bayard 2004/09/04 17:37:28 Added: lang/src/java/org/apache/commons/lang/text MappedMessageFormat.java Log: class from Digester, akin to the Interpolation class in the lang package Revision Changes Path 1.1 jakarta-commons/lang/src/java/org/apache/commons/lang/text/MappedMessageFormat.java Index: MappedMessageFormat.java =================================================================== /* * Copyright 2002-2004 The Apache Software Foundation. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.commons.lang.text; import java.util.Map; import java.util.ArrayList; /** * Provides the ability to substitute values from one or more maps into * designated places within a string. * <p> * For example: * <pre> * "User ${id} has uid ${uid} and path of env{path}" * </pre> * can be expanded using values from a map associated with "$" and a different * map associated with "env". * <p> * This class is similar to the java.text.MessageFormat class, but allows * data to be retrieved from one or maps instead of from a single list. * Unlike the MessageFormat class, however, it simply uses the result of * applying toString() to the referenced values in the map(s) and does not * support any "format" operations applied to the objects before substitution * into the target string. * * @since 2.1 */ public class MappedMessageFormat { private int nEntries = 0; private ArrayList markers = new ArrayList(2); private ArrayList sources = new ArrayList(2); public MappedMessageFormat() { } /** * Defines a source of data that can later be substituted into * strings passed to the "format" methods. */ public void addSource(String marker, Map source) { ++nEntries; markers.add(marker); sources.add(source); } /** * Expands any variable declarations using any of the known * variable marker strings. * * @throws IllegalArgumentException if the input param references * a variable which is not known to the specified source. */ public String format(String param) { for(int i=0; i<nEntries; ++i) { param = format( param, (String) markers.get(i), (Map) sources.get(i)); } return param; } /** * Replace any occurrences within the string of the form * "marker{key}" with the value from source[key]. * <p> * Commonly, the variable marker is "$", in which case variables * are indicated by ${key} in the string. * <p> * Returns the string after performing all substitutions. * <p> * If no substitutions were made, the input string object is * returned (not a copy). * * @throws IllegalArgumentException if the input param references * a variable which is not known to the specified source. */ public static String format(String str, String marker, Map source) { String startMark = marker + "{"; int markLen = startMark.length(); int index = 0; for(;;) { index = str.indexOf(startMark, index); if (index == -1) { return str; } int startIndex = index + markLen; if (startIndex > str.length()) { throw new IllegalArgumentException( "var expression starts at end of string"); } int endIndex = str.indexOf("}", index + markLen); if (endIndex == -1) { throw new IllegalArgumentException( "var expression starts but does not end"); } String key = str.substring(index+markLen, endIndex); Object value = source.get(key); if (value == null) { throw new IllegalArgumentException( "parameter [" + key + "] is not defined."); } String varValue = value.toString(); str = str.substring(0, index) + varValue + str.substring(endIndex+1); index += varValue.length(); } } }
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