org.petitparser.parser.actions.ContinuationParser Maven / Gradle / Ivy

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package org.petitparser.parser.actions;

import org.petitparser.context.Context;
import org.petitparser.context.Result;
import org.petitparser.parser.Parser;
import org.petitparser.parser.combinators.DelegateParser;

import java.util.Objects;
import java.util.function.Function;

/**
 * Continuation parser that when activated captures a continuation function and passes it together
 * with the current context into the handler.
 */
public class ContinuationParser extends DelegateParser {

  @FunctionalInterface
  public interface ContinuationHandler {
    Result apply(Function continuation, Context context);
  }

  private final ContinuationHandler handler;

  public ContinuationParser(Parser delegate, ContinuationHandler handler) {
    super(delegate);
    this.handler = Objects.requireNonNull(handler, "Undefined handler");
  }

  @Override
  public Result parseOn(Context context) {
    return handler.apply(super::parseOn, context);
  }

  @Override
  protected boolean hasEqualProperties(Parser other) {
    return super.hasEqualProperties(other) &&
        Objects.equals(handler, ((ContinuationParser) other).handler);
  }

  @Override
  public ContinuationParser copy() {
    return new ContinuationParser(delegate, handler);
  }
}