Function preprocessFilter

worker/task.go:2424–2497

(tree *pb.FilterTree)

	types.DateTimeID, types.BoolID, types.DefaultID}

func preprocessFilter(tree *pb.FilterTree) (*facetsTree, error) {
	if tree == nil {
		return nil, nil
	}
	ftree := &facetsTree{}
	ftree.op = strings.ToLower(tree.Op)
	if tree.Func != nil {
		ftree.function = &facetsFunc{}
		ftree.function.key = tree.Func.Key
		ftree.function.args = tree.Func.Args

		fnType, fname := parseFuncTypeHelper(tree.Func.Name)
		if len(tree.Func.Args) != 1 {
			return nil, errors.Errorf("One argument expected in %s, but got %d.",
				fname, len(tree.Func.Args))
		}

		ftree.function.name = fname
		ftree.function.fnType = fnType

		switch fnType {
		case compareAttrFn:
			ftree.function.val = types.Val{Tid: types.StringID, Value: []byte(tree.Func.Args[0])}
			ftree.function.typesToVal = make(map[types.TypeID]types.Val, len(commonTypeIDs))
			for _, typeID := range commonTypeIDs {
				// TODO: if conversion is not possible we are not putting anything to map. In
				// applyFacetsTree we check if entry for a type is not present, we try to convert
				// it. This double conversion can be avoided.
				cv, err := types.Convert(ftree.function.val, typeID)
				if err != nil {
					continue
				}
				ftree.function.typesToVal[typeID] = cv
			}
		case standardFn:
			argTokens, aerr := tok.GetTermTokens(tree.Func.Args)
			if aerr != nil { // query error ; stop processing.
				return nil, aerr
			}
			sort.Strings(argTokens)
			ftree.function.tokens = argTokens
		default:
			return nil, errors.Errorf("Fn %s not supported in preprocessFilter.", fname)
		}
		return ftree, nil
	}

	for _, c := range tree.Children {
		ftreec, err := preprocessFilter(c)
		if err != nil {
			return nil, err
		}
		ftree.children = append(ftree.children, ftreec)
	}

	numChild := len(tree.Children)
	switch ftree.op {
	case "not":