path: root/libsolidity/inlineasm/AsmParser.cpp

/*
    This file is part of solidity.

    solidity 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.

    solidity 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 solidity.  If not, see <http://www.gnu.org/licenses/>.
*/
/**
 * @author Christian <c@ethdev.com>
 * @date 2016
 * Solidity inline assembly parser.
 */

#include <libsolidity/inlineasm/AsmParser.h>
#include <ctype.h>
#include <algorithm>
#include <libsolidity/parsing/Scanner.h>

using namespace std;
using namespace dev;
using namespace dev::solidity;
using namespace dev::solidity::assembly;

shared_ptr<assembly::Block> Parser::parse(std::shared_ptr<Scanner> const& _scanner)
{
    try
    {
        m_scanner = _scanner;
        return make_shared<Block>(parseBlock());
    }
    catch (FatalError const&)
    {
        if (m_errors.empty())
            throw; // Something is weird here, rather throw again.
    }
    return nullptr;
}

assembly::Block Parser::parseBlock()
{
    assembly::Block block = createWithLocation<Block>();
    expectToken(Token::LBrace);
    while (m_scanner->currentToken() != Token::RBrace)
        block.statements.emplace_back(parseStatement());
    block.location.end = endPosition();
    m_scanner->next();
    return block;
}

assembly::Statement Parser::parseStatement()
{
    switch (m_scanner->currentToken())
    {
    case Token::Let:
        return parseVariableDeclaration();
    case Token::Function:
        return parseFunctionDefinition();
    case Token::LBrace:
        return parseBlock();
    case Token::Assign:
    {
        assembly::Assignment assignment = createWithLocation<assembly::Assignment>();
        m_scanner->next();
        expectToken(Token::Colon);
        assignment.variableName.location = location();
        assignment.variableName.name = m_scanner->currentLiteral();
        if (instructions().count(assignment.variableName.name))
            fatalParserError("Identifier expected, got instruction name.");
        assignment.location.end = endPosition();
        expectToken(Token::Identifier);
        return assignment;
    }
    case Token::Return: // opcode
    case Token::Byte: // opcode
    default:
        break;
    }
    // Options left:
    // Simple instruction (might turn into functional),
    // literal,
    // identifier (might turn into label or functional assignment)
    Statement statement(parseElementaryOperation());
    switch (m_scanner->currentToken())
    {
    case Token::LParen:
        return parseFunctionalInstruction(std::move(statement));
    case Token::Colon:
    {
        if (statement.type() != typeid(assembly::Identifier))
            fatalParserError("Label name / variable name must precede \":\".");
        assembly::Identifier const& identifier = boost::get<assembly::Identifier>(statement);
        m_scanner->next();
        // identifier:=: should be parsed as identifier: =: (i.e. a label),
        // while identifier:= (being followed by a non-colon) as identifier := (assignment).
        if (m_scanner->currentToken() == Token::Assign && m_scanner->peekNextToken() != Token::Colon)
        {
            // functional assignment
            FunctionalAssignment funAss = createWithLocation<FunctionalAssignment>(identifier.location);
            if (instructions().count(identifier.name))
                fatalParserError("Cannot use instruction names for identifier names.");
            m_scanner->next();
            funAss.variableName = identifier;
            funAss.value.reset(new Statement(parseExpression()));
            funAss.location.end = locationOf(*funAss.value).end;
            return funAss;
        }
        else
        {
            // label
            Label label = createWithLocation<Label>(identifier.location);
            label.name = identifier.name;
            return label;
        }
    }
    case Token::LBrack:
    {
        if (statement.type() != typeid(assembly::Identifier))
            fatalParserError("Label name must precede \"[\".");
        assembly::Identifier const& identifier = boost::get<assembly::Identifier>(statement);
        Label label = createWithLocation<Label>(identifier.location);
        label.name = identifier.name;
        m_scanner->next();
        if (m_scanner->currentToken() == Token::Number)
        {
            label.stackInfo.push_back(m_scanner->currentLiteral());
            m_scanner->next();
        }
        else if (m_scanner->currentToken() == Token::Sub)
        {
            m_scanner->next();
            label.stackInfo.push_back("-" + m_scanner->currentLiteral());
            expectToken(Token::Number);
        }
        else if (m_scanner->currentToken() != Token::RBrack)
            while (true)
            {
                label.stackInfo.push_back(expectAsmIdentifier());
                if (m_scanner->currentToken() == Token::RBrack)
                    break;
                expectToken(Token::Comma);
            }
        // Push an empty string to signify that there were brackets, like in
        // "name[]:", which just resets the stack height to the height of the local variables.
        if (label.stackInfo.empty())
            label.stackInfo.push_back("");
        expectToken(Token::RBrack);
        label.location.end = endPosition();
        expectToken(Token::Colon);
        return label;
    }
    default:
        break;
    }
    return statement;
}

assembly::Statement Parser::parseExpression()
{
    Statement operation = parseElementaryOperation(true);
    if (m_scanner->currentToken() == Token::LParen)
        return parseFunctionalInstruction(std::move(operation));
    else
        return operation;
}

std::map<string, dev::solidity::Instruction> const& Parser::instructions()
{
    // Allowed instructions, lowercase names.
    static map<string, dev::solidity::Instruction> s_instructions;
    if (s_instructions.empty())
    {
        for (auto const& instruction: solidity::c_instructions)
        {
            if (
                instruction.second == solidity::Instruction::JUMPDEST ||
                (solidity::Instruction::PUSH1 <= instruction.second && instruction.second <= solidity::Instruction::PUSH32)
            )
                continue;
            string name = instruction.first;
            transform(name.begin(), name.end(), name.begin(), [](unsigned char _c) { return tolower(_c); });
            s_instructions[name] = instruction.second;
        }

        // add alias for suicide
        s_instructions["suicide"] = solidity::Instruction::SELFDESTRUCT;
    }
    return s_instructions;
}

assembly::Statement Parser::parseElementaryOperation(bool _onlySinglePusher)
{
    Statement ret;
    switch (m_scanner->currentToken())
    {
    case Token::Identifier:
    case Token::Return:
    case Token::Byte:
    case Token::Address:
    {
        string literal;
        if (m_scanner->currentToken() == Token::Return)
            literal = "return";
        else if (m_scanner->currentToken() == Token::Byte)
            literal = "byte";
        else if (m_scanner->currentToken() == Token::Address)
            literal = "address";
        else
            literal = m_scanner->currentLiteral();
        // first search the set of instructions.
        if (instructions().count(literal))
        {
            dev::solidity::Instruction const& instr = instructions().at(literal);
            if (_onlySinglePusher)
            {
                InstructionInfo info = dev::solidity::instructionInfo(instr);
                if (info.ret != 1)
                    fatalParserError("Instruction " + info.name + " not allowed in this context.");
            }
            ret = Instruction{location(), instr};
        }
        else
            ret = Identifier{location(), literal};
        break;
    }
    case Token::StringLiteral:
    case Token::Number:
    {
        ret = Literal{
            location(),
            m_scanner->currentToken() == Token::Number,
            m_scanner->currentLiteral()
        };
        break;
    }
    default:
        fatalParserError("Expected elementary inline assembly operation.");
    }
    m_scanner->next();
    return ret;
}

assembly::VariableDeclaration Parser::parseVariableDeclaration()
{
    VariableDeclaration varDecl = createWithLocation<VariableDeclaration>();
    expectToken(Token::Let);
    varDecl.name = expectAsmIdentifier();
    expectToken(Token::Colon);
    expectToken(Token::Assign);
    varDecl.value.reset(new Statement(parseExpression()));
    varDecl.location.end = locationOf(*varDecl.value).end;
    return varDecl;
}

assembly::FunctionDefinition Parser::parseFunctionDefinition()
{
    FunctionDefinition funDef = createWithLocation<FunctionDefinition>();
    expectToken(Token::Function);
    funDef.name = expectAsmIdentifier();
    expectToken(Token::LParen);
    while (m_scanner->currentToken() != Token::RParen)
    {
        funDef.arguments.push_back(expectAsmIdentifier());
        if (m_scanner->currentToken() == Token::RParen)
            break;
        expectToken(Token::Comma);
    }
    expectToken(Token::RParen);
    if (m_scanner->currentToken() == Token::Sub)
    {
        expectToken(Token::Sub);
        expectToken(Token::GreaterThan);
        expectToken(Token::LParen);
        while (true)
        {
            funDef.returns.push_back(expectAsmIdentifier());
            if (m_scanner->currentToken() == Token::RParen)
                break;
            expectToken(Token::Comma);
        }
        expectToken(Token::RParen);
    }
    funDef.body = parseBlock();
    funDef.location.end = funDef.body.location.end;
    return funDef;
}

assembly::Statement Parser::parseFunctionalInstruction(assembly::Statement&& _instruction)
{
    if (_instruction.type() == typeid(Instruction))
    {
        FunctionalInstruction ret;
        ret.instruction = std::move(boost::get<Instruction>(_instruction));
        ret.location = ret.instruction.location;
        solidity::Instruction instr = ret.instruction.instruction;
        InstructionInfo instrInfo = instructionInfo(instr);
        if (solidity::Instruction::DUP1 <= instr && instr <= solidity::Instruction::DUP16)
            fatalParserError("DUPi instructions not allowed for functional notation");
        if (solidity::Instruction::SWAP1 <= instr && instr <= solidity::Instruction::SWAP16)
            fatalParserError("SWAPi instructions not allowed for functional notation");
        expectToken(Token::LParen);
        unsigned args = unsigned(instrInfo.args);
        for (unsigned i = 0; i < args; ++i)
        {
            ret.arguments.emplace_back(parseExpression());
            if (i != args - 1)
            {
                if (m_scanner->currentToken() != Token::Comma)
                    fatalParserError(string(
                        "Expected comma (" +
                        instrInfo.name +
                        " expects " +
                        boost::lexical_cast<string>(args) +
                        " arguments)"
                    ));
                else
                    m_scanner->next();
            }
        }
        ret.location.end = endPosition();
        if (m_scanner->currentToken() == Token::Comma)
            fatalParserError(
                string("Expected ')' (" + instrInfo.name + " expects " + boost::lexical_cast<string>(args) + " arguments)")
            );
        expectToken(Token::RParen);
        return ret;
    }
    else if (_instruction.type() == typeid(Identifier))
    {
        FunctionCall ret;
        ret.functionName = std::move(boost::get<Identifier>(_instruction));
        ret.location = ret.functionName.location;
        expectToken(Token::LParen);
        while (m_scanner->currentToken() != Token::RParen)
        {
            ret.arguments.emplace_back(parseExpression());
            if (m_scanner->currentToken() == Token::RParen)
                break;
            expectToken(Token::Comma);
        }
        ret.location.end = endPosition();
        expectToken(Token::RParen);
        return ret;
    }
    else
        fatalParserError("Assembly instruction or function name required in front of \"(\")");

    return {};
}

string Parser::expectAsmIdentifier()
{
    string name = m_scanner->currentLiteral();
    if (instructions().count(name))
        fatalParserError("Cannot use instruction names for identifier names.");
    expectToken(Token::Identifier);
    return name;
}