Extract parsing of the WORKSPACE file in two parts

The WORKSPACE file AST is now parsed as a separate SkyFunction
and this will be used to have multiple SkyValue for the same
WORKSPACE file, splitting the execution of the AST after load
statements to enable load statement of external dependencies
in the WORKSPACE file.

--
MOS_MIGRATED_REVID=112768897

1 files changed, 83 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/WorkspaceASTFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/WorkspaceASTFunction.java
new file mode 100644
index 0000000000..d1077d2260
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/WorkspaceASTFunction.java
@@ -0,0 +1,83 @@
+// Copyright 2016 The Bazel Authors. 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.skyframe;
+
+import com.google.devtools.build.lib.packages.RuleClassProvider;
+import com.google.devtools.build.lib.syntax.BuildFileAST;
+import com.google.devtools.build.lib.syntax.ParserInputSource;
+import com.google.devtools.build.lib.vfs.Path;
+import com.google.devtools.build.lib.vfs.PathFragment;
+import com.google.devtools.build.lib.vfs.RootedPath;
+import com.google.devtools.build.skyframe.SkyFunction;
+import com.google.devtools.build.skyframe.SkyFunctionException;
+import com.google.devtools.build.skyframe.SkyFunctionException.Transience;
+import com.google.devtools.build.skyframe.SkyKey;
+import com.google.devtools.build.skyframe.SkyValue;
+
+import java.io.IOException;
+
+/**
+ * A SkyFunction to parse WORKSPACE files into a BuildFileAST.
+ */
+public class WorkspaceASTFunction implements SkyFunction {
+  private final RuleClassProvider ruleClassProvider;
+
+  public WorkspaceASTFunction(RuleClassProvider ruleClassProvider) {
+    this.ruleClassProvider = ruleClassProvider;
+  }
+
+  @Override
+  public SkyValue compute(SkyKey skyKey, Environment env)
+      throws InterruptedException, WorkspaceASTFunctionException {
+    RootedPath workspaceRoot = (RootedPath) skyKey.argument();
+    FileValue workspaceFileValue = (FileValue) env.getValue(FileValue.key(workspaceRoot));
+    if (workspaceFileValue == null) {
+      return null;
+    }
+
+    Path repoWorkspace = workspaceRoot.getRoot().getRelative(workspaceRoot.getRelativePath());
+    PathFragment pathFragment = new PathFragment("/DEFAULT.WORKSPACE");
+    try {
+      BuildFileAST ast = BuildFileAST.parseBuildFile(
+          ParserInputSource.create(ruleClassProvider.getDefaultWorkspaceFile(), pathFragment),
+          env.getListener(), false);
+      if (ast.containsErrors()) {
+        throw new WorkspaceASTFunctionException(
+            new IOException("Failed to parse default WORKSPACE file"), Transience.PERSISTENT);
+      }
+      if (workspaceFileValue.exists()) {
+        ast = BuildFileAST.parseBuildFile(
+            ParserInputSource.create(repoWorkspace), ast.getStatements(), env.getListener(), false);
+        if (ast.containsErrors()) {
+          throw new WorkspaceASTFunctionException(
+              new IOException("Failed to parse WORKSPACE file"), Transience.PERSISTENT);
+        }
+      }
+      return new WorkspaceASTValue(ast);
+    } catch (IOException ex) {
+      throw new WorkspaceASTFunctionException(ex, Transience.TRANSIENT);
+    }
+  }
+
+  private static final class WorkspaceASTFunctionException extends SkyFunctionException {
+    public WorkspaceASTFunctionException(Exception e, Transience transience) {
+      super(e, transience);
+    }
+  }
+  @Override
+  public String extractTag(SkyKey skyKey) {
+    return null;
+  }
+}