parameters.cpp

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// Copyright (C) 2021 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
 
#include "parameters.h"
 
#include "codechunk.h"
#include "tokenizer.h"
 
#include <algorithm>
 
using namespace Qt::Literals::StringLiterals;
 
QT_BEGIN_NAMESPACE
 
QRegularExpression Parameters::s_varComment(R"(^/\*\s*([a-zA-Z_0-9]+)\s*\*/$)");
 
/*!
  \class Parameters
 
  \brief A class for parsing and managing a function parameter list
 
  The constructor is passed a string that is the text inside the
  parentheses of a function declaration. The constructor parses
  the parameter list into a vector of class Parameter.
 
  The Parameters object is then used in function searches to find
  the correct function node given the function name and the signature
  of its parameters.
 */
 
Parameters::Parameters() : m_valid(true), m_privateSignal(false), m_tok(0), m_tokenizer(nullptr)
{
    // nothing.
}
 
Parameters::Parameters(const QString &signature)
    : m_valid(true), m_privateSignal(false), m_tok(0), m_tokenizer(nullptr)
{
    if (!signature.isEmpty()) {
        if (!parse(signature)) {
            m_parameters.clear();
            m_valid = false;
        }
    }
}
 
/*!
  Get the next token from the string being parsed and store
  it in the token variable.
 */
void Parameters::readToken()
{
    m_tok = m_tokenizer->getToken();
}
 
/*!
  Return the current lexeme from the string being parsed.
 */
QString Parameters::lexeme()
{
    return m_tokenizer->lexeme();
}
 
/*!
  Return the previous lexeme read from the string being parsed.
 */
QString Parameters::previousLexeme()
{
    return m_tokenizer->previousLexeme();
}
 
/*!
  If the current token is \a target, read the next token and
  return \c true. Otherwise, return false without reading the
  next token.
 */
bool Parameters::match(int target)
{
    if (m_tok == target) {
        readToken();
        return true;
    }
    return false;
}
 
/*!
  Reads input inside angled brackets, appending tokens to the code chunk held
  by \a type, taking nested brackets, parentheses and square brackets into
  account. Square brackets and regular parentheses are not handled separately.
 
  Processing begins if the first token is a left angle bracket and continues
  until a corresponding right angle bracket is found, the end of input occurs,
  or an excess of right parentheses or square brackets are found.
 
  After processing, the current token is the first token after the closing
  right angle bracket, the end of file token, or the mismatched right bracket
  or parenthesis.
 */
void Parameters::matchTemplateAngles(CodeChunk &type)
{
    if (m_tok == Tok_LeftAngle) {
        int leftAngleDepth = 0;
        int parenAndBraceDepth = 0;
        do {
            if (m_tok == Tok_LeftAngle) {
                leftAngleDepth++;
            } else if (m_tok == Tok_RightAngle) {
                leftAngleDepth--;
            } else if (m_tok == Tok_LeftParen || m_tok == Tok_LeftBrace) {
                ++parenAndBraceDepth;
            } else if (m_tok == Tok_RightParen || m_tok == Tok_RightBrace) {
                if (--parenAndBraceDepth < 0)
                    return;
            }
            type.append(lexeme());
            readToken();
        } while (leftAngleDepth > 0 && m_tok != Tok_Eoi);
    }
}
 
/*!
  Uses the current tokenizer to parse the \a name and \a type
  of the parameter.
 */
bool Parameters::matchTypeAndName(CodeChunk &type, QString &name)
{
    /*
      This code is really hard to follow... sorry. The loop is there to match
      Alpha::Beta::Gamma::...::Omega.
    */
    for (;;) {
        bool virgin = true;
 
        if (m_tok != Tok_Ident) {
            /*
              There is special processing for 'Foo::operator int()'
              and such elsewhere. This is the only case where we
              return something with a trailing gulbrandsen ('Foo::').
            */
            if (m_tok == Tok_operator)
                return true;
 
            /*
              People may write 'const unsigned short' or
              'short unsigned const' or any other permutation.
            */
            while (match(Tok_const) || match(Tok_volatile))
                type.append(previousLexeme());
            QString pending;
            while (m_tok == Tok_signed || m_tok == Tok_int || m_tok == Tok_unsigned
                   || m_tok == Tok_short || m_tok == Tok_long || m_tok == Tok_int64) {
                if (m_tok == Tok_signed)
                    pending = lexeme();
                else {
                    if (m_tok == Tok_unsigned && !pending.isEmpty())
                        type.append(pending);
                    pending.clear();
                    type.append(lexeme());
                }
                readToken();
                virgin = false;
            }
            if (!pending.isEmpty()) {
                type.append(pending);
                pending.clear();
            }
            while (match(Tok_const) || match(Tok_volatile))
                type.append(previousLexeme());
 
            if (match(Tok_Tilde))
                type.append(previousLexeme());
        }
 
        if (virgin) {
            if (match(Tok_Ident)) {
                /*
                  This is a hack until we replace this "parser"
                  with the real one used in Qt Creator.
                  Is it still needed? mws 11/12/2018
                 */
                if (lexeme() == "("
                    && ((previousLexeme() == "QT_PREPEND_NAMESPACE")
                        || (previousLexeme() == "NS"))) {
                    readToken();
                    readToken();
                    type.append(previousLexeme());
                    readToken();
                } else
                    type.append(previousLexeme());
            } else if (match(Tok_void) || match(Tok_int) || match(Tok_char) || match(Tok_double)
                       || match(Tok_Ellipsis)) {
                type.append(previousLexeme());
            } else {
                return false;
            }
        } else if (match(Tok_int) || match(Tok_char) || match(Tok_double)) {
            type.append(previousLexeme());
        }
 
        matchTemplateAngles(type);
 
        while (match(Tok_const) || match(Tok_volatile))
            type.append(previousLexeme());
 
        if (match(Tok_Gulbrandsen))
            type.append(previousLexeme());
        else
            break;
    }
 
    while (match(Tok_Ampersand) || match(Tok_Aster) || match(Tok_const) || match(Tok_Caret)
           || match(Tok_Ellipsis))
        type.append(previousLexeme());
 
    if (match(Tok_LeftParenAster)) {
        /*
          A function pointer. This would be rather hard to handle without a
          tokenizer hack, because a type can be followed with a left parenthesis
          in some cases (e.g., 'operator int()'). The tokenizer recognizes '(*'
          as a single token.
        */
        type.append(" "); // force a space after the type
        type.append(previousLexeme());
        type.appendHotspot();
        if (match(Tok_Ident))
            name = previousLexeme();
        if (!match(Tok_RightParen))
            return false;
        type.append(previousLexeme());
        if (!match(Tok_LeftParen))
            return false;
        type.append(previousLexeme());
 
        /* parse the parameters. Ignore the parameter name from the type */
        while (m_tok != Tok_RightParen && m_tok != Tok_Eoi) {
            QString dummy;
            if (!matchTypeAndName(type, dummy))
                return false;
            if (match(Tok_Comma))
                type.append(previousLexeme());
        }
        if (!match(Tok_RightParen))
            return false;
        type.append(previousLexeme());
    } else {
        /*
          The common case: Look for an optional identifier, then for
          some array brackets.
        */
        type.appendHotspot();
 
        if (match(Tok_Ident)) {
            name = previousLexeme();
        } else if (match(Tok_Comment)) {
            // Use a regular expression to extract any commented out parameter name.
            auto match = s_varComment.match(previousLexeme());
            if (match.hasMatch())
                name = match.captured(1);
        } else if (match(Tok_LeftParen)) {
            name = "(";
            while (m_tok != Tok_RightParen && m_tok != Tok_Eoi) {
                name.append(lexeme());
                readToken();
            }
            name.append(")");
            readToken();
            if (match(Tok_LeftBracket)) {
                name.append("[");
                while (m_tok != Tok_RightBracket && m_tok != Tok_Eoi) {
                    name.append(lexeme());
                    readToken();
                }
                name.append("]");
                readToken();
            }
        }
 
        if (m_tok == Tok_LeftBracket) {
            int bracketDepth0 = m_tokenizer->bracketDepth();
            while ((m_tokenizer->bracketDepth() >= bracketDepth0 && m_tok != Tok_Eoi)
                   || m_tok == Tok_RightBracket) {
                type.append(lexeme());
                readToken();
            }
        }
    }
    return true;
}
 
/*!
  Parse the next function parameter, if there is one, and
  append it to the internal parameter vector. Return true
  if a parameter is parsed correctly. Otherwise return false.
 */
bool Parameters::matchParameter()
{
    if (match(Tok_QPrivateSignal)) {
        m_privateSignal = true;
        return true;
    }
 
    CodeChunk chunk;
    QString name;
    if (!matchTypeAndName(chunk, name))
        return false;
    QString type = chunk.toString();
    QString defaultValue;
    match(Tok_Comment);
    if (match(Tok_Equal)) {
        chunk.clear();
        int pdepth = m_tokenizer->parenDepth();
        while (m_tokenizer->parenDepth() >= pdepth
               && (m_tok != Tok_Comma || (m_tokenizer->parenDepth() > pdepth))
               && m_tok != Tok_Eoi) {
            chunk.append(lexeme());
            readToken();
        }
        defaultValue = chunk.toString();
    }
    append(type, name, defaultValue);
    return true;
}
 
/*!
  This function uses a Tokenizer to parse the \a signature,
  which is a comma-separated list of parameter declarations.
  If an error is detected, the Parameters object is cleared
  and \c false is returned. Otherwise \c true is returned.
 */
bool Parameters::parse(const QString &signature)
{
    Tokenizer *outerTokenizer = m_tokenizer;
    int outerTok = m_tok;
 
    const QByteArray &latin1 = signature.toLatin1();
    Tokenizer stringTokenizer(Location(), latin1);
    stringTokenizer.setParsingFnOrMacro(true);
    m_tokenizer = &stringTokenizer;
 
    readToken();
    do {
        if (!matchParameter()) {
            m_parameters.clear();
            m_valid = false;
            break;
        }
    } while (match(Tok_Comma));
 
    m_tokenizer = outerTokenizer;
    m_tok = outerTok;
    return m_valid;
}
 
/*!
  Append a Parameter constructed from \a type, \a name, and \a value
  to the parameter vector.
 */
void Parameters::append(const QString &type, const QString &name, const QString &value)
{
    m_parameters.append(Parameter(type, name, value));
}
 
/*!
  Returns the list of reconstructed parameters. If \a includeValues
  is true, the default values are included, if any are present.
 */
QString Parameters::signature(bool includeValues) const
{
    QString result;
    if (!m_parameters.empty()) {
        for (int i = 0; i < m_parameters.size(); i++) {
            if (i > 0)
                result += ", ";
            result += m_parameters.at(i).signature(includeValues);
        }
    }
    return result;
}
 
/*!
  Returns the signature of all the parameters with all the
  spaces and commas removed. It is unintelligible, but that
  is what the caller wants.
 
  If \a names is true, the parameter names are included. If
  \a values is true, the default values are included.
 */
QString Parameters::rawSignature(bool names, bool values) const
{
    QString raw;
    const auto params = m_parameters;
    for (const auto &parameter : params) {
        raw += parameter.type();
        if (names)
            raw += parameter.name();
        if (values)
            raw += parameter.defaultValue();
    }
    return raw;
}
 
/*!
  Parse the parameter \a signature by splitting the string,
  and store the individual parameters in the parameter vector.
 
  This method of parsing is naive but sufficient for QML methods
  and macros.
 */
void Parameters::set(const QString &signature)
{
    clear();
    if (!signature.isEmpty()) {
        QStringList commaSplit = signature.split(',');
        m_parameters.resize(commaSplit.size());
        int i = 0;
        for (const auto &item : std::as_const(commaSplit)) {
            QStringList blankSplit = item.split(' ', Qt::SkipEmptyParts);
            QString pDefault;
            qsizetype defaultIdx = blankSplit.indexOf(QStringLiteral("="));
            if (defaultIdx != -1) {
                if (++defaultIdx < blankSplit.size())
                    pDefault = blankSplit.mid(defaultIdx).join(' ');
                blankSplit = blankSplit.mid(0, defaultIdx - 1);
            }
            QString pName = blankSplit.takeLast();
            QString pType = blankSplit.join(' ');
            if (pType.isEmpty() && pName == QLatin1String("..."))
                qSwap(pType, pName);
            else {
                int j = 0;
                while (j < pName.size() && !pName.at(j).isLetter())
                    j++;
                if (j > 0) {
                    pType += QChar(' ') + pName.left(j);
                    pName = pName.mid(j);
                }
            }
            m_parameters[i++].set(pType, pName, pDefault);
        }
    }
}
 
/*!
  Insert all the parameter names into names.
 */
QSet<QString> Parameters::getNames() const
{
    QSet<QString> names;
    const auto params = m_parameters;
    for (const auto &parameter : params) {
        if (!parameter.name().isEmpty())
            names.insert(parameter.name());
    }
    return names;
}
 
/*!
  Construct a list of the parameter types and return it.
 */
QString Parameters::generateTypeList() const
{
    QString out;
    if (count() > 0) {
        for (int i = 0; i < count(); ++i) {
            if (i > 0)
                out += ", ";
            out += m_parameters.at(i).type();
        }
    }
    return out;
}
 
/*!
  Construct a list of the parameter type/name pairs and
  return it.
*/
QString Parameters::generateTypeAndNameList() const
{
    QString out;
    if (count() > 0) {
        for (int i = 0; i < count(); ++i) {
            if (i != 0)
                out += ", ";
            const Parameter &p = m_parameters.at(i);
            out += p.type();
            if (out[out.size() - 1].isLetterOrNumber())
                out += QLatin1Char(' ');
            out += p.name();
        }
    }
    return out;
}
 
/*!
  Construct a list of just the parameter names (without types)
  and return it. Used for generating code snippets where only
  argument names are needed. If a parameter has no name, a
  synthetic name (arg1, arg2, etc.) is generated.
*/
QString Parameters::generateNameList() const
{
    const int n = count();
    if (n == 0)
        return {};
 
    QString out;
 
    for (int i = 0; i < n; ++i) {
        if (i != 0)
            out += ", ";
        const QString &name = m_parameters.at(i).name();
        if (name.isEmpty())
            out += QString("arg%1").arg(i + 1);
        else
            out += name;
    }
    return out;
}
 
/*!
  Returns true if \a parameters contains the same parameter
  signature as this.
 */
bool Parameters::match(const Parameters &parameters) const
{
    return std::equal(m_parameters.cbegin(), m_parameters.cend(), parameters.m_parameters.cbegin(),
                      parameters.m_parameters.cend(),
                      [](const Parameter &a, const Parameter &b) { return a.type() == b.type(); });
}
 
/*!
  Returns a string containing only the list of parameters within
  parentheses in the supplied \a signature, or a null string if
  no parameter list is found.
 
  If a parameter list is found, modifies the signature to remove
  the parameter list and its surrounding parentheses.
 
  An unbalanced signature is left unchanged and returns a null string.
*/
QString Parameters::extractParameters(QString &signature)
{
    if (!signature.endsWith(')'_L1))
        return {};
 
    qsizetype position = signature.size() - 1;
    qsizetype depth{0};
 
    while (position >= 0) {
        if (signature.at(position) == ')'_L1)
            ++depth;
        else if (signature.at(position) == '('_L1) {
            --depth;
            if (depth == 0)
                break;
        }
        --position;
    }
    if (position < 0)
        return {};
 
    // An unmatched parenthesis in the name is not part of a valid signature.
    for (qsizetype i = 0; i < position; ++i) {
        if (signature.at(i) == '('_L1)
            ++depth;
        else if (signature.at(i) == ')'_L1) {
            --depth;
            if (depth < 0)
                return {};
        }
    }
    if (depth != 0)
        return {};
 
    QString parameters = signature.mid(position + 1, signature.size() - position - 2);
    signature.truncate(position);
    return parameters;
}
 
QT_END_NAMESPACE