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package com.fasterxml.jackson.databind.util;
/**
* Helper class used to encapsulate details of name mangling, transforming
* of names using different strategies (prefixes, suffixes).
* Default implementation is "no-operation" (aka identity transformation).
*/
public abstract class NameTransformer
{
/**
* Singleton "no-operation" transformer which simply returns given
* name as is. Used commonly as placeholder or marker.
*/
public final static NameTransformer NOP = new NopTransformer();
protected final static class NopTransformer
extends NameTransformer
implements java.io.Serializable
{
private static final long serialVersionUID = 1L;
@Override
public String transform(String name) {
return name;
}
@Override
public String reverse(String transformed) {
// identity transformation is always reversible:
return transformed;
}
}
protected NameTransformer() { }
/**
* Factory method for constructing a simple transformer based on
* prefix and/or suffix.
*/
public static NameTransformer simpleTransformer(final String prefix, final String suffix)
{
boolean hasPrefix = (prefix != null) && (prefix.length() > 0);
boolean hasSuffix = (suffix != null) && (suffix.length() > 0);
if (hasPrefix) {
if (hasSuffix) {
return new NameTransformer() {
@Override
public String transform(String name) { return prefix + name + suffix; }
@Override
public String reverse(String transformed) {
if (transformed.startsWith(prefix)) {
String str = transformed.substring(prefix.length());
if (str.endsWith(suffix)) {
return str.substring(0, str.length() - suffix.length());
}
}
return null;
}
@Override
public String toString() { return "[PreAndSuffixTransformer('"+prefix+"','"+suffix+"')]"; }
};
}
return new NameTransformer() {
@Override
public String transform(String name) { return prefix + name; }
@Override
public String reverse(String transformed) {
if (transformed.startsWith(prefix)) {
return transformed.substring(prefix.length());
}
return null;
}
@Override
public String toString() { return "[PrefixTransformer('"+prefix+"')]"; }
};
}
if (hasSuffix) {
return new NameTransformer() {
@Override
public String transform(String name) { return name + suffix; }
@Override
public String reverse(String transformed) {
if (transformed.endsWith(suffix)) {
return transformed.substring(0, transformed.length() - suffix.length());
}
return null;
}
@Override
public String toString() { return "[SuffixTransformer('"+suffix+"')]"; }
};
}
return NOP;
}
/**
* Method that constructs transformer that applies given transformers
* as a sequence; essentially combines separate transform operations
* into one logical transformation.
*/
public static NameTransformer chainedTransformer(NameTransformer t1, NameTransformer t2) {
return new Chained(t1, t2);
}
/**
* Method called when (forward) transformation is needed.
*/
public abstract String transform(String name);
/**
* Method called when reversal of transformation is needed; should return
* null if this is not possible, that is, given name cannot have been
* result of calling {@link #transform} of this object.
*/
public abstract String reverse(String transformed);
public static class Chained extends NameTransformer
implements java.io.Serializable
{
private static final long serialVersionUID = 1L;
protected final NameTransformer _t1, _t2;
public Chained(NameTransformer t1, NameTransformer t2) {
_t1 = t1;
_t2 = t2;
}
@Override
public String transform(String name) {
return _t1.transform(_t2.transform(name));
}
@Override
public String reverse(String transformed) {
transformed = _t1.reverse(transformed);
if (transformed != null) {
transformed = _t2.reverse(transformed);
}
return transformed;
}
@Override
public String toString() { return "[ChainedTransformer("+_t1+", "+_t2+")]"; }
}
}
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