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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.SkylarkList.MutableList;
import com.google.devtools.build.lib.syntax.SkylarkList.Tuple;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* Syntax node for list and tuple literals.
*
* <p>(Note that during evaluation, both list and tuple values are represented by java.util.List
* objects, the only difference between them being whether or not they are mutable.)
*/
public final class ListLiteral extends Expression {
/**
* Types of the ListLiteral.
*/
// TODO(laurentlb): This conflicts with Expression.Kind, maybe remove it?
public enum Kind {LIST, TUPLE}
private final Kind kind;
private final List<Expression> elements;
public ListLiteral(Kind kind, List<Expression> elements) {
this.kind = kind;
this.elements = elements;
}
public static ListLiteral makeList(List<Expression> elements) {
return new ListLiteral(Kind.LIST, elements);
}
public static ListLiteral makeTuple(List<Expression> elements) {
return new ListLiteral(Kind.TUPLE, elements);
}
/** A new literal for an empty list, onto which a new location can be specified */
public static ListLiteral emptyList() {
return makeList(Collections.emptyList());
}
public Kind getKind() {
return kind;
}
public List<Expression> getElements() {
return elements;
}
/**
* Returns true if this list is a tuple (a hash table, immutable list).
*/
public boolean isTuple() {
return kind == Kind.TUPLE;
}
@Override
public void prettyPrint(Appendable buffer) throws IOException {
buffer.append(isTuple() ? '(' : '[');
String sep = "";
for (Expression e : elements) {
buffer.append(sep);
e.prettyPrint(buffer);
sep = ", ";
}
if (isTuple() && elements.size() == 1) {
buffer.append(',');
}
buffer.append(isTuple() ? ')' : ']');
}
@Override
public String toString() {
return Printer.printAbbreviatedList(
elements,
isTuple(),
Printer.SUGGESTED_CRITICAL_LIST_ELEMENTS_COUNT,
Printer.SUGGESTED_CRITICAL_LIST_ELEMENTS_STRING_LENGTH);
}
@Override
Object doEval(Environment env) throws EvalException, InterruptedException {
ArrayList<Object> result = new ArrayList<>(elements.size());
for (Expression element : elements) {
// Convert NPEs to EvalExceptions.
if (element == null) {
throw new EvalException(getLocation(), "null expression in " + this);
}
result.add(element.eval(env));
}
return isTuple() ? Tuple.copyOf(result) : MutableList.wrapUnsafe(env, result);
}
@Override
public void accept(SyntaxTreeVisitor visitor) {
visitor.visit(this);
}
@Override
public Expression.Kind kind() {
return Expression.Kind.LIST_LITERAL;
}
}
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