path: root/libsolidity/parsing/Scanner.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
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    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/>.

    This file is derived from the file "scanner.cc", which was part of the
    V8 project. The original copyright header follows:

    Copyright 2006-2012, the V8 project authors. All rights reserved.
    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are
    met:

    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
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      copyright notice, this list of conditions and the following
      disclaimer in the documentation and/or other materials provided
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    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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    LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
 * @author Christian <c@ethdev.com>
 * @date 2014
 * Solidity scanner.
 */

#include <algorithm>
#include <tuple>
#include <libsolidity/interface/Utils.h>
#include <libsolidity/parsing/Scanner.h>

using namespace std;

namespace dev
{
namespace solidity
{

namespace
{
bool isDecimalDigit(char c)
{
    return '0' <= c && c <= '9';
}
bool isHexDigit(char c)
{
    return isDecimalDigit(c)
           || ('a' <= c && c <= 'f')
           || ('A' <= c && c <= 'F');
}
bool isLineTerminator(char c)
{
    return c == '\n';
}
bool isWhiteSpace(char c)
{
    return c == ' ' || c == '\n' || c == '\t' || c == '\r';
}
bool isIdentifierStart(char c)
{
    return c == '_' || c == '$' || ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z');
}
bool isIdentifierPart(char c)
{
    return isIdentifierStart(c) || isDecimalDigit(c);
}

int hexValue(char c)
{
    if (c >= '0' && c <= '9')
        return c - '0';
    else if (c >= 'a' && c <= 'f')
        return c - 'a' + 10;
    else if (c >= 'A' && c <= 'F')
        return c - 'A' + 10;
    else return -1;
}
} // end anonymous namespace



/// Scoped helper for literal recording. Automatically drops the literal
/// if aborting the scanning before it's complete.
enum LiteralType {
    LITERAL_TYPE_STRING,
    LITERAL_TYPE_NUMBER, // not really different from string type in behaviour
    LITERAL_TYPE_COMMENT
};

class LiteralScope
{
public:
    explicit LiteralScope(Scanner* _self, enum LiteralType _type): m_type(_type)
    , m_scanner(_self)
    , m_complete(false)
    {
        if (_type == LITERAL_TYPE_COMMENT)
            m_scanner->m_nextSkippedComment.literal.clear();
        else
            m_scanner->m_nextToken.literal.clear();
    }
    ~LiteralScope()
    {
        if (!m_complete)
        {
            if (m_type == LITERAL_TYPE_COMMENT)
                m_scanner->m_nextSkippedComment.literal.clear();
            else
                m_scanner->m_nextToken.literal.clear();
        }
    }
    void complete() { m_complete = true; }

private:
    enum LiteralType m_type;
    Scanner* m_scanner;
    bool m_complete;
}; // end of LiteralScope class


void Scanner::reset(CharStream const& _source, string const& _sourceName)
{
    m_source = _source;
    m_sourceName = make_shared<string const>(_sourceName);
    reset();
}

void Scanner::reset()
{
    m_source.reset();
    m_char = m_source.get();
    skipWhitespace();
    scanToken();
    next();
}

bool Scanner::scanHexByte(char& o_scannedByte)
{
    char x = 0;
    for (int i = 0; i < 2; i++)
    {
        int d = hexValue(m_char);
        if (d < 0)
        {
            rollback(i);
            return false;
        }
        x = x * 16 + d;
        advance();
    }
    o_scannedByte = x;
    return true;
}


// Ensure that tokens can be stored in a byte.
BOOST_STATIC_ASSERT(Token::NUM_TOKENS <= 0x100);

Token::Value Scanner::next()
{
    m_currentToken = m_nextToken;
    m_skippedComment = m_nextSkippedComment;
    scanToken();

    return m_currentToken.token;
}

Token::Value Scanner::selectToken(char _next, Token::Value _then, Token::Value _else)
{
    advance();
    if (m_char == _next)
        return selectToken(_then);
    else
        return _else;
}

bool Scanner::skipWhitespace()
{
    int const startPosition = sourcePos();
    while (isWhiteSpace(m_char))
        advance();
    // Return whether or not we skipped any characters.
    return sourcePos() != startPosition;
}

bool Scanner::skipWhitespaceExceptLF()
{
    int const startPosition = sourcePos();
    while (isWhiteSpace(m_char) && !isLineTerminator(m_char))
        advance();
    // Return whether or not we skipped any characters.
    return sourcePos() != startPosition;
}

Token::Value Scanner::skipSingleLineComment()
{
    // The line terminator at the end of the line is not considered
    // to be part of the single-line comment; it is recognized
    // separately by the lexical grammar and becomes part of the
    // stream of input elements for the syntactic grammar
    while (!isLineTerminator(m_char))
        if (!advance()) break;

    return Token::Whitespace;
}

Token::Value Scanner::scanSingleLineDocComment()
{
    LiteralScope literal(this, LITERAL_TYPE_COMMENT);
    advance(); //consume the last '/' at ///
    skipWhitespaceExceptLF();
    while (!isSourcePastEndOfInput())
    {
        if (isLineTerminator(m_char))
        {
            // check if next line is also a documentation comment
            skipWhitespace();
            if (!m_source.isPastEndOfInput(3) &&
                m_source.get(0) == '/' &&
                m_source.get(1) == '/' &&
                m_source.get(2) == '/')
            {
                addCommentLiteralChar('\n');
                m_char = m_source.advanceAndGet(3);
            }
            else
                break; // next line is not a documentation comment, we are done

        }
        addCommentLiteralChar(m_char);
        advance();
    }
    literal.complete();
    return Token::CommentLiteral;
}

Token::Value Scanner::skipMultiLineComment()
{
    advance();
    while (!isSourcePastEndOfInput())
    {
        char ch = m_char;
        advance();

        // If we have reached the end of the multi-line comment, we
        // consume the '/' and insert a whitespace. This way all
        // multi-line comments are treated as whitespace.
        if (ch == '*' && m_char == '/')
        {
            m_char = ' ';
            return Token::Whitespace;
        }
    }
    // Unterminated multi-line comment.
    return Token::Illegal;
}

Token::Value Scanner::scanMultiLineDocComment()
{
    LiteralScope literal(this, LITERAL_TYPE_COMMENT);
    bool endFound = false;
    bool charsAdded = false;

    while (!isSourcePastEndOfInput())
    {
        //handle newlines in multline comments
        if (isLineTerminator(m_char))
        {
            skipWhitespace();
            if (!m_source.isPastEndOfInput(1) && m_source.get(0) == '*' && m_source.get(1) != '/')
            { // skip first '*' in subsequent lines
                if (charsAdded)
                    addCommentLiteralChar('\n');
                m_char = m_source.advanceAndGet(2);
            }
            else if (!m_source.isPastEndOfInput(1) && m_source.get(0) == '*' && m_source.get(1) == '/')
            { // if after newline the comment ends, don't insert the newline
                m_char = m_source.advanceAndGet(2);
                endFound = true;
                break;
            }
            else if (charsAdded)
                addCommentLiteralChar('\n');
        }

        if (!m_source.isPastEndOfInput(1) && m_source.get(0) == '*' && m_source.get(1) == '/')
        {
            m_char = m_source.advanceAndGet(2);
            endFound = true;
            break;
        }
        addCommentLiteralChar(m_char);
        charsAdded = true;
        advance();
    }
    literal.complete();
    if (!endFound)
        return Token::Illegal;
    else
        return Token::CommentLiteral;
}

Token::Value Scanner::scanSlash()
{
    int firstSlashPosition = sourcePos();
    advance();
    if (m_char == '/')
    {
        if (!advance()) /* double slash comment directly before EOS */
            return  Token::Whitespace;
        else if (m_char == '/')
        {
            // doxygen style /// comment
            Token::Value comment;
            m_nextSkippedComment.location.start = firstSlashPosition;
            comment = scanSingleLineDocComment();
            m_nextSkippedComment.location.end = sourcePos();
            m_nextSkippedComment.token = comment;
            return Token::Whitespace;
        }
        else
            return skipSingleLineComment();
    }
    else if (m_char == '*')
    {
        // doxygen style /** natspec comment
        if (!advance()) /* slash star comment before EOS */
            return Token::Whitespace;
        else if (m_char == '*')
        {
            advance(); //consume the last '*' at /**
            skipWhitespaceExceptLF();

            // special case of a closed normal multiline comment
            if (!m_source.isPastEndOfInput() && m_source.get(0) == '/')
                advance(); //skip the closing slash
            else // we actually have a multiline documentation comment
            {
                Token::Value comment;
                m_nextSkippedComment.location.start = firstSlashPosition;
                comment = scanMultiLineDocComment();
                m_nextSkippedComment.location.end = sourcePos();
                m_nextSkippedComment.token = comment;
            }
            return Token::Whitespace;
        }
        else
            return skipMultiLineComment();
    }
    else if (m_char == '=')
        return selectToken(Token::AssignDiv);
    else
        return Token::Div;
}

void Scanner::scanToken()
{
    m_nextToken.literal.clear();
    m_nextSkippedComment.literal.clear();
    Token::Value token;
    do
    {
        // Remember the position of the next token
        m_nextToken.location.start = sourcePos();
        switch (m_char)
        {
        case '\n': // fall-through
        case ' ':
        case '\t':
            token = selectToken(Token::Whitespace);
            break;
        case '"':
        case '\'':
            token = scanString();
            break;
        case '<':
            // < <= << <<=
            advance();
            if (m_char == '=')
                token = selectToken(Token::LessThanOrEqual);
            else if (m_char == '<')
                token = selectToken('=', Token::AssignShl, Token::SHL);
            else
                token = Token::LessThan;
            break;
        case '>':
            // > >= >> >>= >>> >>>=
            advance();
            if (m_char == '=')
                token = selectToken(Token::GreaterThanOrEqual);
            else if (m_char == '>')
            {
                // >> >>= >>> >>>=
                advance();
                if (m_char == '=')
                    token = selectToken(Token::AssignSar);
                else if (m_char == '>')
                    token = selectToken('=', Token::AssignShr, Token::SHR);
                else
                    token = Token::SAR;
            }
            else
                token = Token::GreaterThan;
            break;
        case '=':
            // = == =>
            advance();
            if (m_char == '=')
                token = selectToken(Token::Equal);
            else if (m_char == '>')
                token = selectToken(Token::Arrow);
            else
                token = Token::Assign;
            break;
        case '!':
            // ! !=
            advance();
            if (m_char == '=')
                token = selectToken(Token::NotEqual);
            else
                token = Token::Not;
            break;
        case '+':
            // + ++ +=
            advance();
            if (m_char == '+')
                token = selectToken(Token::Inc);
            else if (m_char == '=')
                token = selectToken(Token::AssignAdd);
            else
                token = Token::Add;
            break;
        case '-':
            // - -- -=
            advance();
            if (m_char == '-')
                token = selectToken(Token::Dec);
            else if (m_char == '=')
                token = selectToken(Token::AssignSub);
            else
                token = Token::Sub;
            break;
        case '*':
            // * ** *=
            advance();
            if (m_char == '*')
                token = selectToken(Token::Exp);
            else if (m_char == '=')
                token = selectToken(Token::AssignMul);
            else
                token = Token::Mul;
            break;
        case '%':
            // % %=
            token = selectToken('=', Token::AssignMod, Token::Mod);
            break;
        case '/':
            // /  // /* /=
            token = scanSlash();
            break;
        case '&':
            // & && &=
            advance();
            if (m_char == '&')
                token = selectToken(Token::And);
            else if (m_char == '=')
                token = selectToken(Token::AssignBitAnd);
            else
                token = Token::BitAnd;
            break;
        case '|':
            // | || |=
            advance();
            if (m_char == '|')
                token = selectToken(Token::Or);
            else if (m_char == '=')
                token = selectToken(Token::AssignBitOr);
            else
                token = Token::BitOr;
            break;
        case '^':
            // ^ ^=
            token = selectToken('=', Token::AssignBitXor, Token::BitXor);
            break;
        case '.':
            // . Number
            advance();
            if (isDecimalDigit(m_char))
                token = scanNumber('.');
            else
                token = Token::Period;
            break;
        case ':':
            token = selectToken(Token::Colon);
            break;
        case ';':
            token = selectToken(Token::Semicolon);
            break;
        case ',':
            token = selectToken(Token::Comma);
            break;
        case '(':
            token = selectToken(Token::LParen);
            break;
        case ')':
            token = selectToken(Token::RParen);
            break;
        case '[':
            token = selectToken(Token::LBrack);
            break;
        case ']':
            token = selectToken(Token::RBrack);
            break;
        case '{':
            token = selectToken(Token::LBrace);
            break;
        case '}':
            token = selectToken(Token::RBrace);
            break;
        case '?':
            token = selectToken(Token::Conditional);
            break;
        case '~':
            token = selectToken(Token::BitNot);
            break;
        default:
            if (isIdentifierStart(m_char))
                token = scanIdentifierOrKeyword();
            else if (isDecimalDigit(m_char))
                token = scanNumber();
            else if (skipWhitespace())
                token = Token::Whitespace;
            else if (isSourcePastEndOfInput())
                token = Token::EOS;
            else
                token = selectToken(Token::Illegal);
            break;
        }
        // Continue scanning for tokens as long as we're just skipping
        // whitespace.
    }
    while (token == Token::Whitespace);
    m_nextToken.location.end = sourcePos();
    m_nextToken.token = token;
}

bool Scanner::scanEscape()
{
    char c = m_char;
    advance();
    // Skip escaped newlines.
    if (isLineTerminator(c))
        return true;
    switch (c)
    {
    case '\'':  // fall through
    case '"':  // fall through
    case '\\':
        break;
    case 'b':
        c = '\b';
        break;
    case 'f':
        c = '\f';
        break;
    case 'n':
        c = '\n';
        break;
    case 'r':
        c = '\r';
        break;
    case 't':
        c = '\t';
        break;
    case 'v':
        c = '\v';
        break;
    case 'x':
        if (!scanHexByte(c))
            return false;
        break;
    }

    addLiteralChar(c);
    return true;
}

Token::Value Scanner::scanString()
{
    char const quote = m_char;
    advance();  // consume quote
    LiteralScope literal(this, LITERAL_TYPE_STRING);
    while (m_char != quote && !isSourcePastEndOfInput() && !isLineTerminator(m_char))
    {
        char c = m_char;
        advance();
        if (c == '\\')
        {
            if (isSourcePastEndOfInput() || !scanEscape())
                return Token::Illegal;
        }
        else
            addLiteralChar(c);
    }
    if (m_char != quote)
        return Token::Illegal;
    literal.complete();
    advance();  // consume quote
    return Token::StringLiteral;
}

void Scanner::scanDecimalDigits()
{
    while (isDecimalDigit(m_char))
        addLiteralCharAndAdvance();
}

Token::Value Scanner::scanNumber(char _charSeen)
{
    enum { DECIMAL, HEX, BINARY } kind = DECIMAL;
    LiteralScope literal(this, LITERAL_TYPE_NUMBER);
    if (_charSeen == '.')
    {
        // we have already seen a decimal point of the float
        addLiteralChar('.');
        scanDecimalDigits();  // we know we have at least one digit
    }
    else
    {
        solAssert(_charSeen == 0, "");
        // if the first character is '0' we must check for octals and hex
        if (m_char == '0')
        {
            addLiteralCharAndAdvance();
            // either 0, 0exxx, 0Exxx, 0.xxx or a hex number
            if (m_char == 'x' || m_char == 'X')
            {
                // hex number
                kind = HEX;
                addLiteralCharAndAdvance();
                if (!isHexDigit(m_char))
                    return Token::Illegal; // we must have at least one hex digit after 'x'/'X'
                while (isHexDigit(m_char))
                    addLiteralCharAndAdvance();
            }
        }
        // Parse decimal digits and allow trailing fractional part.
        if (kind == DECIMAL)
        {
            scanDecimalDigits();  // optional
            if (m_char == '.')
            {
                addLiteralCharAndAdvance();
                scanDecimalDigits();  // optional
            }
        }
    }
    // scan exponent, if any
    if (m_char == 'e' || m_char == 'E')
    {
        solAssert(kind != HEX, "'e'/'E' must be scanned as part of the hex number");
        if (kind != DECIMAL)
            return Token::Illegal;
        // scan exponent
        addLiteralCharAndAdvance();
        if (m_char == '+' || m_char == '-')
            addLiteralCharAndAdvance();
        if (!isDecimalDigit(m_char))
            return Token::Illegal; // we must have at least one decimal digit after 'e'/'E'
        scanDecimalDigits();
    }
    // The source character immediately following a numeric literal must
    // not be an identifier start or a decimal digit; see ECMA-262
    // section 7.8.3, page 17 (note that we read only one decimal digit
    // if the value is 0).
    if (isDecimalDigit(m_char) || isIdentifierStart(m_char))
        return Token::Illegal;
    literal.complete();
    return Token::Number;
}

Token::Value Scanner::scanIdentifierOrKeyword()
{
    solAssert(isIdentifierStart(m_char), "");
    LiteralScope literal(this, LITERAL_TYPE_STRING);
    addLiteralCharAndAdvance();
    // Scan the rest of the identifier characters.
    while (isIdentifierPart(m_char))
        addLiteralCharAndAdvance();
    literal.complete();
    return Token::fromIdentifierOrKeyword(m_nextToken.literal);
}

char CharStream::advanceAndGet(size_t _chars)
{
    if (isPastEndOfInput())
        return 0;
    m_position += _chars;
    if (isPastEndOfInput())
        return 0;
    return m_source[m_position];
}

char CharStream::rollback(size_t _amount)
{
    solAssert(m_position >= _amount, "");
    m_position -= _amount;
    return get();
}

string CharStream::lineAtPosition(int _position) const
{
    // if _position points to \n, it returns the line before the \n
    using size_type = string::size_type;
    size_type searchStart = min<size_type>(m_source.size(), _position);
    if (searchStart > 0)
        searchStart--;
    size_type lineStart = m_source.rfind('\n', searchStart);
    if (lineStart == string::npos)
        lineStart = 0;
    else
        lineStart++;
    return m_source.substr(lineStart, min(m_source.find('\n', lineStart),
                                          m_source.size()) - lineStart);
}

tuple<int, int> CharStream::translatePositionToLineColumn(int _position) const
{
    using size_type = string::size_type;
    size_type searchPosition = min<size_type>(m_source.size(), _position);
    int lineNumber = count(m_source.begin(), m_source.begin() + searchPosition, '\n');
    size_type lineStart;
    if (searchPosition == 0)
        lineStart = 0;
    else
    {
        lineStart = m_source.rfind('\n', searchPosition - 1);
        lineStart = lineStart == string::npos ? 0 : lineStart + 1;
    }
    return tuple<int, int>(lineNumber, searchPosition - lineStart);
}


}
}