add an alphabet method

Author: 0xCAFEBABE0

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

@@ -335,6 +335,13 @@ public Builder nonSpace() {
             return this.add("(?:\\S)");
         }
 
+        /**
+         * Add alphabet character: [a-zA-Z]
+         * @return this builder
+         */
+        public Builder alphabet() {
+            return this.add("(?:[a-zA-Z])");
+        }
 
         /*
            --- / end of predefined character classes

src/test/java/ru/lanwen/verbalregex/PredefinedCharClassesTest.java

@@ -20,6 +20,7 @@ public class PredefinedCharClassesTest {
     public static final String DIGITS = "0123456789";
     public static final String NON_LETTERS = ";'[]{}|?/";
     public static final String SPACE = " \t\n\f\r";
+    public static final String LETTERS_ONLY_WORD = "q";
 
     @Test
     public void testWordChar() throws Exception {
@@ -97,4 +98,15 @@ public void testWord() throws Exception {
                 regex.getText(LETTERS_NO_DIGITS + DIGITS + NON_LETTERS + SPACE), is(LETTERS_NO_DIGITS + DIGITS));
 
     }
+
+    @Test
+    public void testAlphabet() throws Exception {
+        VerbalExpression regex = regex().alphabet().build();
+
+        assertThat("matches on letters", regex, matchesTo((LETTERS_ONLY_WORD)));
+        assertThat("not matches on digit", regex, not(matchesTo(DIGITS)));
+        assertThat("Extracts wrong chars",
+                regex.getText(LETTERS_ONLY_WORD + DIGITS + NON_LETTERS + SPACE), equalTo(LETTERS_ONLY_WORD));
+
+    }
 }