines, and it holds for files with syntax errors too. Parsing never fails — malformed input produces SyntaxKind::Error nodes and entries in tree.errors(), so tools can report several problems per run and editors can work with a half-typed buffer.

This is what a formatter needs (rewrite one declaration, leave the comments around it alone) and what an editor needs (a tree for every keystroke).

Example

use gdck_syntax::{SyntaxKind, SyntaxNode};

let tree = gdck_syntax::parse("@export var health: int = 100\n");

for node in tree.root().descendants() {
    if node.kind() == SyntaxKind::VarDecl {
        println!("{:?} at {}", node.text(), node.range());
    }
}

Handled

Full GDScript 4 declaration and expression grammar: annotations, class_name, extends, signals, enums, constants, static and @abstract members, inner classes, property accessors, typed and inferred variables, variadic parameters, lambdas including multi-line ones inside brackets, match patterns with bindings and rest markers, and every literal form ($Node/Path, %Unique, &"StringName", ^"NodePath", raw and triple-quoted strings, all number bases).

Validated against the 324 valid .gd files in godot-gdscript-toolkit's test suites, and round-trips all 353 files there.

Not a validator

This parser is built to understand well-formed code, not to reject every invalid program. It is more permissive than Godot in places. Godot remains the authority on what actually compiles.

License