// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#include "toolchain/parse/context.h"
#include "toolchain/parse/handle.h"
namespace Carbon::Parse {
// Handles VarAs(Regular|Returned).
static auto HandleVar(Context& context, StateKind finish_state_kind,
 Lex::TokenIndex returned_token = Lex::TokenIndex::None)
 -> void {
 auto state = context.PopState();
 // The finished variable declaration will start at the `var` or `returned`.
 context.PushState(state, finish_state_kind);
 // TODO: is there a cleaner way to give VarAfterPattern access to the `var`
 // token?
 state.token = *(context.position() - 1);
 context.PushState(state, StateKind::VarAfterPatternAsVar);
 if (returned_token.has_value()) {
 context.AddLeafNode(NodeKind::ReturnedModifier, returned_token);
 }
 context.PushStateForPattern(StateKind::Pattern, /*in_var_pattern=*/true);
}
auto HandleVarAsRegular(Context& context) -> void {
 HandleVar(context, StateKind::VarFinishAsRegular);
}
auto HandleVarAsReturned(Context& context) -> void {
 auto returned_token = context.Consume();
 if (!context.PositionIs(Lex::TokenKind::Var)) {
 CARBON_DIAGNOSTIC(ExpectedVarAfterReturned, Error,
 "expected `var` after `returned`");
 context.emitter().Emit(*context.position(), ExpectedVarAfterReturned);
 context.AddLeafNode(NodeKind::EmptyDecl,
 context.SkipPastLikelyEnd(returned_token),
 /*has_error=*/true);
 context.PopAndDiscardState();
 return;
 }
 context.AddLeafNode(NodeKind::VariableIntroducer, context.Consume());
 HandleVar(context, StateKind::VarFinishAsRegular, returned_token);
}
auto HandleFieldDecl(Context& context) -> void {
 auto state = context.PopState();
 auto identifier = context.ConsumeIf(Lex::TokenKind::Identifier);
 if (!identifier) {
 CARBON_DIAGNOSTIC(ExpectedFieldIdentifier, Error,
 "expected identifier in field declaration");
 context.emitter().Emit(*context.position(), ExpectedFieldIdentifier);
 }
 auto colon = context.ConsumeIf(Lex::TokenKind::Colon);
 if (identifier && !colon) {
 CARBON_DIAGNOSTIC(ExpectedFieldColon, Error,
 "expected `:` in field declaration");
 context.emitter().Emit(*context.position(), ExpectedFieldColon);
 }
 if (!identifier || !colon) {
 context.AddNode(NodeKind::FieldDecl,
 context.SkipPastLikelyEnd(*(context.position() - 1)),
 /*has_error=*/true);
 state.has_error = true;
 return;
 }
 context.PushState(state, StateKind::VarFinishAsField);
 context.AddLeafNode(NodeKind::IdentifierNameNotBeforeParams, *identifier);
 state.token = *colon;
 context.PushState(state, StateKind::VarAfterPatternAsField);
 context.PushState(StateKind::Expr);
}
static auto HandleVarAfterPattern(Context& context, NodeKind pattern_kind,
 NodeKind init_kind) -> void {
 auto state = context.PopState();
 if (state.has_error) {
 if (auto after_pattern =
 context.FindNextOf({Lex::TokenKind::Equal, Lex::TokenKind::Semi})) {
 context.SkipTo(*after_pattern);
 }
 }
 context.AddNode(pattern_kind, state.token, state.has_error);
 if (context.PositionIs(Lex::TokenKind::Equal)) {
 context.AddLeafNode(init_kind,
 context.ConsumeChecked(Lex::TokenKind::Equal));
 context.PushState(StateKind::Expr);
 }
}
auto HandleVarAfterPatternAsVar(Context& context) -> void {
 HandleVarAfterPattern(context, NodeKind::VariablePattern,
 NodeKind::VariableInitializer);
}
auto HandleVarAfterPatternAsField(Context& context) -> void {
 HandleVarAfterPattern(context, NodeKind::FieldNameAndType,
 NodeKind::FieldInitializer);
}
static auto HandleVarFinish(Context& context, NodeKind node_kind) -> void {
 auto state = context.PopState();
 auto end_token = state.token;
 if (context.PositionIs(Lex::TokenKind::Semi)) {
 end_token = context.Consume();
 } else {
 // TODO: Disambiguate between statement and member declaration.
 context.DiagnoseExpectedDeclSemi(Lex::TokenKind::Var);
 state.has_error = true;
 end_token = context.SkipPastLikelyEnd(state.token);
 }
 context.AddNode(node_kind, end_token, state.has_error);
}
auto HandleVarFinishAsRegular(Context& context) -> void {
 HandleVarFinish(context, NodeKind::VariableDecl);
}
auto HandleVarFinishAsField(Context& context) -> void {
 HandleVarFinish(context, NodeKind::FieldDecl);
}
auto HandleVariablePattern(Context& context) -> void {
 auto state = context.PopState();
 if (state.in_var_pattern) {
 CARBON_DIAGNOSTIC(NestedVar, Error, "`var` nested within another `var`");
 context.emitter().Emit(*context.position(), NestedVar);
 state.has_error = true;
 }
 context.PushState(StateKind::FinishVariablePattern);
 context.ConsumeChecked(Lex::TokenKind::Var);
 context.PushStateForPattern(StateKind::Pattern, /*in_var_pattern=*/true);
}
auto HandleFinishVariablePattern(Context& context) -> void {
 auto state = context.PopState();
 context.AddNode(NodeKind::VariablePattern, state.token, state.has_error);
 // Propagate errors to the parent state so that they can take different
 // actions on invalid patterns.
 if (state.has_error) {
 context.ReturnErrorOnState();
 }
}
} // namespace Carbon::Parse
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