+
−/*
+
− * This Source Code Form is subject to the terms of the Mozilla Public
+
− * License, v. 2.0.  If a copy of the MPL was not distributed with this
+
− * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
− *
+
− * Copyright 1997 - July 2008 CWI, August 2008 - 2020 MonetDB B.V.
+
− */
+
−
+
−package org.monetdb.mcl.parser;
+
−
+
−
+
−/**
+
− * Interface for parsers in MCL.  The parser family in MCL is set up as
+
− * a reusable object.  This allows the same parser to be used again for
+
− * the same type of work.  While this is a very unnatural solution in
+
− * the Java language, it prevents many object creations on a low level
+
− * of the protocol.  This favours performance.
+
− *
+
− * A typical parser has a method parse() which takes a String, and the
+
− * methods hasNext() and next() to retrieve the values that were
+
− * extracted by the parser.  Parser specific methods may be available to
+
− * perform common tasks.
+
− *
+
− * @author Fabian Groffen
+
− */
+
−public abstract class MCLParser {
+
−	/** The String values found while parsing.  Public, you may touch it. */
+
−	public final String values[];
+
−	protected int colnr = 0;
+
−
+
−	/**
+
−	 * Creates an MCLParser targetted at a given number of field values.
+
−	 * The lines parsed by an instance of this MCLParser should have
+
−	 * exactly capacity field values.
+
−	 *
+
−	 * @param capacity the number of field values to expect
+
−	 */
+
−	protected MCLParser(final int capacity) {
+
−		values = new String[capacity];
+
−	}
+
−
+
−	/**
+
−	 * Parse the given string, and populate the internal field array
+
−	 * to allow for next() and hasNext() calls.
+
−	 *
+
−	 * @param source the String containing the line to parse
+
−	 * @return value
+
−	 * @throws MCLParseException if source cannot be (fully) parsed by
+
−	 * this parser
+
−	 * @see #next()
+
−	 * @see #hasNext()
+
−	 */
+
−	abstract public int parse(final String source) throws MCLParseException;
+
−
+
−	/**
+
−	 * Repositions the internal field offset to the start, such that the
+
−	 * next call to next() will return the first field again.
+
−	 */
+
−	final public void reset() {
+
−		colnr = 0;
+
−	}
+
−
+
−	/**
+
−	 * Returns whether the next call to next() or nextInt() succeeds.
+
−	 *
+
−	 * @return true if the next call to next() or nextInt() is bound to
+
−	 * succeed
+
−	 * @see #next()
+
−	 */
+
−	final public boolean hasNext() {
+
−		return colnr < values.length;
+
−	}
+
−
+
−	/**
+
−	 * Returns the current field value, and advances the field counter
+
−	 * to the next value.  This method may fail with a RuntimeError if
+
−	 * the current field counter is out of bounds.  Call hasNext() to
+
−	 * determine if the call to next() will succeed.
+
−	 *
+
−	 * @return the current field value
+
−	 * @see #hasNext()
+
−	 */
+
−	final public String next() {
+
−		return values[colnr++];
+
−	}
+
−}