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feat: implement for-loops with proper scope management

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- Add support for C-style for loops: for (init; condition; increment) { body }
- Implement three-level scoping: loop context + per-iteration contexts
- Add semicolon disabler for increment statements using RAII guards
- Support break/continue/return control flow with scope validation
- Fix semicolon handling in parser for flexible for-loop syntax
This commit is contained in:
PuqiAR
2025-12-21 22:55:46 +08:00
parent acc2d33dbc
commit 014803b705
13 changed files with 327 additions and 59 deletions
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30
include/Ast/ForSt.hpp Normal file
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@@ -0,0 +1,30 @@
#pragma once
#include <Ast/astBase.hpp>
namespace Fig::Ast
{
class ForSt final : public StatementAst
{
public:
Statement initSt;
Expression condition;
Statement incrementSt;
BlockStatement body;
ForSt()
{
type = AstType::ForSt;
}
ForSt(Statement _initSt, Expression _condition, Statement _incrementSt, BlockStatement _body) :
initSt(std::move(_initSt)),
condition(std::move(_condition)),
incrementSt(std::move(_incrementSt)),
body(std::move(_body))
{
type = AstType::ForSt;
}
};
using For = std::shared_ptr<ForSt>;
};

1
include/Ast/astBase.hpp
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@@ -47,6 +47,7 @@ namespace Fig::Ast
VarAssignSt,
WhileSt,
ForSt,
ReturnSt,
BreakSt,
ContinueSt,

1
include/ast.hpp
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@@ -6,6 +6,7 @@
#include <Ast/ContainerInitExprs.hpp>
#include <Ast/ControlSt.hpp>
#include <Ast/ExpressionStmt.hpp>
#include <Ast/ForSt.hpp>
#include <Ast/FunctionCall.hpp>
#include <Ast/functionParameters.hpp>
#include <Ast/FunctionDefSt.hpp>

31
include/context.hpp
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@@ -2,7 +2,7 @@
#include <unordered_map>
#include <iostream>
#include <algorithm>
#include <memory>
#include <context_forward.hpp>
#include <fig_string.hpp>
@@ -10,7 +10,7 @@
namespace Fig
{
struct Context
class Context : public std::enable_shared_from_this<Context>
{
private:
FString scopeName;
@@ -145,6 +145,33 @@ namespace Fig
}
throw RuntimeError(FStringView(std::format("Variable '{}' not defined", name.toBasicString())));
}
bool isInFunctionContext()
{
ContextPtr ctx = shared_from_this();
while (ctx)
{
if (ctx->getScopeName().find(u8"<Function ") == 0)
{
return true;
}
ctx = ctx->parent;
}
return false;
}
bool isInLoopContext()
{
ContextPtr ctx = shared_from_this();
while (ctx)
{
if (ctx->getScopeName().find(u8"<While ") == 0 or
ctx->getScopeName().find(u8"<For ") == 0)
{
return true;
}
ctx = ctx->parent;
}
return false;
}
void printStackTrace(std::ostream &os = std::cerr, int indent = 0) const
{
const Context *ctx = this;

2
include/context_forward.hpp
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@@ -4,6 +4,6 @@
namespace Fig
{
struct Context;
class Context;
using ContextPtr = std::shared_ptr<Context>;
};

1
include/evaluator.hpp
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@@ -111,6 +111,7 @@ namespace Fig
Value evalBinary(const Ast::BinaryExpr &);
Value evalUnary(const Ast::UnaryExpr &);
StatementResult evalBlockStatement(const Ast::BlockStatement &, ContextPtr = nullptr);
StatementResult evalStatement(const Ast::Statement &);
Value evalFunctionCall(const Function &, const Ast::FunctionArguments &, FString fnName = u8"<anonymous>");

1
include/lexer.hpp
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@@ -81,7 +81,6 @@ namespace Fig
{
return warnings;
}
Token nextToken();
Token scanNumber();

69
include/parser.hpp
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@@ -29,6 +29,28 @@ namespace Fig
std::stack<Ast::Expression> exprStack;
bool needSemicolon = true;
class SemicolonDisabler
{
Parser &p;
bool original;
public:
SemicolonDisabler(Parser &parser) :
p(parser), original(p.needSemicolon)
{
p.needSemicolon = false;
}
~SemicolonDisabler()
{
p.needSemicolon = original;
}
// disable copy and assign
SemicolonDisabler(const SemicolonDisabler &) = delete;
SemicolonDisabler &operator=(const SemicolonDisabler &) = delete;
};
void pushNode(const Ast::AstBase &_node)
{
Ast::AstBase node = _node;
@@ -109,7 +131,7 @@ namespace Fig
return currentAAI;
}
inline Token nextToken()
inline const Token &nextToken()
{
// 没有Rollback时, 存在 currentTokenIndex = tokenPruduced - 1
next();
@@ -143,7 +165,7 @@ namespace Fig
setCurrentAAI(Ast::AstAddressInfo{.line = tok.line, .column = tok.column});
previousTokens.push_back(tok);
}
inline Token currentToken()
inline const Token &currentToken()
{
if (tokenPruduced == 0) return nextToken();
return previousTokens.at(currentTokenIndex);
@@ -229,6 +251,41 @@ namespace Fig
}
}
[[nodiscard]] SemicolonDisabler disableSemicolon()
{
return SemicolonDisabler(*this);
}
void expectSemicolon()
{
// if need semicolon and stream has `;`, consume it. if not need semicolon, do nothing
if (!needSemicolon)
{
// disabled semicolon check
if (currentToken().getType() == TokenType::Semicolon)
{
next(); // consume `;`
}
return;
}
// normal semicolon check
expectConsume(TokenType::Semicolon);
}
void expectConsume(TokenType type, FString expected)
{
expect(type, expected);
next();
}
void expectConsume(TokenType type)
{
expect(type);
next();
}
bool isNext(TokenType type)
{
return peekToken().getType() == type;
@@ -244,12 +301,15 @@ namespace Fig
Value __parseValue();
Ast::ValueExpr __parseValueExpr();
Ast::FunctionParameters __parseFunctionParameters(); // entry: current is Token::LeftParen
Ast::Statement __parseStatement(); // entry: (idk)
Ast::BlockStatement __parseBlockStatement(); // entry: current is Token::LeftBrace
Ast::VarAssign __parseVarAssign(FString); // entry: current is Token::Assign, para1 is var name
Ast::If __parseIf(); // entry: current is Token::If
Ast::While __parseWhile(); // entry: current is Token::While
Ast::Statement __parseIncrementStatement(); // only allowed in __parseFor function
Ast::For __parseFor(); // entry: current is Token::For
Ast::Return __parseReturn(); // entry: current is Token::Return
Ast::Break __parseBreak(); // entry: current is Token::Break
Ast::Continue __parseContinue(); // entry: current is Token::Continue
Ast::VarExpr __parseVarExpr(FString);
Ast::FunctionDef __parseFunctionDef(bool); // entry: current is Token::Identifier (isPublic: Bool)
@@ -266,7 +326,8 @@ namespace Fig
Ast::Expression __parseTupleOrParenExpr(); // entry: current is `(`
Ast::FunctionLiteralExpr __parseFunctionLiteralExpr(); // entry: current is Token::LParen after Token::Function
Ast::Statement __parseStatement(); // entry: (idk)
Ast::Expression parseExpression(Precedence, TokenType = TokenType::Semicolon, TokenType = TokenType::Semicolon);
std::vector<Ast::AstBase> parseAll();
};

6
include/token.hpp
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@@ -35,6 +35,8 @@ namespace Fig
Implement, // implement
Public, // public
Return, // return
Break, // break
Continue, // continue
// TypeNull, // Null
// TypeInt, // Int
@@ -130,7 +132,7 @@ namespace Fig
column = _column;
return *this;
}
FString getValue()
const FString& getValue() const
{
return value;
}
@@ -151,7 +153,7 @@ namespace Fig
return type == TokenType::LiteralNull || type == TokenType::LiteralBool || type == TokenType::LiteralNumber || type == TokenType::LiteralString;
}
TokenType getType()
TokenType getType() const
{
return type;
}

143
src/evaluator.cpp
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@@ -261,10 +261,34 @@ namespace Fig
return Value::getNullInstance();
}
}
StatementResult Evaluator::evalBlockStatement(const Ast::BlockStatement &blockSt, ContextPtr context)
{
auto previousContext = currentContext;
if (context)
{
currentContext = context;
}
else
{
currentContext = std::make_shared<Context>(FString(std::format("<Block {}:{}>", blockSt->getAAI().line, blockSt->getAAI().column)), currentContext);
}
StatementResult lstResult = StatementResult::normal();
for (const auto &s : blockSt->stmts)
{
StatementResult sr = evalStatement(s);
if (!sr.isNormal())
{
lstResult = sr;
break;
}
}
currentContext = previousContext;
return lstResult;
}
StatementResult Evaluator::evalStatement(const Ast::Statement &stmt)
{
using Fig::Ast::AstType;
currentAddressInfo = stmt->getAAI();
switch (stmt->getType())
{
case AstType::VarDefSt: {
@@ -312,21 +336,7 @@ namespace Fig
};
case AstType::BlockStatement: {
auto blockSt = std::dynamic_pointer_cast<Ast::BlockStatementAst>(stmt);
auto newContext = std::make_shared<Context>(FString(std::format("<Block {}:{}>", blockSt->getAAI().line, blockSt->getAAI().column)), currentContext);
auto previousContext = currentContext;
currentContext = newContext;
StatementResult lstResult = StatementResult::normal();
for (const auto &s : blockSt->stmts)
{
StatementResult sr = evalStatement(s);
if (!sr.isNormal())
{
lstResult = sr;
break;
}
}
currentContext = previousContext;
return lstResult;
return evalBlockStatement(blockSt); // auto create new context in block statement
};
case AstType::FunctionDefSt: {
auto fnDef = std::dynamic_pointer_cast<Ast::FunctionDefSt>(stmt);
@@ -412,7 +422,7 @@ namespace Fig
}
if (condVal.as<Bool>().getValue())
{
return evalStatement(ifSt->body);
return evalBlockStatement(ifSt->body);
}
// else
for (const auto &elif : ifSt->elifs)
@@ -425,12 +435,12 @@ namespace Fig
}
if (elifCondVal.as<Bool>().getValue())
{
return evalStatement(elif->body);
return evalBlockStatement(elif->body);
}
}
if (ifSt->els)
{
return evalStatement(ifSt->els->body);
return evalBlockStatement(ifSt->els->body);
}
return StatementResult::normal();
};
@@ -442,13 +452,17 @@ namespace Fig
if (condVal.getTypeInfo() != ValueType::Bool)
{
static constexpr char ConditionTypeErrorName[] = "ConditionTypeError";
throw EvaluatorError<ConditionTypeErrorName>(FStringView(u8"While condition must be boolean"), currentAddressInfo);
throw EvaluatorError<ConditionTypeErrorName>(FStringView(u8"While condition must be boolean"), whileSt->condition->getAAI());
}
if (!condVal.as<Bool>().getValue())
{
break;
}
StatementResult sr = evalStatement(whileSt->body);
ContextPtr loopContext = std::make_shared<Context>(
FString(std::format("<While {}:{}>",
whileSt->getAAI().line, whileSt->getAAI().column)),
currentContext); // every loop has its own context
StatementResult sr = evalBlockStatement(whileSt->body, loopContext);
if (sr.shouldReturn())
{
return sr;
@@ -464,22 +478,63 @@ namespace Fig
}
return StatementResult::normal();
};
case AstType::ForSt: {
auto forSt = std::dynamic_pointer_cast<Ast::ForSt>(stmt);
ContextPtr loopContext = std::make_shared<Context>(
FString(std::format("<For {}:{}>",
forSt->getAAI().line, forSt->getAAI().column)),
currentContext); // for loop has its own context
ContextPtr previousContext = currentContext;
currentContext = loopContext;
evalStatement(forSt->initSt); // ignore init statement result
size_t iteration = 0;
while (true) // use while loop to simulate for loop, cause we need to check condition type every iteration
{
Value condVal = eval(forSt->condition);
if (condVal.getTypeInfo() != ValueType::Bool)
{
static constexpr char ConditionTypeErrorName[] = "ConditionTypeError";
throw EvaluatorError<ConditionTypeErrorName>(FStringView(u8"For condition must be boolean"), forSt->condition->getAAI());
}
if (!condVal.as<Bool>().getValue())
{
break;
}
iteration++;
ContextPtr iterationContext = std::make_shared<Context>(
FString(std::format("<For {}:{}, Iteration {}>",
forSt->getAAI().line, forSt->getAAI().column, iteration)),
loopContext); // every loop has its own context
StatementResult sr = evalBlockStatement(forSt->body, iterationContext);
if (sr.shouldReturn())
{
currentContext = previousContext; // restore context before return
return sr;
}
if (sr.shouldBreak())
{
break;
}
if (sr.shouldContinue())
{
// continue to next iteration
continue;
}
currentContext = loopContext; // let increment statement be in loop context
evalStatement(forSt->incrementSt); // ignore increment statement result
}
currentContext = previousContext; // restore context
return StatementResult::normal();
}
case AstType::ReturnSt: {
if (!currentContext->parent)
{
static constexpr char ReturnOutsideFunctionErrorName[] = "ReturnOutsideFunctionError";
throw EvaluatorError<ReturnOutsideFunctionErrorName>(FStringView(u8"'return' statement outside function"), currentAddressInfo);
}
std::shared_ptr<Context> fc = currentContext;
while (fc->parent)
{
if (fc->getScopeName().find(u8"<Function ") == 0)
{
break;
}
fc = fc->parent;
}
if (fc->getScopeName().find(u8"<Function ") != 0)
if (!currentContext->isInFunctionContext())
{
static constexpr char ReturnOutsideFunctionErrorName[] = "ReturnOutsideFunctionError";
throw EvaluatorError<ReturnOutsideFunctionErrorName>(FStringView(u8"'return' statement outside function"), currentAddressInfo);
@@ -487,6 +542,32 @@ namespace Fig
auto returnSt = std::dynamic_pointer_cast<Ast::ReturnSt>(stmt);
return StatementResult::returnFlow(eval(returnSt->retValue));
};
case AstType::BreakSt: {
if (!currentContext->parent)
{
static constexpr char BreakOutsideLoopErrorName[] = "BreakOutsideLoopError";
throw EvaluatorError<BreakOutsideLoopErrorName>(FStringView(u8"'break' statement outside loop"), currentAddressInfo);
}
if (!currentContext->isInLoopContext())
{
static constexpr char BreakOutsideLoopErrorName[] = "BreakOutsideLoopError";
throw EvaluatorError<BreakOutsideLoopErrorName>(FStringView(u8"'break' statement outside loop"), currentAddressInfo);
}
return StatementResult::breakFlow();
};
case AstType::ContinueSt: {
if (!currentContext->parent)
{
static constexpr char ContinueOutsideLoopErrorName[] = "ContinueOutsideLoopError";
throw EvaluatorError<ContinueOutsideLoopErrorName>(FStringView(u8"'continue' statement outside loop"), currentAddressInfo);
}
if (!currentContext->isInLoopContext())
{
static constexpr char ContinueOutsideLoopErrorName[] = "ContinueOutsideLoopError";
throw EvaluatorError<ContinueOutsideLoopErrorName>(FStringView(u8"'continue' statement outside loop"), currentAddressInfo);
}
return StatementResult::continueFlow();
};
default:
throw RuntimeError(FStringView(std::string("Unknown statement type:") + magic_enum::enum_name(stmt->getType()).data()));
}

2
src/lexer.cpp
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@@ -76,6 +76,8 @@ namespace Fig
{FString(u8"implement"), TokenType::Implement},
{FString(u8"public"), TokenType::Public},
{FString(u8"return"), TokenType::Return},
{FString(u8"break"), TokenType::Break},
{FString(u8"continue"), TokenType::Continue},
// {FString(u8"Null"), TokenType::TypeNull},

94
src/parser.cpp
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@@ -61,7 +61,7 @@ namespace Fig
}
if (isThis(TokenType::Semicolon))
{
next();
next(); // consume `;`, no using expectConsume here cause we don't need to check again
return makeAst<Ast::VarDefAst>(isPublic, isConst, name, tiName, nullptr);
}
if (!isThis(TokenType::Assign) and !isThis(TokenType::Walrus)) expect(TokenType::Assign, u8"assign or walrus");
@@ -72,8 +72,7 @@ namespace Fig
}
next();
Ast::Expression exp = parseExpression(0);
expect(TokenType::Semicolon);
next();
expectSemicolon();
return makeAst<Ast::VarDefAst>(isPublic, isConst, name, tiName, exp);
}
@@ -276,8 +275,7 @@ namespace Fig
if (isEOF()) throwAddressableError<SyntaxError>(FStringView(u8"expect an expression"));
initExpr = parseExpression(0);
}
expect(TokenType::Semicolon);
next(); // consume `;`
expectSemicolon();
return Ast::StructDefField(am, fieldName, tiName, initExpr);
};
std::vector<Ast::Statement> stmts;
@@ -359,8 +357,6 @@ namespace Fig
if (isThis(TokenType::EndOfFile)) { return makeAst<Ast::EofStmt>(); }
if (isThis(TokenType::Public))
{
// stmt = __parseVarDef();
// expect(TokenType::Semicolon);
next(); // consume `public`
if (isThis(TokenType::Variable) || isThis(TokenType::Const))
{
@@ -417,16 +413,27 @@ namespace Fig
{
stmt = __parseWhile();
}
else if (isThis(TokenType::For))
{
stmt = __parseFor();
}
else if (isThis(TokenType::Return))
{
stmt = __parseReturn();
}
else if (isThis(TokenType::Break))
{
stmt = __parseBreak();
}
else if (isThis(TokenType::Continue))
{
stmt = __parseContinue();
}
else
{
// expression statement
Ast::Expression exp = parseExpression(0);
expect(TokenType::Semicolon);
next();
expectSemicolon();
stmt = makeAst<Ast::ExpressionStmtAst>(exp);
}
return stmt;
@@ -452,8 +459,7 @@ namespace Fig
// entry: current is `=`
next(); // consume `=`
Ast::Expression exp = parseExpression(0);
expect(TokenType::Semicolon);
next(); // consume `;`
expectSemicolon();
return makeAst<Ast::VarAssignSt>(varName, exp);
}
@@ -462,14 +468,14 @@ namespace Fig
// entry: current is `if`
next(); // consume `if`
Ast::Expression condition;
if (isThis( TokenType::LeftParen))
if (isThis(TokenType::LeftParen))
{
next(); // consume `(`
condition = parseExpression(0, TokenType::RightParen);
expect(TokenType::RightParen);
next(); // consume `)`
}
else
else
{
condition = parseExpression(0);
}
@@ -509,15 +515,73 @@ namespace Fig
Ast::BlockStatement body = __parseBlockStatement();
return makeAst<Ast::WhileSt>(condition, body);
}
Ast::Statement Parser::__parseIncrementStatement()
{
// allowed：
// 1. assignment：i = 1, i += 1
// 2. expression stmt：i++, foo()
// ❌ not allowed：if/while/for/block stmt
if (isThis(TokenType::LeftBrace))
{
throwAddressableError<SyntaxError>(u8"BlockStatement cannot be used as for loop increment");
}
if (isThis(TokenType::If) || isThis(TokenType::While) || isThis(TokenType::For) || isThis(TokenType::Return) || isThis(TokenType::Break) || isThis(TokenType::Continue))
{
throwAddressableError<SyntaxError>(u8"Control flow statements cannot be used as for loop increment");
}
return __parseStatement();
}
Ast::For Parser::__parseFor()
{
// entry: current is `for`
// TODO: support enumeration
next(); // consume `for`
bool paren = isThis(TokenType::LeftParen);
if (paren)
next(); // consume `(`
// support 3-part for loop
// for init; condition; increment {}
Ast::Statement initStmt = __parseStatement(); // auto check ``
Ast::Expression condition = parseExpression(0);
expectSemicolon(); // auto consume `;`
Ast::Statement incrementStmt = nullptr;
if (!isThis(paren ? TokenType::RightParen : TokenType::LeftBrace)) // need parse increment?
{
auto guard = disableSemicolon();
incrementStmt = __parseIncrementStatement();
} // after parse increment, semicolon check state restored
if (paren)
expectConsume(TokenType::RightParen); // consume `)` if has `(`
expect(TokenType::LeftBrace); // {
Ast::BlockStatement body = __parseBlockStatement(); // auto consume `}`
return makeAst<Ast::ForSt>(initStmt, condition, incrementStmt, body);
}
Ast::Return Parser::__parseReturn()
{
// entry: current is `return`
next(); // consume `return`
Ast::Expression retValue = parseExpression(0);
expect(TokenType::Semicolon);
next(); // consume `;`
expectSemicolon();
return makeAst<Ast::ReturnSt>(retValue);
}
Ast::Continue Parser::__parseContinue()
{
// entry: current is `continue`
next(); // consume `continue`
expectSemicolon();
return makeAst<Ast::ContinueSt>();
}
Ast::Break Parser::__parseBreak()
{
// entry: current is `break`
next(); // consume `break`
expectSemicolon();
return makeAst<Ast::BreakSt>();
}
Ast::VarExpr Parser::__parseVarExpr(FString name)
{

5
test.fig
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@@ -1,5 +1,4 @@
while (true)
for (var i=0;i < 10;i = i + 1)
{
__fstdout_println("1");
break;
__fstdout_println(i);
}