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// 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.packages;
import com.google.devtools.build.lib.events.Location;
import com.google.devtools.build.lib.syntax.EvalException;
/**
* An enum that represents different types of rule attributes, based on where their values come
* from.
*/
public enum AttributeValueSource {
COMPUTED_DEFAULT("$", true),
LATE_BOUND(":", true),
DIRECT("$", false);
private static final String SKYLARK_PREFIX = "_";
private final String nativePrefix;
private final boolean mustHaveSkylarkPrefix;
/**
* Creates a new instance and defines the prefixes for both Skylark and native.
*
* @param nativePrefix The prefix when converted to a native attribute name.
* @param mustHaveSkylarkPrefix Whether the Skylark name must start with {@link
* AttributeValueSource#SKYLARK_PREFIX}.
*/
AttributeValueSource(String nativePrefix, boolean mustHaveSkylarkPrefix) {
this.nativePrefix = nativePrefix;
this.mustHaveSkylarkPrefix = mustHaveSkylarkPrefix;
}
/**
* Throws an {@link EvalException} if the given Skylark name is not valid for this type.
*/
public void validateSkylarkName(String attrSkylarkName, Location location) throws EvalException {
if (attrSkylarkName.isEmpty()) {
throw new EvalException(location, "Attribute name must not be empty.");
}
if (mustHaveSkylarkPrefix && !attrSkylarkName.startsWith(SKYLARK_PREFIX)) {
throw new EvalException(
location,
String.format(
"When an attribute value is a function, the attribute must be private "
+ "(i.e. start with '%s'). Found '%s'",
SKYLARK_PREFIX, attrSkylarkName));
}
}
/**
* Converts the given Skylark attribute name to a native attribute name for this type, or throws
* an {@link EvalException} if the given Skylark name is not valid for this type.
*/
public String convertToNativeName(String attrSkylarkName, Location location)
throws EvalException {
validateSkylarkName(attrSkylarkName, location);
// No need to check for mustHaveSkylarkPrefix since this was already done in
// validateSkylarkName().
return attrSkylarkName.startsWith(SKYLARK_PREFIX)
? nativePrefix + attrSkylarkName.substring(SKYLARK_PREFIX.length())
: attrSkylarkName;
}
}
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