qb: extracted function from cmp

qb/func.go

@@ -0,0 +1,51 @@
+// Copyright (C) 2017 ScyllaDB
+// Use of this source code is governed by a ALv2-style
+// license that can be found in the LICENSE file.
+
+package qb
+
+import "bytes"
+
+// Functions reference:
+// https://cassandra.apache.org/doc/latest/cql/functions.html
+
+// Func is a custom database function invocation that can be use in a comparator
+// or update statement.
+type Func struct {
+	// function name
+	Name string
+	// name of the function parameters
+	ParamNames []string
+}
+
+func (f *Func) writeCql(cql *bytes.Buffer) (names []string) {
+	cql.WriteString(f.Name)
+	cql.WriteByte('(')
+	placeholders(cql, len(f.ParamNames))
+	cql.WriteByte(')')
+	names = append(names, f.ParamNames...)
+	return
+}
+
+// Fn creates Func.
+func Fn(name string, paramNames ...string) *Func {
+	return &Func{
+		Name:       name,
+		ParamNames: paramNames,
+	}
+}
+
+// MinTimeuuid produces minTimeuuid(?).
+func MinTimeuuid(name string) *Func {
+	return Fn("minTimeuuid", name)
+}
+
+// MaxTimeuuid produces maxTimeuuid(?).
+func MaxTimeuuid(name string) *Func {
+	return Fn("maxTimeuuid", name)
+}
+
+// Now produces now().
+func Now() *Func {
+	return Fn("now")
+}