plugins/org.eclipse.ocl/src/org/eclipse/ocl/OCLInput.java

/*******************************************************************************
 * Copyright (c) 2007, 2018 IBM Corporation and others.
 * All rights reserved.   This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v2.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v20.html
 *
 * Contributors:
 *   IBM - Initial API and implementation
 *******************************************************************************/
package org.eclipse.ocl;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StringReader;
import java.io.UnsupportedEncodingException;
import java.nio.Buffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;

import org.eclipse.ocl.internal.l10n.OCLMessages;

/**
 * Encapsulation of an OCL document, which may be obtained from a string or from
 * a stream.  The content of the OCL document consists of one or more context
 * declarations (including constraints) with optional package declarations.
 *
 * @author Christian W. Damus (cdamus)
 */
public final class OCLInput {
	private String textString;
	private Reader textReader;

	/**
	 * Creates an OCL document from a string.
	 *
	 * @param oclText the string containing the OCL document
	 */
	public OCLInput(String oclText) {
		this.textString = oclText;
	}

	/**
	 * Creates an OCL document from an input stream, using the default character
	 * set to decode it.
	 *
	 * @param oclStream the input stream providing the OCL document
	 */
	public OCLInput(InputStream oclStream) {
		this.textReader = new InputStreamReader(oclStream, Charset.defaultCharset());
	}

	/**
	 * Creates an OCL document from an input stream in the specified encoding.
	 *
	 * @param oclStream the input stream providing the OCL document
	 * @param encoding the stream's character encoding
	 *
	 * @throws UnsupportedEncodingException if the specified encoding is not
	 *     supported in this virtual machine
	 */
	public OCLInput(InputStream oclStream, String encoding)
			throws UnsupportedEncodingException {
		this.textReader = new InputStreamReader(oclStream, encoding);
	}

	/**
	 * Creates an OCL document from a character stream.
	 *
	 * @param oclReader the stream providing the OCL document
	 */
	public OCLInput(Reader oclReader) {
		this.textReader = oclReader;
	}

	/**
	 * The contents of the OCL document as a character array, suitable for
	 * consumption by the OCL parser.
	 *
	 * @return the OCL document contents
	 *
	 * @throws ParserException on an I/O failure in reading the content
	 */
	public char[] getContent() throws ParserException {
		if (textString != null) {
			return textString.toCharArray();
		}

		StringBuilder builder = buildStringFromReader();

		char[] result = new char[builder.length()];
		builder.getChars(0, result.length, result, 0);
		return result;
	}

	/**
	 * The contents of the OCL document as a character array, suitable for
	 * consumption by the OCL parser.
	 *
	 * @return the OCL document contents
	 *
	 * @throws ParserException on an I/O failure in reading the content
	 */
	public String getContentAsString() throws ParserException {
		if (textString != null) {
			return textString;
		}

		StringBuilder builder = buildStringFromReader();

		return builder.toString();
	}

	private StringBuilder buildStringFromReader() throws ParserException {
		StringBuilder result = new StringBuilder();
		CharBuffer cbuf = CharBuffer.allocate(2048);

		try {
			try {
				for (;;) {
					int read = textReader.read(cbuf);

					if (read < 0) {
						break;
					}

					((Buffer)cbuf).flip();			// See Bug 534950 - cast needed for JDK 8/9 compatibility
					result.append(cbuf);
				}
			} finally {
				textReader.close();
			}
		} catch (IOException e) {
			throw new ParserException(
				OCLMessages.bind(OCLMessages.Input_ERROR_, e.getLocalizedMessage()),
				e);
		}

		return result;
	}

	/**
	 * The contents of the OCL document as a character stream, suitable for
	 * consumption by the OCL parser.
	 *
	 * @return the OCL document contents
	 */
	public Reader getContentAsStream() {
		if (textReader != null) {
			return textReader;
		}

		return new StringReader(textString);
	}
}