decompiler: registry flag to dump original line numbers as comments

src/org/jetbrains/java/decompiler/main/ClassesProcessor.java

@@ -285,6 +285,9 @@ public class ClassesProcessor {
       if (DecompilerContext.getOption(IFernflowerPreferences.BYTECODE_SOURCE_MAPPING)) {
         BytecodeSourceMapper mapper = DecompilerContext.getBytecodeSourceMapper();
         mapper.addTotalOffset(total_offset_lines);
+        if (DecompilerContext.getOption(IFernflowerPreferences.DUMP_ORIGINAL_LINES)) {
+          buffer.dumpOriginalLineNumbers(mapper.getOriginalLinesMapping());
+        }
         if (DecompilerContext.getOption(IFernflowerPreferences.UNIT_TEST_MODE)) {
           buffer.appendLineSeparator();
           mapper.dumpMapping(buffer, true);

src/org/jetbrains/java/decompiler/main/TextBuffer.java

@@ -104,6 +104,9 @@ public class TextBuffer {
   public String toString() {
     String original = myStringBuilder.toString();
     if (myLineToOffsetMapping == null || myLineToOffsetMapping.isEmpty()) {
+      if (myLineMapping != null) {
+        return addOriginalLineNumbers();
+      }
       return original;
     }
     else {
@@ -140,6 +143,26 @@ public class TextBuffer {
     }
   }
 
+  private String addOriginalLineNumbers() {
+    StringBuilder sb = new StringBuilder();
+    int lineStart = 0, lineEnd;
+    int count = 0, length = myLineSeparator.length();
+    while ((lineEnd = myStringBuilder.indexOf(myLineSeparator, lineStart)) > 0) {
+      ++count;
+      sb.append(myStringBuilder.substring(lineStart, lineEnd));
+      Integer integer = myLineMapping.get(count);
+      if (integer != null) {
+        sb.append("// ").append(integer);
+      }
+      sb.append(myLineSeparator);
+      lineStart = lineEnd + length;
+    }
+    if (lineStart < myStringBuilder.length()) {
+      sb.append(myStringBuilder.substring(lineStart));
+    }
+    return sb.toString();
+  }
+
   private void appendLines(StringBuilder res, String[] srcLines, int from, int to, int requiredLineNumber) {
     if (to - from > requiredLineNumber) {
       List<String> strings = compactLines(Arrays.asList(srcLines).subList(from, to) ,requiredLineNumber);
@@ -278,4 +301,14 @@ public class TextBuffer {
   public StringBuilder getOriginalText() {
     return myStringBuilder;
   }
+
+  private Map<Integer, Integer> myLineMapping = null; // new to original
+  public void dumpOriginalLineNumbers(int[] lineMapping) {
+    if (lineMapping.length > 0) {
+      myLineMapping = new HashMap<Integer, Integer>();
+      for (int i = 0; i < lineMapping.length; i+=2) {
+        myLineMapping.put(lineMapping[i+1], lineMapping[i]);
+      }
+    }
+  }
 }

src/org/jetbrains/java/decompiler/main/extern/IFernflowerPreferences.java

@@ -54,6 +54,7 @@ public interface IFernflowerPreferences {
   String INDENT_STRING = "ind";
   String BANNER = "ban";
 
+  String DUMP_ORIGINAL_LINES = "__dump_original_lines__";
   String UNIT_TEST_MODE = "__unit_test_mode__";
 
   String LINE_SEPARATOR_WIN = "\r\n";
@@ -91,5 +92,6 @@ public interface IFernflowerPreferences {
     put(INDENT_STRING, "   ");
     put(BANNER, "");
     put(UNIT_TEST_MODE, "0");
+    put(DUMP_ORIGINAL_LINES, "0");
   }});
 }