Started implementing new query conversion

aql/convertQuery2.go

+/*
+This program has been developed by students from the bachelor Computer Science at Utrecht University within the Software Project course.
+© Copyright Utrecht University (Department of Information and Computing Sciences)
+*/
+
+package aql
+
+import (
+	"errors"
+	"fmt"
+
+	"git.science.uu.nl/graphpolaris/query-conversion/entity"
+)
+
+// Version 1.13
+
+/*
+ConvertQuery converts an IncomingQueryJSON object into AQL
+	JSONQuery: *entity.IncomingQueryJSON, the query to be converted to AQL
+	Returns: *string, the AQL query and a possible error
+*/
+func (s *Service) ConvertQuery(JSONQuery *entity.IncomingQueryJSON) (*string, error) {
+
+	// Check to make sure all indexes exist
+	// The largest possible id for an entity
+	largestEntityID := len(JSONQuery.Entities) - 1
+	// The largest possible id for a relation
+	largestRelationID := len(JSONQuery.Relations) - 1
+
+	// Make sure no entity should be returned that is outside the range of that list
+	for _, e := range JSONQuery.Return.Entities {
+		// If this entity references an entity that is outside the range
+		if e > largestEntityID || e < 0 {
+			return nil, errors.New("non-existing entity referenced in return")
+		}
+	}
+
+	// Make sure that no relation mentions a non-existing entity
+	for _, r := range JSONQuery.Relations {
+		if r.EntityFrom > largestEntityID || r.EntityTo > largestEntityID {
+			return nil, errors.New("non-exisiting entity referenced in relation")
+		}
+	}
+
+	// Make sure no non-existing relation is tried to be returned
+	for _, r := range JSONQuery.Return.Relations {
+		if r > largestRelationID || r < 0 {
+			return nil, errors.New("non-existing relation referenced in return")
+		}
+	}
+	result := createQuery(JSONQuery)
+	return result, nil
+}
+
+/*
+createQuery generates a query based on the json file provided
+	JSONQuery: *entity.IncomingQueryJSON, this is a parsedJSON struct holding all the data needed to form a query,
+	Return: *string, a string containing the corresponding AQL query and an error
+*/
+func createQuery(JSONQuery *entity.IncomingQueryJSON) *string {
+	query := ""
+	for list := range listoflists {
+		for index := range listoflists[list] {
+			element := listoflists[list][index]
+			switch element.typename {
+			case "entity":
+				entity := JSONQuery.Entities[element.pointer]
+				query += entityToQuery(entity)
+			case "relation":
+				relation := JSONQuery.Relations[element.pointer]
+				query += relationToQuery(relation)
+			case "function":
+				function := JSONQuery.GroupBys[element.pointer]
+				query += functionToQuery(function)
+			case "filter":
+				filter := JSONQuery.Filters[element.pointer]
+				query += filterToQuery(filter)
+			}
+		}
+	}
+}
+
+func entityToQuery(element entity.QueryEntityStruct) string {
+	thisname := fmt.Sprintf("e%v", element.ID)
+	ret := createLetFor(thisname, element.Name)
+	return ret
+}
+
+func relationToQuery(element entity.QueryRelationStruct) string {
+	thisname := fmt.Sprintf("e%v", element.ID)
+	ret := createLetFor(thisname, element.Name)
+	return ret
+}
+
+func functionToQuery(element entity.QueryGroupByStruct) string {
+	thisname := fmt.Sprintf("e%v", element.ID)
+	ret := createLetFor(thisname)
+	return ret
+}
+
+func filterToQuery(element entity.QueryFilterStruct) string {
+	thisname := fmt.Sprintf("e%v", element.ID)
+	ret := createLetFor(thisname, fmt.Sprintf("e%v", element.FilteredID))
+	return ret
+}
+
+func createLetFor(variableName string, enumerableName string) string {
+	return "LET " + variableName + " = (\n\tFOR x IN " + enumerableName + "\n"
+}