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/*
* Copyright 2016 Google Inc. 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.turbine.binder.env;
import com.google.turbine.binder.sym.ClassSymbol;
import com.google.turbine.binder.sym.Symbol;
import org.checkerframework.checker.nullness.qual.Nullable;
/**
* An environment that maps {@link Symbol}s {@code S} to bound nodes {@code V}.
*
* <p>For example, {@code BoundClass} represents superclasses as a {@link ClassSymbol}, which only
* contains the binary name of the type. To get the {@code BoundClass} for that supertype, an {@code
* Env<BoundClass>} is used.
*
* <p>The indirection through env makes it possible to represent a graph with cycles using immutable
* nodes, and makes it easy to reason about the information produced and consumed by each pass.
*
* <p>TODO(cushon): keep an eye on the cost of indirections, and consider caching lookups in bound
* nodes if it looks like it would make a difference.
*/
public interface Env<S extends Symbol, V> {
/** Returns the information associated with the given symbol in this environment. */
@Nullable
V get(S sym);
default V getNonNull(S sym) {
V result = get(sym);
if (result == null) {
throw new NullPointerException(sym.toString());
}
return result;
}
}
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