Introduce a level of indirection between files and paths to files.

Summary: This allows rules to depend on a target where they could also expect a path.

Test Plan: buck test --all

src/com/facebook/buck/android/AndroidLibraryRule.java

@@ -21,6 +21,7 @@
 import com.facebook.buck.java.JavacOptions;
 import com.facebook.buck.model.BuildTarget;
 import com.facebook.buck.model.BuildTargetPattern;
+import com.facebook.buck.rules.SourcePath;
 import com.facebook.buck.rules.BuildContext;
 import com.facebook.buck.rules.BuildRuleParams;
 import com.facebook.buck.rules.BuildRuleResolver;
@@ -45,7 +46,7 @@ public class AndroidLibraryRule extends DefaultJavaLibraryRule {
   @VisibleForTesting
   public AndroidLibraryRule(BuildRuleParams buildRuleParams,
       Set<String> srcs,
-      Set<String> resources,
+      Set<SourcePath> resources,
       Optional<String> proguardConfig,
       JavacOptions javacOptions,
       Optional<String> manifestFile) {

src/com/facebook/buck/android/RobolectricTestRule.java

@@ -21,6 +21,7 @@
 import com.facebook.buck.java.JavaTestRule;
 import com.facebook.buck.java.JavacOptions;
 import com.facebook.buck.model.BuildTarget;
+import com.facebook.buck.rules.SourcePath;
 import com.facebook.buck.rules.BuildContext;
 import com.facebook.buck.rules.BuildRuleResolver;
 import com.facebook.buck.rules.BuildRuleParams;
@@ -36,7 +37,7 @@ public class RobolectricTestRule extends JavaTestRule {
 
   protected RobolectricTestRule(BuildRuleParams buildRuleParams,
       Set<String> srcs,
-      Set<String> resources,
+      Set<SourcePath> resources,
       Set<String> labels,
       Optional<String> proguardConfig,
       JavacOptions javacOptions,

src/com/facebook/buck/cli/BuckConfig.java

@@ -16,6 +16,7 @@
 
 package com.facebook.buck.cli;
 
+import com.facebook.buck.java.DefaultJavaPackageFinder;
 import com.facebook.buck.model.BuildTarget;
 import com.facebook.buck.parser.BuildTargetParser;
 import com.facebook.buck.parser.NoSuchBuildTargetException;

src/com/facebook/buck/cli/TestCommand.java

@@ -18,6 +18,7 @@
 
 import com.facebook.buck.command.Build;
 import com.facebook.buck.graph.AbstractBottomUpTraversal;
+import com.facebook.buck.java.DefaultJavaPackageFinder;
 import com.facebook.buck.java.GenerateCodeCoverageReportStep;
 import com.facebook.buck.java.InstrumentStep;
 import com.facebook.buck.java.JUnitStep;

src/com/facebook/buck/cli/TestCommandOptions.java

@@ -16,6 +16,7 @@
 
 package com.facebook.buck.cli;
 
+import com.facebook.buck.java.DefaultJavaPackageFinder;
 import com.google.common.base.Optional;
 import com.google.common.base.Supplier;
 import com.google.common.base.Suppliers;

src/com/facebook/buck/java/BUCK

@@ -1,5 +1,6 @@
 SUPPORT_SRCS = [
   'AnnotationProcessingParams.java',
+  'DefaultJavaPackageFinder.java',
   'HasClasspathEntries.java',
   'JavacOptions.java',
 ]

src/com/facebook/buck/java/DefaultJavaLibraryRule.java

@@ -33,6 +33,7 @@
 import com.facebook.buck.rules.JavaPackageFinder;
 import com.facebook.buck.rules.ResourcesAttributeBuilder;
 import com.facebook.buck.rules.RuleKey;
+import com.facebook.buck.rules.SourcePath;
 import com.facebook.buck.rules.SrcsAttributeBuilder;
 import com.facebook.buck.step.Step;
 import com.facebook.buck.step.fs.MakeCleanDirectoryStep;
@@ -85,7 +86,7 @@ public class DefaultJavaLibraryRule extends AbstractCachingBuildRule
 
   private final ImmutableSortedSet<String> srcs;
 
-  private final ImmutableSortedSet<String> resources;
+  private final ImmutableSortedSet<SourcePath> resources;
 
   private final Optional<String> outputJar;
 
@@ -147,7 +148,7 @@ public ImmutableSet<String> apply(String classPath) {
 
   protected DefaultJavaLibraryRule(BuildRuleParams buildRuleParams,
                                    Set<String> srcs,
-                                   Set<String> resources,
+                                   Set<? extends SourcePath> resources,
                                    Optional<String> proguardConfig,
                                    boolean exportDeps,
                                    JavacOptions javacOptions) {
@@ -167,10 +168,13 @@ protected DefaultJavaLibraryRule(BuildRuleParams buildRuleParams,
     // Note that both srcs and resources are sorted so that the list order is consistent even if
     // the iteration order of the sets passed to the constructor changes. See
     // AbstractBuildRule.getInputsToCompareToOutput() for details.
-    inputsToConsiderForCachingPurposes = ImmutableList.<String>builder()
-        .addAll(this.srcs)
-        .addAll(this.resources)
-        .build();
+    ImmutableList.Builder<String> builder = ImmutableList.<String>builder().addAll(this.srcs);
+    for (SourcePath resource : resources) {
+      builder.add(resource.asReference());
+    }
+    inputsToConsiderForCachingPurposes = builder.build();
+
+
 
     outputClasspathEntriesSupplier =
         Suppliers.memoize(new Supplier<ImmutableSet<String>>() {
@@ -316,7 +320,7 @@ public boolean isLibrary() {
   protected RuleKey.Builder appendToRuleKey(RuleKey.Builder builder) {
     super.appendToRuleKey(builder)
         .set("srcs", srcs)
-        .set("resources", resources)
+        .setSourcePaths("resources", resources)
         .set("proguard", proguardConfig)
         .set("exportDeps", exportDeps);
     javacOptions.appendToRuleKey(builder);
@@ -454,7 +458,7 @@ protected final List<Step> buildInternal(BuildContext context) throws IOExceptio
 
 
     // If there are resources, then link them to the appropriate place in the classes directory.
-    addResourceCommands(commands, outputDirectory, context.getJavaPackageFinder());
+    addResourceCommands(context, commands, outputDirectory, context.getJavaPackageFinder());
 
     if (outputJar.isPresent()) {
       commands.add(new MakeCleanDirectoryStep(getOutputJarDirPath(getBuildTarget())));
@@ -557,11 +561,16 @@ public ImmutableSet<String> apply(ImmutableSet<String> failedImports) {
 
 
   @VisibleForTesting
-  void addResourceCommands(ImmutableList.Builder<Step> commands,
+  void addResourceCommands(BuildContext context,
+                           ImmutableList.Builder<Step> commands,
                            String outputDirectory,
                            JavaPackageFinder javaPackageFinder) {
     if (!resources.isEmpty()) {
-      for (String resource : resources) {
+      String targetPackageDir = javaPackageFinder.findJavaPackageForPath(
+          getBuildTarget().getBasePathWithSlash())
+          .replace('.', File.separatorChar);
+
+      for (SourcePath rawResource : resources) {
         // If the path to the file defining this rule were:
         // "first-party/orca/lib-http/tests/com/facebook/orca/BUILD"
         //
@@ -575,9 +584,21 @@ void addResourceCommands(ImmutableList.Builder<Step> commands,
         // "com/facebook/orca/protocol/base/batch_exception1.txt"
         //
         // Therefore, some path-wrangling is required to produce the correct string.
+
+        String resource = rawResource.resolve(context).toString();
         String javaPackageAsPath = javaPackageFinder.findJavaPackageFolderForPath(resource);
         String relativeSymlinkPath;
-        if ("".equals(javaPackageAsPath)) {
+
+
+        if (resource.startsWith(BuckConstant.BUCK_OUTPUT_DIRECTORY) ||
+            resource.startsWith(BuckConstant.GEN_DIR) ||
+            resource.startsWith(BuckConstant.BIN_DIR) ||
+            resource.startsWith(BuckConstant.ANNOTATION_DIR)) {
+          // Handle the case where we depend on the output of another BuildRule. In that case, just
+          // grab the output and put in the same package as this target would be in.
+          relativeSymlinkPath = String.format(
+              "%s/%s", targetPackageDir, rawResource.resolve(context).getFileName());
+        } else if ("".equals(javaPackageAsPath)) {
           // In this case, the project root is acting as the default package, so the resource path
           // works fine.
           relativeSymlinkPath = resource;
@@ -591,7 +612,6 @@ void addResourceCommands(ImmutableList.Builder<Step> commands,
           relativeSymlinkPath = resource.substring(lastIndex);
         }
         String target = outputDirectory + '/' + relativeSymlinkPath;
-
         MkdirAndSymlinkFileStep link = new MkdirAndSymlinkFileStep(resource, target);
         commands.add(link);
       }
@@ -611,7 +631,7 @@ public static class Builder extends AbstractBuildRuleBuilder<DefaultJavaLibraryR
       SrcsAttributeBuilder, ResourcesAttributeBuilder {
 
     protected Set<String> srcs = Sets.newHashSet();
-    protected Set<String> resources = Sets.newHashSet();
+    protected Set<SourcePath> resources = Sets.newHashSet();
     protected final AnnotationProcessingParams.Builder annotationProcessingBuilder =
         new AnnotationProcessingParams.Builder();
     protected boolean exportDeps = false;
@@ -660,7 +680,7 @@ public Builder addSrc(String src) {
     }
 
     @Override
-    public Builder addResource(String relativePathToResource) {
+    public Builder addResource(SourcePath relativePathToResource) {
       resources.add(relativePathToResource);
       return this;
     }

src/com/facebook/buck/cli/DefaultJavaPackageFinder.java → src/com/facebook/buck/java/DefaultJavaPackageFinder.java

@@ -14,7 +14,7 @@
  * under the License.
  */
 
-package com.facebook.buck.cli;
+package com.facebook.buck.java;
 
 import com.facebook.buck.rules.JavaPackageFinder;
 import com.facebook.buck.util.HumanReadableException;
@@ -27,7 +27,7 @@
 import java.io.File;
 import java.util.Deque;
 
-class DefaultJavaPackageFinder implements JavaPackageFinder {
+public class DefaultJavaPackageFinder implements JavaPackageFinder {
 
   /**
    * Each element in this set is a path prefix from the root of the repository.

src/com/facebook/buck/java/JavaTestRule.java

@@ -18,6 +18,7 @@
 
 import com.facebook.buck.android.UberRDotJavaUtil;
 import com.facebook.buck.model.BuildTarget;
+import com.facebook.buck.rules.SourcePath;
 import com.facebook.buck.rules.BuildContext;
 import com.facebook.buck.rules.BuildRule;
 import com.facebook.buck.rules.BuildRuleParams;
@@ -71,7 +72,7 @@ public class JavaTestRule extends DefaultJavaLibraryRule implements TestRule {
 
   protected JavaTestRule(BuildRuleParams buildRuleParams,
       Set<String> srcs,
-      Set<String> resources,
+      Set<SourcePath> resources,
       Set<String> labels,
       Optional<String> proguardConfig,
       JavacOptions javacOptions,

src/com/facebook/buck/parser/AbstractBuildRuleFactory.java

@@ -18,6 +18,8 @@
 
 import com.facebook.buck.model.BuildTarget;
 import com.facebook.buck.model.BuildTargetPattern;
+import com.facebook.buck.rules.BuildTargetSourcePath;
+import com.facebook.buck.rules.SourcePath;
 import com.facebook.buck.rules.AbstractBuildRuleBuilder;
 import com.facebook.buck.rules.ResourcesAttributeBuilder;
 import com.facebook.buck.rules.SrcsAttributeBuilder;
@@ -71,9 +73,18 @@ public T newInstance(BuildRuleFactoryParams params)
 
     // resources
     if (builder instanceof ResourcesAttributeBuilder) {
+      ResourcesAttributeBuilder attributeBuilder = (ResourcesAttributeBuilder) builder;
+
       for (String resource : params.getOptionalListAttribute("resources")) {
-        String relativePath = params.resolveFilePathRelativeToBuildFileDirectory(resource);
-        ((ResourcesAttributeBuilder)builder).addResource(relativePath);
+        SourcePath path = params.asSourcePath(resource);
+        attributeBuilder.addResource(path);
+
+        // Remember to add the resource as a dependency. On the down side, this means that the file
+        // will appear on the classpath, but there's no elegant way (yet) to avoid this.
+        // TODO(simons): A smarter, more elegant way of adding additional deps not on the classpath.
+        if (path instanceof BuildTargetSourcePath) {
+          builder.addDep(((BuildTargetSourcePath) path).getTarget());
+        }
       }
     }
 

src/com/facebook/buck/parser/BuildRuleFactoryParams.java

@@ -18,6 +18,9 @@
 
 import com.facebook.buck.model.BuildFileTree;
 import com.facebook.buck.model.BuildTarget;
+import com.facebook.buck.rules.BuildTargetSourcePath;
+import com.facebook.buck.rules.FileSourcePath;
+import com.facebook.buck.rules.SourcePath;
 import com.facebook.buck.util.BuckConstant;
 import com.facebook.buck.util.Console;
 import com.facebook.buck.util.HumanReadableException;
@@ -47,6 +50,7 @@ public final class BuildRuleFactoryParams {
   public final BuildTargetParser buildTargetParser;
   public final BuildTargetPatternParser buildTargetPatternParser;
   public final BuildTarget target;
+  private final ParseContext sourcePathContext;
   private final ParseContext visibilityParseContext;
   private final boolean ignoreFileExistenceChecks;
 
@@ -83,8 +87,9 @@ public BuildRuleFactoryParams(
     this.buildFiles = buildFiles;
     this.buildTargetParser = buildTargetParser;
     this.buildTargetPatternParser = new BuildTargetPatternParser(filesystem);
-    this.target = target;
+    this.target = Preconditions.checkNotNull(target);
     this.visibilityParseContext = ParseContext.forVisibilityArgument();
+    this.sourcePathContext = ParseContext.forBaseName(target.getBaseName());
     this.ignoreFileExistenceChecks = ignoreFileExistenceChecks;
 
     this.resolveFilePathRelativeToBuildFileDirectoryTransform = new Function<String, String>() {
@@ -200,6 +205,22 @@ private String resolvePathAgainstBuildTargetBase(String path) {
     }
   }
 
+  public SourcePath asSourcePath(String resource) {
+    // TODO(simons): Don't hard code this check for built-target-ism
+    if (resource.startsWith(BuildTarget.BUILD_TARGET_PREFIX) || resource.charAt(0) == ':') {
+      try {
+        BuildTarget buildTarget = buildTargetParser.parse(resource, sourcePathContext);
+        return new BuildTargetSourcePath(buildTarget);
+      } catch (NoSuchBuildTargetException e) {
+        throw new HumanReadableException(
+            "Unable to find build target '%s' while parsing definition of %s", resource, target);
+      }
+    } else {
+      String relativePath = resolveFilePathRelativeToBuildFileDirectory(resource);
+      return new FileSourcePath(relativePath);
+    }
+  }
+
   public String getRequiredStringAttribute(String attributeName) {
     Optional<String> value = getOptionalStringAttribute(attributeName);
     if (value.isPresent()) {

src/com/facebook/buck/rules/AbstractSourcePath.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2013-present Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License. You may obtain
+ * a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+
+package com.facebook.buck.rules;
+
+import com.google.common.base.Preconditions;
+
+/**
+ * Abstract base class for implementations of {@link SourcePath}.
+ */
+abstract class AbstractSourcePath implements SourcePath {
+  @Override
+  public int compareTo(SourcePath o) {
+    Preconditions.checkNotNull(o);
+
+    return asReference().compareTo(o.asReference());
+  }
+
+  @Override
+  public int hashCode() {
+    return asReference().hashCode();
+  }
+
+  @Override
+  public boolean equals(Object that) {
+    if (that == null || !(that instanceof SourcePath)) {
+      return false;
+    }
+
+    return asReference().equals(((SourcePath) that).asReference());
+  }
+
+  @Override
+  public String toString() {
+    return asReference();
+  }
+}