From 9d64f89c449f7a7c6b0971a4ae2517db10034f6f Mon Sep 17 00:00:00 2001
From: Laxmi Narsimha Rao Oruganti <olnrao@gmail.com>
Date: Mon, 15 Feb 2016 17:10:23 +0530
Subject: [PATCH] RegEx Validation Using Java Patterns (perf)

While using this library we found RhinoHelper takes way too much time for pattern validations using Visual VM CPU Profiling.

Here is an observation:
- JSON Schema: Roughly 30 fields, 10 fields have one or the other validation, 5 of them have patterns (listed below)
- Input Data: An array of 10K messages
- Time Taken:
-- With out pattern annotation: ~6 seconds
-- With Rhino Helper: ~30 seconds
-- With Java Patterns: ~7 seconds

Patterns used:
      "pattern": "^(19[7-9][0-9]|[2-9][0-9][0-9][0-9])-",
      "pattern" : "^[+-][0-1][0-9]:[0-5][0-9]$",
      "pattern": "^(19[7-9][0-9]|[2-9][0-9][0-9][0-9])-",
      "pattern": "[^\\s]{1}",
      "pattern": "[^\\s]{1}",
---
 .../validator/common/PatternValidator.java    | 24 +++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/main/java/com/github/fge/jsonschema/keyword/validator/common/PatternValidator.java b/src/main/java/com/github/fge/jsonschema/keyword/validator/common/PatternValidator.java
index 653428a27..bad68a787 100644
--- a/src/main/java/com/github/fge/jsonschema/keyword/validator/common/PatternValidator.java
+++ b/src/main/java/com/github/fge/jsonschema/keyword/validator/common/PatternValidator.java
@@ -19,6 +19,9 @@
 
 package com.github.fge.jsonschema.keyword.validator.common;
 
+import java.util.HashMap;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.github.fge.jsonschema.core.exceptions.ProcessingException;
 import com.github.fge.jsonschema.core.processing.Processor;
@@ -31,13 +34,15 @@
 /**
  * Keyword validator for {@code pattern}
  *
- * @see RhinoHelper
  */
 public final class PatternValidator
     extends AbstractKeywordValidator
 {
+    private HashMap<String, Pattern> _patterns;
+    
     public PatternValidator(final JsonNode digest)
     {
+        _patterns = new HashMap<String, Pattern>();
         super("pattern");
     }
 
@@ -50,7 +55,11 @@ public void validate(final Processor<FullData, FullData> processor,
         final String regex = data.getSchema().getNode().get(keyword)
             .textValue();
         final String value = data.getInstance().getNode().textValue();
-        if (!RhinoHelper.regMatch(regex, value))
+        
+        Pattern pattern = getPattern(regex);
+        Matcher matches = pattern.matcher(value);
+
+        if (!matches.find())
             report.error(newMsg(data, bundle, "err.common.pattern.noMatch")
                 .putArgument("regex", regex).putArgument("string", value));
     }
@@ -60,4 +69,15 @@ public String toString()
     {
         return keyword;
     }
+
+    private Pattern getPattern(String regex)
+    {
+        // If there is not any existing compiled pattern, create one now!
+        if (!_patterns.containsKey(regex))
+        {
+            _patterns.put(regex, Pattern.compile(regex));
+        }
+
+        return _patterns.get(regex);
+    }
 }