Create an abstraction for user defined data types in Skylark.

This will be used to remove Blaze-specific data types, FilesetEntry, Label and GlobList from the .syntax package.

--
MOS_MIGRATED_REVID=103281375

5 files changed, 96 insertions, 30 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/syntax/EvalUtils.java b/src/main/java/com/google/devtools/build/lib/syntax/EvalUtils.java
index ca5f4684f1..6b6608c89d 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/EvalUtils.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/EvalUtils.java
@@ -128,11 +128,12 @@ public abstract class EvalUtils {
    *         dictionary key) according to the rules of the Build language.
    */
   public static boolean isImmutable(Object o) {
-    if (o instanceof Map<?, ?> || o instanceof BaseFunction
-        || o instanceof FilesetEntry || o instanceof GlobList<?>) {
+    if (o instanceof Map<?, ?> || o instanceof BaseFunction) {
       return false;
     } else if (o instanceof List<?>) {
       return isTuple((List<?>) o); // tuples are immutable, lists are not.
+    } else if (o instanceof SkylarkValue) {
+      return ((SkylarkValue) o).isImmutable();
     } else {
       return true; // string/int
     }
@@ -282,14 +283,10 @@ public abstract class EvalUtils {
       // from native SkylarkList tuple and list.
       // TODO(bazel-team): refactor SkylarkList and use it everywhere.
       return isTuple(c) ? "Tuple" : "List";
-    } else if (GlobList.class.isAssignableFrom(c)) {
-      return "glob list";
     } else if (Map.class.isAssignableFrom(c)) {
       return "dict";
     } else if (BaseFunction.class.isAssignableFrom(c)) {
       return "function";
-    } else if (c.equals(FilesetEntry.class)) {
-      return "FilesetEntry";
     } else if (c.equals(SelectorValue.class)) {
       return "select";
     } else if (NestedSet.class.isAssignableFrom(c) || SkylarkNestedSet.class.isAssignableFrom(c)) {
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/FilesetEntry.java b/src/main/java/com/google/devtools/build/lib/syntax/FilesetEntry.java
index 4586b64f44..c876d6328f 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/FilesetEntry.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/FilesetEntry.java
@@ -30,7 +30,36 @@ import javax.annotation.Nullable;
 /**
  * FilesetEntry is a value object used to represent a "FilesetEntry" inside a "Fileset" BUILD rule.
  */
-public final class FilesetEntry {
+@SkylarkModule(
+    name = "FilesetEntry",
+    doc = "",
+    documented = false)
+public final class FilesetEntry implements SkylarkValue {
+
+  @Override
+  public boolean isImmutable() {
+    return false;
+  }
+
+  @Override
+  public void write(Appendable buffer, char quotationMark) {
+      Printer.append(buffer, "FilesetEntry(srcdir = ");
+      Printer.write(buffer, getSrcLabel().toString(), quotationMark);
+      Printer.append(buffer, ", files = ");
+      Printer.write(buffer, Printer.makeStringList(getFiles()), quotationMark);
+      Printer.append(buffer, ", excludes = ");
+      Printer.write(buffer, Printer.makeList(getExcludes()), quotationMark);
+      Printer.append(buffer, ", destdir = ");
+      Printer.write(buffer, getDestDir().getPathString(), quotationMark);
+      Printer.append(buffer, ", strip_prefix = ");
+      Printer.write(buffer, getStripPrefix(), quotationMark);
+      Printer.append(buffer, ", symlinks = ");
+      Printer.append(buffer, quotationMark);
+      Printer.append(buffer, getSymlinkBehavior().toString());
+      Printer.append(buffer, quotationMark);
+      Printer.append(buffer, ")");
+  }
+
   /** SymlinkBehavior decides what to do when a source file of a FilesetEntry is a symlink. */
   public enum SymlinkBehavior {
     /** Just copies the symlink as-is. May result in dangling links. */
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/GlobList.java b/src/main/java/com/google/devtools/build/lib/syntax/GlobList.java
index 82afd0104d..d468033b80 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/GlobList.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/GlobList.java
@@ -33,7 +33,11 @@ import java.util.List;
  *
  * @param <E> the element this List contains (generally either String or Label)
  */
-public class GlobList<E> extends ForwardingList<E> {
+@SkylarkModule(
+    name = "glob list",
+    doc = "",
+    documented = false)
+public final class GlobList<E> extends ForwardingList<E> implements SkylarkValue {
 
   /** Include/exclude criteria. */
   private final ImmutableList<GlobCriteria> criteria;
@@ -119,4 +123,14 @@ public class GlobList<E> extends ForwardingList<E> {
   protected ImmutableList<E> delegate() {
     return matches;
   }
+
+  @Override
+  public boolean isImmutable() {
+    return false;
+  }
+
+  @Override
+  public void write(Appendable buffer, char quotationMark) {
+    Printer.printList(buffer, this, false, quotationMark);
+  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Printer.java b/src/main/java/com/google/devtools/build/lib/syntax/Printer.java
index 46ccc55763..2586306bf0 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Printer.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Printer.java
@@ -158,27 +158,12 @@ public final class Printer {
     } else if (o instanceof Label) {
       write(buffer, o.toString(), quotationMark);
 
-    } else if (o instanceof FilesetEntry) {
-           FilesetEntry entry = (FilesetEntry) o;
-      append(buffer, "FilesetEntry(srcdir = ");
-      write(buffer, entry.getSrcLabel().toString(), quotationMark);
-      append(buffer, ", files = ");
-      write(buffer, makeStringList(entry.getFiles()), quotationMark);
-      append(buffer, ", excludes = ");
-      write(buffer, makeList(entry.getExcludes()), quotationMark);
-      append(buffer, ", destdir = ");
-      write(buffer, entry.getDestDir().getPathString(), quotationMark);
-      append(buffer, ", strip_prefix = ");
-      write(buffer, entry.getStripPrefix(), quotationMark);
-      append(buffer, ", symlinks = ");
-      append(buffer, quotationMark);
-      append(buffer, entry.getSymlinkBehavior().toString());
-      append(buffer, quotationMark);
-      append(buffer, ")");
-
     } else if (o instanceof PathFragment) {
       append(buffer, ((PathFragment) o).getPathString());
 
+    } else if (o instanceof SkylarkValue) {
+      ((SkylarkValue) o).write(buffer, quotationMark);
+
     } else {
       append(buffer, o.toString());
     }
@@ -206,7 +191,7 @@ public final class Printer {
   // Throughout this file, we transform IOException into AssertionError.
   // During normal operations, we only use in-memory Appendable-s that
   // cannot cause an IOException.
-  private static Appendable append(Appendable buffer, char c) {
+  public static Appendable append(Appendable buffer, char c) {
     try {
       return buffer.append(c);
     } catch (IOException e) {
@@ -214,7 +199,7 @@ public final class Printer {
     }
   }
 
-  private static Appendable append(Appendable buffer, CharSequence s) {
+  public static Appendable append(Appendable buffer, CharSequence s) {
     try {
       return buffer.append(s);
     } catch (IOException e) {
@@ -357,11 +342,11 @@ public final class Printer {
     return listString(list, before, separator, after, singletonTerminator, SKYLARK_QUOTATION_MARK);
   }
 
-  private static List<?> makeList(Collection<?> list) {
+  public static List<?> makeList(Collection<?> list) {
     return list == null ? Lists.newArrayList() : Lists.newArrayList(list);
   }
 
-  private static List<String> makeStringList(List<Label> labels) {
+  public static List<String> makeStringList(List<Label> labels) {
     if (labels == null) {
       return Collections.emptyList();
     }
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkValue.java b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkValue.java
new file mode 100644
index 0000000000..b93b0cda18
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkValue.java
@@ -0,0 +1,41 @@
+// Copyright 2015 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.syntax;
+
+/**
+ * Java objects that are also Skylark values.
+ *
+ * <p>This is used for extending the Skylark interpreted with domain-specific values.
+ */
+public interface SkylarkValue {
+
+  /**
+   * Returns if the value is immutable and thus suitable for being used as a dictionary key.
+   *
+   * <p>Immutability is deep, i.e. in order for a value to be immutable, all values it is composed
+   * of must be immutable, too.
+   */
+  boolean isImmutable();
+
+  /**
+   * Print an official representation of object x.
+   *
+   * <p>For regular data structures, the value should be parsable back into an equal data structure.
+   *
+   * @param buffer the buffer to append the representation to
+   * @param quotationMark The quote style (" or ') to be used
+   */
+  void write(Appendable buffer, char quotationMark);
+}