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https://github.com/carbon-language/carbon-lang.git
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Jon Ross-Perkins
b42612bcec
I've been thinking about this since we decided to add placeholders in the parse tree. This allows a clearer division of work in check handling, where we were doing work for ExprOpenParen that's only necessary for tuples (splitting/renaming handle_paren.cpp accordingly).
115 lines
3.9 KiB
C++
115 lines
3.9 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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namespace Carbon::Parse {
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auto HandleOnlyParenExpr(Context& context) -> void {
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auto state = context.PopState();
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// Advance past the open paren.
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auto open_paren = context.ConsumeChecked(Lex::TokenKind::OpenParen);
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context.AddLeafNode(NodeKind::ParenExprStart, open_paren);
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state.token = open_paren;
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context.PushState(state, State::OnlyParenExprFinish);
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context.PushState(State::Expr);
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}
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static auto FinishParenExpr(Context& context,
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const Context::StateStackEntry& state) -> void {
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context.AddNode(NodeKind::ParenExpr, context.Consume(), state.subtree_start,
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state.has_error);
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}
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auto HandleOnlyParenExprFinish(Context& context) -> void {
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auto state = context.PopState();
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if (!context.PositionIs(Lex::TokenKind::CloseParen)) {
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if (!state.has_error) {
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CARBON_DIAGNOSTIC(UnexpectedTokenInCompoundMemberAccess, Error,
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"Expected `)`.");
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context.emitter().Emit(*context.position(),
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UnexpectedTokenInCompoundMemberAccess);
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state.has_error = true;
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}
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// Recover from the invalid token.
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context.SkipTo(context.tokens().GetMatchedClosingToken(state.token));
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}
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FinishParenExpr(context, state);
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}
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auto HandleParenExpr(Context& context) -> void {
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auto state = context.PopState();
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// Advance past the open paren. The placeholder will be replaced at the end
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// based on whether we determine this is a tuple or parenthesized expression.
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context.AddLeafNode(NodeKind::Placeholder,
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context.ConsumeChecked(Lex::TokenKind::OpenParen));
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if (context.PositionIs(Lex::TokenKind::CloseParen)) {
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context.PushState(state, State::TupleLiteralFinish);
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} else {
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context.PushState(state, State::ParenExprFinish);
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context.PushState(State::ExprAfterOpenParenFinish);
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context.PushState(State::Expr);
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}
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}
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auto HandleExprAfterOpenParenFinish(Context& context) -> void {
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auto state = context.PopState();
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auto list_token_kind = context.ConsumeListToken(
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NodeKind::TupleLiteralComma, Lex::TokenKind::CloseParen, state.has_error);
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if (list_token_kind == Context::ListTokenKind::Close) {
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return;
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}
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// We found a comma, so switch parent state to tuple handling.
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auto finish_state = context.PopState();
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CARBON_CHECK(finish_state.state == State::ParenExprFinish)
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<< "Unexpected parent state, found: " << finish_state.state;
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context.PushState(finish_state, State::TupleLiteralFinish);
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// If the comma is not immediately followed by a close paren, push handlers
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// for the next tuple element.
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if (list_token_kind != Context::ListTokenKind::CommaClose) {
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context.PushState(state, State::TupleLiteralElementFinish);
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context.PushState(State::Expr);
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}
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}
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auto HandleTupleLiteralElementFinish(Context& context) -> void {
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auto state = context.PopState();
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if (context.ConsumeListToken(NodeKind::TupleLiteralComma,
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Lex::TokenKind::CloseParen, state.has_error) ==
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Context::ListTokenKind::Comma) {
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context.PushState(state);
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context.PushState(State::Expr);
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}
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}
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auto HandleParenExprFinish(Context& context) -> void {
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auto state = context.PopState();
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context.ReplacePlaceholderNode(state.subtree_start, NodeKind::ParenExprStart,
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state.token);
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FinishParenExpr(context, state);
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}
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auto HandleTupleLiteralFinish(Context& context) -> void {
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auto state = context.PopState();
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context.ReplacePlaceholderNode(state.subtree_start,
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NodeKind::TupleLiteralStart, state.token);
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context.AddNode(NodeKind::TupleLiteral, context.Consume(),
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state.subtree_start, state.has_error);
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}
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} // namespace Carbon::Parse
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