3 files changed, 55 insertions, 1 deletions
diff --git a/src/main/javassist/bytecode/CodeAttribute.java b/src/main/javassist/bytecode/CodeAttribute.java
index 4c8ea2f2..98479b21 100644
--- a/src/main/javassist/bytecode/CodeAttribute.java
+++ b/src/main/javassist/bytecode/CodeAttribute.java
@@ -348,6 +348,20 @@ public class CodeAttribute extends AttributeInfo implements Opcode {
     }
 
     /**
+     * Adds a line number table.  If another copy of line number table
+     * is already contained, the old one is removed.
+     *
+     * @param lnt       the line number table added to this code attribute.
+     *                  If it is null, a new line number is not added.
+     *                  Only the old line number is removed.
+     */
+    public void setAttribute(LineNumberAttribute lnt) {
+        AttributeInfo.remove(attributes, LineNumberAttribute.tag);
+        if (lnt != null)
+            attributes.add(lnt);
+    }
+
+    /**
      * Copies code.
      */
     private byte[] copyCode(ConstPool destCp, Map<String,String> classnames,
diff --git a/src/main/javassist/bytecode/LineNumberAttribute.java b/src/main/javassist/bytecode/LineNumberAttribute.java
index cead96e0..16b37377 100644
--- a/src/main/javassist/bytecode/LineNumberAttribute.java
+++ b/src/main/javassist/bytecode/LineNumberAttribute.java
@@ -35,7 +35,7 @@ public class LineNumberAttribute extends AttributeInfo {
         super(cp, n, in);
     }
 
-    private LineNumberAttribute(ConstPool cp, byte[] i) {
+    LineNumberAttribute(ConstPool cp, byte[] i) {
         super(cp, tag, i);
     }
 
diff --git a/src/main/javassist/bytecode/LineNumberAttributeBuilder.java b/src/main/javassist/bytecode/LineNumberAttributeBuilder.java
new file mode 100644
index 00000000..52d9d0c8
--- /dev/null
+++ b/src/main/javassist/bytecode/LineNumberAttributeBuilder.java
@@ -0,0 +1,40 @@
+package javassist.bytecode;
+
+import javassist.compiler.ast.ASTree;
+
+import java.io.ByteArrayOutputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+
+public class LineNumberAttributeBuilder {
+    private final HashMap<Integer, Integer> map = new HashMap<>();
+
+    public void put(int newPc, ASTree tree) {
+        if (tree != null)
+            put(newPc, tree.getLineNumber());
+    }
+
+    private void put(int newPc, int lineNum) {
+        Integer pc = map.get(lineNum);
+        if (pc == null || newPc < pc) {
+            map.put(lineNum, newPc);
+        }
+    }
+
+    public LineNumberAttribute build(ConstPool cp) {
+        int size = map.size();
+        try (ByteArrayOutputStream bos = new ByteArrayOutputStream(size * 4 + 2);
+             DataOutputStream dos = new DataOutputStream(bos)) {
+            dos.writeShort(size);
+            for (Map.Entry<Integer, Integer> entry : map.entrySet()) {
+                dos.writeShort(entry.getValue());
+                dos.writeShort(entry.getKey());
+            }
+            return new LineNumberAttribute(cp, bos.toByteArray());
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}