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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.syntax;
// 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 Ident again instead of String as keys.
// (2) Use Ident, 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 Ident extends Expression {
private final String name;
public Ident(String name) {
this.name = name;
}
/**
* Returns the name of the Ident.
*/
public String getName() {
return name;
}
@Override
public String toString() {
return name;
}
@Override
Object eval(Environment env) throws EvalException {
try {
return env.lookup(name);
} catch (Environment.NoSuchVariableException e) {
if (name.equals("$error$")) {
throw new EvalException(getLocation(), "contains syntax error(s)", true);
} else {
throw new EvalException(getLocation(), "name '" + name + "' is not defined");
}
}
}
@Override
public void accept(SyntaxTreeVisitor visitor) {
visitor.visit(this);
}
@Override
void validate(ValidationEnvironment env) throws EvalException {
if (!env.hasSymbolInEnvironment(name)) {
if (name.equals("$error$")) {
throw new EvalException(getLocation(), "contains syntax error(s)", true);
} else {
throw new EvalException(getLocation(), "name '" + name + "' is not defined");
}
}
}
}
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