added dot query in woql (#81)

Author: Neelterminusdb

docs/_sidebar.md

@@ -151,6 +151,7 @@
   - [update_quad](api/woql.js?id=update_quad)
   - [value](api/woql.js?id=value)
   - [link](api/woql.js?id=link)
+  - [dot](api/woql.js?id=dot)
 - [WOQLLibrary](api/woqlLibrary.js?id=WOQLLibrary)
   - [branches](api/woqlLibrary.js?id=branches)
   - [commits](api/woqlLibrary.js?id=commits)

docs/api/woql.js.md

@@ -1417,3 +1417,16 @@ Creates a pattern matching rule for a quad [Subject, Predicate, Object, Graph] o
 | object | <code>string</code> | The IRI of a node or a variable, or a literal |
 | [graphRef] | <code>typedef.GraphRef</code> | specify a graph type, default is instance schema|instance |
 
+
+### dot
+#### WOQL.dot(document, field, value) ⇒ <code>WOQLQuery</code>
+Extract the value of a key in a bound document.
+
+**Returns**: <code>WOQLQuery</code> - A WOQLQuery which contains the a dot Statement  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| document | <code>string</code> | Document which is being accessed. |
+| field | <code>string</code> | The field from which the document which is being accessed. |
+| value | <code>string</code> | The value for the document and field. |
+

lib/query/woqlQuery.js

@@ -971,6 +971,15 @@ WOQLQuery.prototype.path = function(Subject, Pattern, Object, Path) {
     return this
 }
 
+WOQLQuery.prototype.dot = function(Document, Field, Value) {
+    if (this.cursor['@type']) this.wrapCursorWithAnd()
+    this.cursor['@type'] = 'Dot'
+    this.cursor['document'] = this.expandValueVariable(Document)
+    this.cursor['field'] =  this.cleanDataValue(Field, 'xsd:string')
+    this.cursor['value'] = this.expandValueVariable(Value)
+    return this
+}
+
 WOQLQuery.prototype.size = function(Graph, Size) {
     //if (Graph && Graph == 'args') 
     //return ['resource', 'size']

lib/woql.js

@@ -1279,5 +1279,15 @@ WOQL.link = function(subject, predicate, object, graphRef) {
     return new WOQLQuery().link(subject, predicate, object, graphRef)
 }
 
+/**
+ * Extract the value of a key in a bound document.
+ * @param {string} document - Document which is being accessed.
+ * @param {string} field - The field from which the document which is being accessed.
+ * @param {string} value - The value for the document and field.
+ * @returns {WOQLQuery} A WOQLQuery which contains the a dot Statement
+ */
+ WOQL.dot = function(document, field, value) {
+    return new WOQLQuery().dot(document, field, value);
+}
 
 module.exports = WOQL