Change Scan / decodeX to use ValueReader

Also improve Rows.Scan and Rows.Values error handling.
2014-07-12 19:39:58 -05:00
parent 70c32fadc6
commit f215c8bf5f
5 changed files with 320 additions and 184 deletions
@@ -0,0 +1,123 @@
+package pgx
+
+import (
+	"errors"
+)
+
+// ValueReader the mechanism for implementing the BinaryDecoder interface.
+type ValueReader struct {
+	mr                  *MsgReader
+	fd                  *FieldDescription
+	valueBytesRemaining int32
+	err                 error
+}
+
+// Err returns any error that the ValueReader has experienced
+func (r *ValueReader) Err() error {
+	return r.err
+}
+
+// Fatal tells r that a Fatal error has occurred
+func (r *ValueReader) Fatal(err error) {
+	r.err = err
+}
+
+// Len returns the number of unread bytes
+func (r *ValueReader) Len() int32 {
+	return r.valueBytesRemaining
+}
+
+// Type returns the *FieldDescription of the value
+func (r *ValueReader) Type() *FieldDescription {
+	return r.fd
+}
+
+func (r *ValueReader) ReadByte() byte {
+	if r.err != nil {
+		return 0
+	}
+
+	r.valueBytesRemaining -= 1
+	if r.valueBytesRemaining < 0 {
+		r.Fatal(errors.New("read past end of value"))
+		return 0
+	}
+
+	return r.mr.ReadByte()
+}
+
+func (r *ValueReader) ReadInt16() int16 {
+	if r.err != nil {
+		return 0
+	}
+
+	r.valueBytesRemaining -= 2
+	if r.valueBytesRemaining < 0 {
+		r.Fatal(errors.New("read past end of value"))
+		return 0
+	}
+
+	return r.mr.ReadInt16()
+}
+
+func (r *ValueReader) ReadInt32() int32 {
+	if r.err != nil {
+		return 0
+	}
+
+	r.valueBytesRemaining -= 4
+	if r.valueBytesRemaining < 0 {
+		r.Fatal(errors.New("read past end of value"))
+		return 0
+	}
+
+	return r.mr.ReadInt32()
+}
+
+func (r *ValueReader) ReadInt64() int64 {
+	if r.err != nil {
+		return 0
+	}
+
+	r.valueBytesRemaining -= 8
+	if r.valueBytesRemaining < 0 {
+		r.Fatal(errors.New("read past end of value"))
+		return 0
+	}
+
+	return r.mr.ReadInt64()
+}
+
+func (r *ValueReader) ReadOid() Oid {
+	return Oid(r.ReadInt32())
+}
+
+// ReadString reads count bytes and returns as string
+func (r *ValueReader) ReadString(count int32) string {
+	if r.err != nil {
+		return ""
+	}
+
+	r.valueBytesRemaining -= count
+	if r.valueBytesRemaining < 0 {
+		r.Fatal(errors.New("read past end of value"))
+		return ""
+	}
+
+	return r.mr.ReadString(count)
+}
+
+// ReadBytes reads count bytes and returns as []byte
+func (r *ValueReader) ReadBytes(count int32) []byte {
+	if r.err != nil {
+		return nil
+	}
+
+	r.valueBytesRemaining -= count
+	if r.valueBytesRemaining < 0 {
+		r.Fatal(errors.New("read past end of value"))
+		return nil
+	}
+
+	return r.mr.ReadBytes(count)
+}