ecommons/org.eclipse.statet.ecommons.runtime.core/src/org/eclipse/statet/ecommons/runtime/core/util/MessageBuilder.java

/*=============================================================================#
 # Copyright (c) 2005, 2021 Stephan Wahlbrink and others.
 # 
 # This program and the accompanying materials are made available under the
 # terms of the Eclipse Public License 2.0 which is available at
 # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
 # which is available at https://www.apache.org/licenses/LICENSE-2.0.
 # 
 # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
 # 
 # Contributors:
 #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
 #=============================================================================*/

package org.eclipse.statet.ecommons.runtime.core.util;

import org.eclipse.statet.jcommons.lang.NonNullByDefault;


/**
 * Creates text message like {@link org.eclipse.osgi.util.NLS} bind.
 * 
 * This class is intent to use when creating messages repeatedly in a single thread.
 * It is not thread safe.
 */
@NonNullByDefault
public class MessageBuilder {
	
	
	private static final Object[] EMPTY_ARGS= new Object[0];
	
	
	private final StringBuilder builder;
	
	
	public MessageBuilder() {
		this(128);
	}
	
	public MessageBuilder(final int initialBufferLength) {
		this.builder= new StringBuilder(initialBufferLength);
	}
	
	
	/**
	 * Bind the given message's substitution locations with the given string value.
	 * 
	 * @param message the message to be manipulated
	 * @param binding the object to be inserted into the message
	 * @return the manipulated String
	 * @throws IllegalArgumentException if the text appearing within curly braces in the given message does not map to an integer 
	 */
	public String bind(final String message, final Object binding) {
		return internalBind(message, null, String.valueOf(binding), null);
	}
	
	/**
	 * Bind the given message's substitution locations with the given string values.
	 * 
	 * @param message the message to be manipulated
	 * @param binding1 An object to be inserted into the message
	 * @param binding2 A second object to be inserted into the message
	 * @return the manipulated String
	 * @throws IllegalArgumentException if the text appearing within curly braces in the given message does not map to an integer
	 */
	public String bind(final String message, final Object binding1, final Object binding2) {
		return internalBind(message, null, String.valueOf(binding1), String.valueOf(binding2));
	}
	
	/**
	 * Bind the given message's substitution locations with the given string values.
	 * 
	 * @param message the message to be manipulated
	 * @param bindings An array of objects to be inserted into the message
	 * @return the manipulated String
	 * @throws IllegalArgumentException if the text appearing within curly braces in the given message does not map to an integer
	 */
	public String bind(final String message, final Object[] bindings) {
		return internalBind(message, bindings, null, null);
	}
	
	/*
	 * Perform the string substitution on the given message with the specified args.
	 * See the class comment for exact details.
	 */
	private String internalBind(final String message, Object[] args, final String argZero, final String argOne) {
		if (message == null) {
			return "No message available."; //$NON-NLS-1$
		}
		if (args == null || args.length == 0) {
			args= EMPTY_ARGS;
		}
		
		this.builder.setLength(0);
		
		final int length= message.length();
		{	int bufLen= length + (args.length * 5);
			if (argZero != null) {
				bufLen+= argZero.length() - 3;
				if (argOne != null) {
					bufLen+= argOne.length() - 3;
				}
			}
			this.builder.ensureCapacity(bufLen);
		}
		for (int i= 0; i < length; i++) {
			final char c= message.charAt(i);
			switch (c) {
			case '{' :
				int index= message.indexOf('}', i);
				// if we don't have a matching closing brace then...
				if (index == -1) {
					this.builder.append(c);
					break;
				}
				i++;
				if (i >= length) {
					this.builder.append(c);
					break;
				}
				// look for a substitution
				int number= -1;
				try {
					number= Integer.parseInt(message.substring(i, index));
				}
				catch (final NumberFormatException e) {
					throw new IllegalArgumentException(e);
				}
				if (number == 0 && argZero != null) {
					this.builder.append(argZero);
				}
				else if (number == 1 && argOne != null) {
					this.builder.append(argOne);
				}
				else if (number >= 0 && number < args.length) {
					this.builder.append(args[number]);
				}
				else {
					this.builder.append("<missing argument>"); //$NON-NLS-1$
				}
				i= index;
				break;
			case '\'' :
				// if a single quote is the last char on the line then skip it
				final int nextIndex= i + 1;
				if (nextIndex >= length) {
					this.builder.append(c);
					break;
				}
				final char next= message.charAt(nextIndex);
				// if the next char is another single quote then write out one
				if (next == '\'') {
					i++;
					this.builder.append(c);
					break;
				}
				// otherwise we want to read until we get to the next single quote
				index= message.indexOf('\'', nextIndex);
				// if there are no more in the string, then skip it
				if (index == -1) {
					this.builder.append(c);
					break;
				}
				// otherwise write out the chars inside the quotes
				this.builder.append(message.substring(nextIndex, index));
				i= index;
				break;
			default :
				this.builder.append(c);
			}
		}
		return this.builder.toString();
	}
	
}