Issue #53 - Add initial support for lookups via json pointer

lib/jsv.js

@@ -243,6 +243,20 @@ var exports = exports || this,
 			return o.toString();
 		}
 	}
+
+    function traversePointer(obj, pointer) {
+        if (pointer !== "/") {
+            var parr = pointer.split("/").slice(1);
+            for (var part = parr.shift(); part; part = parr.shift()) {
+                if (obj.hasOwnProperty(part)) {
+                    obj = obj[part];
+                } else {
+                    return null;
+                }
+            }
+        }
+        return obj;
+    }
 
 	/**
 	 * The exception that is thrown when a schema fails to be created.
@@ -1055,11 +1069,29 @@ var exports = exports || this,
 	 * Returns the schema registered with the provided URI.
 	 * 
 	 * @param {String} uri The absolute URI of the required schema
+	 * @param {JSONSchema} [parentSchema] The schema of the parent/containing instance, used in case the schema is referenced by JSON pointer.
 	 * @returns {JSONSchema|undefined} The request schema, or <code>undefined</code> if not found
 	 */
 
 	Environment.prototype.findSchema = function (uri) {
-		return this._schemas[formatURI(uri)];
+		var furi = formatURI(uri);
+		var schema = null;
+		if (furi in this._schemas) {
+			schema = this._schemas[furi];
+		} else {
+			var base = furi.substr(0, furi.indexOf("#"));
+			if (formatURI(base) != furi) {
+				var baseSchema = this.findSchema(base);
+				if (baseSchema) {
+					var fragment = furi.substr(base.length);
+					var targetElem = traversePointer(baseSchema.getValue(), fragment);
+					if (targetElem) {
+						schema = this.createSchema(targetElem, null, furi);
+					}
+				}
+			}
+		}
+		return schema;
 	};
 
 	/**
@@ -1494,4 +1526,4 @@ var exports = exports || this,
 
 	require("./environments");  //load default environments
 
-}());
+}());