VFormat => PatternFormatter with added interface

* src/validate/ValidatorFormatter.js: Interface added.
* src/validate/formatter/PatternFormatter.js: Renamed from ../VFormat.js.
* test/validate/formatter/PatternFormatterTest.js: Renamed from
  ../VFormatTest.js.

src/validate/ValidatorFormatter.js

@@ -0,0 +1,57 @@
+/**
+ * Validator-formatter
+ *
+ *  Copyright (C) 2016 LoVullo Associates, Inc.
+ *
+ *  This file is part of liza.
+ *
+ *  liza is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+var Interface = require( 'easejs' ).Interface;
+
+
+module.exports = Interface( 'ValidatorFormatter',
+{
+    /**
+     * Format the given data or fail if no match is found
+     *
+     * If the given data matches a pattern, it will be formatted with
+     * respect to the first matched pattern.  Otherwise, an error will
+     * be thrown indicating a validation failure.
+     *
+     * @param {string} data data to parse
+     *
+     * @return {string} formatted string, if a match is found
+     */
+    'public parse': [ 'data' ],
+
+
+    /**
+     * Retrieve data that may require formatting for display
+     *
+     * Return formatting is optional. No formatting will be done if no pattern
+     * was given when the instance was constructed.
+     *
+     * To ensure consistency and correctness, *any data returned by this method
+     * must be reversible* --- that is, parse( retrieve( data ) ) should not
+     * throw an exception.
+     *
+     * @param {string} data data to format for display
+     *
+     * @return {string} data formatted for display
+     */
+    'public retrieve': [ 'data' ]
+} );

src/validate/formatter/PatternFormatter.js

@@ -1,5 +1,5 @@
 /**
- * Validator-formatter
+ * Pattern-based validator-formatter
  *
  *  Copyright (C) 2016 LoVullo Associates, Inc.
  *
@@ -20,13 +20,17 @@
  */
 
 
-var Class = require( 'easejs' ).Class;
+var Class              = require( 'easejs' ).Class,
+    ValidatorFormatter = require( '../ValidatorFormatter' );
 
 
 /**
- * Data validation and formatting
+ * Data validation and formatting based on patterns and their
+ * replacements
  */
-module.exports = Class( 'VFormat',
+module.exports = Class( 'VFormat' )
+    .implement( ValidatorFormatter )
+    .extend(
 {
     /**
      * Pattern definition

test/validate/formatter/PatternFormatterTest.js

@@ -1,5 +1,5 @@
 /**
- * Test validator-formatter
+ * Test pattern-based validator-formatter
  *
  *  Copyright (C) 2016 LoVullo Associates, Inc.
  *
@@ -19,8 +19,10 @@
  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-var liza   = require( '../../' ),
-    Sut    = liza.validate.VFormat,
+var liza   = require( '../../../' ),
+    Sut    = liza.validate.formatter.PatternFormatter,
+    VFmt   = liza.validate.ValidatorFormatter,
+    Class  = require( 'easejs' ).Class,
     expect = require( 'chai' ).expect,
     assert = require( 'assert' ),
     dfn    = [
@@ -30,8 +32,15 @@ var liza   = require( '../../' ),
     ];
 
 
-describe( 'VFormat', function()
+describe( 'PatternFormatter', function()
 {
+    it( 'is a ValidatorFormatter', function()
+    {
+        expect( Class.isA( VFmt, createSut( [] ) ) )
+            .to.be.true;
+    } );
+
+
     describe( '#parse', function()
     {
         it( 'formats string according to given definition', function()