Add QueryArgs

sql.go

@@ -0,0 +1,29 @@
+package pgx
+
+import (
+	"strconv"
+)
+
+// QueryArgs is a container for arguments to an SQL query. It is helpful when
+// building SQL statements where the number of arguments is variable.
+type QueryArgs []interface{}
+
+var placeholders []string
+
+func init() {
+	placeholders = make([]string, 64)
+
+	for i := 1; i < 64; i++ {
+		placeholders[i] = "$" + strconv.FormatInt(int64(i), 10)
+	}
+}
+
+// Append adds a value to qa and returns the placeholder value for the
+// argument. e.g. $1, $2, etc.
+func (qa *QueryArgs) Append(v interface{}) string {
+	*qa = append(*qa, v)
+	if len(*qa) < len(placeholders) {
+		return placeholders[len(*qa)]
+	}
+	return "$" + strconv.FormatInt(int64(len(*qa)), 10)
+}

sql_test.go

@@ -0,0 +1,35 @@
+package pgx_test
+
+import (
+	"github.com/JackC/pgx"
+	"strconv"
+	"testing"
+)
+
+func TestQueryArgs(t *testing.T) {
+	var qa pgx.QueryArgs
+
+	for i := 1; i < 512; i++ {
+		expectedPlaceholder := "$" + strconv.FormatInt(int64(i), 10)
+		placeholder := qa.Append(i)
+		if placeholder != expectedPlaceholder {
+			t.Errorf(`Expected qa.Append to return "%s", but it returned "%s"`, expectedPlaceholder, placeholder)
+		}
+	}
+}
+
+func BenchmarkQueryArgs(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		qa := pgx.QueryArgs(make([]interface{}, 0, 16))
+		qa.Append("foo1")
+		qa.Append("foo2")
+		qa.Append("foo3")
+		qa.Append("foo4")
+		qa.Append("foo5")
+		qa.Append("foo6")
+		qa.Append("foo7")
+		qa.Append("foo8")
+		qa.Append("foo9")
+		qa.Append("foo10")
+	}
+}