com.google.devtools.build.lib.query2.engine.AggregatingQueryExpressionVisitor.java Source code

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// Copyright 2017 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.query2.engine;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.common.primitives.Booleans;
import com.google.devtools.build.lib.query2.engine.QueryEnvironment.Argument;
import com.google.devtools.build.lib.query2.engine.QueryEnvironment.ArgumentType;
import com.google.devtools.build.lib.query2.engine.QueryEnvironment.QueryFunction;

/**
 * An implementation of {@link QueryExpressionVisitor} which recursively visits all nested {@link
 * QueryExpression}s
 */
public abstract class AggregatingQueryExpressionVisitor<T> implements QueryExpressionVisitor<T> {

    @Override
    public T visit(BinaryOperatorExpression binaryOperatorExpression) {
        ImmutableMap.Builder<QueryExpression, T> builder = ImmutableMap.builder();
        for (QueryExpression expr : binaryOperatorExpression.getOperands()) {
            builder.put(expr, expr.accept(this));
        }

        return aggregate(builder.build());
    }

    @Override
    public T visit(FunctionExpression functionExpression) {
        ImmutableMap.Builder<QueryExpression, T> builder = ImmutableMap.builder();
        for (Argument argument : functionExpression.getArgs()) {
            if (argument.getType() == ArgumentType.EXPRESSION) {
                builder.put(argument.getExpression(), argument.getExpression().accept(this));
            }
        }

        return aggregate(builder.build());
    }

    @Override
    public T visit(LetExpression letExpression) {
        return aggregate(ImmutableMap.of(letExpression.getVarExpr(), letExpression.getVarExpr().accept(this),
                letExpression.getBodyExpr(), letExpression.getBodyExpr().accept(this)));
    }

    @Override
    public T visit(SetExpression setExpression) {
        ImmutableMap.Builder<QueryExpression, T> builder = ImmutableMap.builder();
        for (TargetLiteral targetLiteral : setExpression.getWords()) {
            builder.put(targetLiteral, targetLiteral.accept(this));
        }

        return aggregate(builder.build());
    }

    /**
     * Aggregates results from all sub-expression visitations. The map is guaranteed to include
     * results for all direct sub-expressions.
     */
    protected abstract T aggregate(ImmutableMap<QueryExpression, T> resultMap);

    /**
     * Returns {@code true} when the query expression contains at least one {@link QueryFunction}
     * whose name is in the set of {@code functionName}.
     */
    public static class ContainsFunctionQueryExpressionVisitor extends AggregatingQueryExpressionVisitor<Boolean>
            implements QueryExpressionVisitor<Boolean> {

        private final ImmutableSet<String> functionNames;

        public ContainsFunctionQueryExpressionVisitor(Iterable<String> functionNames) {
            this.functionNames = ImmutableSet.copyOf(functionNames);
        }

        @Override
        public Boolean visit(TargetLiteral targetLiteral) {
            return false;
        }

        @Override
        public Boolean visit(SetExpression setExpression) {
            return false;
        }

        @Override
        public Boolean visit(FunctionExpression functionExpression) {
            QueryFunction function = functionExpression.getFunction();
            if (functionNames.contains(function.getName())) {
                return true;
            } else {
                return super.visit(functionExpression);
            }
        }

        @Override
        protected Boolean aggregate(ImmutableMap<QueryExpression, Boolean> resultMap) {
            return Booleans.contains(Booleans.toArray(resultMap.values()), true);
        }
    }
}