add support for named var like :var1 in sql stmt

Author: akq

lib/query.js

@@ -152,9 +152,35 @@ Query.prototype.submit = function (connection) {
   if (this.text && previous && this.text !== previous) {
     return new Error(`Prepared statements must be unique - '${this.name}' was used for a different statement`)
   }
-  if (this.values && !Array.isArray(this.values)) {
-    return new Error('Query values must be an array')
-  }
+//   if (this.values && !Array.isArray(this.values)) {
+//     return new Error('Query values must be an array')
+//   }
+  if (this.values && !(Array.isArray(this.values)||typeof this.values == 'object') ){
+//     const err = new Error('Query values must be an array or object')
+//     connection.emit('error', err)
+//     connection.emit('readyForQuery')
+//     return
+      return new Error('Query values must be an array or object');    
+  }
+  if(!Array.isArray(this.values)){
+    var sql = this.text
+      , data = this.values
+      , values = []
+      ;
+    this.text = sql.replace(/(:)?:(\w+)/g, function($0, $1,  key) {
+      // lookbehind is not supported by node js 6.11.
+      // this.text = sql.replace(/(?<!:):{1}([a-zA-Z][\w]*)/g, function(_, key) {
+      if($1) return $0;        
+      if (key in data) {
+        values.push(data[key])
+        return '$' + values.length
+      } else {
+        throw new Error('Missing value for statement.\n' + key + ' not provided for statement:\n' + sql + '\nthis was provided:\n' + JSON.stringify(data))
+      }
+    });
+    this.values = values;
+  }
+  
   if (this.requiresPreparation()) {
     this.prepare(connection)
   } else {