Module ast 

Typed AST wrappers over CST nodes.

Each struct wraps a SyntaxNode and provides typed accessors. Cast is infallible for correct SyntaxKind - validation happens elsewhere.

String Lifetime Limitation

SyntaxToken::text() returns &str tied to the token’s lifetime, not to the source &'q str. This is a rowan design: tokens store interned strings, not spans into the original source.

When building data structures that need source-lifetime strings (e.g., SymbolTable<'q>), use token_src instead of token.text().

Structs

AltExpr

Anchor

AnonymousNode

Anonymous node: string literal ("+") or wildcard (_). Maps from CST Str or Wildcard.

Branch

CapturedExpr

Def

FieldExpr

NamedNode

NegatedField

NodePredicate

QuantifiedExpr

Ref

RegexLiteral

Root

SeqExpr

Type

Enums

AltKind

Whether an alternation uses tagged or untagged branches.

Expr

Expression: any pattern that can appear in the tree.

PredicateOp

Predicate operator for node text filtering.

PredicateValue

Predicate value: either a string or a regex pattern.

SeqItem

Either an expression or an anchor in a sequence.

Functions

is_truly_empty_scope

Checks if expression is a truly empty scope (sequence/alternation with no children). Used to distinguish { } @x (empty struct) from {(expr) @_} @x (Node capture).

predicate_op_from_syntax_kind

Convert SyntaxKind to PredicateOp.

token_src

Extracts token text with source lifetime.