qt-creator/src/plugins/clangcodemodel/clangcompletioncontextanalyzer.cpp

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#include "clangcompletioncontextanalyzer.h"

#include "activationsequenceprocessor.h"
#include "activationsequencecontextprocessor.h"

#include <texteditor/codeassist/assistinterface.h>

#include <cplusplus/BackwardsScanner.h>
#include <cplusplus/ExpressionUnderCursor.h>
#include <cplusplus/SimpleLexer.h>

#include <utils/qtcassert.h>

#include <QDebug>
#include <QTextBlock>
#include <QTextCursor>

using namespace CPlusPlus;

namespace {

bool isTokenForIncludePathCompletion(unsigned tokenKind)
{
    return tokenKind == T_STRING_LITERAL
        || tokenKind == T_ANGLE_STRING_LITERAL
        || tokenKind == T_SLASH;
}

bool isTokenForPassThrough(unsigned tokenKind)
{
    return tokenKind == T_EOF_SYMBOL
        || tokenKind == T_DOT
        || tokenKind == T_COLON_COLON
        || tokenKind == T_ARROW
        || tokenKind == T_DOT_STAR;
}

} // anonymous namespace

namespace ClangCodeModel {
namespace Internal {

ClangCompletionContextAnalyzer::ClangCompletionContextAnalyzer(
        const ClangCompletionAssistInterface *assistInterface,
        CPlusPlus::LanguageFeatures languageFeatures)
    : m_interface(assistInterface)
    , m_languageFeatures(languageFeatures)
{
}

void ClangCompletionContextAnalyzer::analyze()
{
    QTC_ASSERT(m_interface, return);
    setActionAndClangPosition(PassThroughToLibClang, -1);

    ActivationSequenceContextProcessor activationSequenceContextProcessor(m_interface);
    m_completionOperator = activationSequenceContextProcessor.completionKind();
    int afterOperatorPosition = activationSequenceContextProcessor.positionAfterOperator();
    m_positionEndOfExpression = activationSequenceContextProcessor.positionBeforeOperator();
    m_positionForProposal = activationSequenceContextProcessor.positionAfterOperator();

    const bool actionIsSet = handleNonFunctionCall(afterOperatorPosition);
    if (!actionIsSet) {
        handleCommaInFunctionCall();
        handleFunctionCall(afterOperatorPosition);
    }
}

ClangCompletionContextAnalyzer::FunctionInfo
ClangCompletionContextAnalyzer::analyzeFunctionCall(int endOfOperator) const
{
    int index = skipPrecedingWhitespace(endOfOperator);
    QTextCursor textCursor(m_interface->textDocument());
    textCursor.setPosition(index);

    ExpressionUnderCursor euc(m_languageFeatures);
    index = euc.startOfFunctionCall(textCursor);
    const int functionNameStart = findStartOfName(index);

    QTextCursor textCursor2(m_interface->textDocument());
    textCursor2.setPosition(functionNameStart);
    textCursor2.setPosition(index, QTextCursor::KeepAnchor);

    FunctionInfo info;
    info.functionNamePosition = functionNameStart;
    info.functionName = textCursor2.selectedText().trimmed();
    return info;
}

int ClangCompletionContextAnalyzer::findStartOfName(int position) const
{
    if (position == -1)
        position = m_interface->position();
    QChar chr;

    do {
        chr = m_interface->characterAt(--position);
        // TODO: Check also chr.isHighSurrogate() / ch.isLowSurrogate()?
        // See also CppTools::isValidFirstIdentifierChar
    } while (chr.isLetterOrNumber() || chr == QLatin1Char('_'));

    return position + 1;
}

int ClangCompletionContextAnalyzer::skipPrecedingWhitespace(int position) const
{
    QTC_ASSERT(position >= 0, return position);
    while (m_interface->characterAt(position - 1).isSpace())
        --position;
    return position;
}

void ClangCompletionContextAnalyzer::setActionAndClangPosition(CompletionAction action,
                                                               int position)
{
    QTC_CHECK(position >= -1);
    m_completionAction = action;
    m_positionForClang = position;
}

void
ClangCompletionContextAnalyzer::setAction(ClangCompletionContextAnalyzer::CompletionAction action)
{
    setActionAndClangPosition(action, -1);
}

void ClangCompletionContextAnalyzer::handleCommaInFunctionCall()
{
    if (m_completionOperator == T_COMMA) {
        ExpressionUnderCursor expressionUnderCursor(m_languageFeatures);
        QTextCursor textCursor(m_interface->textDocument());
        textCursor.setPosition(m_positionEndOfExpression);
        const int start = expressionUnderCursor.startOfFunctionCall(textCursor);
        m_positionEndOfExpression = start;
        m_positionForProposal = start + 1; // After '(' of function call
        m_completionOperator = T_LPAREN;
    }
}

void ClangCompletionContextAnalyzer::handleFunctionCall(int afterOperatorPosition)
{
    if (m_completionOperator == T_LPAREN) {
        ExpressionUnderCursor expressionUnderCursor(m_languageFeatures);
        QTextCursor textCursor(m_interface->textDocument());
        textCursor.setPosition(m_positionEndOfExpression);
        const QString expression = expressionUnderCursor(textCursor);

        if (expression.endsWith(QLatin1String("SIGNAL"))) {
            setActionAndClangPosition(CompleteSignal, afterOperatorPosition);
        } else if (expression.endsWith(QLatin1String("SLOT"))) {
            setActionAndClangPosition(CompleteSlot, afterOperatorPosition);
        } else if (m_interface->position() != afterOperatorPosition) {
            // No function completion if cursor is not after '(' or ','
            m_positionForProposal = afterOperatorPosition;
            setActionAndClangPosition(PassThroughToLibClang, afterOperatorPosition);
        } else {
            const FunctionInfo functionInfo = analyzeFunctionCall(afterOperatorPosition);
            m_functionName = functionInfo.functionName;
            setActionAndClangPosition(PassThroughToLibClangAfterLeftParen,
                                      functionInfo.functionNamePosition);
        }
    }
}

bool ClangCompletionContextAnalyzer::handleNonFunctionCall(int position)
{
    if (isTokenForPassThrough(m_completionOperator)) {
        setActionAndClangPosition(PassThroughToLibClang, position);
        return true;
    } else if (m_completionOperator == T_DOXY_COMMENT) {
        setAction(CompleteDoxygenKeyword);
        return true;
    } else if (m_completionOperator == T_POUND) {
        // TODO: Check if libclang can complete preprocessor directives
        setAction(CompletePreprocessorDirective);
        return true;
    } else if (isTokenForIncludePathCompletion(m_completionOperator)) {
        setAction(CompleteIncludePath);
        return true;
    }

    return false;
}

} // namespace Internal
} // namespace ClangCodeModel