Add named-capturing group (#70)

* Add named-capturing group

* Update coveralls-maven-plugin version

* Add usage example for Builder#capture(String) and getText(String, String)

* Fix local variable name to camelCase

* Use assertThat instead of assertEquals

Author: zawataki

.travis.yml

@@ -12,7 +12,7 @@ before_install:
   - if [ ! -z "$GPG_OWNERTRUST" ]; then echo $GPG_OWNERTRUST | base64 --decode | $GPG_EXECUTABLE --import-ownertrust; fi
 
 after_success:
-  - mvn clean cobertura:cobertura -Dcobertura.report.format=xml org.eluder.coveralls:coveralls-maven-plugin:3.0.1:report
+  - mvn clean cobertura:cobertura -Dcobertura.report.format=xml org.eluder.coveralls:coveralls-maven-plugin:4.3.0:report
 
 notifications:
  email: false

src/main/java/ru/lanwen/verbalregex/VerbalExpression.java

@@ -578,8 +578,30 @@ public Builder oneOf(final String... pValues) {
          * @return this builder
          */
         public Builder capture() {
+            return this.capture(null);
+        }
+
+        /**
+         * Adds named-capture - open brace to current position and closed to suffixes
+         * <p>
+         * <pre>Example:{@code
+         * String text = "test@example.com";
+         * VerbalExpression regex = regex()
+         *         .find("@")
+         *         .capture("domain").anything().build();
+         * regex.getText(text, "domain"); // => "example.com"
+         * }</pre>
+         *
+         * @return this builder
+         * @since 1.6
+         */
+        public Builder capture(final String name) {
             this.suffixes.append(")");
-            return this.add("(");
+
+            if (name == null || name.trim().isEmpty()) {
+                return this.add("(");
+            }
+            return this.add("(?<" + name + ">");
         }
 
         /**
@@ -592,6 +614,16 @@ public Builder capt() {
             return this.capture();
         }
 
+        /**
+         * Shortcut for {@link #capture(String)}
+         *
+         * @return this builder
+         * @since 1.6
+         */
+        public Builder capt(final String name) {
+            return this.capture(name);
+        }
+
         /**
          * Same as {@link #capture()}, but don't save result
          * May be used to set count of duplicated captures, without creating a new saved capture
@@ -716,6 +748,25 @@ public String getText(final String toTest, final int group) {
         return result.toString();
     }
 
+    /**
+     * Extract exact named-group from string
+     * <p>
+     * Example is see to {@link Builder#capture(String)}
+     *
+     * @param toTest - string to extract from
+     * @param group  - group to extract
+     * @return extracted group
+     * @since 1.6
+     */
+    public String getText(final String toTest, final String group) {
+        Matcher m = pattern.matcher(toTest);
+        StringBuilder result = new StringBuilder();
+        while (m.find()) {
+            result.append(m.group(group));
+        }
+        return result.toString();
+    }
+
     /**
      * Extract exact group from string and add it to list
      *