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/*
 * Copyright 2013-2024 Netherlands Forensic Institute
 * Copyright 2021-2024 Infix Technologies B.V.
 *
 * 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 io.parsingdata.metal.token;

import static io.parsingdata.metal.Util.checkNotNull;
import static io.parsingdata.metal.Util.failure;
import static io.parsingdata.metal.expression.value.NotAValue.NOT_A_VALUE;

import java.util.Objects;
import java.util.Optional;

import io.parsingdata.metal.data.Environment;
import io.parsingdata.metal.data.ParseState;
import io.parsingdata.metal.encoding.Encoding;
import io.parsingdata.metal.expression.value.SingleValueExpression;
import io.parsingdata.metal.expression.value.ValueExpression;

/**
 * A {@link Token} that specifies a bounded repetition of a token.
 * 
 * A RepN consists of a token (a {@link Token}) and an
 * n (a {@link SingleValueExpression}). First n is
 * evaluated. The token is then parsed for an amount of times equal to the
 * evaluated value of n. RepN succeeds if this succeeds.
 *
 * @see Rep
 * @see ValueExpression
 */
public class RepN extends IterableToken {

    public final SingleValueExpression n;

    public RepN(final String name, final Token token, final SingleValueExpression n, final Encoding encoding) {
        super(name, token, encoding);
        this.n = checkNotNull(n, "n");
    }

    @Override
    protected Optional parseImpl(final Environment environment) {
        return n.evalSingle(environment.parseState, environment.encoding)
            .filter(count -> !count.equals(NOT_A_VALUE))
            .flatMap(count -> parse(environment, env -> env.parseState.iterations.head.right.compareTo(count.asNumeric()) >= 0, env -> failure()));
    }

    @Override
    public String toString() {
        return getClass().getSimpleName() + "(" + makeNameFragment() + token + "," + n + ")";
    }

    @Override
    public boolean equals(final Object obj) {
        return super.equals(obj)
            && Objects.equals(n, ((RepN)obj).n);
    }

    @Override
    public int immutableHashCode() {
        return Objects.hash(super.immutableHashCode(), n);
    }

}