termui/textbuilder.go

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package termui
import (
"regexp"
"strings"
)
// TextBuilder is a minial interface to produce text []Cell using sepcific syntax (markdown).
type TextBuilder interface {
Build(s string, fg, bg Attribute) []Cell
}
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// DefaultTxBuilder is set to be MarkdownTxBuilder.
var DefaultTxBuilder = NewMarkdownTxBuilder()
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// MarkdownTxBuilder implements TextBuilder interface, using markdown syntax.
type MarkdownTxBuilder struct {
baseFg Attribute
baseBg Attribute
plainTx []rune
markers []marker
}
type marker struct {
st int
ed int
fg Attribute
bg Attribute
}
var colorMap = map[string]Attribute{
"red": ColorRed,
"blue": ColorBlue,
"black": ColorBlack,
"cyan": ColorCyan,
"white": ColorWhite,
"default": ColorDefault,
"green": ColorGreen,
"magenta": ColorMagenta,
}
var attrMap = map[string]Attribute{
"bold": AttrBold,
"underline": AttrUnderline,
"reverse": AttrReverse,
}
func rmSpc(s string) string {
reg := regexp.MustCompile(`\s+`)
return reg.ReplaceAllString(s, "")
}
// readAttr translates strings like `fg-red,fg-bold,bg-white` to fg and bg Attribute
func (mtb MarkdownTxBuilder) readAttr(s string) (Attribute, Attribute) {
fg := mtb.baseFg
bg := mtb.baseBg
updateAttr := func(a Attribute, attrs []string) Attribute {
for _, s := range attrs {
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// replace the color
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if c, ok := colorMap[s]; ok {
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a &= 0xFF00 // erase clr 0 ~ 8 bits
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a |= c // set clr
}
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// add attrs
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if c, ok := attrMap[s]; ok {
a |= c
}
}
return a
}
ss := strings.Split(s, ",")
fgs := []string{}
bgs := []string{}
for _, v := range ss {
subs := strings.Split(v, "-")
if len(subs) > 1 {
if subs[0] == "fg" {
fgs = append(fgs, subs[1])
}
if subs[0] == "bg" {
bgs = append(bgs, subs[1])
}
}
}
fg = updateAttr(fg, fgs)
bg = updateAttr(bg, bgs)
return fg, bg
}
func (mtb *MarkdownTxBuilder) reset() {
mtb.plainTx = []rune{}
mtb.markers = []marker{}
}
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// parse streams and parses text into normalized text and render sequence.
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func (mtb *MarkdownTxBuilder) parse(str string) {
rs := str2runes(str)
normTx := []rune{}
square := []rune{}
brackt := []rune{}
accSquare := false
accBrackt := false
cntSquare := 0
reset := func() {
square = []rune{}
brackt = []rune{}
accSquare = false
accBrackt = false
cntSquare = 0
}
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// pipe stacks into normTx and clear
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rollback := func() {
normTx = append(normTx, square...)
normTx = append(normTx, brackt...)
reset()
}
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// chop first and last
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chop := func(s []rune) []rune {
return s[1 : len(s)-1]
}
for i, r := range rs {
switch {
// stacking brackt
case accBrackt:
brackt = append(brackt, r)
if ')' == r {
fg, bg := mtb.readAttr(string(chop(brackt)))
st := len(normTx)
ed := len(normTx) + len(square) - 2
mtb.markers = append(mtb.markers, marker{st, ed, fg, bg})
normTx = append(normTx, chop(square)...)
reset()
} else if i+1 == len(rs) {
rollback()
}
// stacking square
case accSquare:
switch {
// squares closed and followed by a '('
case cntSquare == 0 && '(' == r:
accBrackt = true
brackt = append(brackt, '(')
// squares closed but not followed by a '('
case cntSquare == 0:
rollback()
if '[' == r {
accSquare = true
cntSquare = 1
brackt = append(brackt, '[')
} else {
normTx = append(normTx, r)
}
// hit the end
case i+1 == len(rs):
square = append(square, r)
rollback()
case '[' == r:
cntSquare++
square = append(square, '[')
case ']' == r:
cntSquare--
square = append(square, ']')
// normal char
default:
square = append(square, r)
}
// stacking normTx
default:
if '[' == r {
accSquare = true
cntSquare = 1
square = append(square, '[')
} else {
normTx = append(normTx, r)
}
}
}
mtb.plainTx = normTx
}
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// Build implements TextBuilder interface.
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func (mtb MarkdownTxBuilder) Build(s string, fg, bg Attribute) []Cell {
mtb.baseFg = fg
mtb.baseBg = bg
mtb.reset()
mtb.parse(s)
cs := make([]Cell, len(mtb.plainTx))
for i := range cs {
cs[i] = Cell{Ch: mtb.plainTx[i], Fg: fg, Bg: bg}
}
for _, mrk := range mtb.markers {
for i := mrk.st; i < mrk.ed; i++ {
cs[i].Fg = mrk.fg
cs[i].Bg = mrk.bg
}
}
return cs
}
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// NewMarkdownTxBuilder returns a TextBuilder employing markdown syntax.
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func NewMarkdownTxBuilder() TextBuilder {
return MarkdownTxBuilder{}
}