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feat: 添加If语句及块语句解析支持

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PuqiAR
2026-02-20 15:46:33 +08:00
parent 2631f76da1
commit eb20993e27
6 changed files with 288 additions and 23 deletions
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196
src/Parser/StmtParser.cpp
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@@ -9,7 +9,34 @@
namespace Fig
{
Result<VarDecl *, Error> Parser::parseVarDecl(bool isPublic) // 由 parseStatement调用, 当前token为 var
Result<BlockStmt *, Error> Parser::parseBlockStmt() // 当前token为 {
{
SourceLocation location = makeSourceLocation(consumeToken()); // consume `{`
BlockStmt *stmt = new BlockStmt();
while (true)
{
if (isEOF)
{
return std::unexpected(Error(ErrorType::SyntaxError,
"unclosed braces in block stmt",
"insert `}`",
location));
}
if (match(TokenType::RightBrace))
{
break;
}
const auto &result = parseStatement();
if (!result)
{
return std::unexpected(result.error());
}
stmt->nodes.push_back(*result);
}
return stmt;
}
Result<VarDecl *, Error> Parser::parseVarDecl(
bool isPublic) // 由 parseStatement调用, 当前token为 var
{
state = State::ParsingVarDecl;
@@ -50,8 +77,147 @@ namespace Fig
VarDecl *varDecl = new VarDecl(isPublic, name, typeSpeicifer, initExpr, location);
return varDecl;
}
Result<IfStmt *, Error> Parser::parseIfStmt() // 由 parseStatement调用, 当前token is if
{
state = State::ParsingIf;
SourceLocation location = makeSourceLocation(consumeToken()); // consume `if`
Expr *cond = nullptr;
if (match(TokenType::LeftParen)) // match and consume `(`
{
const Token &lpToken = prevToken();
const auto &result = parseExpression(0, TokenType::RightParen, TokenType::LeftBrace);
if (!result)
{
return std::unexpected(result.error());
}
if (!match(TokenType::RightParen))
{
return std::unexpected(Error(ErrorType::SyntaxError,
"unclosed parenthese in if condition",
"insert `)`",
makeSourceLocation(lpToken)));
}
cond = *result;
}
else
{
const auto &result = parseExpression(0, TokenType::LeftBrace);
if (!result)
{
return std::unexpected(result.error());
}
cond = *result;
}
state = State::ParsingIf;
if (currentToken().type != TokenType::LeftBrace)
{
return std::unexpected(
makeUnexpectTokenError("IfStmt", "LeftBrace `{`", currentToken()));
}
const auto &result = parseBlockStmt();
if (!result)
{
return std::unexpected(result.error());
}
BlockStmt *consequent = *result;
DynArray<ElseIfStmt *> elifs;
BlockStmt *alternate = nullptr;
while (match(TokenType::Else))
{
SourceLocation elseLocation = makeSourceLocation(prevToken());
if (match(TokenType::If))
{
// else if
if (alternate)
{
return std::unexpected(Error(ErrorType::SyntaxError,
"else if after else",
"remove else if",
elseLocation));
}
Expr *cond = nullptr;
if (match(TokenType::LeftParen)) // `(`
{
const Token &lpToken = prevToken();
const auto &result =
parseExpression(0, TokenType::RightParen, TokenType::LeftBrace);
if (!result)
{
return std::unexpected(result.error());
}
state = State::ParsingIf;
if (!match(TokenType::RightParen))
{
return std::unexpected(Error(ErrorType::SyntaxError,
"unclosed parenthese in if condition",
"insert `)`",
makeSourceLocation(lpToken)));
}
cond = *result;
}
else
{
const auto &result = parseExpression(0, TokenType::LeftBrace);
if (!result)
{
return std::unexpected(result.error());
}
state = State::ParsingIf;
cond = *result;
}
if (currentToken().type != TokenType::LeftBrace)
{
return std::unexpected(
makeUnexpectTokenError("ElseIfStmt", "LeftBrace `{`", currentToken()));
}
const auto &result = parseBlockStmt();
if (!result)
{
return std::unexpected(result.error());
}
state = State::ParsingIf;
BlockStmt *consequent = *result;
ElseIfStmt *elif = new ElseIfStmt(cond, consequent, elseLocation);
elifs.push_back(elif);
}
else
{
// else
if (alternate)
{
return std::unexpected(Error(ErrorType::SyntaxError,
"duplicate else in if stmt",
"remove it",
elseLocation));
}
if (currentToken().type != TokenType::LeftBrace)
{
return std::unexpected(
makeUnexpectTokenError("ElseStmt", "LeftBrace `{`", currentToken()));
}
const auto &result = parseBlockStmt();
if (!result)
{
return std::unexpected(result.error());
}
state = State::ParsingIf;
alternate = *result;
}
}
IfStmt *ifStmt = new IfStmt(cond, consequent, elifs, alternate, location);
return ifStmt;
}
Result<Stmt *, Error> Parser::parseStatement()
{
state = State::Standby;
if (currentToken().type == TokenType::Public)
{
consumeToken(); // consume `public`
@@ -60,23 +226,25 @@ namespace Fig
return parseVarDecl(true);
}
}
else if (currentToken().type == TokenType::Variable)
if (currentToken().type == TokenType::Variable)
{
return parseVarDecl(false);
}
else
if (currentToken().type == TokenType::If)
{
const auto &expr_result = parseExpression(0);
if (!expr_result)
{
return std::unexpected(expr_result.error());
}
ExprStmt *exprStmt = new ExprStmt(*expr_result);
if (!match(TokenType::Semicolon))
{
return std::unexpected(makeExpectSemicolonError());
}
return exprStmt;
return parseIfStmt();
}
const auto &expr_result = parseExpression(0);
if (!expr_result)
{
return std::unexpected(expr_result.error());
}
ExprStmt *exprStmt = new ExprStmt(*expr_result);
if (!match(TokenType::Semicolon))
{
return std::unexpected(makeExpectSemicolonError());
}
return exprStmt;
}
}; // namespace Fig