Initial proof-of-concept for pgtype

Squashed commit of the following:

commit c19454582b335ce5bdda6320f7e4e8c76cfeaf44
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Fri Mar 3 15:24:47 2017 -0600

    Add AssignTo to pgtype.Timestamptz

    Also handle infinity for pgtype.Date

commit 7329933610b38f4bc15731b1f7c55c520b49e300
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Fri Mar 3 15:12:18 2017 -0600

    Implement AssignTo for most pgtypes

commit cc3d1e4af896d34ec98c3bf2e982d0367451f21c
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Thu Mar 2 21:19:07 2017 -0600

    Use pgtype.Int2Array in pgx

commit 36da5cc2178d1a31a56dc6e6f128843bd80dea0b
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Tue Feb 28 21:45:33 2017 -0600

    Add text array transcoding

commit 1b0f18d99f38b69f8c2db26388815e67b2b03d59
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Mon Feb 27 19:28:55 2017 -0600

    Add ParseUntypedTextArray

commit 0f50ce3e833fc38495d333228daf04f5142be676
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Mon Feb 27 18:54:20 2017 -0600

    wip

commit d934f273627d79997035c282416db922f2fbe87a
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Sun Feb 26 17:14:32 2017 -0600

    WIP - beginning text format array parsing

commit 7276ad33ce7fa9c250745a3ed909998f3dae4a32
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Sat Feb 25 22:50:11 2017 -0600

    Beginning binary arrays

commit 917faa5a3175d376222423c10aca297a20f96448
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Sat Feb 25 19:36:35 2017 -0600

    Fix incomplete tests

commit de8c140cfb98b7b047d53c5718ccbf12eaf813a1
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Sat Feb 25 19:32:22 2017 -0600

    Add timestamptz null and infinity

commit 7d9f954de4e071a1eccac762248079b90dbeb53f
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Sat Feb 25 18:19:38 2017 -0600

    Add infinity to pgtype.Date

commit 7bf783ae20ba05571c2fb9f661183233c95eab41
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Sat Feb 25 17:19:55 2017 -0600

    Add Status to pgtype.Date

commit 984500455c9b9a4b6221758540d248e6410d93a4
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Sat Feb 25 16:54:01 2017 -0600

    Add status to Int4 and Int8

commit 6fe76fcfc2de31552790db3b093480a9d5b2a742
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Sat Feb 25 16:40:27 2017 -0600

    Extract testSuccessfulTranscode

commit 001647c1da03f796014cf21f41c9a7fd2cfadfde
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Sat Feb 25 16:15:51 2017 -0600

    Add Status to pgtype.Int2

commit 720451f06d13d9c9fa2a0482e010f24bf4627c2a
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Sat Feb 25 15:56:44 2017 -0600

    Add status to pgtype.Bool

commit 325f700b6edff215a692b10bc5b94cdfe1100769
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Fri Feb 24 17:28:15 2017 -0600

    Add date to conversion system

commit 4a9343e45d3897f59eab98a0009d2ddbe07e02d7
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Fri Feb 24 16:28:35 2017 -0600

    Add bool to oid based encoding

commit d984fcafab1476cf84852485b6711f4b2069eb6d
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Fri Feb 24 16:15:38 2017 -0600

    Add pgtype interfaces

commit 0f93bfc2de4023b069b966c0988bf7f0469d1809
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Fri Feb 24 14:48:34 2017 -0600

    Begin introduction of Convert

commit e5707023cac7c07342b8c910e480d09a1caaf6ee
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Fri Feb 24 14:10:56 2017 -0600

    Move bool to pgtype

commit bb764d2129efe7fb21e841dbb35e6d0dc7586d37
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Fri Feb 24 13:45:05 2017 -0600

    Add Int2 test

commit 08c49437f455a32f7c3f0a524cd21a895d440301
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Fri Feb 24 13:44:09 2017 -0600

    Add Int4 test

commit 16722952222fd15c53c8fa84974645504a6d0dc0
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Fri Feb 24 08:56:59 2017 -0600

    Add int8 tests

commit 83a5447cd2c46b58d0880023cc4e9af0c84988a2
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Wed Feb 22 18:08:05 2017 -0600

    wip

commit 0ca0ee72068a72b016729b01fccef22474595285
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Mon Feb 20 18:56:52 2017 -0600

    wip

commit d2c2baf4ea2cd0793d68c7094c425217df952bec
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Mon Feb 20 18:46:10 2017 -0600

    wip

commit f78371da0098356527b193fd496a338da5fe414b
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Mon Feb 20 17:43:39 2017 -0600

    wip

commit 3366699bea62ec0110db05f3cb2998d58ac9ce5d
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Mon Feb 20 14:07:47 2017 -0600

    wip

commit 66b79e940870fd0133ebb10ac1547e1d4d7d0b51
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Mon Feb 20 13:35:37 2017 -0600

    Extract pgio

commit 8b07d97d1305ed98fd76db6e306a289c0af92d56
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Mon Feb 20 13:20:00 2017 -0600

    wip

commit 62f1adb3427f4317b708da075dce50c4d4daff7b
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Mon Feb 20 12:08:46 2017 -0600

    wip

commit a712d2546933a5a8433c65eef0ff2ee135077c87
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Mon Feb 20 09:30:52 2017 -0600

    wip

commit 4faf97cc588126dda160fc360680719572a23105
Author: Jack Christensen <jack@jackchristensen.com>
Date:   Fri Feb 17 22:20:18 2017 -0600

    wip

doc.go

@@ -0,0 +1,8 @@
+// Package pgio a extremely low-level IO toolkit for the PostgreSQL wire protocol.
+/*
+pgio provides functions for reading and writing integers from io.Reader and
+io.Writer while doing byte order conversion. It publishes interfaces which
+readers and writers may implement to decode and encode messages with the minimum
+of memory allocations.
+*/
+package pgio

read.go

@@ -0,0 +1,104 @@
+package pgio
+
+import (
+	"encoding/binary"
+	"io"
+)
+
+type Uint16Reader interface {
+	ReadUint16() (n uint16, err error)
+}
+
+type Uint32Reader interface {
+	ReadUint32() (n uint32, err error)
+}
+
+type Uint64Reader interface {
+	ReadUint64() (n uint64, err error)
+}
+
+// ReadByte reads a byte from r.
+func ReadByte(r io.Reader) (byte, error) {
+	if r, ok := r.(io.ByteReader); ok {
+		return r.ReadByte()
+	}
+
+	buf := make([]byte, 1)
+	_, err := r.Read(buf)
+	return buf[0], err
+}
+
+// ReadUint16 reads an uint16 from r in PostgreSQL wire format (network byte order). This
+// may be more efficient than directly using Read if r provides a ReadUint16
+// method.
+func ReadUint16(r io.Reader) (uint16, error) {
+	if r, ok := r.(Uint16Reader); ok {
+		return r.ReadUint16()
+	}
+
+	buf := make([]byte, 2)
+	_, err := io.ReadFull(r, buf)
+	if err != nil {
+		return 0, err
+	}
+
+	return binary.BigEndian.Uint16(buf), nil
+}
+
+// ReadInt16 reads an int16 r in PostgreSQL wire format (network byte order). This
+// may be more efficient than directly using Read if r provides a ReadUint16
+// method.
+func ReadInt16(r io.Reader) (int16, error) {
+	n, err := ReadUint16(r)
+	return int16(n), err
+}
+
+// ReadUint32 reads an uint32 r in PostgreSQL wire format (network byte order). This
+// may be more efficient than directly using Read if r provides a ReadUint32
+// method.
+func ReadUint32(r io.Reader) (uint32, error) {
+	if r, ok := r.(Uint32Reader); ok {
+		return r.ReadUint32()
+	}
+
+	buf := make([]byte, 4)
+	_, err := io.ReadFull(r, buf)
+	if err != nil {
+		return 0, err
+	}
+
+	return binary.BigEndian.Uint32(buf), nil
+}
+
+// ReadInt32 reads an int32 r in PostgreSQL wire format (network byte order). This
+// may be more efficient than directly using Read if r provides a ReadUint32
+// method.
+func ReadInt32(r io.Reader) (int32, error) {
+	n, err := ReadUint32(r)
+	return int32(n), err
+}
+
+// ReadUint64 reads an uint64 r in PostgreSQL wire format (network byte order). This
+// may be more efficient than directly using Read if r provides a ReadUint64
+// method.
+func ReadUint64(r io.Reader) (uint64, error) {
+	if r, ok := r.(Uint64Reader); ok {
+		return r.ReadUint64()
+	}
+
+	buf := make([]byte, 8)
+	_, err := io.ReadFull(r, buf)
+	if err != nil {
+		return 0, err
+	}
+
+	return binary.BigEndian.Uint64(buf), nil
+}
+
+// ReadInt64 reads an int64 r in PostgreSQL wire format (network byte order). This
+// may be more efficient than directly using Read if r provides a ReadUint64
+// method.
+func ReadInt64(r io.Reader) (int64, error) {
+	n, err := ReadUint64(r)
+	return int64(n), err
+}

write.go

@@ -0,0 +1,97 @@
+package pgio
+
+import (
+	"encoding/binary"
+	"io"
+)
+
+type Uint16Writer interface {
+	WriteUint16(uint16) (n int, err error)
+}
+
+type Uint32Writer interface {
+	WriteUint32(uint32) (n int, err error)
+}
+
+type Uint64Writer interface {
+	WriteUint64(uint64) (n int, err error)
+}
+
+// WriteByte writes b to w.
+func WriteByte(w io.Writer, b byte) error {
+	if w, ok := w.(io.ByteWriter); ok {
+		return w.WriteByte(b)
+	}
+	_, err := w.Write([]byte{b})
+	return err
+}
+
+// WriteUint16 writes n to w in PostgreSQL wire format (network byte order). This
+// may be more efficient than directly using Write if w provides a WriteUint16
+// method.
+func WriteUint16(w io.Writer, n uint16) (int, error) {
+	if w, ok := w.(Uint16Writer); ok {
+		return w.WriteUint16(n)
+	}
+	b := make([]byte, 2)
+	binary.BigEndian.PutUint16(b, n)
+	return w.Write(b)
+}
+
+// WriteInt16 writes n to w in PostgreSQL wire format (network byte order). This
+// may be more efficient than directly using Write if w provides a WriteUint16
+// method.
+func WriteInt16(w io.Writer, n int16) (int, error) {
+	return WriteUint16(w, uint16(n))
+}
+
+// WriteUint32 writes n to w in PostgreSQL wire format (network byte order). This
+// may be more efficient than directly using Write if w provides a WriteUint32
+// method.
+func WriteUint32(w io.Writer, n uint32) (int, error) {
+	if w, ok := w.(Uint32Writer); ok {
+		return w.WriteUint32(n)
+	}
+	b := make([]byte, 4)
+	binary.BigEndian.PutUint32(b, n)
+	return w.Write(b)
+}
+
+// WriteInt32 writes n to w in PostgreSQL wire format (network byte order). This
+// may be more efficient than directly using Write if w provides a WriteUint32
+// method.
+func WriteInt32(w io.Writer, n int32) (int, error) {
+	return WriteUint32(w, uint32(n))
+}
+
+// WriteUint64 writes n to w in PostgreSQL wire format (network byte order). This
+// may be more efficient than directly using Write if w provides a WriteUint64
+// method.
+func WriteUint64(w io.Writer, n uint64) (int, error) {
+	if w, ok := w.(Uint64Writer); ok {
+		return w.WriteUint64(n)
+	}
+	b := make([]byte, 8)
+	binary.BigEndian.PutUint64(b, n)
+	return w.Write(b)
+}
+
+// WriteInt64 writes n to w in PostgreSQL wire format (network byte order). This
+// may be more efficient than directly using Write if w provides a WriteUint64
+// method.
+func WriteInt64(w io.Writer, n int64) (int, error) {
+	return WriteUint64(w, uint64(n))
+}
+
+// WriteCString writes s to w followed by a null byte.
+func WriteCString(w io.Writer, s string) (int, error) {
+	n, err := io.WriteString(w, s)
+	if err != nil {
+		return n, err
+	}
+	err = WriteByte(w, 0)
+	if err != nil {
+		return n, err
+	}
+	return n + 1, nil
+}