1 files changed, 185 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppModuleMapAction.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppModuleMapAction.java
new file mode 100644
index 0000000000..a350fc4618
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppModuleMapAction.java
@@ -0,0 +1,185 @@
+// Copyright 2014 Google Inc. All rights reserved.
+//
+// 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.google.devtools.build.lib.rules.cpp;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Strings;
+import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.lib.actions.ActionOwner;
+import com.google.devtools.build.lib.actions.Artifact;
+import com.google.devtools.build.lib.actions.Executor;
+import com.google.devtools.build.lib.actions.ResourceSet;
+import com.google.devtools.build.lib.analysis.actions.AbstractFileWriteAction;
+import com.google.devtools.build.lib.events.EventHandler;
+import com.google.devtools.build.lib.util.Fingerprint;
+import com.google.devtools.build.lib.vfs.PathFragment;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+/**
+ * Creates C++ module map artifact genfiles. These are then passed to Clang to
+ * do dependency checking.
+ */
+public class CppModuleMapAction extends AbstractFileWriteAction {
+
+  private static final String GUID = "4f407081-1951-40c1-befc-d6b4daff5de3";
+
+  // C++ module map of the current target
+  private final CppModuleMap cppModuleMap;
+  
+  /**
+   * If set, the paths in the module map are relative to the current working directory instead
+   * of relative to the module map file's location. 
+   */
+  private final boolean moduleMapHomeIsCwd;
+
+  // Headers and dependencies list
+  private final ImmutableList<Artifact> privateHeaders;
+  private final ImmutableList<Artifact> publicHeaders;
+  private final ImmutableList<CppModuleMap> dependencies;
+  private final ImmutableList<PathFragment> additionalExportedHeaders;
+  private final boolean compiledModule;
+
+  public CppModuleMapAction(ActionOwner owner, CppModuleMap cppModuleMap,
+      Iterable<Artifact> privateHeaders, Iterable<Artifact> publicHeaders,
+      Iterable<CppModuleMap> dependencies, Iterable<PathFragment> additionalExportedHeaders,
+      boolean compiledModule, boolean moduleMapHomeIsCwd) {
+    super(owner, ImmutableList.<Artifact>of(), cppModuleMap.getArtifact(),
+        /*makeExecutable=*/false);
+    this.cppModuleMap = cppModuleMap;
+    this.moduleMapHomeIsCwd = moduleMapHomeIsCwd;
+    this.privateHeaders = ImmutableList.copyOf(privateHeaders);
+    this.publicHeaders = ImmutableList.copyOf(publicHeaders);
+    this.dependencies = ImmutableList.copyOf(dependencies);
+    this.additionalExportedHeaders = ImmutableList.copyOf(additionalExportedHeaders);
+    this.compiledModule = compiledModule;
+  }
+
+  @Override
+  public DeterministicWriter newDeterministicWriter(EventHandler eventHandler, Executor executor)  {
+    return new DeterministicWriter() {
+      @Override
+      public void writeOutputFile(OutputStream out) throws IOException {
+        StringBuilder content = new StringBuilder();
+        PathFragment fragment = cppModuleMap.getArtifact().getExecPath();
+        int segmentsToExecPath = fragment.segmentCount() - 1;
+
+        // For details about the different header types, see:
+        // http://clang.llvm.org/docs/Modules.html#header-declaration
+        String leadingPeriods = moduleMapHomeIsCwd ? "" : Strings.repeat("../", segmentsToExecPath);
+        content.append("module \"").append(cppModuleMap.getName()).append("\" {\n");
+        content.append("  export *\n");
+        for (Artifact artifact : privateHeaders) {
+          appendHeader(content, "private", artifact.getExecPath(), leadingPeriods,
+              /*canCompile=*/true);
+        }
+        for (Artifact artifact : publicHeaders) {
+          appendHeader(content, "", artifact.getExecPath(), leadingPeriods, /*canCompile=*/true);
+        }
+        for (PathFragment additionalExportedHeader : additionalExportedHeaders) {
+          appendHeader(content, "", additionalExportedHeader, leadingPeriods, /*canCompile*/false);
+        }
+        for (CppModuleMap dep : dependencies) {
+          content.append("  use \"").append(dep.getName()).append("\"\n");
+        }
+        content.append("}");
+        for (CppModuleMap dep : dependencies) {
+          content.append("\nextern module \"")
+              .append(dep.getName())
+              .append("\" \"")
+              .append(leadingPeriods)
+              .append(dep.getArtifact().getExecPath())
+              .append("\"");
+        }
+        out.write(content.toString().getBytes(StandardCharsets.ISO_8859_1));
+      }
+    };
+  }
+  
+  private void appendHeader(StringBuilder content, String visibilitySpecifier, PathFragment path,
+      String leadingPeriods, boolean canCompile) {
+    content.append("  ");
+    if (!visibilitySpecifier.isEmpty()) {
+      content.append(visibilitySpecifier).append(" ");
+    }
+    if (!canCompile || !shouldCompileHeader(path)) {
+      content.append("textual ");
+    }
+    content.append("header \"").append(leadingPeriods).append(path).append("\"\n");
+  }
+  
+  private boolean shouldCompileHeader(PathFragment path) {
+    return compiledModule && !CppFileTypes.CPP_TEXTUAL_INCLUDE.matches(path);
+  }
+
+  @Override
+  public String getMnemonic() {
+    return "CppModuleMap";
+  }
+
+  @Override
+  protected String computeKey() {
+    Fingerprint f = new Fingerprint();
+    f.addString(GUID);
+    f.addInt(privateHeaders.size());
+    for (Artifact artifact : privateHeaders) {
+      f.addPath(artifact.getRootRelativePath());
+    }
+    f.addInt(publicHeaders.size());
+    for (Artifact artifact : publicHeaders) {
+      f.addPath(artifact.getRootRelativePath());
+    }
+    f.addInt(dependencies.size());
+    for (CppModuleMap dep : dependencies) {
+      f.addPath(dep.getArtifact().getExecPath());
+    }
+    f.addPath(cppModuleMap.getArtifact().getExecPath());
+    f.addString(cppModuleMap.getName());
+    return f.hexDigestAndReset();
+  }
+
+  @Override
+  public ResourceSet estimateResourceConsumptionLocal() {
+    return new ResourceSet(/*memoryMb=*/0, /*cpuUsage=*/0, /*ioUsage=*/0.02);
+  }
+
+  @VisibleForTesting
+  public Collection<Artifact> getPublicHeaders() {
+    return publicHeaders;
+  }
+
+  @VisibleForTesting
+  public Collection<Artifact> getPrivateHeaders() {
+    return privateHeaders;
+  }
+  
+  @VisibleForTesting
+  public ImmutableList<PathFragment> getAdditionalExportedHeaders() {
+    return additionalExportedHeaders;
+  }
+
+  @VisibleForTesting
+  public Collection<Artifact> getDependencyArtifacts() {
+    List<Artifact> artifacts = new ArrayList<>();
+    for (CppModuleMap map : dependencies) {
+      artifacts.add(map.getArtifact());
+    }
+    return artifacts;
+  }
+}