org.apache.tools.ant.property.ParseProperties 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.tools.ant.property;
import java.text.ParsePosition;
import java.util.Collection;
import org.apache.tools.ant.Project;
/**
* Parse properties using a collection of expanders.
*
* @since Ant 1.8.0
*/
public class ParseProperties implements ParseNextProperty {
private final Project project;
private final GetProperty getProperty;
private final Collection expanders;
/**
* Constructor with a getProperty.
* @param project the current Ant project.
* @param expanders a sequence of expanders
* @param getProperty property resolver.
*/
public ParseProperties(Project project, Collection expanders, GetProperty getProperty) {
this.project = project;
this.expanders = expanders;
this.getProperty = getProperty;
}
/**
* Get the project.
* @return the current Ant project.
*/
public Project getProject() {
return project;
}
/**
* Decode properties from a String representation.
*
*
*
* - This implementation starts parsing the
value
* parameter (unsurprisingly) at the beginning and asks each
* {@link PropertyExpander PropertyExpander} whether there is a
* property reference at that point. PropertyExpanders return
* the name of a property they may find and may advance the parse
* position.
*
* - If the PropertyExpander returns
null the
* method continues with the next PropertyExpander, otherwise it
* tries to look up the property's value using the configured
* {@link GetProperty GetProperty} instance.
*
* - Once all PropertyExpanders have been consulted, the parse
* position is advanced by one character and the process repeated
* until
value is exhausted.
*
*
*
* If the entire contents of value resolves to a
* single property, the looked up property value is returned.
* Otherwise a String is returned that concatenates the
* non-property parts of value and the expanded
* values of the properties that have been found.
*
* @param value The string to be scanned for property references.
* May be null, in which case this
* method returns immediately with no effect.
*
* @return the original string with the properties replaced, or
* null if the original string is null.
*/
public Object parseProperties(String value) {
if (value == null || "".equals(value)) {
return value;
}
final int len = value.length();
ParsePosition pos = new ParsePosition(0);
Object o = parseNextProperty(value, pos);
if (o != null && pos.getIndex() >= len) {
return o;
}
StringBuffer sb = new StringBuffer(len * 2);
if (o == null) {
sb.append(value.charAt(pos.getIndex()));
pos.setIndex(pos.getIndex() + 1);
} else {
sb.append(o);
}
while (pos.getIndex() < len) {
o = parseNextProperty(value, pos);
if (o == null) {
sb.append(value.charAt(pos.getIndex()));
pos.setIndex(pos.getIndex() + 1);
} else {
sb.append(o);
}
}
return sb.toString();
}
/**
* Learn whether a String contains replaceable properties.
*
* Uses the configured {@link PropertyExpander
* PropertyExpanders} and scans through the string. Returns true
* as soon as any expander finds a property.
*
* @param value the String to check.
* @return true if value contains property notation.
*/
public boolean containsProperties(String value) {
if (value == null) {
return false;
}
final int len = value.length();
for (ParsePosition pos = new ParsePosition(0); pos.getIndex() < len;) {
if (parsePropertyName(value, pos) != null) {
return true;
}
pos.setIndex(pos.getIndex() + 1);
}
return false;
}
/**
* Return any property that can be parsed from the specified position
* in the specified String.
*
* Uses the configured {@link PropertyExpander
* PropertyExpanders} and {@link GetProperty GetProperty}
* instance .
*
* @param value String to parse
* @param pos ParsePosition
* @return Object or null if no property is at the current
* location. If a property reference has been found but the
* property doesn't expand to a value, the property's name is
* returned.
*/
public Object parseNextProperty(String value, ParsePosition pos) {
final int start = pos.getIndex();
if (start > value.length()) {
// early exit, can't find any property here, no need to
// consult all the delegates.
return null;
}
String propertyName = parsePropertyName(value, pos);
if (propertyName != null) {
Object result = getProperty(propertyName);
if (result != null) {
return result;
}
if (project != null) {
project.log(
"Property \"" + propertyName
+ "\" has not been set", Project.MSG_VERBOSE);
}
return value.substring(start, pos.getIndex());
}
return null;
}
private String parsePropertyName(String value, ParsePosition pos) {
for (PropertyExpander propertyExpander : expanders) {
String propertyName = propertyExpander.parsePropertyName(value, pos, this);
if (propertyName == null) {
continue;
}
return propertyName;
}
return null;
}
private Object getProperty(String propertyName) {
return getProperty.getProperty(propertyName);
}
}