// 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 <optional>
#include "toolchain/parse/context.h"
#include "toolchain/parse/handle.h"
namespace Carbon::Parse {
auto HandleStatement(Context& context) -> void {
 context.PopAndDiscardState();
 switch (context.PositionKind()) {
 case Lex::TokenKind::Break: {
 context.PushState(StateKind::StatementBreakFinish);
 context.AddLeafNode(NodeKind::BreakStatementStart, context.Consume());
 break;
 }
 case Lex::TokenKind::Continue: {
 context.PushState(StateKind::StatementContinueFinish);
 context.AddLeafNode(NodeKind::ContinueStatementStart, context.Consume());
 break;
 }
 case Lex::TokenKind::For: {
 context.PushState(StateKind::StatementForFinish);
 context.PushState(StateKind::StatementForHeader);
 context.ConsumeAndDiscard();
 break;
 }
 case Lex::TokenKind::If: {
 context.PushState(StateKind::StatementIf);
 break;
 }
 case Lex::TokenKind::Return: {
 context.PushState(StateKind::StatementReturn);
 break;
 }
 case Lex::TokenKind::Returned: {
 // TODO: Consider handling this as a modifier.
 context.PushState(StateKind::VarAsReturned);
 break;
 }
 case Lex::TokenKind::While: {
 context.PushState(StateKind::StatementWhile);
 break;
 }
 case Lex::TokenKind::Match: {
 context.PushState(StateKind::MatchIntroducer);
 break;
 }
#define CARBON_PARSE_NODE_KIND(Name)
#define CARBON_PARSE_NODE_KIND_TOKEN_MODIFIER(Name) case Lex::TokenKind::Name:
#include "toolchain/parse/node_kind.def"
 case Lex::TokenKind::Adapt:
 case Lex::TokenKind::Alias:
 case Lex::TokenKind::Choice:
 case Lex::TokenKind::Class:
 case Lex::TokenKind::Constraint:
 case Lex::TokenKind::Fn:
 case Lex::TokenKind::Import:
 case Lex::TokenKind::Interface:
 case Lex::TokenKind::Let:
 case Lex::TokenKind::Library:
 case Lex::TokenKind::Namespace:
 // We intentionally don't handle Package here, because `package.` can be
 // used at the start of an expression, and it's not worth disambiguating it.
 case Lex::TokenKind::Var: {
 context.PushState(StateKind::DeclAsRegular);
 break;
 }
 default: {
 context.PushState(StateKind::ExprStatementFinish);
 context.PushStateForExpr(PrecedenceGroup::ForExprStatement());
 break;
 }
 }
}
// Handles the `;` after a keyword statement.
static auto HandleStatementKeywordFinish(Context& context, NodeKind node_kind)
 -> void {
 auto state = context.PopState();
 auto semi = context.ConsumeIf(Lex::TokenKind::Semi);
 if (!semi) {
 CARBON_DIAGNOSTIC(ExpectedStatementSemi, Error,
 "`{0}` statements must end with a `;`", Lex::TokenKind);
 context.emitter().Emit(*context.position(), ExpectedStatementSemi,
 context.tokens().GetKind(state.token));
 state.has_error = true;
 // Recover to the next semicolon if possible.
 semi = context.SkipPastLikelyEnd(state.token);
 }
 context.AddNode(node_kind, *semi, state.has_error);
}
auto HandleStatementBreakFinish(Context& context) -> void {
 HandleStatementKeywordFinish(context, NodeKind::BreakStatement);
}
auto HandleStatementContinueFinish(Context& context) -> void {
 HandleStatementKeywordFinish(context, NodeKind::ContinueStatement);
}
auto HandleStatementForHeader(Context& context) -> void {
 auto state = context.PopState();
 std::optional<lex::tokenindex> open_paren =
 context.ConsumeAndAddOpenParen(state.token, NodeKind::ForHeaderStart);
 if (open_paren) {
 state.token = *open_paren;
 }
 state.kind = StateKind::StatementForHeaderIn;
 context.PushState(state);
 context.PushState(StateKind::Pattern);
}
auto HandleStatementForHeaderIn(Context& context) -> void {
 auto state = context.PopState();
 auto end_token = state.token;
 if (context.PositionIs(Lex::TokenKind::In)) {
 end_token = context.Consume();
 } else if (context.PositionIs(Lex::TokenKind::Colon)) {
 CARBON_DIAGNOSTIC(ExpectedInNotColon, Error,
 "`:` should be replaced by `in`");
 context.emitter().Emit(*context.position(), ExpectedInNotColon);
 state.has_error = true;
 end_token = context.Consume();
 } else if (!state.has_error) {
 CARBON_DIAGNOSTIC(ExpectedIn, Error, "expected `in` after loop pattern");
 context.emitter().Emit(*context.position(), ExpectedIn);
 state.has_error = true;
 }
 context.AddNode(NodeKind::ForIn, end_token, state.has_error);
 context.PushState(state, StateKind::StatementForHeaderFinish);
 // If we had a parse error, try to skip to the closing paren rather than
 // parsing an expression.
 if (state.has_error) {
 auto open_token = context.state_stack().back().token;
 if (context.tokens().GetKind(open_token).is_opening_symbol()) {
 context.SkipTo(context.tokens().GetMatchedClosingToken(open_token));
 return;
 }
 }
 context.PushState(StateKind::Expr);
}
auto HandleStatementForHeaderFinish(Context& context) -> void {
 auto state = context.PopState();
 context.ConsumeAndAddCloseSymbol(state.token, state, NodeKind::ForHeader);
 context.PushState(StateKind::CodeBlock);
}
auto HandleStatementForFinish(Context& context) -> void {
 auto state = context.PopState();
 context.AddNode(NodeKind::ForStatement, state.token, state.has_error);
}
auto HandleStatementIf(Context& context) -> void {
 context.PopAndDiscardState();
 context.PushState(StateKind::StatementIfConditionFinish);
 context.PushState(StateKind::ParenConditionAsIf);
 context.ConsumeAndDiscard();
}
auto HandleStatementIfConditionFinish(Context& context) -> void {
 auto state = context.PopState();
 context.PushState(state, StateKind::StatementIfThenBlockFinish);
 context.PushState(StateKind::CodeBlock);
}
auto HandleStatementIfThenBlockFinish(Context& context) -> void {
 auto state = context.PopState();
 if (context.ConsumeAndAddLeafNodeIf(Lex::TokenKind::Else,
 NodeKind::IfStatementElse)) {
 context.PushState(state, StateKind::StatementIfElseBlockFinish);
 // `else if` is permitted as a special case.
 context.PushState(context.PositionIs(Lex::TokenKind::If)
 ? StateKind::StatementIf
 : StateKind::CodeBlock);
 } else {
 context.AddNode(NodeKind::IfStatement, state.token, state.has_error);
 }
}
auto HandleStatementIfElseBlockFinish(Context& context) -> void {
 auto state = context.PopState();
 context.AddNode(NodeKind::IfStatement, state.token, state.has_error);
}
auto HandleStatementReturn(Context& context) -> void {
 auto state = context.PopState();
 context.PushState(state, StateKind::StatementReturnFinish);
 context.AddLeafNode(NodeKind::ReturnStatementStart, context.Consume());
 if (auto var_token = context.ConsumeIf(Lex::TokenKind::Var)) {
 // `return var;`
 context.AddLeafNode(NodeKind::ReturnVarModifier, *var_token);
 } else if (!context.PositionIs(Lex::TokenKind::Semi)) {
 // `return <expression>;`
 context.PushState(StateKind::Expr);
 } else {
 // `return;`
 }
}
auto HandleStatementReturnFinish(Context& context) -> void {
 HandleStatementKeywordFinish(context, NodeKind::ReturnStatement);
}
auto HandleStatementScopeLoop(Context& context) -> void {
 // This maintains the current state until we're at the end of the scope.
 auto token_kind = context.PositionKind();
 if (token_kind == Lex::TokenKind::CloseCurlyBrace) {
 auto state = context.PopState();
 if (state.has_error) {
 context.ReturnErrorOnState();
 }
 } else {
 context.PushState(StateKind::Statement);
 }
}
auto HandleStatementWhile(Context& context) -> void {
 context.PopAndDiscardState();
 context.PushState(StateKind::StatementWhileConditionFinish);
 context.PushState(StateKind::ParenConditionAsWhile);
 context.ConsumeAndDiscard();
}
auto HandleStatementWhileConditionFinish(Context& context) -> void {
 auto state = context.PopState();
 context.PushState(state, StateKind::StatementWhileBlockFinish);
 context.PushState(StateKind::CodeBlock);
}
auto HandleStatementWhileBlockFinish(Context& context) -> void {
 auto state = context.PopState();
 context.AddNode(NodeKind::WhileStatement, state.token, state.has_error);
}
} // namespace Carbon::Parse
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