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**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of Qt Creator.
**
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** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
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** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 as published by the Free Software
** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
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#include "cppcompletionassistprocessor.h"

#include <cppeditor/cppeditorconstants.h>

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

#include <QTextBlock>
#include <QTextCursor>
#include <QTextDocument>

using namespace CPlusPlus;

namespace CppTools {

CppCompletionAssistProcessor::CppCompletionAssistProcessor()
    : m_positionForProposal(-1)
    , m_preprocessorCompletions(QStringList()
          << QLatin1String("define")
          << QLatin1String("error")
          << QLatin1String("include")
          << QLatin1String("line")
          << QLatin1String("pragma")
          << QLatin1String("pragma once")
          << QLatin1String("pragma omp atomic")
          << QLatin1String("pragma omp parallel")
          << QLatin1String("pragma omp for")
          << QLatin1String("pragma omp ordered")
          << QLatin1String("pragma omp parallel for")
          << QLatin1String("pragma omp section")
          << QLatin1String("pragma omp sections")
          << QLatin1String("pragma omp parallel sections")
          << QLatin1String("pragma omp single")
          << QLatin1String("pragma omp master")
          << QLatin1String("pragma omp critical")
          << QLatin1String("pragma omp barrier")
          << QLatin1String("pragma omp flush")
          << QLatin1String("pragma omp threadprivate")
          << QLatin1String("undef")
          << QLatin1String("if")
          << QLatin1String("ifdef")
          << QLatin1String("ifndef")
          << QLatin1String("elif")
          << QLatin1String("else")
          << QLatin1String("endif"))
    , m_hintProposal(0)
    , m_snippetCollector(QLatin1String(CppEditor::Constants::CPP_SNIPPETS_GROUP_ID),
                         QIcon(QLatin1String(":/texteditor/images/snippet.png")))
{
}

void CppCompletionAssistProcessor::addSnippets()
{
    m_completions.append(m_snippetCollector.collect());
}

static bool isDoxygenTagCompletionCharacter(const QChar &character)
{
    return character == QLatin1Char('\\')
        || character == QLatin1Char('@') ;
}

void CppCompletionAssistProcessor::startOfOperator(QTextDocument *textDocument,
        int positionInDocument,
        unsigned *kind,
        int &start,
        const CPlusPlus::LanguageFeatures &languageFeatures,
        bool adjustForQt5SignalSlotCompletion,
        DotAtIncludeCompletionHandler dotAtIncludeCompletionHandler)
{
    if (start != positionInDocument) {
        QTextCursor tc(textDocument);
        tc.setPosition(positionInDocument);

        // Include completion: make sure the quote character is the first one on the line
        if (*kind == T_STRING_LITERAL) {
            QTextCursor s = tc;
            s.movePosition(QTextCursor::StartOfLine, QTextCursor::KeepAnchor);
            QString sel = s.selectedText();
            if (sel.indexOf(QLatin1Char('"')) < sel.length() - 1) {
                *kind = T_EOF_SYMBOL;
                start = positionInDocument;
            }
        }

        if (*kind == T_COMMA) {
            ExpressionUnderCursor expressionUnderCursor(languageFeatures);
            if (expressionUnderCursor.startOfFunctionCall(tc) == -1) {
                *kind = T_EOF_SYMBOL;
                start = positionInDocument;
            }
        }

        SimpleLexer tokenize;
        tokenize.setLanguageFeatures(languageFeatures);
        tokenize.setSkipComments(false);
        const Tokens &tokens = tokenize(tc.block().text(), BackwardsScanner::previousBlockState(tc.block()));
        const int tokenIdx = SimpleLexer::tokenBefore(tokens, qMax(0, tc.positionInBlock() - 1)); // get the token at the left of the cursor
        const Token tk = (tokenIdx == -1) ? Token() : tokens.at(tokenIdx);
        const QChar characterBeforePositionInDocument
                = textDocument->characterAt(positionInDocument - 1);

        if (adjustForQt5SignalSlotCompletion && *kind == T_AMPER && tokenIdx > 0) {
            const Token &previousToken = tokens.at(tokenIdx - 1);
            if (previousToken.kind() == T_COMMA)
                start = positionInDocument - (tk.utf16charOffset - previousToken.utf16charOffset) - 1;
        } else if (*kind == T_DOXY_COMMENT && !(tk.is(T_DOXY_COMMENT) || tk.is(T_CPP_DOXY_COMMENT))) {
            *kind = T_EOF_SYMBOL;
            start = positionInDocument;
        // Do not complete in comments, except in doxygen comments for doxygen commands.
        // Do not complete in strings, except it is for include completion.
        } else if (tk.is(T_COMMENT) || tk.is(T_CPP_COMMENT)
                 || ((tk.is(T_CPP_DOXY_COMMENT) || tk.is(T_DOXY_COMMENT))
                        && !isDoxygenTagCompletionCharacter(characterBeforePositionInDocument))
                 || (tk.isLiteral() && (*kind != T_STRING_LITERAL
                                     && *kind != T_ANGLE_STRING_LITERAL
                                     && *kind != T_SLASH
                                     && *kind != T_DOT))) {
            *kind = T_EOF_SYMBOL;
            start = positionInDocument;
        // Include completion: can be triggered by slash, but only in a string
        } else if (*kind == T_SLASH && (tk.isNot(T_STRING_LITERAL) && tk.isNot(T_ANGLE_STRING_LITERAL))) {
            *kind = T_EOF_SYMBOL;
            start = positionInDocument;
        } else if (*kind == T_LPAREN) {
            if (tokenIdx > 0) {
                const Token &previousToken = tokens.at(tokenIdx - 1); // look at the token at the left of T_LPAREN
                switch (previousToken.kind()) {
                case T_IDENTIFIER:
                case T_GREATER:
                case T_SIGNAL:
                case T_SLOT:
                    break; // good

                default:
                    // that's a bad token :)
                    *kind = T_EOF_SYMBOL;
                    start = positionInDocument;
                }
            }
        }
        // Check for include preprocessor directive
        else if (*kind == T_STRING_LITERAL || *kind == T_ANGLE_STRING_LITERAL || *kind == T_SLASH
                 || (*kind == T_DOT
                        && (tk.is(T_STRING_LITERAL) || tk.is(T_ANGLE_STRING_LITERAL)))) {
            bool include = false;
            if (tokens.size() >= 3) {
                if (tokens.at(0).is(T_POUND) && tokens.at(1).is(T_IDENTIFIER) && (tokens.at(2).is(T_STRING_LITERAL) ||
                                                                                  tokens.at(2).is(T_ANGLE_STRING_LITERAL))) {
                    const Token &directiveToken = tokens.at(1);
                    QString directive = tc.block().text().mid(directiveToken.utf16charsBegin(),
                                                              directiveToken.utf16chars());
                    if (directive == QLatin1String("include") ||
                            directive == QLatin1String("include_next") ||
                            directive == QLatin1String("import")) {
                        include = true;
                    }
                }
            }

            if (!include) {
                *kind = T_EOF_SYMBOL;
                start = positionInDocument;
            } else if (*kind == T_DOT && dotAtIncludeCompletionHandler){
                dotAtIncludeCompletionHandler(start, kind);
            }
        }
    }
}

} // namespace CppTools