path: root/libsolidity/inlineasm/AsmParser.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 2016
 * Solidity inline assembly parser.
 */

#include <libsolidity/inlineasm/AsmParser.h>
#include <ctype.h>
#include <algorithm>
#include <libevmcore/Instruction.h>
#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<assembly::Block>(parseBlock());
    }
    catch (FatalError const&)
    {
        if (m_errors.empty())
            throw; // Something is weird here, rather throw again.
    }
    return nullptr;
}

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

assembly::Statement Parser::parseStatement()
{
    switch (m_scanner->currentToken())
    {
    case Token::Let:
        return parseVariableDeclaration();
    case Token::LBrace:
        return parseBlock();
    case Token::Assign:
    {
        m_scanner->next();
        expectToken(Token::Colon);
        string name = m_scanner->currentLiteral();
        expectToken(Token::Identifier);
        return assembly::Assignment{assembly::Identifier{name}};
    }
    case Token::Return: // 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(statement);
    case Token::Colon:
    {
        if (statement.type() != typeid(assembly::Identifier))
            fatalParserError("Label name / variable name must precede \":\".");
        string const& name = boost::get<assembly::Identifier>(statement).name;
        m_scanner->next();
        if (m_scanner->currentToken() == Token::Assign)
        {
            // functional assignment
            m_scanner->next();
            unique_ptr<Statement> value;
            value.reset(new Statement(parseExpression()));
            return FunctionalAssignment{{std::move(name)}, std::move(value)};
        }
        else
            // label
            return Label{name};
    }
    default:
        break;
    }
    return statement;
}

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

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

    //@TODO track location

    switch (m_scanner->currentToken())
    {
    case Token::Identifier:
    case Token::Return:
    {
        string literal;
        if (m_scanner->currentToken() == Token::Return)
            literal = "return";
        else
            literal = m_scanner->currentLiteral();
        // first search the set of instructions.
        if (s_instructions.count(literal))
        {
            eth::Instruction const& instr = s_instructions[literal];
            if (_onlySinglePusher)
            {
                eth::InstructionInfo info = eth::instructionInfo(instr);
                if (info.ret != 1)
                    fatalParserError("Instruction " + info.name + " not allowed in this context.");
            }
            m_scanner->next();
            return Instruction{instr};
        }
        else
            m_scanner->next();
            return Identifier{literal};
        break;
    }
    case Token::StringLiteral:
    case Token::Number:
    {
        Literal literal{
            m_scanner->currentToken() == Token::Number,
            m_scanner->currentLiteral()
        };
        m_scanner->next();
        return literal;
    }
    default:
        break;
    }
    fatalParserError("Expected elementary inline assembly operation.");
    return {};
}

assembly::VariableDeclaration Parser::parseVariableDeclaration()
{
    expectToken(Token::Let);
    string name = m_scanner->currentLiteral();
    expectToken(Token::Identifier);
    expectToken(Token::Colon);
    expectToken(Token::Assign);
    unique_ptr<Statement> value;
    value.reset(new Statement(parseExpression()));
    return VariableDeclaration{name, std::move(value)};
}

FunctionalInstruction Parser::parseFunctionalInstruction(assembly::Statement const& _instruction)
{
    if (_instruction.type() != typeid(Instruction))
        fatalParserError("Assembly instruction required in front of \"(\")");
    eth::Instruction instr = boost::get<Instruction>(_instruction).instruction;
    eth::InstructionInfo instrInfo = eth::instructionInfo(instr);
    if (eth::Instruction::DUP1 <= instr && instr <= eth::Instruction::DUP16)
        fatalParserError("DUPi instructions not allowed for functional notation");
    if (eth::Instruction::SWAP1 <= instr && instr <= eth::Instruction::SWAP16)
        fatalParserError("SWAPi instructions not allowed for functional notation");

    expectToken(Token::LParen);
    vector<Statement> arguments;
    unsigned args = unsigned(instrInfo.args);
    for (unsigned i = 0; i < args; ++i)
    {
        arguments.push_back(parseExpression());
        if (i != args - 1)
            expectToken(Token::Comma);
    }
    expectToken(Token::RParen);
    return FunctionalInstruction{{instr}, std::move(arguments)};
}