Make Path parameter optional (#80)

Fixes #74

Author: Neelterminusdb

docs/api/woql.js.md

@@ -1029,7 +1029,7 @@ when(true()).triple("a", "b", "c")
 ```
 
 ### path
-#### WOQL.path(subject, pattern, object, resultVarName) ⇒ <code>WOQLQuery</code>
+#### WOQL.path(subject, pattern, object, [resultVarName]) ⇒ <code>WOQLQuery</code>
 Performs a path regular expression match on the graph
 
 **Returns**: <code>WOQLQuery</code> - - A WOQLQuery which contains the path regular expression matching expression  
@@ -1039,7 +1039,7 @@ Performs a path regular expression match on the graph
 | subject | <code>string</code> | An IRI or variable that refers to an IRI representing the subject, i.e. the starting point of the path |
 | pattern | <code>string</code> | (string) - A path regular expression describing a pattern through multiple edges of the graph Path regular expressions consist of a sequence of predicates and / or a set of alternatives, with quantification operators The characters that are interpreted specially are the following: | representing alternative choices , - representing a sequence of predcitates + - Representing a quantification of 1 or more of the preceding pattern in a sequence {min, max} - Representing at least min examples and at most max examples of the preceding pattern - Representing any predicate () - Parentheses, interpreted in the normal way to group clauses |
 | object | <code>string</code> | An IRI or variable that refers to an IRI representing the object, i.e. ending point of the path |
-| resultVarName | <code>string</code> | A variable in which the actual paths traversed will be stored |
+| [resultVarName] | <code>string</code> | A variable in which the actual paths traversed will be stored |
 
 **Example**  
 ```js

lib/query/woqlQuery.js

@@ -939,7 +939,9 @@ WOQLQuery.prototype.path = function(Subject, Pattern, Object, Path) {
     if (typeof Pattern == 'string') Pattern = this.compilePathPattern(Pattern)
     this.cursor['pattern'] = Pattern
     this.cursor['object'] = this.cleanObject(Object)
-    this.cursor['path'] = this.varj(Path)
+    if(typeof Path !== 'undefined') {
+        this.cursor['path'] = this.varj(Path)
+    }
     return this
 }
 

lib/woql.js

@@ -925,7 +925,7 @@ WOQL.true = function() {
  * - Representing any predicate
  * () - Parentheses, interpreted in the normal way to group clauses
  * @param {string} object - An IRI or variable that refers to an IRI representing the object, i.e. ending point of the path
- * @param {string} resultVarName - A variable in which the actual paths traversed will be stored
+ * @param {string} [resultVarName] - A variable in which the actual paths traversed will be stored
  * @returns {WOQLQuery} - A WOQLQuery which contains the path regular expression matching expression
  * @example
  * let [person, grand_uncle, lineage] = vars("person", "grand uncle", "lineage")