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LANG-935: Possible performance improvement on string escape functions. Thanks to Fabian Lange and Thomas Neidhart. 

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/lang/trunk@1668348 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Benedikt Ritter 2015-03-22 09:52:25 +00:00
parent bf6ee5c56e
commit 7bb99bcb6b
2 changed files with 12 additions and 0 deletions
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1
src/changes/changes.xml
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@ -22,6 +22,7 @@
<body> <body>
<release version="3.4" date="tba" description="tba"> <release version="3.4" date="tba" description="tba">
<action issue="LANG-935" type="update" dev="britter" due-to="Fabian Lange, Thomas Neidhart">Possible performance improvement on string escape functions</action>
<action issue="LANG-948" type="fix" dev="britter" due-to="Andrey Khobnya">Exception while using ExtendedMessageFormat and escaping braces</action> <action issue="LANG-948" type="fix" dev="britter" due-to="Andrey Khobnya">Exception while using ExtendedMessageFormat and escaping braces</action>
<action issue="LANG-1098" type="update" dev="britter" due-to="Mikhail Mazurskiy, Fabian Lange">Avoid String allocation in StrBuilder.append(CharSequence)</action> <action issue="LANG-1098" type="update" dev="britter" due-to="Mikhail Mazurskiy, Fabian Lange">Avoid String allocation in StrBuilder.append(CharSequence)</action>
<action issue="LANG-1098" type="update" dev="britter" due-to="Michał Kordas">Update maven-checkstyle-plugin to 2.14</action> <action issue="LANG-1098" type="update" dev="britter" due-to="Michał Kordas">Update maven-checkstyle-plugin to 2.14</action>

11
src/main/java/org/apache/commons/lang3/text/translate/LookupTranslator.java
View File

@ -19,6 +19,7 @@ package org.apache.commons.lang3.text.translate;
import java.io.IOException; import java.io.IOException;
import java.io.Writer; import java.io.Writer;
import java.util.HashMap; import java.util.HashMap;
import java.util.HashSet;
/** /**
* Translates a value using a lookup table. * Translates a value using a lookup table.
@ -29,6 +30,7 @@ import java.util.HashMap;
public class LookupTranslator extends CharSequenceTranslator { public class LookupTranslator extends CharSequenceTranslator {
private final HashMap<String, CharSequence> lookupMap; private final HashMap<String, CharSequence> lookupMap;
private final HashSet<Character> prefixSet;
private final int shortest; private final int shortest;
private final int longest; private final int longest;
@ -44,11 +46,13 @@ public class LookupTranslator extends CharSequenceTranslator {
*/ */
public LookupTranslator(final CharSequence[]... lookup) { public LookupTranslator(final CharSequence[]... lookup) {
lookupMap = new HashMap<String, CharSequence>(); lookupMap = new HashMap<String, CharSequence>();
prefixSet = new HashSet<Character>();
int _shortest = Integer.MAX_VALUE; int _shortest = Integer.MAX_VALUE;
int _longest = 0; int _longest = 0;
if (lookup != null) { if (lookup != null) {
for (final CharSequence[] seq : lookup) { for (final CharSequence[] seq : lookup) {
this.lookupMap.put(seq[0].toString(), seq[1]); this.lookupMap.put(seq[0].toString(), seq[1]);
this.prefixSet.add(seq[0].charAt(0));
final int sz = seq[0].length(); final int sz = seq[0].length();
if (sz < _shortest) { if (sz < _shortest) {
_shortest = sz; _shortest = sz;
@ -71,10 +75,17 @@ public class LookupTranslator extends CharSequenceTranslator {
if (index + longest > input.length()) { if (index + longest > input.length()) {
max = input.length() - index; max = input.length() - index;
} }
if (!prefixSet.contains(input.charAt(index))) {
// no translation exists for the input at position index
return 0;
}
// descend so as to get a greedy algorithm // descend so as to get a greedy algorithm
for (int i = max; i >= shortest; i--) { for (int i = max; i >= shortest; i--) {
final CharSequence subSeq = input.subSequence(index, index + i); final CharSequence subSeq = input.subSequence(index, index + i);
final CharSequence result = lookupMap.get(subSeq.toString()); final CharSequence result = lookupMap.get(subSeq.toString());
if (result != null) { if (result != null) {
out.write(result.toString()); out.write(result.toString());
return i; return i;