Initial commit

vendor/github.com/jackc/pgproto3/v2/describe.go

@@ -0,0 +1,88 @@
+package pgproto3
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+
+	"github.com/jackc/pgio"
+)
+
+type Describe struct {
+	ObjectType byte // 'S' = prepared statement, 'P' = portal
+	Name       string
+}
+
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
+func (*Describe) Frontend() {}
+
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
+func (dst *Describe) Decode(src []byte) error {
+	if len(src) < 2 {
+		return &invalidMessageFormatErr{messageType: "Describe"}
+	}
+
+	dst.ObjectType = src[0]
+	rp := 1
+
+	idx := bytes.IndexByte(src[rp:], 0)
+	if idx != len(src[rp:])-1 {
+		return &invalidMessageFormatErr{messageType: "Describe"}
+	}
+
+	dst.Name = string(src[rp : len(src)-1])
+
+	return nil
+}
+
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
+func (src *Describe) Encode(dst []byte) []byte {
+	dst = append(dst, 'D')
+	sp := len(dst)
+	dst = pgio.AppendInt32(dst, -1)
+
+	dst = append(dst, src.ObjectType)
+	dst = append(dst, src.Name...)
+	dst = append(dst, 0)
+
+	pgio.SetInt32(dst[sp:], int32(len(dst[sp:])))
+
+	return dst
+}
+
+// MarshalJSON implements encoding/json.Marshaler.
+func (src Describe) MarshalJSON() ([]byte, error) {
+	return json.Marshal(struct {
+		Type       string
+		ObjectType string
+		Name       string
+	}{
+		Type:       "Describe",
+		ObjectType: string(src.ObjectType),
+		Name:       src.Name,
+	})
+}
+
+// UnmarshalJSON implements encoding/json.Unmarshaler.
+func (dst *Describe) UnmarshalJSON(data []byte) error {
+	// Ignore null, like in the main JSON package.
+	if string(data) == "null" {
+		return nil
+	}
+
+	var msg struct {
+		ObjectType string
+		Name       string
+	}
+	if err := json.Unmarshal(data, &msg); err != nil {
+		return err
+	}
+	if len(msg.ObjectType) != 1 {
+		return errors.New("invalid length for Describe.ObjectType")
+	}
+
+	dst.ObjectType = byte(msg.ObjectType[0])
+	dst.Name = msg.Name
+	return nil
+}