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// Copyright 2014 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.syntax;
import com.google.devtools.build.lib.syntax.compiler.DebugInfo;
import com.google.devtools.build.lib.syntax.compiler.Variable.SkylarkVariable;
import com.google.devtools.build.lib.syntax.compiler.VariableScope;
import net.bytebuddy.implementation.bytecode.ByteCodeAppender;
import javax.annotation.Nullable;
// TODO(bazel-team): for extra performance:
// (1) intern the strings, so we can use == to compare, and have .equals use the assumption.
// Then have Argument and Parameter use Identifier again instead of String as keys.
// (2) Use Identifier, not String, as keys in the Environment, which will be cleaner.
// (3) For performance, avoid doing HashMap lookups at runtime, and compile local variable access
// into array reference with a constant index. Variable lookups are currently a speed bottleneck,
// as previously measured in an experiment.
/**
* Syntax node for an identifier.
*/
public final class Identifier extends Expression {
private final String name;
public Identifier(String name) {
this.name = name;
}
/**
* Returns the name of the Identifier.
*/
public String getName() {
return name;
}
public boolean isPrivate() {
return name.startsWith("_");
}
@Override
public String toString() {
return name;
}
@Override
public boolean equals(@Nullable Object object) {
if (object instanceof Identifier) {
Identifier that = (Identifier) object;
return this.name.equals(that.name);
}
return false;
}
@Override
public int hashCode() {
return name.hashCode();
}
@Override
Object doEval(Environment env) throws EvalException {
Object value = env.lookup(name);
if (value == null) {
throw createInvalidIdentifierException();
}
return value;
}
@Override
public void accept(SyntaxTreeVisitor visitor) {
visitor.visit(this);
}
@Override
void validate(ValidationEnvironment env) throws EvalException {
if (!env.hasSymbolInEnvironment(name)) {
throw createInvalidIdentifierException();
}
}
private EvalException createInvalidIdentifierException() {
return name.equals("$error$")
? new EvalException(getLocation(), "contains syntax error(s)", true)
: new EvalException(getLocation(), "name '" + name + "' is not defined");
}
@Override
ByteCodeAppender compile(VariableScope scope, DebugInfo debugInfo) {
SkylarkVariable variable = scope.getVariable(this);
return variable.load(scope, debugInfo.add(this));
}
}
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