Fix codehaus-plexus#3 : Filtering fails when target contains multiple escapes

Author: belingueres

src/main/java/org/codehaus/plexus/interpolation/multi/MultiDelimiterStringSearchInterpolator.java

@@ -201,13 +201,17 @@ private String interpolate( String input, RecursionInterceptor recursionIntercep
 
                 if ( startIdx >= 0 && escapeString != null && escapeString.length() > 0 )
                 {
-                    int startEscapeIdx = startIdx == 0 ? 0 : startIdx - escapeString.length();
+                    int startEscapeIdx = ( startIdx == 0 ) ? 0 : startIdx - escapeString.length();
                     if ( startEscapeIdx >= 0 )
                     {
                         String escape = input.substring( startEscapeIdx, startIdx );
                         if ( escape != null && escapeString.equals( escape ) )
                         {
                             result.append( wholeExpr );
+                            if ( startEscapeIdx > 0 )
+                            {
+                                --startEscapeIdx;
+                            }
                             result.replace( startEscapeIdx, startEscapeIdx + escapeString.length(), "" );
                             continue;
                         }

src/test/java/org/codehaus/plexus/interpolation/multi/MultiDelimiterStringSearchInterpolatorTest.java

@@ -85,4 +85,22 @@ public void testInterpolationWithMultipleEscapes()
             assertEquals( "#${first} and ${last}", result );
         }
 
+    public void testInterpolationWithMultipleEscapes2()
+        throws InterpolationException
+    {
+        Map ctx = new HashMap();
+        ctx.put( "name", "User" );
+        ctx.put( "otherName", "#${first} and ##${last}" );
+
+        String input = "${otherName}";
+
+        ValueSource vs = new MapBasedValueSource( ctx );
+        MultiDelimiterStringSearchInterpolator interpolator =
+            new MultiDelimiterStringSearchInterpolator().withValueSource( vs );
+        interpolator.setEscapeString( "#" );
+
+        String result = interpolator.interpolate( input );
+
+        assertEquals( "${first} and #${last}", result );
+    }
 }