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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * accompanied this code).
 *
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package hat.dialect;

import jdk.incubator.code.dialect.core.CoreOp;
import jdk.incubator.code.dialect.java.MethodRef;

import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public record DialectModule(DialectFunction entryPoint, List<DialectFunction> helpers) {

    public DialectModule {
        if (entryPoint == null) {
            throw new IllegalStateException("entryPoint is null");
        }
        // Make helpers immutable list, thus, we can't accidentally modify them
        helpers = List.copyOf(helpers);
    }

    /**
     * Returns a stream of functions in the correct order for code generation. The last function
     * in the stream is always the entrypoint.
     *
     * @return {@link Stream<DialectFunction>}
     */
    public Stream<DialectFunction> functions() {
        return Stream.concat(helpers.stream(), Stream.of(entryPoint));
    }

    /**
     * Convert a function stream into a HashMap which identifies MethodRef -> Function.
     * This is useful when HAT builds the {@link hat.callgraph.MethodCallDag} before generating the low-level code.
     *
     * @return {@code Map<MethodRef, CoreOp.FuncOp>}
     */
    public Map<MethodRef, CoreOp.FuncOp> functionsByMethod() {
        return functions()
                .collect(Collectors.toMap(
                        DialectFunction::methodRef,
                        DialectFunction::function,
                        (a, b) -> b));
    }
}