path: root/Parser.cpp

/*
    This file is part of cpp-ethereum.

    cpp-ethereum is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    cpp-ethereum is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
/**
 * @author Christian <c@ethdev.com>
 * @date 2014
 * Solidity parser.
 */

#include <libdevcore/Log.h>
#include <libsolidity/BaseTypes.h>
#include <libsolidity/Parser.h>
#include <libsolidity/Scanner.h>
#include <libsolidity/Exceptions.h>

namespace dev {
namespace solidity {

ptr<ContractDefinition> Parser::parse(std::shared_ptr<Scanner> const& _scanner)
{
    m_scanner = _scanner;

    return parseContractDefinition();
}


/// AST node factory that also tracks the begin and end position of an AST node
/// while it is being parsed
class Parser::ASTNodeFactory
{
public:
    ASTNodeFactory(const Parser& _parser)
        : m_parser(_parser), m_location(_parser.getPosition(), -1)
    {}

    void markEndPosition() { m_location.end = m_parser.getEndPosition(); }

    void setLocationEmpty() { m_location.end = m_location.start; }

    /// Set the end position to the one of the given node.
    void setEndPositionFromNode(const ptr<ASTNode>& _node)
    {
        m_location.end = _node->getLocation().end;
    }

    /// @todo: check that this actually uses perfect forwarding
    template <class NodeType, typename... Args>
    ptr<NodeType> createNode(Args&&... _args)
    {
        if (m_location.end < 0)
            markEndPosition();
        return std::make_shared<NodeType>(m_location, std::forward<Args>(_args)...);
    }

private:
    const Parser& m_parser;
    Location m_location;
};

int Parser::getPosition() const
{
    return m_scanner->getCurrentLocation().start;
}

int Parser::getEndPosition() const
{
    return m_scanner->getCurrentLocation().end;
}


ptr<ContractDefinition> Parser::parseContractDefinition()
{
    ASTNodeFactory nodeFactory(*this);

    expectToken(Token::CONTRACT);
    ptr<ASTString> name = expectIdentifierToken();
    expectToken(Token::LBRACE);

    vecptr<StructDefinition> structs;
    vecptr<VariableDeclaration> stateVariables;
    vecptr<FunctionDefinition> functions;
    bool visibilityIsPublic = true;
    while (true) {
        Token::Value currentToken = m_scanner->getCurrentToken();
        if (currentToken == Token::RBRACE) {
            break;
        } else if (currentToken == Token::PUBLIC || currentToken == Token::PRIVATE) {
            visibilityIsPublic = (m_scanner->getCurrentToken() == Token::PUBLIC);
            m_scanner->next();
            expectToken(Token::COLON);
        } else if (currentToken == Token::FUNCTION) {
            functions.push_back(parseFunctionDefinition(visibilityIsPublic));
        } else if (currentToken == Token::STRUCT) {
            structs.push_back(parseStructDefinition());
        } else if (currentToken == Token::IDENTIFIER || currentToken == Token::MAPPING ||
                   Token::IsElementaryTypeName(currentToken)) {
            bool const allowVar = false;
            stateVariables.push_back(parseVariableDeclaration(allowVar));
            expectToken(Token::SEMICOLON);
        } else {
            throwExpectationError("Function, variable or struct declaration expected.");
        }
    }
    nodeFactory.markEndPosition();

    expectToken(Token::RBRACE);
    expectToken(Token::EOS);

    return nodeFactory.createNode<ContractDefinition>(name, structs, stateVariables, functions);
}

ptr<FunctionDefinition> Parser::parseFunctionDefinition(bool _isPublic)
{
    ASTNodeFactory nodeFactory(*this);

    expectToken(Token::FUNCTION);
    ptr<ASTString> name(expectIdentifierToken());
    ptr<ParameterList> parameters(parseParameterList());
    bool isDeclaredConst = false;
    if (m_scanner->getCurrentToken() == Token::CONST) {
        isDeclaredConst = true;
        m_scanner->next();
    }
    ptr<ParameterList> returnParameters;
    if (m_scanner->getCurrentToken() == Token::RETURNS) {
        const bool permitEmptyParameterList = false;
        m_scanner->next();
        returnParameters = parseParameterList(permitEmptyParameterList);
    } else {
        // create an empty parameter list at a zero-length location
        ASTNodeFactory nodeFactory(*this);
        nodeFactory.setLocationEmpty();
        returnParameters = nodeFactory.createNode<ParameterList>(vecptr<VariableDeclaration>());
    }
    ptr<Block> block = parseBlock();
    nodeFactory.setEndPositionFromNode(block);
    return nodeFactory.createNode<FunctionDefinition>(name, _isPublic, parameters,
                                                      isDeclaredConst, returnParameters, block);
}

ptr<StructDefinition> Parser::parseStructDefinition()
{
    ASTNodeFactory nodeFactory(*this);

    expectToken(Token::STRUCT);
    ptr<ASTString> name = expectIdentifierToken();
    vecptr<VariableDeclaration> members;
    expectToken(Token::LBRACE);
    while (m_scanner->getCurrentToken() != Token::RBRACE) {
        bool const allowVar = false;
        members.push_back(parseVariableDeclaration(allowVar));
        expectToken(Token::SEMICOLON);
    }
    nodeFactory.markEndPosition();
    expectToken(Token::RBRACE);

    return nodeFactory.createNode<StructDefinition>(name, members);
}

ptr<VariableDeclaration> Parser::parseVariableDeclaration(bool _allowVar)
{
    ASTNodeFactory nodeFactory(*this);

    ptr<TypeName> type = parseTypeName(_allowVar);
    nodeFactory.markEndPosition();
    return nodeFactory.createNode<VariableDeclaration>(type, expectIdentifierToken());
}

ptr<TypeName> Parser::parseTypeName(bool _allowVar)
{
    ptr<TypeName> type;
    Token::Value token = m_scanner->getCurrentToken();
    if (Token::IsElementaryTypeName(token)) {
        type = ASTNodeFactory(*this).createNode<ElementaryTypeName>(token);
        m_scanner->next();
    } else if (token == Token::VAR) {
        if (!_allowVar)
            throwExpectationError("Expected explicit type name.");
        m_scanner->next();
    } else if (token == Token::MAPPING) {
        type = parseMapping();
    } else if (token == Token::IDENTIFIER) {
        ASTNodeFactory nodeFactory(*this);
        nodeFactory.markEndPosition();
        type = nodeFactory.createNode<UserDefinedTypeName>(expectIdentifierToken());
    } else {
        throwExpectationError("Expected type name");
    }

    return type;
}

ptr<Mapping> Parser::parseMapping()
{
    ASTNodeFactory nodeFactory(*this);

    expectToken(Token::MAPPING);
    expectToken(Token::LPAREN);

    if (!Token::IsElementaryTypeName(m_scanner->getCurrentToken()))
        throwExpectationError("Expected elementary type name for mapping key type");
    ptr<ElementaryTypeName> keyType;
    keyType = ASTNodeFactory(*this).createNode<ElementaryTypeName>(m_scanner->getCurrentToken());
    m_scanner->next();

    expectToken(Token::ARROW);
    bool const allowVar = false;
    ptr<TypeName> valueType = parseTypeName(allowVar);
    nodeFactory.markEndPosition();
    expectToken(Token::RPAREN);

    return nodeFactory.createNode<Mapping>(keyType, valueType);
}

ptr<ParameterList> Parser::parseParameterList(bool _allowEmpty)
{
    ASTNodeFactory nodeFactory(*this);

    vecptr<VariableDeclaration> parameters;
    expectToken(Token::LPAREN);
    if (!_allowEmpty || m_scanner->getCurrentToken() != Token::RPAREN) {
        bool const allowVar = false;
        parameters.push_back(parseVariableDeclaration(allowVar));
        while (m_scanner->getCurrentToken() != Token::RPAREN) {
            expectToken(Token::COMMA);
            parameters.push_back(parseVariableDeclaration(allowVar));
        }
    }
    nodeFactory.markEndPosition();
    m_scanner->next();
    return nodeFactory.createNode<ParameterList>(parameters);
}

ptr<Block> Parser::parseBlock()
{
    ASTNodeFactory nodeFactory(*this);
    expectToken(Token::LBRACE);
    vecptr<Statement> statements;
    while (m_scanner->getCurrentToken() != Token::RBRACE) {
        statements.push_back(parseStatement());
    }
    nodeFactory.markEndPosition();
    expectToken(Token::RBRACE);
    return nodeFactory.createNode<Block>(statements);
}

ptr<Statement> Parser::parseStatement()
{
    ptr<Statement> statement;

    switch (m_scanner->getCurrentToken()) {
    case Token::IF:
        return parseIfStatement();
    case Token::WHILE:
        return parseWhileStatement();
    case Token::LBRACE:
        return parseBlock();

    // starting from here, all statements must be terminated by a semicolon
    case Token::CONTINUE:
        statement = ASTNodeFactory(*this).createNode<Continue>();
        break;
    case Token::BREAK:
        statement = ASTNodeFactory(*this).createNode<Break>();
        break;
    case Token::RETURN:
        {
            ASTNodeFactory nodeFactory(*this);
            ptr<Expression> expression;
            if (m_scanner->next() != Token::SEMICOLON) {
                expression = parseExpression();
                nodeFactory.setEndPositionFromNode(expression);
            }
            statement = nodeFactory.createNode<Return>(expression);
        }
        break;
    default:
        // distinguish between variable definition (and potentially assignment) and expressions
        // (which include assignments to other expressions and pre-declared variables)
        // We have a variable definition if we ge a keyword that specifies a type name, or
        // in the case of a user-defined type, we have two identifiers following each other.
        if (m_scanner->getCurrentToken() == Token::MAPPING ||
                m_scanner->getCurrentToken() == Token::VAR ||
                Token::IsElementaryTypeName(m_scanner->getCurrentToken()) ||
                (m_scanner->getCurrentToken() == Token::IDENTIFIER &&
                 m_scanner->peek() == Token::IDENTIFIER)) {
            statement = parseVariableDefinition();
        } else {
            // "ordinary" expression
            statement = parseExpression();
        }
    }
    expectToken(Token::SEMICOLON);
    return statement;
}

ptr<IfStatement> Parser::parseIfStatement()
{
    ASTNodeFactory nodeFactory(*this);
    expectToken(Token::IF);
    expectToken(Token::LPAREN);
    ptr<Expression> condition = parseExpression();
    expectToken(Token::RPAREN);
    ptr<Statement> trueBody = parseStatement();
    ptr<Statement> falseBody;
    if (m_scanner->getCurrentToken() == Token::ELSE) {
        m_scanner->next();
        falseBody = parseStatement();
        nodeFactory.setEndPositionFromNode(falseBody);
    } else {
        nodeFactory.setEndPositionFromNode(trueBody);
    }
    return nodeFactory.createNode<IfStatement>(condition, trueBody, falseBody);
}

ptr<WhileStatement> Parser::parseWhileStatement()
{
    ASTNodeFactory nodeFactory(*this);
    expectToken(Token::WHILE);
    expectToken(Token::LPAREN);
    ptr<Expression> condition = parseExpression();
    expectToken(Token::RPAREN);
    ptr<Statement> body = parseStatement();
    nodeFactory.setEndPositionFromNode(body);
    return nodeFactory.createNode<WhileStatement>(condition, body);
}

ptr<VariableDefinition> Parser::parseVariableDefinition()
{
    ASTNodeFactory nodeFactory(*this);
    bool const allowVar = true;
    ptr<VariableDeclaration> variable = parseVariableDeclaration(allowVar);
    ptr<Expression> value;
    if (m_scanner->getCurrentToken() == Token::ASSIGN) {
        m_scanner->next();
        value = parseExpression();
        nodeFactory.setEndPositionFromNode(value);
    } else {
        nodeFactory.setEndPositionFromNode(variable);
    }
    return nodeFactory.createNode<VariableDefinition>(variable, value);
}

ptr<Expression> Parser::parseExpression()
{
    ASTNodeFactory nodeFactory(*this);
    ptr<Expression> expression = parseBinaryExpression();
    if (!Token::IsAssignmentOp(m_scanner->getCurrentToken()))
        return expression;

    Token::Value assignmentOperator = expectAssignmentOperator();
    ptr<Expression> rightHandSide = parseExpression();
    nodeFactory.setEndPositionFromNode(rightHandSide);
    return nodeFactory.createNode<Assignment>(expression, assignmentOperator, rightHandSide);
}

ptr<Expression> Parser::parseBinaryExpression(int _minPrecedence)
{
    ASTNodeFactory nodeFactory(*this);
    ptr<Expression> expression = parseUnaryExpression();
    int precedence = Token::Precedence(m_scanner->getCurrentToken());
    for (; precedence >= _minPrecedence; --precedence) {
        while (Token::Precedence(m_scanner->getCurrentToken()) == precedence) {
            Token::Value op = m_scanner->getCurrentToken();
            m_scanner->next();
            ptr<Expression> right = parseBinaryExpression(precedence + 1);
            nodeFactory.setEndPositionFromNode(right);
            expression = nodeFactory.createNode<BinaryOperation>(expression, op, right);
        }
    }
    return expression;
}

ptr<Expression> Parser::parseUnaryExpression()
{
    ASTNodeFactory nodeFactory(*this);
    Token::Value token = m_scanner->getCurrentToken();
    if (Token::IsUnaryOp(token) || Token::IsCountOp(token)) {
        // prefix expression
        m_scanner->next();
        ptr<Expression> subExpression = parseUnaryExpression();
        nodeFactory.setEndPositionFromNode(subExpression);
        return nodeFactory.createNode<UnaryOperation>(token, subExpression, true);
    } else {
        // potential postfix expression
        ptr<Expression> subExpression = parseLeftHandSideExpression();
        token = m_scanner->getCurrentToken();
        if (!Token::IsCountOp(token))
            return subExpression;
        nodeFactory.markEndPosition();
        m_scanner->next();
        return nodeFactory.createNode<UnaryOperation>(token, subExpression, false);
    }
}

ptr<Expression> Parser::parseLeftHandSideExpression()
{
    ASTNodeFactory nodeFactory(*this);
    ptr<Expression> expression = parsePrimaryExpression();

    while (true) {
        switch (m_scanner->getCurrentToken()) {
        case Token::LBRACK:
            {
                m_scanner->next();
                ptr<Expression> index = parseExpression();
                nodeFactory.markEndPosition();
                expectToken(Token::RBRACK);
                expression = nodeFactory.createNode<IndexAccess>(expression, index);
            }
            break;
        case Token::PERIOD:
            {
                m_scanner->next();
                nodeFactory.markEndPosition();
                expression = nodeFactory.createNode<MemberAccess>(expression, expectIdentifierToken());
            }
            break;
        case Token::LPAREN:
            {
                m_scanner->next();
                vecptr<Expression> arguments = parseFunctionCallArguments();
                nodeFactory.markEndPosition();
                expectToken(Token::RPAREN);
                expression = nodeFactory.createNode<FunctionCall>(expression, arguments);
            }
            break;
        default:
            return expression;
        }
    }
}

ptr<Expression> Parser::parsePrimaryExpression()
{
    ASTNodeFactory nodeFactory(*this);
    Token::Value token = m_scanner->getCurrentToken();
    ptr<Expression> expression;

    switch (token) {
    case Token::TRUE_LITERAL:
    case Token::FALSE_LITERAL:
        expression = nodeFactory.createNode<Literal>(token, ptr<ASTString>());
        m_scanner->next();
        break;
    case Token::NUMBER:
    case Token::STRING_LITERAL:
        nodeFactory.markEndPosition();
        expression = nodeFactory.createNode<Literal>(token, getLiteralAndAdvance());
        break;
    case Token::IDENTIFIER:
        nodeFactory.markEndPosition();
        expression = nodeFactory.createNode<Identifier>(getLiteralAndAdvance());
        break;
    case Token::LPAREN:
        {
            m_scanner->next();
            ptr<Expression> expression = parseExpression();
            expectToken(Token::RPAREN);
            return expression;
        }
    default:
        if (Token::IsElementaryTypeName(token)) {
            // used for casts
            expression = nodeFactory.createNode<ElementaryTypeNameExpression>(token);
            m_scanner->next();
        } else {
            throwExpectationError("Expected primary expression.");
            return ptr<Expression>(); // this is not reached
        }
    }
    return expression;
}

vecptr<Expression> Parser::parseFunctionCallArguments()
{
    vecptr<Expression> arguments;
    if (m_scanner->getCurrentToken() != Token::RPAREN) {
        arguments.push_back(parseExpression());
        while (m_scanner->getCurrentToken() != Token::RPAREN) {
            expectToken(Token::COMMA);
            arguments.push_back(parseExpression());
        }
    }
    return arguments;
}

void Parser::expectToken(Token::Value _value)
{
    if (m_scanner->getCurrentToken() != _value)
        throwExpectationError(std::string("Expected token ") + std::string(Token::Name(_value)));
    m_scanner->next();
}

Token::Value Parser::expectAssignmentOperator()
{
    Token::Value op = m_scanner->getCurrentToken();
    if (!Token::IsAssignmentOp(op))
        throwExpectationError(std::string("Expected assignment operator"));
    m_scanner->next();
    return op;
}

ptr<ASTString> Parser::expectIdentifierToken()
{
    if (m_scanner->getCurrentToken() != Token::IDENTIFIER)
        throwExpectationError("Expected identifier");

    return getLiteralAndAdvance();
}

ptr<ASTString> Parser::getLiteralAndAdvance()
{
    ptr<ASTString> identifier = std::make_shared<ASTString>(m_scanner->getCurrentLiteral());
    m_scanner->next();
    return identifier;
}

void Parser::throwExpectationError(const std::string& _description)
{
    //@todo put some of this stuff into ParserError
    int line, column;
    std::tie(line, column) = m_scanner->translatePositionToLineColumn(getPosition());
    std::stringstream buf;
    buf << "Solidity parser error: " << _description
        << " at line " << (line + 1)
        << ", column " << (column + 1) << "\n"
        << m_scanner->getLineAtPosition(getPosition()) << "\n"
        << std::string(column, ' ') << "^";

    BOOST_THROW_EXCEPTION(ParserError() << errinfo_comment(buf.str()));
}


} }