Extract extendedQueryBuilder

extended_query_builder.go

@@ -0,0 +1,128 @@
+package pgx
+
+import (
+	"database/sql/driver"
+	"fmt"
+	"reflect"
+
+	"github.com/jackc/pgtype"
+)
+
+type extendedQueryBuilder struct {
+	paramValues     [][]byte
+	paramValueBytes []byte
+	paramFormats    []int16
+	resultFormats   []int16
+
+	resetCount int
+}
+
+func (eqb *extendedQueryBuilder) AppendParam(ci *pgtype.ConnInfo, oid pgtype.OID, arg interface{}) error {
+	f := chooseParameterFormatCode(ci, oid, arg)
+	eqb.paramFormats = append(eqb.paramFormats, f)
+
+	v, err := eqb.encodeExtendedParamValue(ci, oid, arg)
+	if err != nil {
+		return err
+	}
+	eqb.paramValues = append(eqb.paramValues, v)
+
+	return nil
+}
+
+func (eqb *extendedQueryBuilder) AppendResultFormat(f int16) {
+	eqb.resultFormats = append(eqb.resultFormats, f)
+}
+
+func (eqb *extendedQueryBuilder) Reset() {
+	eqb.paramValues = eqb.paramValues[0:0]
+	eqb.paramValueBytes = eqb.paramValueBytes[0:0]
+	eqb.paramFormats = eqb.paramFormats[0:0]
+	eqb.resultFormats = eqb.resultFormats[0:0]
+
+	eqb.resetCount += 1
+
+	// Every so often shrink our reserved memory if it is abnormally high
+	if eqb.resetCount%128 == 0 {
+		if cap(eqb.paramValues) > 64 {
+			eqb.paramValues = make([][]byte, 0, cap(eqb.paramValues)/2)
+		}
+
+		if cap(eqb.paramValueBytes) > 256 {
+			eqb.paramValueBytes = make([]byte, 0, cap(eqb.paramValueBytes)/2)
+		}
+
+		if cap(eqb.paramFormats) > 64 {
+			eqb.paramFormats = make([]int16, 0, cap(eqb.paramFormats)/2)
+		}
+		if cap(eqb.resultFormats) > 64 {
+			eqb.resultFormats = make([]int16, 0, cap(eqb.resultFormats)/2)
+		}
+	}
+
+}
+
+func (eqb *extendedQueryBuilder) encodeExtendedParamValue(ci *pgtype.ConnInfo, oid pgtype.OID, arg interface{}) ([]byte, error) {
+	if arg == nil {
+		return nil, nil
+	}
+
+	if eqb.paramValueBytes == nil {
+		eqb.paramValueBytes = make([]byte, 0, 128)
+	}
+
+	var err error
+	pos := len(eqb.paramValueBytes)
+
+	switch arg := arg.(type) {
+	case pgtype.BinaryEncoder:
+		eqb.paramValueBytes, err = arg.EncodeBinary(ci, eqb.paramValueBytes)
+		if err != nil {
+			return nil, err
+		}
+		return eqb.paramValueBytes[pos:], nil
+	case pgtype.TextEncoder:
+		eqb.paramValueBytes, err = arg.EncodeText(ci, eqb.paramValueBytes)
+		if err != nil {
+			return nil, err
+		}
+		return eqb.paramValueBytes[pos:], nil
+	case string:
+		return []byte(arg), nil
+	}
+
+	refVal := reflect.ValueOf(arg)
+
+	if refVal.Kind() == reflect.Ptr {
+		if refVal.IsNil() {
+			return nil, nil
+		}
+		arg = refVal.Elem().Interface()
+		return eqb.encodeExtendedParamValue(ci, oid, arg)
+	}
+
+	if dt, ok := ci.DataTypeForOID(oid); ok {
+		value := dt.Value
+		err := value.Set(arg)
+		if err != nil {
+			{
+				if arg, ok := arg.(driver.Valuer); ok {
+					v, err := callValuerValue(arg)
+					if err != nil {
+						return nil, err
+					}
+					return eqb.encodeExtendedParamValue(ci, oid, v)
+				}
+			}
+
+			return nil, err
+		}
+
+		return eqb.encodeExtendedParamValue(ci, oid, value)
+	}
+
+	if strippedArg, ok := stripNamedType(&refVal); ok {
+		return eqb.encodeExtendedParamValue(ci, oid, strippedArg)
+	}
+	return nil, SerializationError(fmt.Sprintf("Cannot encode %T into oid %v - %T must implement Encoder or be converted to a string", arg, oid, arg))
+}