// 2024 - Christian Lee Seibold
// License: MIT
package main
import (
"bufio"
"fmt"
"strings"
"unicode"
)
func main() {
reader := strings.NewReader("This is **some text** to show _how_ italics ** and bold __ could _**work.**_ along with `monospace.`")
printWithEmphasisAndStrong(bufio.NewReader(reader))
}
// Emphasis - one underscore
// Strong - two asterisks
// Monospace - one backtick (`)
func printWithEmphasisAndStrong(reader *bufio.Reader) {
previousRune := '\n'
inStrong := false
inEmphasis := false
inMonospace := false
for {
r, _, err := reader.ReadRune()
if err != nil {
// EOF - reset everything, since this should be the end of the paragraph
fmt.Printf("\x1B[m")
return
}
if r == '`' || (!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,
// print the runes and continue
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 == '*' {
fmt.Printf("*")
_ = reader.UnreadRune()
previousRune = '*'
continue
}
if (!unicode.IsSpace(r) && r != toggleRune) || (!unicode.IsSpace(previousRune) && previousRune != toggleRune) {
switch toggleRune {
case '`':
if inMonospace {
// Reset
inMonospace = false
fmt.Printf("\x1B[22m")
// Since 22m disables bold *and* dim, set bold again if necessary
if inStrong {
fmt.Printf("\x1B[1m")
}
} else {
// Set
inMonospace = true
fmt.Printf("\x1B[2m")
}
case '*':
if inStrong {
// Reset
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
inStrong = true
fmt.Printf("\x1B[1m")
}
case '_':
if inEmphasis {
// Reset
inEmphasis = false
fmt.Printf("\x1B[23m")
} else {
// Set
inEmphasis = true
fmt.Printf("\x1B[3m") // Replace this with 4m for underline in terminals that don't support emphasis.
}
}
_ = reader.UnreadRune()
if unread {
previousRune = toggleRune
}
} else {
// Not a toggle, print the toggle and unread the rune
fmt.Printf("%s", toggle)
_ = reader.UnreadRune()
previousRune = toggleRune
}
} else {
fmt.Printf("%c", r)
previousRune = r
}
}
}
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