added paging functions

Author: kevinchekovfeeney

lib/woql.js

@@ -36,6 +36,8 @@ function WOQLQuery(query, results){
 	this.results = (results ? results : false);	
 	this.chain_ended = false;
 	this.contains_update = false;
+	//operators which preserve global paging
+	this.paging_transitive_properties = ['select', 'from', 'start', 'when', 'opt', 'limit'];
 	return this;
 }
 
@@ -61,6 +63,123 @@ WOQLQuery.prototype.last = function(){
 	return this;
 }
 
+WOQLQuery.prototype.isPaged = function(q){
+	q = (q ? q : this.query);
+	for (const prop of Object.keys(q)) {
+		if(prop == "limit") return true;
+		else if(paging_transitive_properties.indexOf(prop) !== -1){
+			return this.isPaged(q[prop][q[prop].length-1])
+		}
+	}
+}
+
+WOQLQuery.prototype.getPagingProperty = function(pageprop, q){
+	q = (q ? q : this.query);	
+	for (const prop of Object.keys(q)) {
+		if(prop == pageprop) return q[prop][0];
+		else if(paging_transitive_properties.indexOf(prop) !== -1){
+			var val = this.getPagingProperty(pageprop, q[prop][q[prop].length-1]);
+			if(typeof val != "undefined"){
+				return val;
+			}
+		}
+	}
+}
+
+WOQLQuery.prototype.setPagingProperty = function(pageprop, val, q){
+	q = (q ? q : this.query);	
+	for (const prop of Object.keys(q)) {
+		if(prop == pageprop) {
+			q[prop][0] = val;
+		}
+		else if(paging_transitive_properties.indexOf(prop) !== -1){
+			this.setPagingProperty(pageprop, val, q[prop][q[prop].length-1]);
+		}
+	}
+	return this;
+}
+
+WOQLQuery.prototype.addStart = function(val, q){
+	q = (q ? q : this.query);	
+	for (const prop of Object.keys(q)) {
+		if(prop == limit) {
+			var nval = { "start": [0, q[prop][1]]}
+			q[prop][1] = nval;
+		}
+		else if(paging_transitive_properties.indexOf(prop) !== -1){
+			this.addStart(val, q[prop][q[prop].length-1]);
+		}
+	}
+	return this;
+}
+
+
+
+WOQLQuery.prototype.getLimit = function(){
+	return this.getPagingProperty("limit");
+}
+
+WOQLQuery.prototype.getPage = function(){
+	if(this.isPaged()){
+		var psize = this.getLimit();
+		if(this.hasStart()){
+			var s = this.getStart();
+			return ((s % psize) + 1);
+		}
+		else return 1;
+	}
+	else return false;
+}
+
+WOQLQuery.prototype.setPage = function(pagenum){
+	var pstart = (this.getLimit() * (pagenum - 1));
+	if(this.hasStart()){
+		this.setStart(pstart);
+	}
+	else {
+		this.addStart(pstart);
+	}
+	return this;
+}
+
+
+WOQLQuery.prototype.hasStart = function(){
+	return (typeof this.getPagingProperty("start") != "undefined");
+}
+
+WOQLQuery.prototype.getStart = function(){
+	return this.getPagingProperty("start");
+}
+
+WOQLQuery.prototype.nextPage = function(){
+	return this.setPage(this.getPage() + 1);
+}
+	
+WOQLQuery.prototype.firstPage = function(){
+	return this.setPage(1);
+}
+
+WOQLQuery.prototype.previousPage = function(){
+	const npage = this.getPage() - 1;
+	if(npage > 0) this.setPage(npage);
+	return this;
+}
+
+WOQLQuery.prototype.setStart = function(start){
+	return this.setPagingProperty("start", start); 
+}
+
+WOQLQuery.prototype.setPageSize = function(size){
+	this.setPagingProperty("limit", size); 
+	if(this.hasStart()){
+		this.setStart(0);
+	}
+	else {
+		this.addStart(0);
+	}
+	return this;
+}
+
 /*
  * Called to indicate an update that is the last chainable element in a query
  */
@@ -431,6 +550,7 @@ WOQLResult.prototype.getBindings = function(){
 	return this.bindings;
 }
 
+
 function WOQLViewer(client, config){
 	this.client = client;
 	this.config = config;