Format ready for 2.1
git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/lang/trunk@137894 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Stephen Colebourne
parent
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package org.apache.commons.lang;
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import java.util.HashMap;
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import java.util.Iterator;
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import java.util.Map;
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/**
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* Performs basic variable interpolation on a String for variables within
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* a Map. Variables of the form, ${var}, are supported.
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* <p>Performs basic variable interpolation on a String for variables within a Map.
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* Variables of the form, ${var}, are supported.</p>
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*
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* @author Ken Fitzpatrick
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* @author Henri Yandell
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* @since 2.1
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* @version $Id: Interpolation.java,v 1.2 2004/08/15 23:18:43 scolebourne Exp $
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*/
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public class Interpolation {
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// QUERY: Anyway to escape the ${..} variable so it is not interpolated?
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// TODO: Consider making these configurable?
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/** The marker used to start a variable. */
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private static final String SYMBOLIC_VALUE_MARKER_START = "${";
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/** The marker used to end a variable. */
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private static final String SYMBOLIC_VALUE_MARKER_END = "}";
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/**
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* <p>
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* Returns a String that is the result of having performed
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* variable interpolation on <code>templateString</code>,
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* using the value set found in <code>values</code>.
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* </p>
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* <p>
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* The solution is compatible with all JDK versions
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* where Jakarta/Commons/Lang also is supported.
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* </p>
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* <p>
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* The expected format of <code>templateString</code> is:
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*<code><pre>
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* <p>Interpolates a String to replace variables of the form <code>${...}</code>.</p>
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*
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* <p>This method is useful for enabling simple strings to be modified based
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* on a map of data. A typical use case might be to add data from configuration
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* to an error message. This method, and this class, does not seek to replace
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* full interpolation mechanisms, for example Velocity.</p>
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*
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* <p>The expected format of <code>templateString</code> is:
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* <code><pre>
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* The ${animal} jumped over the ${target}.
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*</pre></code>
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* such that the key/value pairs found in <code>values</code>
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* are substituted into the string at the <code>${key-name}</code> markers.
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* In the above example, <code>valuesMap</code> could have been populated as:
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*<code><pre>
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* </pre></code>
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* such that the key/value pairs found in <code>values</code>
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* are substituted into the string at the <code>${key-name}</code> markers.
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* In the above example, <code>valuesMap</code> could have been populated as:
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* <code><pre>
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* Map valuesMap = HashMap();
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* valuesMap.put( "animal", "quick brown fox" );
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* valuesMap.put( "target", "lazy dog" );
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* String resolvedString = StringUtils.interpolate( templateString, valuesMap );
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*</pre></code>
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* yielding:
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*<code><pre>
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* </pre></code>
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* yielding:
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* <code><pre>
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* The quick brown fox jumped over the lazy dog.
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*</pre></code>
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* </p>
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* <p>
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* The same <code>templateString</code> from the above example could be reused as:
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*<code><pre>
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* </pre></code></p>
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*
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* <p>The same <code>templateString</code> from the above example could be reused as:
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* <code><pre>
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* Map valuesMap = HashMap();
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* valuesMap.put( "animal", "cow" );
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* valuesMap.put( "target", "moon" );
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* String resolvedString = StringUtils.interpolate( templateString, valuesMap );
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*</pre></code>
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* yielding:
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*<code><pre>
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* </pre></code>
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* yielding:
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* <code><pre>
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* The cow jumped over the moon.
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*</pre></code>
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* </p>
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* <p>
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* The value of <code>templateString</code> is returned in an unaltered if <code>templateString</code>
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* is null, empty, or contains no marked variables that can be resolved by the key/value pairs found in
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* <code>valuesMap</code>, or if <code>valuesMap</code> is null, empty or has no key/value pairs that can be
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* applied to the marked variables within <code>templateString</code>.
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* </p>
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* @param templateString String containing any mixture of variable and non-variable
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* </pre></code></p>
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*
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* <p>The value of <code>templateString</code> is returned in an unaltered
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* if <code>templateString</code> is null, empty, or contains no marked variables
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* that can be resolved by the key/value pairs found in <code>valuesMap</code>,
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* or if <code>valuesMap</code> is null, empty or has no key/value pairs that can be
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* applied to the marked variables within <code>templateString</code>.</p>
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*
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* <p>If a <code>valuesMap</code> value is null, it will be treated as "".</p>
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*
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* @param templateString String containing any mixture of variable and non-variable
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* content, to be used as a template for the value substitution process
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* @param valuesMap Map containing the key/value pairs to be used to resolve
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* @param valuesMap Map containing the key/value pairs to be used to resolve
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* the values of the marked variables found within <code>templateString</code>
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* @return String
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* @return the interpolated String
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*/
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public static String interpolate( String templateString, Map valuesMap ) {
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public static String interpolate(String templateString, Map valuesMap) {
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// pre-conditions
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if ( valuesMap == null )
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if (templateString == null || valuesMap == null ||
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templateString.length() == 0 || valuesMap.isEmpty()) {
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return templateString;
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if ( templateString == null )
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return templateString;
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if ( templateString.length() < 1 )
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return templateString;
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if ( valuesMap.isEmpty() )
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return templateString;
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}
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// default the returned String to the templateString
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String returnString = templateString;
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String nextKey = null;
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Object substitutionBean = null;
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String substitutionValue = null;
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String nextValueToBeSubstituted = null;
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// get a list of substitution valuesMap
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Iterator keys = valuesMap.keySet().iterator();
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while( keys.hasNext() ) {
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nextKey = ( String ) keys.next();
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substitutionValue = StringUtils.defaultString( ( String ) valuesMap.get( nextKey ) );
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while (keys.hasNext()) {
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nextKey = (String) keys.next();
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substitutionValue = StringUtils.defaultString((String) valuesMap.get(nextKey));
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nextValueToBeSubstituted = SYMBOLIC_VALUE_MARKER_START + nextKey + SYMBOLIC_VALUE_MARKER_END;
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returnString = StringUtils.replace( returnString, nextValueToBeSubstituted, substitutionValue );
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returnString = StringUtils.replace(returnString, nextValueToBeSubstituted, substitutionValue);
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}
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return returnString;
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}
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/**
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* <p>
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* Returns a String that is the result of having performed variable interpolation on
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* <code>templateString</code>, using the value set found in <code>values</code>,
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* repeatedly until there are no changes.
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* </p>
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* <p>
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* The expected format of <code>templateString</code> is:
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*<code><pre>
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* <p>Interpolates a String to replace variables of the form <code>${...}</code>
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* where the replace strings may also contain variables to interpolate.</p>
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*
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* <p>This method is useful for enabling simple strings to be modified based
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* on a map of data. A typical use case might be to add data from configuration
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* to an error message. This method, and this class, does not seek to replace
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* full interpolation mechanisms, for example Velocity.</p>
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*
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* <p>This method calls {@link #interpolate(String, Map)} repeatedly until the
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* returned string does not change. This has the effect of allowing the replace
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* strings in <code>valuesMap</code> to contain variables that should also be
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* interpolated.</p>
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*
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* <p>The expected format of <code>templateString</code> is:
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* <code><pre>
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* The ${animal} jumped over the ${target}.
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*</pre></code>
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* such that the key/value pairs found in <code>values</code> are substituted into the string at the
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* <code>${key-name}</code> markers. In the above example, <code>valuesMap</code>
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* could have been populated as:
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*<code><pre>
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* </pre></code>
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* such that the key/value pairs found in <code>values</code> are substituted into the string at the
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* <code>${key-name}</code> markers. In the above example, <code>valuesMap</code>
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* could have been populated as:
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* <code><pre>
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* Map valuesMap = HashMap();
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* valuesMap.put( "animal", "${critter}" );
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* valuesMap.put( "target", "${pet}" );
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@ -130,52 +129,40 @@ public class Interpolation {
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* valuesMap.put( "critterColor", "brown" );
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* valuesMap.put( "critterType", "fox" );
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* String resolvedString = StringUtils.interpolate( templateString, valuesMap, true );
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*</pre></code>
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* yielding:
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*<code><pre>
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* </pre></code>
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* yielding:
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* <code><pre>
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* The quick brown fox jumped over the lazy dog.
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*</pre></code>
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* </p>
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* yielding:
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*<code><pre>
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* The cow jumped over the moon.
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*</pre></code>
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* </p>
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* <p>
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* The value of <code>templateString</code> is returned in an unaltered form if
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* <code>templateString</code> is null, empty, or
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* contains no marked variables that can be resolved by the key/value pairs found in
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* <code>valuesMap</code>, or if <code>valuesMap</code> is null, empty or has no key/value
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* pairs that can be applied to the marked variables within <code>templateString</code>.
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* </p>
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* @param templateString String containing any mixture of variable and non-variable
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* </pre></code></p>
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*
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* <p>The value of <code>templateString</code> is returned in an unaltered
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* if <code>templateString</code> is null, empty, or contains no marked variables
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* that can be resolved by the key/value pairs found in <code>valuesMap</code>,
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* or if <code>valuesMap</code> is null, empty or has no key/value pairs that can be
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* applied to the marked variables within <code>templateString</code>.</p>
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*
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* <p>If a <code>valuesMap</code> value is null, it will be treated as "".</p>
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*
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* @param templateString String containing any mixture of variable and non-variable
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* content, to be used as a template for the value substitution process
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* @param valuesMap Map containing the key/value pairs to be used to resolve
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* @param valuesMap Map containing the key/value pairs to be used to resolve
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* the values of the marked variables found within <code>templateString</code>
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* @return String
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* @return the interpolated String
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*/
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public static String interpolateRepeatedly(
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String templateString,
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Map valuesMap)
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{
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public static String interpolateRepeatedly(String templateString, Map valuesMap) {
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// pre-conditions
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if ( valuesMap == null )
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if (templateString == null || valuesMap == null ||
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templateString.length() == 0 || valuesMap.isEmpty()) {
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return templateString;
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if ( templateString == null )
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return templateString;
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if ( templateString.length() < 1 )
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return templateString;
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if ( valuesMap.isEmpty() )
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return templateString;
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}
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String currentResult = templateString;
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String previousResult = null;
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while( ! StringUtils.equals( currentResult, previousResult ) )
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{
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while (!StringUtils.equals(currentResult, previousResult)) {
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previousResult = currentResult;
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currentResult = Interpolation.interpolate( previousResult, valuesMap );
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currentResult = Interpolation.interpolate(previousResult, valuesMap);
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}
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return currentResult;
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}
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