mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 22:02:23 +01:00
Burak Emir
80639a02f0
This adds the necessary parser infrastructure to recognize and parse lambda expressions in Carbon. Key changes: - Added and Parse Node Kinds. - Updated to use to accommodate the growing number of node kinds. - Implemented parser states and handlers for lambda syntax ( or ). - Added structure to . - Added diagnostics for missing lambda bodies. - Added a stub in phase to defer semantic analysis using . - Added parser tests for lambdas.
101 lines
3.7 KiB
C++
101 lines
3.7 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 HandleLambdaIntroducer(Context& context) -> void {
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auto state = context.PopState();
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context.AddLeafNode(NodeKind::LambdaIntroducer, context.Consume());
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context.PushState(state, StateKind::LambdaAfterIntroducer);
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}
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auto HandleLambdaAfterIntroducer(Context& context) -> void {
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auto state = context.PopState();
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if (context.PositionIs(Lex::TokenKind::OpenSquareBracket)) {
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context.PushState(state, StateKind::LambdaAfterImplicitParams);
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context.PushState(StateKind::PatternListAsImplicit);
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} else if (context.PositionIs(Lex::TokenKind::OpenParen)) {
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context.PushState(state, StateKind::LambdaAfterParams);
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context.PushState(StateKind::PatternListAsExplicit);
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} else {
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// No implicit or explicit params.
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context.PushState(state, StateKind::LambdaAfterParams);
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}
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}
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auto HandleLambdaAfterImplicitParams(Context& context) -> void {
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auto state = context.PopState();
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if (context.PositionIs(Lex::TokenKind::OpenParen)) {
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context.PushState(state, StateKind::LambdaAfterParams);
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context.PushState(StateKind::PatternListAsExplicit);
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} else {
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// No explicit params after implicit params.
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context.PushState(state, StateKind::LambdaAfterParams);
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}
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}
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auto HandleLambdaAfterParams(Context& context) -> void {
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auto state = context.PopState();
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if (context.PositionIs(Lex::TokenKind::MinusGreater)) {
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// Has return type.
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context.PushState(state, StateKind::LambdaBody);
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context.PushState(StateKind::FunctionReturnTypeFinish);
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context.ConsumeAndDiscard();
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context.PushStateForExpr(PrecedenceGroup::ForType());
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} else if (context.PositionIs(Lex::TokenKind::EqualGreater)) {
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// Terse body `=> expr`
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context.AddLeafNode(NodeKind::TerseBodyArrow, context.Consume());
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context.PushState(state, StateKind::LambdaBodyFinish);
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context.PushStateForExpr(PrecedenceGroup::ForTopLevelExpr());
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} else if (context.PositionIs(Lex::TokenKind::OpenCurlyBrace)) {
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// Block body `{ ... }`
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context.PushState(state, StateKind::LambdaBodyFinish);
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context.PushState(StateKind::CodeBlock);
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} else {
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CARBON_DIAGNOSTIC(ExpectedLambdaBody, Error,
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"expected `->`, `=>`, or `{{`");
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context.emitter().Emit(*context.position(), ExpectedLambdaBody);
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state.has_error = true;
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context.ReturnErrorOnState();
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}
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}
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auto HandleLambdaBody(Context& context) -> void {
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auto state = context.PopState();
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// We arrive here after parsing return type.
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// So we look for `=>` or `{`.
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if (context.PositionIs(Lex::TokenKind::EqualGreater)) {
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// Terse body `=> expr`
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context.AddLeafNode(NodeKind::TerseBodyArrow, context.Consume());
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context.PushState(state, StateKind::LambdaBodyFinish);
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context.PushStateForExpr(PrecedenceGroup::ForTopLevelExpr());
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} else if (context.PositionIs(Lex::TokenKind::OpenCurlyBrace)) {
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// Block body `{ ... }`
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context.PushState(state, StateKind::LambdaBodyFinish);
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context.PushState(StateKind::CodeBlock);
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} else {
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CARBON_DIAGNOSTIC(ExpectedLambdaBodyAfterReturnType, Error,
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"expected `=>` or `{{` after return type");
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context.emitter().Emit(*context.position(),
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ExpectedLambdaBodyAfterReturnType);
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state.has_error = true;
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context.ReturnErrorOnState();
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}
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}
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auto HandleLambdaBodyFinish(Context& context) -> void {
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auto state = context.PopState();
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context.AddNode(NodeKind::Lambda, state.token, state.has_error);
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}
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} // namespace Carbon::Parse
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