ClangTools: Fix applying fixits one by one

If a file had multiple fixits and only a subset was applied, the
remaining fixits in that file were invalidated. Fix this by adjusting
the locations of the not yet applied fixits.

Change-Id: I2c190412e871e9011c4d4a62ed938e76ad4cdf72
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>

src/plugins/clangtools/clangfixitsrefactoringchanges.cpp

@@ -0,0 +1,148 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** 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
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+****************************************************************************/
+
+#include "clangfixitsrefactoringchanges.h"
+
+#include <coreplugin/editormanager/editormanager.h>
+
+#include <QDebug>
+#include <QFileInfo>
+#include <QLoggingCategory>
+#include <QTextBlock>
+#include <QTextCursor>
+
+#include <utils/qtcassert.h>
+
+Q_LOGGING_CATEGORY(fixitsLog, "qtc.clangtools.fixits");
+
+using namespace Utils;
+
+namespace ClangTools {
+namespace Internal {
+
+int FixitsRefactoringFile::position(unsigned line, unsigned column) const
+{
+    QTC_ASSERT(line != 0, return -1);
+    QTC_ASSERT(column != 0, return -1);
+    return document()->findBlockByNumber(line - 1).position() + column - 1;
+}
+
+static QDebug operator<<(QDebug debug, const ReplacementOperation &op)
+{
+    debug.nospace() << "ReplacementOperation("
+                    << op.pos << ", "
+                    << op.length << ", "
+                    << op.text << ", "
+                    << op.apply
+                    << ")"
+                    ;
+
+    return debug;
+}
+
+bool FixitsRefactoringFile::apply()
+{
+    qCDebug(fixitsLog) << "Applying fixits for" << m_filePath;
+
+    if (m_replacementOperations.isEmpty())
+        return false; // Error nothing to apply TODO: Is this correct to return?
+
+    QTC_ASSERT(!m_filePath.isEmpty(), return false);
+
+    // Check for permissions
+    if (!QFileInfo(m_filePath).isWritable())
+        return false; // Error file not writable
+
+    // Apply changes
+    QTextDocument *doc = document();
+    QTextCursor cursor(doc);
+
+    for (int i=0; i < m_replacementOperations.size(); ++i) {
+        ReplacementOperation &op = *m_replacementOperations[i];
+        if (op.apply) {
+            qCDebug(fixitsLog) << " " << i << "Applying" << op;
+
+            // Shift subsequent operations that are affected
+            shiftAffectedReplacements(op, i + 1);
+
+            // Apply
+            cursor.setPosition(op.pos);
+            cursor.setPosition(op.pos + op.length, QTextCursor::KeepAnchor);
+            cursor.insertText(op.text);
+        }
+    }
+
+    // Write file
+    if (!m_textFileFormat.codec)
+        return false; // Error reading file
+
+    QString error;
+    if (!m_textFileFormat.writeFile(m_filePath, doc->toPlainText(), &error)) {
+        qCDebug(fixitsLog) << "ERROR: Could not write file" << m_filePath << ":" << error;
+        return false; // Error writing file
+    }
+
+    return true;
+}
+
+QTextDocument *FixitsRefactoringFile::document() const
+{
+    if (!m_document) {
+        QString fileContents;
+        if (!m_filePath.isEmpty()) {
+            QString error;
+            QTextCodec *defaultCodec = Core::EditorManager::defaultTextCodec();
+            TextFileFormat::ReadResult result = TextFileFormat::readFile(
+                        m_filePath, defaultCodec,
+                        &fileContents, &m_textFileFormat,
+                        &error);
+            if (result != TextFileFormat::ReadSuccess) {
+                qCDebug(fixitsLog) << "ERROR: Could not read " << m_filePath << ":" << error;
+                m_textFileFormat.codec = nullptr;
+            }
+        }
+        // always make a QTextDocument to avoid excessive null checks
+        m_document = new QTextDocument(fileContents);
+    }
+    return m_document;
+}
+
+void FixitsRefactoringFile::shiftAffectedReplacements(const ReplacementOperation &op, int startIndex)
+{
+    for (int i = startIndex; i < m_replacementOperations.size(); ++i) {
+        ReplacementOperation &current = *m_replacementOperations[i];
+        ReplacementOperation before = current;
+
+        if (op.pos <= current.pos)
+            current.pos += op.text.size();
+        if (op.pos < current.pos)
+            current.pos -= op.length;
+
+        qCDebug(fixitsLog) << "    shift:" << i << before << " ====> " << current;
+    }
+}
+
+} // namespace Internal
+} // namespace ClangTools