public static string ToRomaji(string input, WanaKanaOptions?options = null)
{
if (input is null)
{
throw new ArgumentNullException(nameof(input));
}
options ??= new WanaKanaOptions();
if (input.Length == 0)
{
return(string.Empty);
}
// just throw away the substring index information and just concatenate all the kana
var romajiTokens = SplitIntoRomaji(input, options);
var builder = new StringBuilder();
foreach (var token in romajiTokens)
{
var(start, end, romaji) = token;
var makeUppercase = options.UppercaseKatakana && KatakanaChecker.IsKatakana(input.Substring(start, end - start));
builder.Append(makeUppercase ? romaji?.ToUpperInvariant() ?? string.Empty : romaji);
}
return(builder.ToString());
}
public static string KatakanaToHiragana(string input, bool isDestinationRomaji = false)
{
if (input is null)
{
throw new ArgumentNullException(nameof(input));
}
char?previousKana = null;
var builder = new StringBuilder();
for (int index = 0; index < input.Length; index++)
{
var character = input[index];
// Short circuit to avoid incorrect codeshift for 'ー' and '・'
if (SpecialCharacterChecker.IsSlashDot(character) || IsInitialLongDash(character, index) || IsKanaAsSymbol(character))
{
builder.Append(character);
// Transform long vowels: 'オー' to 'おう'
}
else if (previousKana != null && IsInnerLongDash(character, index))
{
// Transform previousKana back to romaji, and slice off the vowel
var romaji = RomajiConverter.ToRomaji(previousKana.ToString()).Last();
// However, ensure 'オー' => 'おお' => 'oo' if this is a transform on the way to romaji
if (KatakanaChecker.IsKatakana(input[index - 1]) && romaji == 'o' && isDestinationRomaji)
{
builder.Append('お');
}
else
{
builder.Append(_longVowels[romaji]);
}
}
else if (!SpecialCharacterChecker.IsLongDash(character) && KatakanaChecker.IsKatakana(character))
{
// Shift charcode.
var hiraganaCode = (character - CharacterRanges.KatakanaStart) + CharacterRanges.HiraganaStart;
var hiragana = (char)hiraganaCode;
previousKana = hiragana;
builder.Append(hiragana);
}
else
{
// Pass non katakana chars through
previousKana = null;
builder.Append(character);
}
}
return(builder.ToString());
}
/// <summary> /// Test if input is katakana. /// </summary> /// <param name="input">Input.</param> /// <returns>A value indicating whether input is katakana.</returns> public static bool IsKatakana(string input) => KatakanaChecker.IsKatakana(input);
private static string GetTokenType(char character, bool compact = false)
{
if (compact)
{
if (IsJaNumber(character))
{
return(TokenTypes.Other);
}
if (IsEnNumber(character))
{
return(TokenTypes.Other);
}
if (IsEnSpace(character))
{
return(TokenTypes.English);
}
if (SpecialCharacterChecker.IsEnglishPunctuation(character))
{
return(TokenTypes.Other);
}
if (IsJaSpace(character))
{
return(TokenTypes.Japanese);
}
if (SpecialCharacterChecker.IsJapanesePunctuation(character))
{
return(TokenTypes.Other);
}
if (JapaneseChecker.IsJapanese(character))
{
return(TokenTypes.Japanese);
}
if (RomajiChecker.IsRomaji(character))
{
return(TokenTypes.English);
}
}
else
{
if (IsJaSpace(character))
{
return(TokenTypes.Space);
}
if (IsEnSpace(character))
{
return(TokenTypes.Space);
}
if (IsJaNumber(character))
{
return(TokenTypes.JapaneseNumber);
}
if (IsEnNumber(character))
{
return(TokenTypes.EnglishNumber);
}
if (SpecialCharacterChecker.IsEnglishPunctuation(character))
{
return(TokenTypes.EnglishPunctuation);
}
if (SpecialCharacterChecker.IsJapanesePunctuation(character))
{
return(TokenTypes.JapanesePunctuation);
}
if (KanjiChecker.IsKanji(character))
{
return(TokenTypes.Kanji);
}
if (HiraganaChecker.IsHiragana(character))
{
return(TokenTypes.Hiragana);
}
if (KatakanaChecker.IsKatakana(character))
{
return(TokenTypes.Katakana);
}
if (JapaneseChecker.IsJapanese(character))
{
return(TokenTypes.Japanese);
}
if (RomajiChecker.IsRomaji(character))
{
return(TokenTypes.English);
}
}
return(TokenTypes.Other);
}
/// <summary> /// Test if input is katakana. /// </summary> /// <param name="input">Input.</param> /// <returns>A value indicating whether input is katakana.</returns> public static bool IsKatakana(char input) => KatakanaChecker.IsKatakana(input);