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// 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.collect.ImmutableList;
import com.google.devtools.build.lib.syntax.Label;
import javax.annotation.Nullable;
/**
* The interface for accessing a {@link Rule}'s attributes.
*
* <p>Since what an attribute lookup should return can be ambiguous (e.g. for configurable
* attributes, should we return a configuration-resolved value or the original, unresolved
* selection expression?), different implementations can apply different policies for how to
* fulfill these methods. Calling code can then use the appropriate implementation for whatever
* its particular needs are.
*/
public interface AttributeMap {
/**
* Returns the name of the rule; this is equivalent to {@code getLabel().getName()}.
*/
String getName();
/**
* Returns the label of the rule.
*/
Label getLabel();
/**
* Returns the value of the named rule attribute, which must be of the given type. This may
* be null (for example, for an attribute with no default value that isn't explicitly set in
* the rule - see {@link Type#getDefaultValue}).
*
* <p>If the rule doesn't have this attribute with the specified type, throws an
* {@link IllegalArgumentException}.
*/
@Nullable
<T> T get(String attributeName, Type<T> type);
/**
* Returns the names of all attributes covered by this map.
*/
Iterable<String> getAttributeNames();
/**
* Returns the type of the given attribute, if it exists. Otherwise returns null.
*/
@Nullable Type<?> getAttributeType(String attrName);
/**
* Returns the attribute definition whose name is {@code attrName}, or null
* if not found.
*/
@Nullable Attribute getAttributeDefinition(String attrName);
/**
* Returns true iff the value of the specified attribute is explicitly set in the BUILD file (as
* opposed to its default value). This also returns true if the value from the BUILD file is the
* same as the default value.
*
* <p>It is probably a good idea to avoid this method in default value and implicit outputs
* computation, because it is confusing that setting an attribute to an empty list (for example)
* is different from not setting it at all.
*/
boolean isAttributeValueExplicitlySpecified(String attributeName);
/**
* An interface which accepts {@link Attribute}s, used by {@link #visitLabels}.
*/
interface AcceptsLabelAttribute {
/**
* Accept a (Label, Attribute) pair describing a dependency edge.
*
* @param label the target node of the (Rule, Label) edge.
* The source node should already be known.
* @param attribute the attribute.
*/
void acceptLabelAttribute(Label label, Attribute attribute);
}
/**
* For all attributes that contain labels in their values (either by *being* a label or
* being a collection that includes labels), visits every label and notifies the
* specified observer at each visit.
*/
void visitLabels(AcceptsLabelAttribute observer);
// TODO(bazel-team): These methods are here to support computed defaults that inherit
// package-level default values. Instead, we should auto-inherit and remove the computed
// defaults. If we really need to give access to package-level defaults, we should come up with
// a more generic interface.
String getPackageDefaultHdrsCheck();
Boolean getPackageDefaultTestOnly();
String getPackageDefaultDeprecation();
ImmutableList<String> getPackageDefaultCopts();
/**
* @return true if an attribute with the given name and type is present
*/
boolean has(String attrName, Type<?> type);
}
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