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simontran7
64ce58dd64
Fixes the malformed parse tree produced for an invalid let struct
pattern containing a single identifier (e.g., `let {s};`).
As pointed out by @DavidLoftus, the parser should produce a parse tree
similar to that of `let {ref s};`, since both are missing a binding
power operator `:`, and both do not have a `.` preceding the identifier
(i.e., `state.in_field_shorthand_pattern == true`).
This means that the parser can produce an the `InvalidParse` node just
as it does for `let {ref s};`.
Closes #7674
97 lines
3.8 KiB
C++
97 lines
3.8 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#include "toolchain/parse/context.h"
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#include "toolchain/parse/handle.h"
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namespace Carbon::Parse {
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auto HandlePattern(Context& context) -> void {
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auto state = context.PopState();
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switch (context.PositionKind()) {
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case Lex::TokenKind::OpenParen:
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context.PushStateForPattern(
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StateKind::PatternListAsTuple, state.in_var_pattern,
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state.in_unused_pattern, state.in_field_shorthand_pattern,
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state.binding_context, state.ambient_precedence);
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break;
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case Lex::TokenKind::OpenCurlyBrace:
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context.PushStateForPattern(
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StateKind::PatternListAsStruct, state.in_var_pattern,
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state.in_unused_pattern, state.in_field_shorthand_pattern,
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state.binding_context, state.ambient_precedence);
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break;
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case Lex::TokenKind::Var:
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context.PushStateForPattern(
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StateKind::VariablePattern, state.in_var_pattern,
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state.in_unused_pattern, state.in_field_shorthand_pattern,
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state.binding_context, state.ambient_precedence);
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break;
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case Lex::TokenKind::Unused:
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context.PushStateForPattern(
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StateKind::UnusedPattern, state.in_var_pattern,
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state.in_unused_pattern, state.in_field_shorthand_pattern,
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state.binding_context, state.ambient_precedence);
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break;
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case Lex::TokenKind::Template:
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case Lex::TokenKind::Generic:
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case Lex::TokenKind::Runtime:
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case Lex::TokenKind::Ref:
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// `self` is always a binding, even when its type is omitted (and so is not
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// followed by a `:`).
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case Lex::TokenKind::SelfValueIdentifier:
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context.PushStateForPattern(
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StateKind::BindingPattern, state.in_var_pattern,
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state.in_unused_pattern, state.in_field_shorthand_pattern,
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state.binding_context, state.ambient_precedence);
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break;
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default:
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if ((context.PositionKind().is_word() &&
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context.PositionKind(Lookahead::NextToken)
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.is_binding_pattern_operator()) ||
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state.in_field_shorthand_pattern) {
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context.PushStateForPattern(
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StateKind::BindingPattern, state.in_var_pattern,
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state.in_unused_pattern, state.in_field_shorthand_pattern,
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state.binding_context, state.ambient_precedence);
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break;
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}
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context.PushStateForPattern(
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StateKind::ExprPattern, state.in_var_pattern, state.in_unused_pattern,
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state.in_field_shorthand_pattern, state.binding_context,
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state.ambient_precedence);
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context.PushStateForExpr(state.ambient_precedence);
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break;
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}
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}
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auto HandleExprPattern(Context& context) -> void {
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auto state = context.PopState();
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// If we parsed an expression followed by a binding operator, we most likely
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// have a malformed attempt to introduce a binding pattern that we interpreted
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// as an expression pattern, so diagnose that here rather than diagnosing a
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// missing `;` at an outer level.
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if (context.PositionKind().is_binding_pattern_operator()) {
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if (!state.has_error) {
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CARBON_DIAGNOSTIC(ExpectedBindingName, Error,
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"unexpected expression before {0} in binding pattern",
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Lex::TokenKind);
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// TODO: Underline the parsed expression.
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context.emitter().Emit(*context.position(), ExpectedBindingName,
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context.PositionKind());
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state.has_error = true;
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}
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context.Consume();
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// It'd be nice to skip the type expression here too, but we can't determine
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// the end of it.
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}
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if (state.has_error) {
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context.ReturnErrorOnState();
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}
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}
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} // namespace Carbon::Parse
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