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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;
import com.google.common.collect.ImmutableMap;
import java.util.LinkedHashMap;
import java.util.Map;
/**
* Syntax node for dictionary comprehension expressions.
*/
public class DictComprehension extends Expression {
private final Expression keyExpression;
private final Expression valueExpression;
private final Ident loopVar;
private final Expression listExpression;
public DictComprehension(Expression keyExpression, Expression valueExpression, Ident loopVar,
Expression listExpression) {
this.keyExpression = keyExpression;
this.valueExpression = valueExpression;
this.loopVar = loopVar;
this.listExpression = listExpression;
}
Expression getKeyExpression() {
return keyExpression;
}
Expression getValueExpression() {
return valueExpression;
}
Ident getLoopVar() {
return loopVar;
}
Expression getListExpression() {
return listExpression;
}
@Override
Object eval(Environment env) throws EvalException, InterruptedException {
// We want to keep the iteration order
LinkedHashMap<Object, Object> map = new LinkedHashMap<>();
Iterable<?> elements = EvalUtils.toIterable(listExpression.eval(env), getLocation());
for (Object element : elements) {
env.update(loopVar.getName(), element);
Object key = keyExpression.eval(env);
map.put(key, valueExpression.eval(env));
}
return ImmutableMap.copyOf(map);
}
@Override
SkylarkType validate(ValidationEnvironment env) throws EvalException {
SkylarkType elementsType = listExpression.validate(env);
// TODO(bazel-team): GenericType1 should be a SkylarkType.
Class<?> listElementType = elementsType.getGenericType1();
SkylarkType listElementSkylarkType = listElementType.equals(Object.class)
? SkylarkType.UNKNOWN : SkylarkType.of(listElementType);
env.update(loopVar.getName(), listElementSkylarkType, getLocation());
SkylarkType keyType = keyExpression.validate(env);
if (!keyType.isSimple()) {
// TODO(bazel-team): this is most probably dead code but it's better to have it here
// in case we enable e.g. list of lists or we validate function calls on Java objects
throw new EvalException(getLocation(), "Dict comprehension key must be of a simple type");
}
valueExpression.validate(env);
if (elementsType != SkylarkType.UNKNOWN && !elementsType.isList()) {
throw new EvalException(getLocation(), "Dict comprehension elements must be a list");
}
return SkylarkType.of(Map.class, keyType.getType());
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append('{').append(keyExpression).append(": ").append(valueExpression);
sb.append(" for ").append(loopVar).append(" in ").append(listExpression);
sb.append('}');
return sb.toString();
}
@Override
public void accept(SyntaxTreeVisitor visitor) {
visitor.accept(this);
}
}
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