PorygonLang/src/Parser/Parser.cpp

#include "Parser.hpp"
#include "UnaryOperatorKind.hpp"
#include "BinaryOperatorKind.hpp"


ParsedScriptStatement* Parser::Parse() {
    vector<ParsedStatement*> statements;
    while (true){
        auto next = this -> Next();
        if (next->GetKind() == TokenKind::EndOfFile){
            break;
        }
        if (next->GetKind() == TokenKind::WhiteSpace){
            continue;
        }
        statements.push_back(this -> ParseStatement(next));
    }
    return new ParsedScriptStatement(statements);
}

ParsedStatement* Parser::ParseStatement(IToken* current){
    return new ParsedExpressionStatement(this -> ParseExpression(current));
}

ParsedExpression* Parser::ParseExpression(IToken* current){
    return this -> ParseBinaryExpression(current, OperatorPrecedence::No);
}


OperatorPrecedence GetUnaryPrecedence(TokenKind kind){
    switch (kind){
        case TokenKind::PlusToken:
        case TokenKind::MinusToken:
        case TokenKind::NotKeyword:
            return OperatorPrecedence::Unary;
        default:
            return OperatorPrecedence::No;
    }
}

UnaryOperatorKind GetUnaryOperatorKind(TokenKind kind){
    switch (kind){
        case TokenKind::PlusToken: return UnaryOperatorKind::Identity;
        case TokenKind::MinusToken: return UnaryOperatorKind::Negation;
        case TokenKind::NotKeyword: return UnaryOperatorKind::LogicalNegation;
        default: // This should never trigger, so throw.
            throw;
    }
}

BinaryOperatorKind GetBinaryOperatorKind(TokenKind kind){
    switch (kind){
        case TokenKind::PlusToken: return BinaryOperatorKind ::Addition;
        case TokenKind::MinusToken: return BinaryOperatorKind ::Subtraction;
        case TokenKind::StarToken: return BinaryOperatorKind ::Multiplication;
        case TokenKind::SlashToken: return BinaryOperatorKind ::Division;
        case TokenKind::EqualityToken: return BinaryOperatorKind ::Equality;
        case TokenKind::AndKeyword: return BinaryOperatorKind ::LogicalAnd;
        case TokenKind::OrKeyword: return BinaryOperatorKind ::LogicalOr;
        default: // This should never trigger, so throw.
            throw;
    }
}

OperatorPrecedence GetBinaryPrecedence(TokenKind kind){
    switch (kind){
        case TokenKind::PlusToken: return OperatorPrecedence ::Additive;
        case TokenKind::MinusToken: return OperatorPrecedence ::Additive;
        case TokenKind::StarToken: return OperatorPrecedence ::Multiplication;
        case TokenKind::SlashToken: return OperatorPrecedence ::Multiplication;
        case TokenKind::EqualityToken: return OperatorPrecedence ::Equality;
        case TokenKind::AndKeyword: return OperatorPrecedence ::LogicalAnd;
        case TokenKind::OrKeyword: return OperatorPrecedence ::LogicalOr;
        default:
            return OperatorPrecedence::No;
    }
}

ParsedExpression* Parser::ParseBinaryExpression(IToken* current, OperatorPrecedence parentPrecedence){
    OperatorPrecedence unaryPrecedence = GetUnaryPrecedence(current -> GetKind());
    ParsedExpression* left;
    if (unaryPrecedence != OperatorPrecedence::No && unaryPrecedence >= parentPrecedence){
        UnaryOperatorKind operatorKind = GetUnaryOperatorKind(current -> GetKind());
        auto next = this -> Next();
        auto operand = this -> ParseBinaryExpression(next, unaryPrecedence);
        auto startPos = current -> GetStartPosition();
        left = new UnaryExpression(operatorKind, operand, startPos, operand -> GetEndPosition() - startPos);
    } else{
        left = this -> ParsePrimaryExpression(current);
    }
    while (true){
        auto next  = this -> Peek();
        OperatorPrecedence binaryPrecedence = GetBinaryPrecedence(next -> GetKind());
        if (binaryPrecedence == OperatorPrecedence::No || binaryPrecedence <= parentPrecedence){
            break;
        }
        auto operatorKind = GetBinaryOperatorKind(next -> GetKind());
        this -> Next();
        auto right = ParseBinaryExpression(this -> Next(), binaryPrecedence);
        auto startPos = left -> GetStartPosition();
        left = new BinaryExpression(operatorKind, left, right, startPos, right -> GetEndPosition() - startPos);
    }
    return left;
}

ParsedExpression *Parser::ParsePrimaryExpression(IToken *current) {
    switch (current -> GetKind()){
        case TokenKind ::Integer: return new LiteralIntegerExpression((IntegerToken*)current);
        case TokenKind ::Float: return new LiteralFloatExpression((FloatToken*)current);
        case TokenKind ::TrueKeyword: return new LiteralBoolExpression(current);
        case TokenKind ::FalseKeyword: return new LiteralBoolExpression(current);
        default:
            this -> ScriptData -> Diagnostics -> LogError(DiagnosticCode::UnexpectedToken, current->GetStartPosition(), current->GetLength());
            return new BadExpression(current->GetStartPosition(), current->GetLength());
    }
}


IToken *Parser::Peek() {
    return this -> _tokens[_position];
}

IToken *Parser::Next() {
    this -> _position++;
    return this -> _tokens[_position - 1];
}

#ifdef TESTS_BUILD
#include <catch.hpp>

TEST_CASE( "Parse single true keyword", "[parser]" ) {
    vector<IToken*> v {new SimpleToken(TokenKind::TrueKeyword,0,0), new SimpleToken(TokenKind::EndOfFile,0,0)};
    Parser parser = Parser(v, nullptr);
    auto parsedStatements = parser.Parse() -> GetStatements();
    REQUIRE(parsedStatements.size() == 1);
    auto firstStatement = parsedStatements[0];
    REQUIRE(firstStatement -> GetKind() == ParsedStatementKind::Expression);
    auto expression = ((ParsedExpressionStatement*)firstStatement)->GetExpression();
    REQUIRE(expression -> GetKind() == ParsedExpressionKind::LiteralBool);
    auto boolean = ((LiteralBoolExpression*)expression);
    REQUIRE(boolean->GetValue() == true);
}

TEST_CASE( "Parse single false keyword", "[parser]" ) {
    vector<IToken*> v {new SimpleToken(TokenKind::FalseKeyword,0,0), new SimpleToken(TokenKind::EndOfFile,0,0)};
    Parser parser = Parser(v, nullptr);
    auto parsedStatements = parser.Parse() -> GetStatements();
    REQUIRE(parsedStatements.size() == 1);
    auto firstStatement = parsedStatements[0];
    REQUIRE(firstStatement -> GetKind() == ParsedStatementKind::Expression);
    auto expression = ((ParsedExpressionStatement*)firstStatement)->GetExpression();
    REQUIRE(expression -> GetKind() == ParsedExpressionKind::LiteralBool);
    auto boolean = ((LiteralBoolExpression*)expression);
    REQUIRE(boolean->GetValue() == false);
}

TEST_CASE( "Parse simple addition", "[parser]" ) {
    vector<IToken*> v {
        new IntegerToken(5, 0, 0),
        new SimpleToken(TokenKind::PlusToken,0,0),
        new IntegerToken(10, 0, 0),
        new SimpleToken(TokenKind::EndOfFile,0,0)
    };
    Parser parser = Parser(v, nullptr);
    auto parsedStatements = parser.Parse() -> GetStatements();
    REQUIRE(parsedStatements.size() == 1);
    auto firstStatement = parsedStatements[0];
    REQUIRE(firstStatement -> GetKind() == ParsedStatementKind::Expression);
    auto expression = ((ParsedExpressionStatement*)firstStatement)->GetExpression();
    REQUIRE(expression -> GetKind() == ParsedExpressionKind::Binary);
    auto binary = ((BinaryExpression*)expression);
    CHECK(binary -> GetOperatorKind() == BinaryOperatorKind::Addition);
    auto left = binary->GetLeft();
    auto right = binary->GetRight();
    REQUIRE(left->GetKind() == ParsedExpressionKind::LiteralInteger);
    REQUIRE(right->GetKind() == ParsedExpressionKind::LiteralInteger);
    CHECK(((LiteralIntegerExpression*)left)->GetValue() == 5);
    CHECK(((LiteralIntegerExpression*)right)->GetValue() == 10);
}

TEST_CASE( "Parse simple negation", "[parser]" ) {
    vector<IToken*> v {
            new SimpleToken(TokenKind::MinusToken,0,0),
            new IntegerToken(10, 0, 0),
            new SimpleToken(TokenKind::EndOfFile,0,0)
    };
    Parser parser = Parser(v, nullptr);
    auto parsedStatements = parser.Parse() -> GetStatements();
    REQUIRE(parsedStatements.size() == 1);
    auto firstStatement = parsedStatements[0];
    REQUIRE(firstStatement -> GetKind() == ParsedStatementKind::Expression);
    auto expression = ((ParsedExpressionStatement*)firstStatement)->GetExpression();
    REQUIRE(expression -> GetKind() == ParsedExpressionKind::Unary);
    auto unary = ((UnaryExpression*)expression);
    CHECK(unary -> GetOperatorKind() == UnaryOperatorKind::Negation);
    auto operand = unary->GetOperand();
    REQUIRE(operand->GetKind() == ParsedExpressionKind::LiteralInteger);
    CHECK(((LiteralIntegerExpression*)operand)->GetValue() == 10);
}

TEST_CASE( "Parse logical negation", "[parser]" ) {
    vector<IToken*> v {
            new SimpleToken(TokenKind::NotKeyword,0,0),
            new SimpleToken(TokenKind::FalseKeyword,0,0),
            new SimpleToken(TokenKind::EndOfFile,0,0)
    };
    Parser parser = Parser(v, nullptr);
    auto parsedStatements = parser.Parse() -> GetStatements();
    REQUIRE(parsedStatements.size() == 1);
    auto firstStatement = parsedStatements[0];
    REQUIRE(firstStatement -> GetKind() == ParsedStatementKind::Expression);
    auto expression = ((ParsedExpressionStatement*)firstStatement)->GetExpression();
    REQUIRE(expression -> GetKind() == ParsedExpressionKind::Unary);
    auto unary = ((UnaryExpression*)expression);
    CHECK(unary -> GetOperatorKind() == UnaryOperatorKind::LogicalNegation);
    auto operand = unary->GetOperand();
    REQUIRE(operand->GetKind() == ParsedExpressionKind::LiteralBool);
    CHECK(((LiteralBoolExpression*)operand)->GetValue() == false);
}

TEST_CASE( "Assert binary precedence", "[parser]" ) {
    vector<IToken*> v {
            new IntegerToken(5, 0, 0),
            new SimpleToken(TokenKind::PlusToken,0,0),
            new IntegerToken(10, 0, 0),
            new SimpleToken(TokenKind::StarToken,0,0),
            new IntegerToken(6, 0, 0),
            new SimpleToken(TokenKind::EndOfFile,0,0)
    };
    Parser parser = Parser(v, nullptr);
    auto parsedStatements = parser.Parse() -> GetStatements();
    REQUIRE(parsedStatements.size() == 1);
    auto firstStatement = parsedStatements[0];
    REQUIRE(firstStatement -> GetKind() == ParsedStatementKind::Expression);
    auto expression = ((ParsedExpressionStatement*)firstStatement)->GetExpression();
    REQUIRE(expression -> GetKind() == ParsedExpressionKind::Binary);
    auto binary = ((BinaryExpression*)expression);
    CHECK(binary -> GetOperatorKind() == BinaryOperatorKind::Addition);
    auto left = binary->GetLeft();
    auto right = binary->GetRight();
    REQUIRE(left->GetKind() == ParsedExpressionKind::LiteralInteger);
    REQUIRE(right->GetKind() == ParsedExpressionKind::Binary);
    CHECK(((LiteralIntegerExpression*)left)->GetValue() == 5);
    left = ((BinaryExpression*)right)->GetLeft();
    right = ((BinaryExpression*)right)->GetRight();
    CHECK(((LiteralIntegerExpression*)left)->GetValue() == 10);
    CHECK(((LiteralIntegerExpression*)right)->GetValue() == 6);
}


#endif