Add inv (de)serialization

1 files changed, 116 insertions, 0 deletions

diff --git a/readrune.go b/readrune.go
new file mode 100644
index 0000000..775e06f
--- /dev/null
+++ b/readrune.go
@@ -0,0 +1,116 @@
+/*
+Based on go1.16/src/fmt/scan.go.
+
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+package mt
+
+import (
+	"errors"
+	"io"
+	"unicode/utf8"
+)
+
+// readRune is a structure to enable reading UTF-8 encoded code points
+// from an io.Reader. It is used if the Reader given to the scanner does
+// not already implement io.RuneScanner.
+type readRune struct {
+	io.Reader
+	buf      [utf8.UTFMax]byte // used only inside ReadRune
+	pending  int               // number of bytes in pendBuf; only >0 for bad UTF-8
+	pendBuf  [utf8.UTFMax]byte // bytes left over
+	peekRune rune              // if >=0 next rune; when <0 is ^(previous Rune)
+}
+
+// readByte returns the next byte from the input, which may be
+// left over from a previous read if the UTF-8 was ill-formed.
+func (r *readRune) readByte() (b byte, err error) {
+	if r.pending > 0 {
+		b = r.pendBuf[0]
+		copy(r.pendBuf[0:], r.pendBuf[1:])
+		r.pending--
+		return
+	}
+	n, err := io.ReadFull(r, r.pendBuf[:1])
+	if n != 1 {
+		return 0, err
+	}
+	return r.pendBuf[0], err
+}
+
+// ReadRune returns the next UTF-8 encoded code point from the
+// io.Reader inside r.
+func (r *readRune) ReadRune() (rr rune, size int, err error) {
+	if r.peekRune >= 0 {
+		rr = r.peekRune
+		r.peekRune = ^r.peekRune
+		size = utf8.RuneLen(rr)
+		return
+	}
+	r.buf[0], err = r.readByte()
+	if err != nil {
+		return
+	}
+	if r.buf[0] < utf8.RuneSelf { // fast check for common ASCII case
+		rr = rune(r.buf[0])
+		size = 1 // Known to be 1.
+		// Flip the bits of the rune so it's available to UnreadRune.
+		r.peekRune = ^rr
+		return
+	}
+	var n int
+	for n = 1; !utf8.FullRune(r.buf[:n]); n++ {
+		r.buf[n], err = r.readByte()
+		if err != nil {
+			if err == io.EOF {
+				err = nil
+				break
+			}
+			return
+		}
+	}
+	rr, size = utf8.DecodeRune(r.buf[:n])
+	if size < n { // an error, save the bytes for the next read
+		copy(r.pendBuf[r.pending:], r.buf[size:n])
+		r.pending += n - size
+	}
+	// Flip the bits of the rune so it's available to UnreadRune.
+	r.peekRune = ^rr
+	return
+}
+
+func (r *readRune) UnreadRune() error {
+	if r.peekRune >= 0 {
+		return errors.New("fmt: scanning called UnreadRune with no rune available")
+	}
+	// Reverse bit flip of previously read rune to obtain valid >=0 state.
+	r.peekRune = ^r.peekRune
+	return nil
+}