com.github.akurilov.commons.io.el.ExpressionInput Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of java-commons Show documentation
Common functionality Java library
The newest version!
package com.github.akurilov.commons.io.el;

import com.github.akurilov.commons.io.Input;

import de.odysseus.el.ExpressionFactoryImpl;

import javax.el.ELException;
import javax.el.ExpressionFactory;
import javax.el.PropertyNotFoundException;
import java.lang.reflect.Method;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.regex.Pattern;

/**
 @param 
 */
public interface ExpressionInput
extends Callable, Input {

	String SELF_REF_ID = "this";
	String ASYNC_MARKER = "#{";
	String SYNC_MARKER = "${";
	String INIT_MARKER = "%{";
	Pattern EXPRESSION_PATTERN = Pattern.compile("([$#]\\{[^}]+})?(%\\{[^}]+})?");
	ExpressionFactory FACTORY = new ExpressionFactoryImpl();

	/**
	 Perform the expression evaluation
	 @return the expression evaluation result
	 */
	@Override
	T call();

	/**
	 * @return the result of the last expression evaluation
	 */
	T last();

	/**
	 Get a value. A user should invoke call() method by itself to evaluate the expression if the given expression
	 input is not synchronous. The initial value only would be returned otherwise.
	 @throws PropertyNotFoundException
	 @throws ELException
	 */
	@Override
	T get()
	throws PropertyNotFoundException, ELException;

	/**
	 Bulk values get. A user should invoke call() method by itself to evaluate the expression if the given expression
	 input is not synchronous. The initial value only would be returned otherwise.
	 @param buffer buffer for the values
	 @param limit max count of the values to put into the buffer
	 @throws PropertyNotFoundException
	 @throws ELException
	 */
	@Override
	int get(final List buffer, final int limit)
	throws PropertyNotFoundException, ELException;

	/**
	 * Skip some items.
	 * @param count count of items should be skipped from the input stream
	 */
	@Override
	long skip(final long count);

	/**
	 Set the last value to the initial one.
	 */
	@Override
	void reset();

	/**
	 @return the expression string
	 */
	String expr();

	interface Builder {

		Builder expression(final String expr);

		Builder function(final String prefix, final String name, final Method method);

		Builder value(final String name, final Object value, final Class type);

		> U build();
	}

	static Builder builder() {
		return new ExpressionInputBuilder();
	}
}