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Add initial support for parsing struct patterns (#7446)

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Implements parsing of struct patterns as per
https://github.com/carbon-language/carbon-lang/issues/6680.

This handles the full and short syntax given in the [design
doc](https://github.com/carbon-language/carbon-lang/blob/trunk/docs/design/pattern_matching.md#struct-patterns),
but the handling of the shorthand syntax may need to change as I move on
to implementing Check support (currently the shorthand is represented as
one of `LetBindingPattern`, `VarBindingPattern`, or `VariablePattern`).

This implementation assumes that the answer to
https://github.com/carbon-language/carbon-lang/issues/7404 is that
trailing commas are allowed in the struct pattern, except for the case
where an `_` is present, in which case the next token must be the
closing brace `}`.
This commit is contained in:
oli-ej
2026-07-30 16:37:46 +00:00
committed by GitHub
parent 8f224222a1
commit a683fb574b
21 changed files with 1999 additions and 57 deletions
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toolchain/parse/handle_pattern.cpp
+28 -19
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@@ -11,22 +11,28 @@ auto HandlePattern(Context& context) -> void {
auto state = context.PopState();
switch (context.PositionKind()) {
case Lex::TokenKind::OpenParen:
context.PushStateForPattern(StateKind::PatternListAsTuple,
state.in_var_pattern, state.in_unused_pattern,
state.binding_context,
state.ambient_precedence);
context.PushStateForPattern(
StateKind::PatternListAsTuple, state.in_var_pattern,
state.in_unused_pattern, state.in_field_shorthand_pattern,
state.binding_context, state.ambient_precedence);
break;
case Lex::TokenKind::OpenCurlyBrace:
context.PushStateForPattern(
StateKind::PatternListAsStruct, state.in_var_pattern,
state.in_unused_pattern, state.in_field_shorthand_pattern,
state.binding_context, state.ambient_precedence);
break;
case Lex::TokenKind::Var:
context.PushStateForPattern(StateKind::VariablePattern,
state.in_var_pattern, state.in_unused_pattern,
state.binding_context,
state.ambient_precedence);
context.PushStateForPattern(
StateKind::VariablePattern, state.in_var_pattern,
state.in_unused_pattern, state.in_field_shorthand_pattern,
state.binding_context, state.ambient_precedence);
break;
case Lex::TokenKind::Unused:
context.PushStateForPattern(StateKind::UnusedPattern,
state.in_var_pattern, state.in_unused_pattern,
state.binding_context,
state.ambient_precedence);
context.PushStateForPattern(
StateKind::UnusedPattern, state.in_var_pattern,
state.in_unused_pattern, state.in_field_shorthand_pattern,
state.binding_context, state.ambient_precedence);
break;
case Lex::TokenKind::Template:
case Lex::TokenKind::Generic:
@@ -35,10 +41,10 @@ auto HandlePattern(Context& context) -> void {
// `self` is always a binding, even when its type is omitted (and so is not
// followed by a `:`).
case Lex::TokenKind::SelfValueIdentifier:
context.PushStateForPattern(StateKind::BindingPattern,
state.in_var_pattern, state.in_unused_pattern,
state.binding_context,
state.ambient_precedence);
context.PushStateForPattern(
StateKind::BindingPattern, state.in_var_pattern,
state.in_unused_pattern, state.in_field_shorthand_pattern,
state.binding_context, state.ambient_precedence);
break;
default:
if (context.PositionKind().is_word() &&
@@ -46,11 +52,14 @@ auto HandlePattern(Context& context) -> void {
.is_binding_pattern_operator()) {
context.PushStateForPattern(
StateKind::BindingPattern, state.in_var_pattern,
state.in_unused_pattern, state.binding_context,
state.ambient_precedence);
state.in_unused_pattern, state.in_field_shorthand_pattern,
state.binding_context, state.ambient_precedence);
break;
}
context.PushState(StateKind::ExprPattern);
context.PushStateForPattern(
StateKind::ExprPattern, state.in_var_pattern, state.in_unused_pattern,
state.in_field_shorthand_pattern, state.binding_context,
state.ambient_precedence);
context.PushStateForExpr(state.ambient_precedence);
break;
}