| // 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.common.annotations.VisibleForTesting; |
| import com.google.devtools.build.lib.events.Location; |
| |
| import java.io.Serializable; |
| |
| /** |
| * Root class for nodes in the Abstract Syntax Tree of the Build language. |
| */ |
| public abstract class ASTNode implements Serializable { |
| |
| private Location location; |
| |
| protected ASTNode() {} |
| |
| /** |
| * Returns whether this node represents a new scope, e.g. a function call. |
| */ |
| protected boolean isNewScope() { |
| return false; |
| } |
| |
| /** |
| * Returns an exception which should be thrown instead of the original one. |
| */ |
| protected final EvalException handleException(Exception original) { |
| // If there is already a non-empty stack trace, we only add this node iff it describes a |
| // new scope (e.g. FuncallExpression). |
| if (original instanceof EvalExceptionWithStackTrace) { |
| EvalExceptionWithStackTrace real = (EvalExceptionWithStackTrace) original; |
| if (isNewScope()) { |
| real.registerNode(this); |
| } |
| return real; |
| } |
| |
| // Returns the original exception if it cannot be attached to a stack trace. |
| if (original instanceof EvalException && !((EvalException) original).canBeAddedToStackTrace()) { |
| return (EvalException) original; |
| } |
| |
| return new EvalExceptionWithStackTrace(original, this); |
| } |
| |
| @VisibleForTesting // productionVisibility = Visibility.PACKAGE_PRIVATE |
| public void setLocation(Location location) { |
| this.location = location; |
| } |
| |
| public Location getLocation() { |
| return location; |
| } |
| |
| /** @return the same node with its location set, in a slightly more fluent style */ |
| public static <NODE extends ASTNode> NODE setLocation(Location location, NODE node) { |
| node.setLocation(location); |
| return node; |
| } |
| |
| /** |
| * Print the syntax node in a form useful for debugging. The output is not |
| * precisely specified, and should not be used by pretty-printing routines. |
| */ |
| @Override |
| public abstract String toString(); |
| |
| @Override |
| public int hashCode() { |
| throw new UnsupportedOperationException(); // avoid nondeterminism |
| } |
| |
| @Override |
| public boolean equals(Object that) { |
| throw new UnsupportedOperationException(); |
| } |
| |
| /** |
| * Implements the double dispatch by calling into the node specific |
| * <code>visit</code> method of the {@link SyntaxTreeVisitor} |
| * |
| * @param visitor the {@link SyntaxTreeVisitor} instance to dispatch to. |
| */ |
| public abstract void accept(SyntaxTreeVisitor visitor); |
| |
| } |