csharp4405de34 | 1 | using Eto.Parse; |
| 2 | |
| 3 | namespace CascadeIDE.Services.ChordNotation; |
| 4 | |
| 5 | /// <summary> |
| 6 | /// Грамматика Eto.Parse для нотации аккордов. Соответствует EBNF в <c>docs/chord-notation-cascadeide.md</c> (§ EBNF). |
| 7 | /// </summary> |
| 8 | internal static class ChordNotationGrammar |
| 9 | { |
| 10 | private static readonly Lazy<Grammar> Lazy = new(Build); |
| 11 | |
| 12 | public static Grammar Instance => Lazy.Value; |
| 13 | |
| 14 | /// <summary>Сборка fluent-грамматики (эквивалент EBNF в документе).</summary> |
| 15 | private static Grammar Build() |
| 16 | { |
| 17 | Parser mod(string s) => s; |
| 18 | var modifier = |
| 19 | mod("Alt-") | mod("C-") | mod("M-") | mod("A-") | mod("S-") | mod("D-"); |
| 20 | |
| 21 | var key = (+Terminals.LetterOrDigit).Named("key"); |
| 22 | |
| 23 | var bracketInner = modifier.Repeat(0) & key; |
| 24 | |
| 25 | var bracket = ("<" & bracketInner & ">").Named("bracket"); |
| 26 | |
| 27 | var plain = (+Terminals.LetterOrDigit).Named("plain"); |
| 28 | |
| 29 | var step = (bracket | plain).Named("step"); |
| 30 | |
| 31 | var sp = +Terminals.WhiteSpace; |
| 32 | |
| 33 | var sequence = Terminals.WhiteSpace.Repeat(0) & step & (sp & step).Repeat(0) & Terminals.WhiteSpace.Repeat(0) & Terminals.End; |
| 34 | |
| 35 | return new Grammar("chord_sequence", sequence); |
| 36 | } |
| 37 | } |
| 38 | |
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