shiny/text: implement ReadXxx.
Change-Id: Ide648c2ed487a318f293e8e73e287538ba3e40e3 Reviewed-on: https://go-review.googlesource.com/19113 Reviewed-by: Andrew Gerrand <adg@golang.org> Reviewed-by: David Crawshaw <crawshaw@golang.org>
This commit is contained in:
Nigel Tao
Родитель
731fba202d
Коммит
efa3f21b09
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@ -8,7 +8,9 @@ package text
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// now.
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import (
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"io"
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"strings"
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"unicode/utf8"
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"golang.org/x/image/math/fixed"
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)
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@ -49,7 +51,7 @@ type Caret struct {
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k int32
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}
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// TODO: many Caret methods: Seek, ReadXxx, WriteXxx, Delete, maybe others.
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// TODO: many Caret methods: Seek, WriteXxx, Delete, maybe others.
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// Close closes the Caret.
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func (c *Caret) Close() error {
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@ -68,6 +70,116 @@ func (c *Caret) Close() error {
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return nil
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}
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// leanForwards moves the Caret from the right end of one Box to the left end
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// of the next Box, crossing Lines and Paragraphs to find that next Box. It
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// returns whether the Caret moved; false means that the Caret was located at
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// the end of the Frame's text.
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//
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// Diagramatically, suppose we have two adjacent boxes (shown by square
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// brackets below), with the Caret (an integer location called Caret.pos in the
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// Frame's text) in the middle of the "foo2bar3" word:
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// [foo0 foo1 foo2]^[bar3 bar4 bar5]
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// leanForwards moves Caret.k from fooBox.j to barBox.i, also updating the
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// Caret's p, l and b. Caret.pos remains unchanged.
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func (c *Caret) leanForwards() bool {
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// Assert that the Caret c is at the end of its Box.
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if c.k != c.f.boxes[c.b].j {
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panic("text: invalid state")
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}
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if nextB := c.f.boxes[c.b].next; nextB != 0 {
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c.b = nextB
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c.k = c.f.boxes[c.b].i
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return true
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}
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if nextL := c.f.lines[c.l].next; nextL != 0 {
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c.l = nextL
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c.b = c.f.lines[c.l].firstB
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c.k = c.f.boxes[c.b].i
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return true
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}
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if nextP := c.f.paragraphs[c.p].next; nextP != 0 {
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c.p = nextP
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c.l = c.f.paragraphs[c.p].firstL
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c.b = c.f.lines[c.l].firstB
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c.k = c.f.boxes[c.b].i
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return true
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}
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return false
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}
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// Read satisfies the io.Reader interface by copying those bytes after the
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// Caret and incrementing the Caret.
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func (c *Caret) Read(buf []byte) (n int, err error) {
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for len(buf) > 0 {
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if j := c.f.boxes[c.b].j; c.k < j {
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nn := copy(buf, c.f.text[c.k:j])
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n += nn
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c.pos += int32(nn)
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c.k += int32(nn)
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if c.k == j && buf[nn-1] == '\n' {
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// A Caret can't be placed at the end of a Paragraph, unless it
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// is the final Paragraph.
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c.leanForwards()
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}
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buf = buf[nn:]
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continue
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}
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if !c.leanForwards() {
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break
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}
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}
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if int(c.pos) == c.f.len {
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err = io.EOF
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}
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return n, err
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}
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// ReadByte returns the next byte after the Caret and increments the Caret.
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func (c *Caret) ReadByte() (x byte, err error) {
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for {
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if j := c.f.boxes[c.b].j; c.k < j {
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x = c.f.text[c.k]
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c.pos++
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c.k++
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if x == '\n' {
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// A Caret can't be placed at the end of a Paragraph, unless it
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// is the final Paragraph.
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c.leanForwards()
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}
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return x, nil
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}
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if !c.leanForwards() {
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return 0, io.EOF
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}
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}
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}
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// ReadRune returns the next rune after the Caret and increments the Caret.
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func (c *Caret) ReadRune() (r rune, size int, err error) {
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for {
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if j := c.f.boxes[c.b].j; c.k < j {
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r, size = utf8.DecodeRune(c.f.text[c.k:j])
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if r >= utf8.RuneSelf && size == 1 {
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// We decoded invalid UTF-8, possibly because a valid UTF-8 rune
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// straddled this box and the next one.
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panic("TODO: invalid UTF-8")
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}
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c.pos += int32(size)
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c.k += int32(size)
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if r == '\n' {
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// A Caret can't be placed at the end of a Paragraph, unless it
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// is the final Paragraph.
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c.leanForwards()
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}
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return r, size, nil
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}
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if !c.leanForwards() {
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return 0, 0, io.EOF
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}
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}
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}
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// WriteString inserts s into the Frame's text at the Caret.
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//
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// The error returned is always nil.
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@ -0,0 +1,112 @@
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// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package text
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import (
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"image"
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"io"
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"io/ioutil"
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"reflect"
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"testing"
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"golang.org/x/image/math/fixed"
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)
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// toyFace implements the font.Face interface by measuring every rune's width
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// as 1 pixel.
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type toyFace struct{}
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func (toyFace) Close() error {
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return nil
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}
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func (toyFace) Glyph(dot fixed.Point26_6, r rune) (image.Rectangle, image.Image, image.Point, fixed.Int26_6, bool) {
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panic("unimplemented")
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}
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func (toyFace) GlyphBounds(r rune) (fixed.Rectangle26_6, fixed.Int26_6, bool) {
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panic("unimplemented")
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}
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func (toyFace) GlyphAdvance(r rune) (fixed.Int26_6, bool) {
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return fixed.I(1), true
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}
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func (toyFace) Kern(r0, r1 rune) fixed.Int26_6 {
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return 0
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}
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// iRobot is some text that contains both ASCII and non-ASCII runes.
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const iRobot = "\"I, Robot\" in Russian is \"Я, робот\".\nIt's about robots.\n"
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func iRobotFrame() *Frame {
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f := new(Frame)
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f.SetFace(toyFace{})
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f.SetMaxWidth(fixed.I(10))
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c := f.NewCaret()
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c.WriteString(iRobot)
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c.Close()
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return f
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}
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func TestRead(t *testing.T) {
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f := iRobotFrame()
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c := f.NewCaret()
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defer c.Close()
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asBytes, err := ioutil.ReadAll(c)
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if err != nil {
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t.Fatalf("ReadAll: %v", err)
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}
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got, want := string(asBytes), iRobot
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if got != want {
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t.Fatalf("\ngot: %q\nwant: %q", got, want)
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}
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}
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func TestReadByte(t *testing.T) {
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f := iRobotFrame()
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c := f.NewCaret()
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defer c.Close()
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got, want := []byte(nil), []byte(iRobot)
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for {
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x, err := c.ReadByte()
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if err == io.EOF {
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break
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}
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if err != nil {
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t.Fatalf("ReadByte: %v", err)
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}
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got = append(got, x)
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}
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if !reflect.DeepEqual(got, want) {
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t.Fatalf("\ngot: %v\nwant: %v", got, want)
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}
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}
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func TestReadRune(t *testing.T) {
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f := iRobotFrame()
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c := f.NewCaret()
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defer c.Close()
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got, want := []rune(nil), []rune(iRobot)
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for {
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r, _, err := c.ReadRune()
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if err == io.EOF {
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break
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}
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if err != nil {
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t.Fatalf("ReadRune: %v", err)
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}
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got = append(got, r)
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}
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if !reflect.DeepEqual(got, want) {
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t.Fatalf("\ngot: %v\nwant: %v", got, want)
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}
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}
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// TODO: fuzz-test that all the invariants remain true when modifying a Frame's
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// text.
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//
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// TODO: enumerate all of the invariants, e.g. that the Boxes' i:j ranges do
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// not overlap.
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