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// Copyright 2014 The gocui Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package gocui
import (
"strconv"
"github.com/go-errors/errors"
)
type escapeInterpreter struct {
state escapeState
curch rune
csiParam []string
curFgColor, curBgColor Attribute
mode OutputMode
}
type (
escapeState int
fontEffect int
)
const (
stateNone escapeState = iota
stateEscape
stateCSI
stateParams
bold fontEffect = 1
underline fontEffect = 4
reverse fontEffect = 7
setForegroundColor fontEffect = 38
setBackgroundColor fontEffect = 48
)
var (
errNotCSI = errors.New("Not a CSI escape sequence")
errCSIParseError = errors.New("CSI escape sequence parsing error")
errCSITooLong = errors.New("CSI escape sequence is too long")
)
// runes in case of error will output the non-parsed runes as a string.
func (ei *escapeInterpreter) runes() []rune {
switch ei.state {
case stateNone:
return []rune{0x1b}
case stateEscape:
return []rune{0x1b, ei.curch}
case stateCSI:
return []rune{0x1b, '[', ei.curch}
case stateParams:
ret := []rune{0x1b, '['}
for _, s := range ei.csiParam {
ret = append(ret, []rune(s)...)
ret = append(ret, ';')
}
return append(ret, ei.curch)
}
return nil
}
// newEscapeInterpreter returns an escapeInterpreter that will be able to parse
// terminal escape sequences.
func newEscapeInterpreter(mode OutputMode) *escapeInterpreter {
ei := &escapeInterpreter{
state: stateNone,
curFgColor: ColorDefault,
curBgColor: ColorDefault,
mode: mode,
}
return ei
}
// reset sets the escapeInterpreter in initial state.
func (ei *escapeInterpreter) reset() {
ei.state = stateNone
ei.curFgColor = ColorDefault
ei.curBgColor = ColorDefault
ei.csiParam = nil
}
// parseOne parses a rune. If isEscape is true, it means that the rune is part
// of an escape sequence, and as such should not be printed verbatim. Otherwise,
// it's not an escape sequence.
func (ei *escapeInterpreter) parseOne(ch rune) (isEscape bool, err error) {
// Sanity checks
if len(ei.csiParam) > 20 {
return false, errCSITooLong
}
if len(ei.csiParam) > 0 && len(ei.csiParam[len(ei.csiParam)-1]) > 255 {
return false, errCSITooLong
}
ei.curch = ch
switch ei.state {
case stateNone:
if ch == 0x1b {
ei.state = stateEscape
return true, nil
}
return false, nil
case stateEscape:
if ch == '[' {
ei.state = stateCSI
return true, nil
}
return false, errNotCSI
case stateCSI:
switch {
case ch >= '0' && ch <= '9':
ei.csiParam = append(ei.csiParam, "")
case ch == 'm':
ei.csiParam = append(ei.csiParam, "0")
default:
return false, errCSIParseError
}
ei.state = stateParams
fallthrough
case stateParams:
switch {
case ch >= '0' && ch <= '9':
ei.csiParam[len(ei.csiParam)-1] += string(ch)
return true, nil
case ch == ';':
ei.csiParam = append(ei.csiParam, "")
return true, nil
case ch == 'm':
var err error
switch ei.mode {
case OutputNormal:
err = ei.outputNormal()
case Output256:
err = ei.output256()
}
if err != nil {
return false, errCSIParseError
}
ei.state = stateNone
ei.csiParam = nil
return true, nil
default:
return false, errCSIParseError
}
}
return false, nil
}
// outputNormal provides 8 different colors:
// black, red, green, yellow, blue, magenta, cyan, white
func (ei *escapeInterpreter) outputNormal() error {
for _, param := range ei.csiParam {
p, err := strconv.Atoi(param)
if err != nil {
return errCSIParseError
}
switch {
case p >= 30 && p <= 37:
ei.curFgColor = Attribute(p - 30 + 1)
case p == 39:
ei.curFgColor = ColorDefault
case p >= 40 && p <= 47:
ei.curBgColor = Attribute(p - 40 + 1)
case p == 49:
ei.curBgColor = ColorDefault
case p == 1:
ei.curFgColor |= AttrBold
case p == 4:
ei.curFgColor |= AttrUnderline
case p == 7:
ei.curFgColor |= AttrReverse
case p == 0:
ei.curFgColor = ColorDefault
ei.curBgColor = ColorDefault
}
}
return nil
}
// output256 allows you to leverage the 256-colors terminal mode:
// 0x01 - 0x08: the 8 colors as in OutputNormal
// 0x09 - 0x10: Color* | AttrBold
// 0x11 - 0xe8: 216 different colors
// 0xe9 - 0x1ff: 24 different shades of grey
func (ei *escapeInterpreter) output256() error {
if len(ei.csiParam) < 3 {
return ei.outputNormal()
}
mode, err := strconv.Atoi(ei.csiParam[1])
if err != nil {
return errCSIParseError
}
if mode != 5 {
return ei.outputNormal()
}
for _, param := range splitFgBg(ei.csiParam) {
fgbg, err := strconv.Atoi(param[0])
if err != nil {
return errCSIParseError
}
color, err := strconv.Atoi(param[2])
if err != nil {
return errCSIParseError
}
switch fontEffect(fgbg) {
case setForegroundColor:
ei.curFgColor = Attribute(color + 1)
for _, s := range param[3:] {
p, err := strconv.Atoi(s)
if err != nil {
return errCSIParseError
}
switch fontEffect(p) {
case bold:
ei.curFgColor |= AttrBold
case underline:
ei.curFgColor |= AttrUnderline
case reverse:
ei.curFgColor |= AttrReverse
}
}
case setBackgroundColor:
ei.curBgColor = Attribute(color + 1)
default:
return errCSIParseError
}
}
return nil
}
func splitFgBg(params []string) [][]string {
var out [][]string
var current []string
for _, p := range params {
if len(current) == 3 && (p == "48" || p == "38") {
out = append(out, current)
current = []string{}
}
current = append(current, p)
}
if len(current) > 0 {
out = append(out, current)
}
return out
}
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