Allow mapping of Java source files.

src/main/groovy/com/github/j2objccontrib/j2objcgradle/J2objcConfig.groovy

@@ -332,6 +332,26 @@ class J2objcConfig {
         return ConfigureUtil.configure(cl, translatePattern)
     }
 
+    /**
+     * A mapping from source file names (in the project Java sourcesets) to alternate
+     * source files.
+     * Both before and after names (keys and values) are evaluated using project.file(...).
+     * <p/>
+     * Mappings can be used to have completely different implementations in your Java
+     * jar vs. your Objective-C library.  This can be especially useful when compiling
+     * a third-party library and you need to provide non-trivial OCNI implementations
+     * in Objective-C.
+     */
+    Map<String, String> translateSourceMapping = [:]
+
+    /**
+     * Adds a new source mapping.
+     * @see #translateSourceMapping
+     */
+    void translateSourceMapping(String before, String after) {
+        translateSourceMapping.put(before, after)
+    }
+
     /**
      * @see #dependsOnJ2objcLib(org.gradle.api.Project)
      * @deprecated Use `dependencies { j2objcLinkage project(':beforeProjectName') }` or

src/main/groovy/com/github/j2objccontrib/j2objcgradle/tasks/CycleFinderTask.groovy

@@ -36,7 +36,7 @@ import org.gradle.api.tasks.TaskAction
 class CycleFinderTask extends DefaultTask {
 
     @InputFiles
-    FileTree getSrcInputFiles() {
+    FileCollection getSrcInputFiles() {
         // Note that translatePattern does not need to be an @Input because it is
         // solely an input to this method, which is already an input (via @InputFiles).
         FileTree allFiles = Utils.srcSet(project, 'main', 'java')
@@ -45,7 +45,7 @@ class CycleFinderTask extends DefaultTask {
         if (J2objcConfig.from(project).translatePattern != null) {
             ret = allFiles.matching(J2objcConfig.from(project).translatePattern)
         }
-        return ret
+        return Utils.mapSourceFiles(project, ret, getTranslateSourceMapping())
     }
 
     // All input files that could affect translation output, except those in j2objc itself.
@@ -82,6 +82,9 @@ class CycleFinderTask extends DefaultTask {
     @Input
     List<String> getTranslateJ2objcLibs() { return J2objcConfig.from(project).translateJ2objcLibs }
 
+    @Input
+    Map<String, String> getTranslateSourceMapping() { return J2objcConfig.from(project).translateSourceMapping }
+
     @Input
     boolean getFilenameCollisionCheck() { return J2objcConfig.from(project).filenameCollisionCheck }
 

src/main/groovy/com/github/j2objccontrib/j2objcgradle/tasks/TranslateTask.groovy

@@ -51,8 +51,10 @@ class TranslateTask extends DefaultTask {
             allFiles = allFiles.matching(J2objcConfig.from(project).translatePattern)
         }
         FileCollection ret = allFiles
+        ret = Utils.mapSourceFiles(project, ret, getTranslateSourceMapping())
+
         if (additionalSrcFiles != null) {
-            ret = allFiles.plus(additionalSrcFiles)
+            ret = ret.plus(additionalSrcFiles)
         }
         return ret
     }
@@ -99,6 +101,9 @@ class TranslateTask extends DefaultTask {
     @Input
     List<String> getTranslateJ2objcLibs() { return J2objcConfig.from(project).translateJ2objcLibs }
 
+    @Input
+    Map<String, String> getTranslateSourceMapping() { return J2objcConfig.from(project).translateSourceMapping }
+
     @Input
     boolean getFilenameCollisionCheck() { return J2objcConfig.from(project).filenameCollisionCheck }
 

src/main/groovy/com/github/j2objccontrib/j2objcgradle/tasks/Utils.groovy

@@ -585,4 +585,16 @@ class Utils {
     static boolean projectMkDir(Project proj, Object path) {
         return proj.mkdir(path)
     }
+
+    static FileCollection mapSourceFiles(Project proj, FileCollection files,
+                                         Map<String, String> sourceMapping) {
+        for (String before : sourceMapping.keySet()) {
+            if (files.contains(proj.file(before))) {
+                // Replace the before file with the after file.
+                files = files.minus(proj.files(before)).plus(
+                        proj.files(sourceMapping.get(before)))
+            }
+        }
+        return files
+    }
 }