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morse.go
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morse.go
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package kowalski
import (
"fmt"
"regexp"
"strings"
)
var morseLetters = map[string]rune {
".-": 'a',
"-...": 'b',
"-.-.": 'c',
"-..": 'd',
".": 'e',
"..-.": 'f',
"--.": 'g',
"....": 'h',
"..": 'i',
".---": 'j',
"-.-": 'k',
".-..": 'l',
"--": 'm',
"-.": 'n',
"---": 'o',
".--.": 'p',
"--.-": 'q',
".-.": 'r',
"...": 's',
"-": 't',
"..-": 'u',
"...-": 'v',
".--": 'w',
"-..-": 'x',
"-.--": 'y',
"--..": 'z',
}
var nonMorseRegexp = regexp.MustCompile("[^.\\-]")
// FromMorse takes a sequence of morse signals (as ASCII dots and hyphens) and returns a set of possible words
// that could be constructed from them.
func FromMorse(checker *SpellChecker, input string) []string {
return fromMorse(checker, nonMorseRegexp.ReplaceAllString(input, ""), "")
}
func fromMorse(checker *SpellChecker, input string, prefix string) []string {
var res []string
for p := range morseLetters {
if strings.HasPrefix(input, p) {
next := fmt.Sprintf("%s%c", prefix, morseLetters[p])
left := input[len(p):]
if len(left) == 0 && checker.Valid(next) {
res = append(res, next)
} else if len(left) > 0 && checker.Prefix(next) {
res = append(res, fromMorse(checker, left, next)...)
}
}
}
return res
}