Update CucumberExpression.java

Refactored `escapeRegex` with ~7 times performance improvement.

Author: jkronegg

java/src/main/java/io/cucumber/cucumberexpressions/CucumberExpression.java

@@ -24,8 +24,27 @@
 
 @API(status = API.Status.STABLE)
 public final class CucumberExpression implements Expression {
-    private static final Pattern ESCAPE_PATTERN = Pattern.compile("[\\\\^\\[({$.|?*+})\\]]");
-
+    /**
+     * List of characters to be escaped.
+     * The last char is '}' with index 125, so we need only 126 characters.
+     */
+    private static final boolean[] CHAR_TO_ESCAPE = new boolean[126];
+    static {
+        CHAR_TO_ESCAPE['^'] = true;
+        CHAR_TO_ESCAPE['$'] = true;
+        CHAR_TO_ESCAPE['['] = true;
+        CHAR_TO_ESCAPE[']'] = true;
+        CHAR_TO_ESCAPE['('] = true;
+        CHAR_TO_ESCAPE[')'] = true;
+        CHAR_TO_ESCAPE['{'] = true;
+        CHAR_TO_ESCAPE['}'] = true;
+        CHAR_TO_ESCAPE['.'] = true;
+        CHAR_TO_ESCAPE['|'] = true;
+        CHAR_TO_ESCAPE['?'] = true;
+        CHAR_TO_ESCAPE['*'] = true;
+        CHAR_TO_ESCAPE['+'] = true;
+        CHAR_TO_ESCAPE['\\'] = true;
+    }
     private final List<ParameterType<?>> parameterTypes = new ArrayList<>();
     private final String source;
     private final TreeRegexp treeRegexp;
@@ -62,7 +81,17 @@ private String rewriteToRegex(Node node) {
     }
 
     private static String escapeRegex(String text) {
-        return ESCAPE_PATTERN.matcher(text).replaceAll("\\\\$0");
+        int length = text.length();
+        StringBuilder sb = new StringBuilder(length * 2); // prevent resizes
+        int maxChar = CHAR_TO_ESCAPE.length;
+        for (int i = 0; i < length; i++) {
+            char currentChar = text.charAt(i);
+            if (currentChar < maxChar && CHAR_TO_ESCAPE[currentChar]) {
+                sb.append('\\');
+            }
+            sb.append(currentChar);
+        }
+        return sb.toString();
     }
 
     private String rewriteOptional(Node node) {