org.apache.solr.handler.dataimport.TemplateString Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.solr.handler.dataimport;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
*
* Provides functionality for replacing variables in a templatized string. It
* can also be used to get the place-holders (variables) in a templatized
* string.
*
*
* This API is experimental and may change in the future.
*
* @version $Id: TemplateString.java 826732 2009-10-19 17:47:38Z shalin $
* @since solr 1.3
*/
public class TemplateString {
private List variables = new ArrayList();
private List pcs = new ArrayList();
private Map cache;
public TemplateString() {
cache = new ConcurrentHashMap();
}
private TemplateString(String s) {
Matcher m = WORD_PATTERN.matcher(s);
int idx = 0;
while (m.find()) {
String aparam = s.substring(m.start() + 2, m.end() - 1);
variables.add(aparam);
pcs.add(s.substring(idx, m.start()));
idx = m.end();
}
pcs.add(s.substring(idx));
}
/**
* Returns a string with all variables replaced by the known values. An
* unknown variable is replaced by an empty string.
*
* @param string the String to be resolved
* @param resolver the VariableResolver instance to be used for evaluation
* @return the string with all variables replaced
*/
public String replaceTokens(String string, VariableResolver resolver) {
if (string == null)
return null;
TemplateString ts = cache.get(string);
if (ts == null) {
ts = new TemplateString(string);
cache.put(string, ts);
}
return ts.fillTokens(resolver);
}
private String fillTokens(VariableResolver resolver) {
String[] s = new String[variables.size()];
for (int i = 0; i < variables.size(); i++) {
Object val = resolver.resolve(variables.get(i));
s[i] = val == null ? "" : getObjectAsString(val);
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < pcs.size(); i++) {
sb.append(pcs.get(i));
if (i < s.length) {
sb.append(s[i]);
}
}
return sb.toString();
}
private String getObjectAsString(Object val) {
if (val instanceof Date) {
Date d = (Date) val;
return DataImporter.DATE_TIME_FORMAT.get().format(d);
}
return val.toString();
}
/**
* Returns the variables in the given string.
*
* @param s the templatized string
* @return the list of variables (strings) in the given templatized string.
*/
public static List getVariables(String s) {
return new TemplateString(s).variables;
}
static final Pattern WORD_PATTERN = Pattern.compile("(\\$\\{.*?\\})");
}