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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;
/**
* Base {@link AttributeMap} implementation providing direct, unmanipulated access to
* underlying attribute data as stored within the Rule.
*
* <p>Any instantiable subclass should define a clear policy of what it does with this
* data before exposing it to consumers.
*/
public abstract class AbstractAttributeMapper implements AttributeMap {
private final Package pkg;
private final RuleClass ruleClass;
private final Label ruleLabel;
private final AttributeContainer attributes;
public AbstractAttributeMapper(Package pkg, RuleClass ruleClass, Label ruleLabel,
AttributeContainer attributes) {
this.pkg = pkg;
this.ruleClass = ruleClass;
this.ruleLabel = ruleLabel;
this.attributes = attributes;
}
@Override
public String getName() {
return ruleLabel.getName();
}
@Override
public Label getLabel() {
return ruleLabel;
}
@Nullable
@Override
public <T> T get(String attributeName, Type<T> type) {
int index = getIndexWithTypeCheck(attributeName, type);
Object value = attributes.getAttributeValue(index);
if (value instanceof Attribute.ComputedDefault) {
value = ((Attribute.ComputedDefault) value).getDefault(this);
}
return type.cast(value);
}
/**
* Returns the given attribute if it's a computed default, null otherwise.
*
* @throws IllegalArgumentException if the given attribute doesn't exist with the specified
* type. This happens whether or not it's a computed default.
*/
protected <T> Attribute.ComputedDefault getComputedDefault(String attributeName, Type<T> type) {
int index = getIndexWithTypeCheck(attributeName, type);
Object value = attributes.getAttributeValue(index);
if (value instanceof Attribute.ComputedDefault) {
return (Attribute.ComputedDefault) value;
} else {
return null;
}
}
@Override
public Iterable<String> getAttributeNames() {
ImmutableList.Builder<String> names = ImmutableList.builder();
for (Attribute a : ruleClass.getAttributes()) {
names.add(a.getName());
}
return names.build();
}
@Nullable
@Override
public Type<?> getAttributeType(String attrName) {
Attribute attr = getAttributeDefinition(attrName);
return attr == null ? null : attr.getType();
}
@Nullable
@Override
public Attribute getAttributeDefinition(String attrName) {
return ruleClass.getAttributeByNameMaybe(attrName);
}
@Override
public boolean isAttributeValueExplicitlySpecified(String attributeName) {
return attributes.isAttributeValueExplicitlySpecified(attributeName);
}
@Override
public String getPackageDefaultHdrsCheck() {
return pkg.getDefaultHdrsCheck();
}
@Override
public Boolean getPackageDefaultObsolete() {
return pkg.getDefaultObsolete();
}
@Override
public Boolean getPackageDefaultTestOnly() {
return pkg.getDefaultTestOnly();
}
@Override
public String getPackageDefaultDeprecation() {
return pkg.getDefaultDeprecation();
}
@Override
public ImmutableList<String> getPackageDefaultCopts() {
return pkg.getDefaultCopts();
}
@Override
public void visitLabels(AcceptsLabelAttribute observer) {
for (Attribute attribute : ruleClass.getAttributes()) {
Type<?> type = attribute.getType();
// TODO(bazel-team): This is incoherent: we shouldn't have to special-case these types
// for our visitation policy (e.g., why is Type.NODEP_LABEL_LIST excluded but not
// Type.NODEP_LABEL?). But this is the semantics the calling code requires. Audit
// exactly which calling code expects what and clean up this interface.
if (type == Type.OUTPUT || type == Type.OUTPUT_LIST || type == Type.NODEP_LABEL_LIST) {
continue;
}
for (Object value : visitAttribute(attribute.getName(), type)) {
if (value == null) {
// This is particularly possible for computed defaults.
continue;
}
for (Label label : type.getLabels(value)) {
observer.acceptLabelAttribute(label, attribute);
}
}
}
}
/**
* Implementations should provide policy-appropriate mappings when an attribute is requested in
* the context of a rule visitation.
*/
protected abstract <T> Iterable<T> visitAttribute(String attributeName, Type<T> type);
/**
* Returns a {@link Type.Selector} for the given attribute if the attribute is configurable
* for this rule, null otherwise.
*
* @return a {@link Type.Selector} if the attribute takes the form
* "attrName = { 'a': value1_of_type_T, 'b': value2_of_type_T }") for this rule, null
* if it takes the form "attrName = value_of_type_T", null if it doesn't exist
* @throws IllegalArgumentException if the attribute is configurable but of the wrong type
*/
@Nullable
protected <T> Type.Selector<T> getSelector(String attributeName, Type<T> type) {
Integer index = ruleClass.getAttributeIndex(attributeName);
if (index == null) {
return null;
}
Object attrValue = attributes.getAttributeValue(index);
if (!(attrValue instanceof Type.Selector<?>)) {
return null;
}
if (((Type.Selector<?>) attrValue).getOriginalType() != type) {
throw new IllegalArgumentException("Attribute " + attributeName
+ " is not of type " + type + " in rule " + ruleLabel.getName());
}
return (Type.Selector<T>) attrValue;
}
/**
* Returns the index of the specified attribute, if its type is 'type'. Throws
* an exception otherwise.
*/
private int getIndexWithTypeCheck(String attrName, Type<?> type) {
Integer index = ruleClass.getAttributeIndex(attrName);
if (index == null) {
throw new IllegalArgumentException("No such attribute " + attrName
+ " in rule " + ruleLabel.getName());
}
Attribute attr = ruleClass.getAttribute(index);
if (attr.getType() != type) {
throw new IllegalArgumentException("Attribute " + attrName
+ " is not of type " + type + " in rule " + ruleLabel.getName());
}
return index;
}
/**
* Helper routine that just checks the given attribute has the given type for this rule and
* throws an IllegalException if not.
*/
protected void checkType(String attrName, Type<?> type) {
getIndexWithTypeCheck(attrName, type);
}
}
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