Utils: make FileInProjectFinder work with same file names

Consider having files with the same name in different subdirectories of
your project. The FileInProjectFinder will now choose the best matching
file path, which is the one that has the longest right-aligned common
substring with the path to find.

For the candidates
    ["/home/jim/MyProject/Resources/qml/1/foo.qml",
     "/home/jim/MyProject/Resources/qml/2/foo.qml"]
and the file path to find being "/SomeWhere/Else/qml/2/foo.qml" the
ranks are 8 and 10. Therefore, the second path is chosen.

Task-number: QTCREATORBUG-12908
Change-Id: I6225fd1dce8cc79a90d02ae0a54cdf80f75f45af
Reviewed-by: Kai Koehne <kai.koehne@theqtcompany.com>
Reviewed-by: Ulf Hermann <ulf.hermann@theqtcompany.com>

src/libs/utils/fileinprojectfinder.cpp

@@ -36,6 +36,8 @@
 #include <QFileInfo>
 #include <QUrl>
 
+#include <algorithm>
+
 enum { debug = false };
 
 namespace Utils {
@@ -212,20 +214,19 @@ QString FileInProjectFinder::findFile(const QUrl &fileUrl, bool *success) const
         }
     }
 
-    // find (solely by filename) in project files
+    // find best matching file path in project files
     if (debug)
         qDebug() << "FileInProjectFinder: checking project files ...";
 
-    const QString fileName = FileName::fromString(originalPath).fileName();
-    foreach (const QString &f, m_projectFiles) {
-        if (FileName::fromString(f).fileName() == fileName) {
-            m_cache.insert(originalPath, f);
+    const QString matchedFilePath
+            = bestMatch(
+                filesWithSameFileName(FileName::fromString(originalPath).fileName()),
+                originalPath);
+    if (!matchedFilePath.isEmpty()) {
+        m_cache.insert(originalPath, matchedFilePath);
         if (success)
             *success = true;
-            if (debug)
-                qDebug() << "FileInProjectFinder: found" << f << "in project files";
-            return f;
-        }
+        return matchedFilePath;
     }
 
     if (debug)
@@ -252,4 +253,44 @@ QString FileInProjectFinder::findFile(const QUrl &fileUrl, bool *success) const
     return originalPath;
 }
 
+QStringList FileInProjectFinder::filesWithSameFileName(const QString &fileName) const
+{
+    QStringList result;
+    foreach (const QString &f, m_projectFiles) {
+        if (FileName::fromString(f).fileName() == fileName)
+            result << f;
+    }
+    return result;
+}
+
+int FileInProjectFinder::rankFilePath(const QString &candidatePath, const QString &filePathToFind)
+{
+    int rank = 0;
+    for (int a = candidatePath.length(), b = filePathToFind.length();
+         --a >= 0 && --b >= 0 && candidatePath.at(a) == filePathToFind.at(b);)
+        rank++;
+    return rank;
+}
+
+QString FileInProjectFinder::bestMatch(const QStringList &filePaths, const QString &filePathToFind)
+{
+    if (filePaths.isEmpty())
+        return QString();
+    if (filePaths.length() == 1) {
+        if (debug)
+            qDebug() << "FileInProjectFinder: found" << filePaths.first() << "in project files";
+        return filePaths.first();
+    }
+    auto it = std::max_element(filePaths.constBegin(), filePaths.constEnd(),
+        [&filePathToFind] (const QString &a, const QString &b) -> bool {
+            return rankFilePath(a, filePathToFind) < rankFilePath(b, filePathToFind);
+    });
+    if (it != filePaths.cend()) {
+        if (debug)
+            qDebug() << "FileInProjectFinder: found best match" << *it << "in project files";
+        return *it;
+    }
+    return QString();
+}
+
 } // namespace Utils

src/libs/utils/fileinprojectfinder.h

@@ -54,6 +54,10 @@ public:
     QString findFile(const QUrl &fileUrl, bool *success = 0) const;
 
 private:
+    QStringList filesWithSameFileName(const QString &fileName) const;
+    static int rankFilePath(const QString &candidatePath, const QString &filePathToFind);
+    static QString bestMatch(const QStringList &filePaths, const QString &filePathToFind);
+
     QString m_projectDir;
     QString m_sysroot;
     QStringList m_projectFiles;