named: address bulk insert v1.3.1 issues

This change-set is how I addressed the issues of bulk inserts not being
handled cleanly when they're not at the end of the query.

It works by first adding VALUES to the expression (not sure if this is
universally applicable to all supported SQL dialects) then adding a
submatch to the regular expression for the fields we want to repeat.
Using the submatch, we're able to repeat the fields that we're concerned
with to expand the insertion parameters.

named.go

@@ -224,21 +224,28 @@ func bindStruct(bindType int, query string, arg interface{}, m *reflectx.Mapper)
 	return bound, arglist, nil
 }
 
-var valueBracketReg = regexp.MustCompile(`\([^(]*.[^(]\)\s*$`)
+var valueBracketReg = regexp.MustCompile(`VALUES\s+(\([^(]*.[^(]\))`)
 
 func fixBound(bound string, loop int) string {
-	loc := valueBracketReg.FindStringIndex(bound)
-	if len(loc) != 2 {
+	loc := valueBracketReg.FindAllStringSubmatchIndex(bound, -1)
+	// Either no VALUES () found or more than one found??
+	if len(loc) != 1 {
+		return bound
+	}
+	// defensive guard. loc should be len 4 representing the starting and
+	// ending index for the whole regex match and the starting + ending
+	// index for the single inside group
+	if len(loc[0]) != 4 {
 		return bound
 	}
 	var buffer bytes.Buffer
 
-	buffer.WriteString(bound[0:loc[1]])
+	buffer.WriteString(bound[0:loc[0][1]])
 	for i := 0; i < loop-1; i++ {
 		buffer.WriteString(",")
-		buffer.WriteString(bound[loc[0]:loc[1]])
+		buffer.WriteString(bound[loc[0][2]:loc[0][3]])
 	}
-	buffer.WriteString(bound[loc[1]:])
+	buffer.WriteString(bound[loc[0][1]:])
 	return buffer.String()
 }