// 2024 - Christian Lee Seibold
// License: MIT
package main
import (
"bufio"
"fmt"
"unicode"
)
type TextParsingState struct {
previousRune rune
inStrong bool
inEmphasis bool
inMonospace bool
}
// Emphasis - one asterisk or one underscore
// Strong - two asterisks (or two underscores)
// Monospace - one backtick (`)
// Nesting is not supported. Pass in a bool to not reset the state on EOF
func (state *TextParsingState) print_markdown(reader *bufio.Reader, noEOFReset bool) {
isBoundary := func(r rune) bool {
return unicode.IsSpace(r) || unicode.IsPunct(r)
}
state.previousRune = '\n'
for {
r, _, err := reader.ReadRune()
if err != nil {
// EOF - reset everything, since this should be the end of the paragraph
if !noEOFReset {
fmt.Printf("\x1B[m")
state.inStrong = false
state.inEmphasis = false
state.inMonospace = false
}
return
}
if r == '`' || (!state.inMonospace && (r == '*' || r == '_')) {
toggleRune := r
toggle := string(r)
unread := true
// Get the next rune
r, _, err = reader.ReadRune()
if err != nil {
// Set rune to new line, so it registers as a whitespace.
r = '\n'
unread = false
}
// If r is an asterisk, we require two for the toggle, so read the next rune. Otherwise, if just one asterisk,
// continue on as it's an italic.
if toggleRune == '*' && r == '*' {
toggle = "**"
r, _, err = reader.ReadRune()
if err != nil {
// Set rune to new line, so it registers as a whitespace.
r = '\n'
unread = false
}
} else if toggleRune == '_' && r == '_' {
toggle = "__"
r, _, err = reader.ReadRune()
if err != nil {
// Set rune to new line, so it registers as a whitespace.
r = '\n'
unread = false
}
}
if (isBoundary(state.previousRune) && !unicode.IsSpace(r) && r != toggleRune) || (!unicode.IsSpace(state.previousRune) && state.previousRune != toggleRune && isBoundary(r)) {
switch toggleRune {
case '`':
if state.inMonospace {
// Reset
state.inMonospace = false
fmt.Printf("\x1B[22m")
// Since 22m disables bold *and* dim, set bold again if necessary
if state.inStrong {
fmt.Printf("\x1B[1m")
}
} else {
// Set
state.inMonospace = true
fmt.Printf("\x1B[2m")
}
case '*':
if toggle == "**" { // Bold
if state.inStrong {
// Reset
state.inStrong = false
// 22m disables bold *and* dim. However, we cannot use strong inside monospace toggles, so this doesn't matter.
fmt.Printf("\x1B[22m")
} else {
// Set
state.inStrong = true
fmt.Printf("\x1B[1m")
}
} else { // Italics
if state.inEmphasis {
// Reset
state.inEmphasis = false
fmt.Printf("\x1B[23m")
} else {
// Set
state.inEmphasis = true
fmt.Printf("\x1B[3m") // Replace this with 4m for underline in terminals that don't support emphasis.
}
}
case '_':
if toggle == "__" { // Bold
if state.inStrong {
// Reset
state.inStrong = false
// 22m disables bold *and* dim. However, we cannot use strong inside monospace toggles, so this doesn't matter.
fmt.Printf("\x1B[22m")
} else {
// Set
state.inStrong = true
fmt.Printf("\x1B[1m")
}
} else { // Italics
if state.inEmphasis {
// Reset
state.inEmphasis = false
fmt.Printf("\x1B[23m")
} else {
// Set
state.inEmphasis = true
fmt.Printf("\x1B[3m") // Replace this with 4m for underline in terminals that don't support emphasis.
}
}
}
_ = reader.UnreadRune()
if unread {
state.previousRune = toggleRune
}
} else {
// Not a toggle, print the toggle and unread the rune
fmt.Printf("%s", toggle)
_ = reader.UnreadRune()
state.previousRune = toggleRune
}
} else {
fmt.Printf("%c", r)
state.previousRune = r
}
}
}
// Emphasis - one underscore
// Strong - two asterisks
// Monospace - one backtick (`)
// Pass in a bool to not reset the state on EOF
func (state *TextParsingState) print_scroll(reader *bufio.Reader, noEOFReset bool) {
isWhitespace := unicode.IsSpace
state.previousRune = '\n'
for {
r, _, err := reader.ReadRune()
if err != nil {
// EOF - reset everything, since this should be the end of the paragraph
if !noEOFReset {
fmt.Printf("\x1B[m")
state.inStrong = false
state.inMonospace = false
state.inEmphasis = false
}
return
}
if r == '`' || (!state.inMonospace && (r == '*' || r == '_')) {
toggleRune := r
toggle := string(r)
unread := true
// Get the next rune
r, _, err = reader.ReadRune()
if err != nil {
// Set rune to space, so it registers as a whitespace.
r = ' '
unread = false
}
// If r is an asterisk, we require two for the toggle, so read the next rune. Otherwise, if just one asterisk,
// print the runes and continue
if toggleRune == '*' && r == '*' {
toggle = "**"
r, _, err = reader.ReadRune()
if err != nil {
// Set rune to space, so it registers as a whitespace.
r = ' '
unread = false
}
} else if toggleRune == '*' {
fmt.Printf("*")
_ = reader.UnreadRune()
state.previousRune = '*'
continue
}
if (!isWhitespace(r) && r != toggleRune) || (!isWhitespace(state.previousRune) && state.previousRune != toggleRune) {
switch toggleRune {
case '`':
if state.inMonospace {
// Reset
state.inMonospace = false
fmt.Printf("\x1B[22m")
// Since 22m disables bold *and* dim, set bold again if necessary
if state.inStrong {
fmt.Printf("\x1B[1m")
}
} else {
// Set
state.inMonospace = true
fmt.Printf("\x1B[2m")
}
case '*':
if state.inStrong {
// Reset
state.inStrong = false
// 22m disables bold *and* dim. However, we cannot use strong inside monospace toggles, so this doesn't matter.
fmt.Printf("\x1B[22m")
} else {
// Set
state.inStrong = true
fmt.Printf("\x1B[1m")
}
case '_':
if state.inEmphasis {
// Reset
state.inEmphasis = false
fmt.Printf("\x1B[23m")
} else {
// Set
state.inEmphasis = true
fmt.Printf("\x1B[3m") // Replace this with 4m for underline in terminals that don't support emphasis.
}
}
_ = reader.UnreadRune()
if unread {
state.previousRune = toggleRune
}
} else {
// Not a toggle, print the toggle and unread the rune
fmt.Printf("%s", toggle)
_ = reader.UnreadRune()
state.previousRune = toggleRune
}
} else {
fmt.Printf("%c", r)
state.previousRune = r
}
}
}
// Emphasis - one underscore
// Strong - one asterisk
// Monospace - one backtick (`)
// Pass in a bool to not reset the state on EOF
func (state *TextParsingState) print_asciidoc(reader *bufio.Reader, noEOFReset bool) {
isWhitespace := unicode.IsSpace
state.previousRune = '\n'
for {
r, _, err := reader.ReadRune()
if err != nil {
// EOF - reset everything, since this should be the end of the paragraph
if !noEOFReset {
fmt.Printf("\x1B[m")
state.inStrong = false
state.inMonospace = false
state.inEmphasis = false
}
return
}
if r == '`' || (!state.inMonospace && (r == '*' || r == '_')) {
toggleRune := r
toggle := string(r)
unread := true
// Get the next rune
r, _, err = reader.ReadRune()
if err != nil {
// Set rune to space, so it registers as a whitespace.
r = ' '
unread = false
}
if (!isWhitespace(r) && r != toggleRune) || (!isWhitespace(state.previousRune) && state.previousRune != toggleRune) {
switch toggleRune {
case '`':
if state.inMonospace {
// Reset
state.inMonospace = false
fmt.Printf("\x1B[22m")
// Since 22m disables bold *and* dim, set bold again if necessary
if state.inStrong {
fmt.Printf("\x1B[1m")
}
} else {
// Set
state.inMonospace = true
fmt.Printf("\x1B[2m")
}
case '*':
if state.inStrong {
// Reset
state.inStrong = false
// 22m disables bold *and* dim. However, we cannot use strong inside monospace toggles, so this doesn't matter.
fmt.Printf("\x1B[22m")
} else {
// Set
state.inStrong = true
fmt.Printf("\x1B[1m")
}
case '_':
if state.inEmphasis {
// Reset
state.inEmphasis = false
fmt.Printf("\x1B[23m")
} else {
// Set
state.inEmphasis = true
fmt.Printf("\x1B[3m") // Replace this with 4m for underline in terminals that don't support emphasis.
}
}
_ = reader.UnreadRune()
if unread {
state.previousRune = toggleRune
}
} else {
// Not a toggle, print the toggle and unread the rune
fmt.Printf("%s", toggle)
_ = reader.UnreadRune()
state.previousRune = toggleRune
}
} else {
fmt.Printf("%c", r)
state.previousRune = r
}
}
}
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