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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.search.query.profile;
import com.yahoo.processing.request.Properties;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
/**
* A string which contains one or more elements of the form %{name},
* where these occurrences are to be replaced by a query profile lookup on name.
* <p>
* This objects does the analysis on creation and provides a (reasonably) fast method of
* performing the actual substitution (at lookup time).
* <p>
* This is a value object. Lookups in this are thread safe.
*
* @author bratseth
*/
public class SubstituteString {
private final List<Component> components;
private final String stringValue;
/**
* Returns a new SubstituteString if the given string contains substitutions, null otherwise.
*/
public static SubstituteString create(String value) {
int lastEnd = 0;
int start = value.indexOf("%{");
if (start < 0) return null; // Shortcut
List<Component> components = new ArrayList<>();
while (start >= 0) {
int end = value.indexOf("}", start + 2);
if (end < 0)
throw new IllegalArgumentException("Unterminated value substitution '" + value.substring(start) + "'");
String propertyName = value.substring(start+2,end);
if (propertyName.indexOf("%{") >= 0)
throw new IllegalArgumentException("Unterminated value substitution '" + value.substring(start) + "'");
components.add(new StringComponent(value.substring(lastEnd, start)));
components.add(new PropertyComponent(propertyName));
lastEnd = end+1;
start = value.indexOf("%{", lastEnd);
}
components.add(new StringComponent(value.substring(lastEnd)));
return new SubstituteString(components, value);
}
private SubstituteString(List<Component> components, String stringValue) {
this.components = components;
this.stringValue = stringValue;
}
/**
* Perform the substitution in this, by looking up in the given query profile,
* and returns the resulting string
*/
public String substitute(Map<String, String> context, Properties substitution) {
StringBuilder b = new StringBuilder();
for (Component component : components)
b.append(component.getValue(context,substitution));
return b.toString();
}
@Override
public int hashCode() {
return stringValue.hashCode();
}
@Override
public boolean equals(Object other) {
if (other == this) return true;
if ( ! (other instanceof SubstituteString)) return false;
return this.stringValue.equals(((SubstituteString)other).stringValue);
}
/** Returns this string in original (unsubstituted) form */
@Override
public String toString() {
return stringValue;
}
private abstract static class Component {
protected abstract String getValue(Map<String, String> context, Properties substitution);
}
private final static class StringComponent extends Component {
private final String value;
public StringComponent(String value) {
this.value = value;
}
@Override
public String getValue(Map<String, String> context, Properties substitution) {
return value;
}
@Override
public String toString() {
return value;
}
}
private final static class PropertyComponent extends Component {
private final String propertyName;
public PropertyComponent(String propertyName) {
this.propertyName = propertyName;
}
@Override
public String getValue(Map<String,String> context, Properties substitution) {
Object value = substitution.get(propertyName, context, substitution);
if (value == null) return "";
return String.valueOf(value);
}
@Override
public String toString() {
return "%{" + propertyName + "}";
}
}
}
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