software.amazon.awssdk.services.qldb.endpoints.internal.Scope Maven / Gradle / Ivy

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The AWS Java SDK for QLDB module holds the client classes that are used for communicating with QLDB.

There is a newer version: 2.28.3

/*
 * Copyright Amazon.com, Inc. or its affiliates. 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. A copy of the License is located at
 * 
 * http://aws.amazon.com/apache2.0
 * 
 * or in the "license" file accompanying this file. This file 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 software.amazon.awssdk.services.qldb.endpoints.internal;

import java.util.ArrayDeque;
import java.util.Deque;
import java.util.HashMap;
import java.util.Optional;
import java.util.function.Supplier;
import software.amazon.awssdk.annotations.SdkInternalApi;

@SdkInternalApi
public class Scope {
    private final Deque> scope;

    public Scope() {
        this.scope = new ArrayDeque<>();
        this.scope.push(new FatScope());
    }

    public void push() {
        scope.push(new FatScope<>());
    }

    public void pop() {
        scope.pop();
    }

    public void insert(String name, T value) {
        this.insert(Identifier.of(name), value);
    }

    public void insert(Identifier name, T value) {
        this.scope.getFirst().types().put(name, value);
    }

    public void insertFact(Expr name, T value) {
        this.scope.getFirst().facts().put(name, value);
    }

    public  U inScope(Supplier func) {
        this.push();
        try {
            return func.get();
        } finally {
            this.pop();
        }
    }

    @Override
    public String toString() {
        HashMap toPrint = new HashMap<>();
        for (FatScope layer : scope) {
            toPrint.putAll(layer.types());
        }
        return toPrint.toString();
    }

    /**
     * Search the fact stack for an explicitly calculated value for [expr]
     * 
     * Currently, this is only impacted by the `isSet` function which will record `T`, rather than {@code Option} for
     * its arguments
     *
     * @param expr
     *        The expression to evaluate
     * @return The value from the scope
     */
    public Optional eval(Expr expr) {
        for (FatScope layer : scope) {
            if (layer.facts().containsKey(expr)) {
                return Optional.of(layer.facts().get(expr));
            }
        }
        return Optional.empty();
    }

    public T expectValue(Identifier name) {
        for (FatScope layer : scope) {
            if (layer.types().containsKey(name)) {
                return layer.types().get(name);
            }
        }
        throw new InnerParseError(String.format("No field named %s", name));
    }

    public Optional getValue(Identifier name) {
        for (FatScope layer : scope) {
            if (layer.types().containsKey(name)) {
                return Optional.of(layer.types().get(name));
            }
        }
        return Optional.empty();
    }
}