Auto detect EOL mode (#693)

Closes #607

Author: dail8859

src/NotepadNext/EditorManager.cpp

@@ -266,6 +266,9 @@ void EditorManager::setupEditor(ScintillaNext *editor)
     editor->setIndentationGuides(settings->showIndentGuide() ? SC_IV_LOOKBOTH : SC_IV_NONE);
     editor->setWrapMode(settings->wordWrap() ? SC_WRAP_WORD : SC_WRAP_NONE);
 
+    // TODO: make this optional
+    editor->setEOLMode(detectEOLMode(editor));
+
     // Decorators
     SmartHighlighter *s = new SmartHighlighter(editor);
     s->setEnabled(true);
@@ -316,3 +319,53 @@ QList<QPointer<ScintillaNext> > EditorManager::getEditors()
     purgeOldEditorPointers();
     return editors;
 }
+
+int EditorManager::detectEOLMode(ScintillaNext *editor) const
+{
+    qInfo(Q_FUNC_INFO);
+
+    const int MIN_LINE_THRESHOLD = 3;
+    const int MAX_BYTES_TO_CHECK = 10*1024;
+
+    int index = 0;
+    int lf = 0;
+    int cr = 0;
+    int crlf = 0;
+    int chPrev = ' ';
+    int chNext = editor->charAt(index);
+
+    for (int i = 0; i < qMin(MAX_BYTES_TO_CHECK, (int) editor->length()); ++i) {
+        int ch = chNext;
+        chNext = editor->charAt(i + 1);
+
+        if (ch == '\r') {
+            if (chNext == '\n') crlf++;
+            else cr++;
+        }
+        else if (ch == '\n') {
+            if (chPrev != '\r') lf++;
+        }
+
+        chPrev = ch;
+
+        // If any meet some minimum threshold then just declare victory
+        if (crlf == MIN_LINE_THRESHOLD) return SC_EOL_CRLF;
+        else if (cr == MIN_LINE_THRESHOLD) return SC_EOL_CR;
+        else if (lf == MIN_LINE_THRESHOLD) return SC_EOL_LF;
+    }
+
+    // There are either no lines or only a few, so make a best effort determination
+
+    if (crlf > cr && crlf > lf) {
+        return SC_EOL_CRLF;
+    }
+    else if (cr > lf) {
+        return SC_EOL_CR;
+    }
+    else if (lf > cr) {
+        return SC_EOL_LF;
+    }
+    else {
+        return editor->eOLMode();
+    }
+}

src/NotepadNext/EditorManager.h

@@ -49,6 +49,7 @@ class EditorManager : public QObject
     void setupEditor(ScintillaNext *editor);
     void purgeOldEditorPointers();
     QList<QPointer<ScintillaNext>> getEditors();
+    int detectEOLMode(ScintillaNext *editor) const;
 
     QList<QPointer<ScintillaNext>> editors;
     ApplicationSettings *settings;