Previously, a bare child pattern in a query took whatever the next
child of the iterator was and either matched or failed: it would not
scan ahead to find a match. So `(foo ("baz"))` against a `foo` whose
implicit `child` field was `["bar", "baz"]` would fail (the pattern
took "bar" first).
Switch to forward-scan semantics: a SingleNode matcher advances through
the iterator until it finds a child that matches its sub-query. Patterns
that are named-only continue to skip past unnamed children for free.
Order is preserved across multiple bare patterns at the same level —
each pattern advances the shared iterator past whatever it consumed —
so a query cannot match children out of source order.
Captures from a failed match attempt are rolled back via a snapshot, so
partial captures from a complex sub-query do not leak across attempts.
Add two regression tests against the `do` body wrapper in a Ruby
for-loop, whose implicit `child` field contains [do, identifier, end]:
- a query for ("end") matches by skipping past `do` and the identifier
- a query for ("end") then ("do") fails, demonstrating order preservation
Schema::from_language registered unnamed kinds via or_insert(id), where
`id` came from iterating 0..node_kind_count. For names with multiple
unnamed IDs (notably "end" in tree-sitter-ruby has IDs 0 and 13, where
ID 0 is the reserved error token), this picked the first encountered
ID — typically the wrong one.
The visitor sets node.kind via language.id_for_node_kind(name, false),
which returns the canonical ID. So a query for ("end") would compare
node.kind=13 against schema=0 and silently fail to match, with no
diagnostic.
Use language.id_for_node_kind(name, false) to obtain the canonical ID
when registering, mirroring the named-kind path that already does the
same with id_for_node_kind(name, true).
Three improvements to the query parser, all aimed at allowing query
patterns to refer to unnamed tokens:
1. Bare-literal capture: `"=" @op` now captures the unnamed `=` token,
matching the parenthesized form `("=") @op`. Previously the literal
branch in parse_query_list skipped the maybe_wrap_capture call, so
the `@op` was a leftover token and would error.
2. Bare `_` matches any node, named or unnamed. Previously bare `_` and
`(_)` both produced QueryNode::Any with the same matches_named_only
behaviour, so bare `_` would skip unnamed children. Now Any carries a
match_unnamed flag: false for `(_)` (named-only, tree-sitter default)
and true for bare `_` (any node).
3. Named fields and bare child patterns may be intermixed in any order.
Previously, once parse_query_fields saw a bare pattern it would stop
accepting named fields. The fix accumulates bare patterns into the
implicit `child` field and keeps parsing.
Each named field independently selects its target field for matching, so
the source-order of fields in the query is purely cosmetic and intermixing
is safe.
Add tests covering parenthesized capture, bare-literal capture, and the
named-vs-any distinction between `(_)` and bare `_`. Update query-syntax
docs to reflect all three.
Extend the desugaring config from a single flat list of rules to an
ordered sequence of named Phases. Each phase runs to completion (a
full traversal applying its rules) before the next phase starts.
Rules in different phases never compete for matches.
The config is built via the new chainable API:
DesugaringConfig::new()
.add_phase("cleanup", cleanup_rules)
.add_phase("desugar", desugar_rules)
.with_output_node_types_yaml(yaml);
Single-phase configs are just .add_phase(...) called once.
A single FreshScope is shared across phases so generated identifier
names (e.g. $tmp-N) are unique throughout the run.
Phase names appear in error messages, e.g. "Phase `desugar`:
exceeded maximum rewrite depth".
Add two regression tests: one verifying basic two-phase chained
desugaring, and one verifying that errors include the failing phase
name.
