Update from Google.

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MOE_MIGRATED_REVID=85702957

1 files changed, 218 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/packages/AggregatingAttributeMapper.java b/src/main/java/com/google/devtools/build/lib/packages/AggregatingAttributeMapper.java
new file mode 100644
index 0000000000..2aef2242bb
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/packages/AggregatingAttributeMapper.java
@@ -0,0 +1,218 @@
+// 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.packages;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.lib.syntax.Label;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+
+import javax.annotation.Nullable;
+
+/**
+ * {@link AttributeMap} implementation that provides the ability to retrieve *all possible*
+ * values an attribute might take.
+ */
+public class AggregatingAttributeMapper extends AbstractAttributeMapper {
+
+  /**
+   * Store for all of this rule's attributes that are non-configurable. These are
+   * unconditionally  available to computed defaults no matter what dependencies
+   * they've declared.
+   */
+  private final List<String> nonconfigurableAttributes;
+
+  private AggregatingAttributeMapper(Rule rule) {
+    super(rule.getPackage(), rule.getRuleClassObject(), rule.getLabel(),
+        rule.getAttributeContainer());
+
+    ImmutableList.Builder<String> nonconfigurableAttributesBuilder = ImmutableList.builder();
+    for (Attribute attr : rule.getAttributes()) {
+      if (!attr.isConfigurable()) {
+        nonconfigurableAttributesBuilder.add(attr.getName());
+      }
+    }
+    nonconfigurableAttributes = nonconfigurableAttributesBuilder.build();
+  }
+
+  public static AggregatingAttributeMapper of(Rule rule) {
+    return new AggregatingAttributeMapper(rule);
+  }
+
+  /**
+   * Override that also visits the rule's configurable attribute keys (which are
+   * themselves labels).
+   */
+  @Override
+  public void visitLabels(AcceptsLabelAttribute observer) {
+    super.visitLabels(observer);
+    for (String attrName : getAttributeNames()) {
+      Attribute attribute = getAttributeDefinition(attrName);
+      Type.Selector<?> selector = getSelector(attrName, attribute.getType());
+      if (selector != null) {
+        for (Label configLabel : selector.getEntries().keySet()) {
+          if (!Type.Selector.isReservedLabel(configLabel)) {
+            observer.acceptLabelAttribute(configLabel, attribute);
+          }
+        }
+      }
+    }
+  }
+
+  /**
+   * Returns a list of all possible values an attribute can take for this rule.
+   */
+  @Override
+  public <T> Iterable<T> visitAttribute(String attributeName, Type<T> type) {
+    // If this attribute value is configurable, visit all possible values.
+    Type.Selector<T> selector = getSelector(attributeName, type);
+    if (selector != null) {
+      ImmutableList.Builder<T> builder = ImmutableList.builder();
+      for (Map.Entry<Label, T> entry : selector.getEntries().entrySet()) {
+        builder.add(entry.getValue());
+      }
+      return builder.build();
+    }
+
+    // If this attribute is a computed default, feed it all possible value combinations of
+    // its declared dependencies and return all computed results. For example, if this default
+    // uses attributes x and y, x can configurably be x1 or x2, and y can configurably be y1
+    // or y1, then compute default values for the (x1,y1), (x1,y2), (x2,y1), and (x2,y2) cases.
+    Attribute.ComputedDefault computedDefault = getComputedDefault(attributeName, type);
+    if (computedDefault != null) {
+      // This will hold every (value1, value2, ..) combination of the declared dependencies.
+      List<Map<String, Object>> depMaps = new LinkedList<>();
+      // Collect those combinations.
+      mapDepsForComputedDefault(computedDefault.dependencies(), depMaps,
+          ImmutableMap.<String, Object>of());
+      List<T> possibleValues = new ArrayList<>(); // Not ImmutableList.Builder: values may be null.
+      // For each combination, call getDefault on a specialized AttributeMap providing those values.
+      for (Map<String, Object> depMap : depMaps) {
+        possibleValues.add(type.cast(computedDefault.getDefault(mapBackedAttributeMap(depMap))));
+      }
+      return possibleValues;
+    }
+
+    // For any other attribute, just return its direct value.
+    T value = get(attributeName, type);
+    return value == null ? ImmutableList.<T>of() : ImmutableList.of(value);
+  }
+
+  /**
+   * Given (possibly configurable) attributes that a computed default depends on, creates an
+   * {attrName -> attrValue} map for every possible combination of those attribute values and
+   * returns a list of all the maps. This defines the complete dependency space that can affect
+   * the computed default's values.
+   *
+   * <p>For example, given dependencies x and y, which might respectively have values x1, x2 and
+   * y1, y2, this returns:
+   * <pre>
+   *   [
+   *    {x: x1, y: y1},
+   *    {x: x1, y: y2},
+   *    {x: x2, y: y1},
+   *    {x: x2, y: y2}
+   *   ]
+   * </pre>
+   *
+   * @param depAttributes the names of the attributes this computed default depends on
+   * @param mappings the list of {attrName --> attrValue} maps defining the computed default's
+   *                 dependency space. This is where this method's results are written.
+   * @param currentMap a (possibly non-empty) map to add {attrName --> attrValue}
+   *                   entries to. Outside callers can just pass in an empty map.
+   */
+  private void mapDepsForComputedDefault(List<String> depAttributes,
+      List<Map<String, Object>> mappings, Map<String, Object> currentMap) {
+    // Because this method uses exponential time/space on the number of inputs, keep the
+    // maximum number of inputs conservatively small.
+    Preconditions.checkState(depAttributes.size() <= 2);
+
+    if (depAttributes.isEmpty()) {
+      // Recursive base case: store whatever's already been populated in currentMap.
+      mappings.add(currentMap);
+      return;
+    }
+
+    // Take the first attribute in the dependency list and iterate over all its values. For each
+    // value x, copy currentMap with the additional entry { firstAttrName: x }, then feed
+    // this recursively into a subcall over all remaining dependencies. This recursively
+    // continues until we run out of values.
+    String firstAttribute = depAttributes.get(0);
+    for (Object value : visitAttribute(firstAttribute, getAttributeType(firstAttribute))) {
+      Map<String, Object> newMap = new HashMap<>();
+      newMap.putAll(currentMap);
+      newMap.put(firstAttribute, value);
+      mapDepsForComputedDefault(depAttributes.subList(1, depAttributes.size()), mappings, newMap);
+    }
+  }
+
+  /**
+   * A custom {@link AttributeMap} that reads attribute values from the given Map. All
+   * non-configurable attributes are also readable. Any attempt to read an attribute
+   * that's not in one of these two cases triggers an IllegalArgumentException.
+   */
+  private AttributeMap mapBackedAttributeMap(final Map<String, Object> directMap) {
+    final AggregatingAttributeMapper owner = AggregatingAttributeMapper.this;
+    return new AttributeMap() {
+
+      @Override
+      public <T> T get(String attributeName, Type<T> type) {
+        owner.checkType(attributeName, type);
+        if (nonconfigurableAttributes.contains(attributeName)) {
+          return owner.get(attributeName, type);
+        }
+        if (!directMap.containsKey(attributeName)) {
+          throw new IllegalArgumentException("attribute \"" + attributeName
+              + "\" isn't available in this computed default context");
+        }
+        return type.cast(directMap.get(attributeName));
+      }
+
+      @Override public String getName() { return owner.getName(); }
+      @Override public Label getLabel() { return owner.getLabel(); }
+      @Override public Iterable<String> getAttributeNames() {
+        return ImmutableList.<String>builder()
+            .addAll(directMap.keySet()).addAll(nonconfigurableAttributes).build();
+      }
+      @Override
+      public void visitLabels(AcceptsLabelAttribute observer) { owner.visitLabels(observer); }
+      @Override
+      public String getPackageDefaultHdrsCheck() { return owner.getPackageDefaultHdrsCheck(); }
+      @Override
+      public Boolean getPackageDefaultObsolete() { return owner.getPackageDefaultObsolete(); }
+      @Override
+      public Boolean getPackageDefaultTestOnly() { return owner.getPackageDefaultTestOnly(); }
+      @Override
+      public String getPackageDefaultDeprecation() { return owner.getPackageDefaultDeprecation(); }
+      @Override
+      public ImmutableList<String> getPackageDefaultCopts() {
+        return owner.getPackageDefaultCopts();
+      }
+      @Nullable @Override
+      public Type<?> getAttributeType(String attrName) { return owner.getAttributeType(attrName); }
+      @Nullable @Override  public Attribute getAttributeDefinition(String attrName) {
+        return owner.getAttributeDefinition(attrName);
+      }
+      @Override public boolean isAttributeValueExplicitlySpecified(String attributeName) {
+        return owner.isAttributeValueExplicitlySpecified(attributeName);
+      }
+    };
+  }
+}