com.google.devtools.build.lib.syntax.Callstack.java Source code

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Here is the source code for com.google.devtools.build.lib.syntax.Callstack.java

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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.syntax;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import java.util.ArrayList;
import java.util.List;

/**
 * Holds the Skylark callstack in thread-local storage. Contains all Expressions and BaseFunctions
 * currently being evaluated.
 *
 * <p>This is needed for memory tracking, since the evaluator is not available in the context of
 * instrumentation. It should not be used by normal Skylark interpreter logic.
 */
public class Callstack {
    private static boolean enabled;
    private static final ThreadLocal<List<Object>> callstack = ThreadLocal.withInitial(ArrayList::new);

    public static void setEnabled(boolean enabled) {
        Callstack.enabled = enabled;
    }

    public static void push(ASTNode node) {
        if (enabled) {
            callstack.get().add(node);
        }
    }

    public static void push(BaseFunction function) {
        if (enabled) {
            callstack.get().add(function);
        }
    }

    public static void pop() {
        if (enabled) {
            List<Object> threadStack = callstack.get();
            threadStack.remove(threadStack.size() - 1);
        }
    }

    public static List<Object> get() {
        Preconditions.checkState(enabled, "Must call Callstack#setEnabled before getting");
        return callstack.get();
    }

    @VisibleForTesting
    public static void resetStateForTest() {
        enabled = false;
        callstack.get().clear();
    }
}