| 1 | using System.Globalization; |
| 2 | |
| 3 | namespace CascadeIDE.Services.Presentation; |
| 4 | |
| 5 | /// <summary>Парсер строки <c>presentation</c> / <c>zone_screen_layout</c> (EBNF — ADR 0017). Внутри одного экрана <c>(…)</c> — <see cref="PresentationInnerEtoGrammar"/> (Eto.Parse); перед разбором содержимое скобок нормализуется: все символы <see cref="char.IsWhiteSpace(char)"/> удаляются (удобочитаемые пробелы вокруг <c>+</c> и т.д.). Литералы якорей задаются в TOML (<see cref="PresentationGrammarTokens"/>).</summary> |
| 6 | public static class PresentationParser |
| 7 | { |
| 8 | private const double WeightSumTolerance = 1e-6; |
| 9 | |
| 10 | /// <summary>Пустая или пробельная строка — пустой список экранов (снаружи: «не задано»).</summary> |
| 11 | public static PresentationParseResult Parse(string? presentation, PresentationGrammarTokens grammar) |
| 12 | { |
| 13 | if (string.IsNullOrWhiteSpace(presentation)) |
| 14 | return PresentationParseResult.Ok(Array.Empty<IReadOnlyList<PresentationAnchorSlot>>()); |
| 15 | |
| 16 | var text = presentation.Trim(); |
| 17 | var screens = new List<IReadOnlyList<PresentationAnchorSlot>>(); |
| 18 | var i = 0; |
| 19 | SkipScreenSeparators(text, grammar.ScreenSeparator, ref i); |
| 20 | |
| 21 | while (i < text.Length) |
| 22 | { |
| 23 | if (text[i] != grammar.ScreenOpen) |
| 24 | { |
| 25 | return PresentationParseResult.Fail( |
| 26 | string.Format(CultureInfo.InvariantCulture, "Ожидался '{0}' начала экрана на позиции {1}.", grammar.ScreenOpen, i)); |
| 27 | } |
| 28 | |
| 29 | i++; |
| 30 | var startInner = i; |
| 31 | while (i < text.Length && text[i] != grammar.ScreenClose) |
| 32 | i++; |
| 33 | |
| 34 | if (i >= text.Length) |
| 35 | return PresentationParseResult.Fail($"Не найден закрывающий символ '{grammar.ScreenClose}' для экрана."); |
| 36 | |
| 37 | var inner = text.AsSpan(startInner, i - startInner); |
| 38 | i++; |
| 39 | |
| 40 | var anchors = ParseAnchorsInner(inner, grammar); |
| 41 | if (anchors.Error is { } err) |
| 42 | return PresentationParseResult.Fail(err); |
| 43 | |
| 44 | screens.Add(anchors.Value); |
| 45 | |
| 46 | SkipScreenSeparators(text, grammar.ScreenSeparator, ref i); |
| 47 | } |
| 48 | |
| 49 | return PresentationParseResult.Ok(screens); |
| 50 | } |
| 51 | |
| 52 | private static void SkipScreenSeparators(string text, string separator, ref int i) |
| 53 | { |
| 54 | while (i < text.Length) |
| 55 | { |
| 56 | if (separator.Length > 0 && i + separator.Length <= text.Length && text.AsSpan(i).StartsWith(separator, StringComparison.Ordinal)) |
| 57 | { |
| 58 | i += separator.Length; |
| 59 | continue; |
| 60 | } |
| 61 | |
| 62 | if (char.IsWhiteSpace(text[i])) |
| 63 | { |
| 64 | i++; |
| 65 | continue; |
| 66 | } |
| 67 | |
| 68 | break; |
| 69 | } |
| 70 | } |
| 71 | |
| 72 | private static (List<PresentationAnchorSlot> Value, string? Error) ParseAnchorsInner(ReadOnlySpan<char> inner, PresentationGrammarTokens grammar) |
| 73 | { |
| 74 | var list = new List<PresentationAnchorSlot>(); |
| 75 | var s = CollapseInnerWhitespace(inner); |
| 76 | if (s.Length == 0) |
| 77 | return (list, "Пустой список якорей внутри границ экрана."); |
| 78 | |
| 79 | var innerGrammar = PresentationInnerEtoGrammar.GetOrCreate(grammar); |
| 80 | var eto = innerGrammar.Match(s); |
| 81 | if (!eto.Success) |
| 82 | { |
| 83 | return (list, "Неверная последовательность якорей или разделителей внутри экрана."); |
| 84 | } |
| 85 | |
| 86 | var sSpan = s.AsSpan(); |
| 87 | var i = 0; |
| 88 | while (i < sSpan.Length) |
| 89 | { |
| 90 | if (list.Count > 0) |
| 91 | { |
| 92 | if (!TrySkipZoneSeparator(sSpan, grammar, ref i)) |
| 93 | return (list, $"Ожидался разделитель якорей на позиции {i}."); |
| 94 | } |
| 95 | |
| 96 | double? weight = null; |
| 97 | if (TryConsumeWeight(sSpan, ref i, out var w)) |
| 98 | weight = w; |
| 99 | |
| 100 | if (!TryConsumeAnchorToken(sSpan, grammar, ref i, out var kind)) |
| 101 | return (list, $"Неизвестный якорь на позиции {i}."); |
| 102 | |
| 103 | list.Add(new PresentationAnchorSlot(kind, weight)); |
| 104 | } |
| 105 | |
| 106 | if (ValidateScreenWeights(list) is { } err) |
| 107 | return (list, err); |
| 108 | |
| 109 | return (list, null); |
| 110 | } |
| 111 | |
| 112 | /// <summary>Удаляет все пробельные символы внутри одного экрана <c>(…)</c> (после <see cref="ReadOnlySpan{T}.Trim()"/>).</summary> |
| 113 | private static string CollapseInnerWhitespace(ReadOnlySpan<char> inner) |
| 114 | { |
| 115 | inner = inner.Trim(); |
| 116 | if (inner.IsEmpty) |
| 117 | return string.Empty; |
| 118 | |
| 119 | var remove = 0; |
| 120 | for (var j = 0; j < inner.Length; j++) |
| 121 | { |
| 122 | if (char.IsWhiteSpace(inner[j])) |
| 123 | remove++; |
| 124 | } |
| 125 | |
| 126 | if (remove == 0) |
| 127 | return inner.ToString(); |
| 128 | |
| 129 | return string.Create(inner.Length - remove, inner, static (dst, src) => |
| 130 | { |
| 131 | var d = 0; |
| 132 | for (var j = 0; j < src.Length; j++) |
| 133 | { |
| 134 | if (!char.IsWhiteSpace(src[j])) |
| 135 | dst[d++] = src[j]; |
| 136 | } |
| 137 | }); |
| 138 | } |
| 139 | |
| 140 | private static string? ValidateScreenWeights(List<PresentationAnchorSlot> list) |
| 141 | { |
| 142 | if (list.Count == 0) |
| 143 | return null; |
| 144 | |
| 145 | if (list.Count == 1) |
| 146 | return list[0].Weight is not null |
| 147 | ? "Один якорь в группе не может иметь коэффициент." |
| 148 | : null; |
| 149 | |
| 150 | var any = false; |
| 151 | var all = true; |
| 152 | for (var i = 0; i < list.Count; i++) |
| 153 | { |
| 154 | var has = list[i].Weight.HasValue; |
| 155 | if (has) |
| 156 | any = true; |
| 157 | else |
| 158 | all = false; |
| 159 | } |
| 160 | |
| 161 | if (any && !all) |
| 162 | return "Смешение якорей с коэффициентами и без в одной группе недопустимо."; |
| 163 | |
| 164 | if (!any) |
| 165 | return null; |
| 166 | |
| 167 | var sum = 0.0; |
| 168 | for (var i = 0; i < list.Count; i++) |
| 169 | sum += list[i].Weight!.Value; |
| 170 | |
| 171 | if (Math.Abs(sum - 1.0) > WeightSumTolerance) |
| 172 | { |
| 173 | return string.Format( |
| 174 | CultureInfo.InvariantCulture, |
| 175 | "Сумма коэффициентов в группе должна быть 1, получено {0}.", |
| 176 | sum); |
| 177 | } |
| 178 | |
| 179 | return null; |
| 180 | } |
| 181 | |
| 182 | /// <summary>Десятичная точка U+002E, инвариантная культура; во входной строке пробелы внутри <c>(…)</c> удаляются до разбора (<see cref="CollapseInnerWhitespace"/>).</summary> |
| 183 | private static bool TryConsumeWeight(ReadOnlySpan<char> s, ref int i, out double weight) |
| 184 | { |
| 185 | weight = 0; |
| 186 | if (i >= s.Length) |
| 187 | return false; |
| 188 | |
| 189 | var c = s[i]; |
| 190 | if (!char.IsDigit(c) && c != '.') |
| 191 | return false; |
| 192 | |
| 193 | var start = i; |
| 194 | while (i < s.Length && (char.IsDigit(s[i]) || s[i] == '.')) |
| 195 | i++; |
| 196 | |
| 197 | var numSpan = s.Slice(start, i - start); |
| 198 | if (numSpan.Length == 0) |
| 199 | { |
| 200 | i = start; |
| 201 | return false; |
| 202 | } |
| 203 | |
| 204 | if (!double.TryParse(numSpan, NumberStyles.Float, CultureInfo.InvariantCulture, out weight)) |
| 205 | { |
| 206 | i = start; |
| 207 | return false; |
| 208 | } |
| 209 | |
| 210 | if (weight <= 0 || double.IsNaN(weight) || double.IsInfinity(weight)) |
| 211 | { |
| 212 | i = start; |
| 213 | return false; |
| 214 | } |
| 215 | |
| 216 | return true; |
| 217 | } |
| 218 | |
| 219 | private static bool TrySkipZoneSeparator(ReadOnlySpan<char> s, PresentationGrammarTokens g, ref int i) |
| 220 | { |
| 221 | if (g.ZoneSeparator.Length > 0 && RemainingStartsWith(s, i, g.ZoneSeparator)) |
| 222 | { |
| 223 | i += g.ZoneSeparator.Length; |
| 224 | return true; |
| 225 | } |
| 226 | |
| 227 | return false; |
| 228 | } |
| 229 | |
| 230 | private static bool TryConsumeAnchorToken(ReadOnlySpan<char> s, PresentationGrammarTokens g, ref int i, out PresentationAnchorKind kind) |
| 231 | { |
| 232 | kind = default; |
| 233 | var r = s.Slice(i); |
| 234 | |
| 235 | var pairs = new (string Token, PresentationAnchorKind K)[] |
| 236 | { |
| 237 | (g.PfdZoneIdentifier, PresentationAnchorKind.Pfd), |
| 238 | (g.ForwardZoneIdentifier, PresentationAnchorKind.Forward), |
| 239 | (g.MfdZoneIdentifier, PresentationAnchorKind.Mfd), |
| 240 | }; |
| 241 | |
| 242 | Array.Sort(pairs, static (a, b) => b.Token.Length.CompareTo(a.Token.Length)); |
| 243 | |
| 244 | foreach (var (token, k) in pairs) |
| 245 | { |
| 246 | if (token.Length == 0) |
| 247 | continue; |
| 248 | |
| 249 | if (token.Length == 1) |
| 250 | { |
| 251 | if (r.Length < 1) |
| 252 | continue; |
| 253 | if (char.ToUpperInvariant(r[0]) == char.ToUpperInvariant(token[0])) |
| 254 | { |
| 255 | i += 1; |
| 256 | kind = k; |
| 257 | return true; |
| 258 | } |
| 259 | |
| 260 | continue; |
| 261 | } |
| 262 | |
| 263 | if (r.StartsWith(token, StringComparison.Ordinal)) |
| 264 | { |
| 265 | i += token.Length; |
| 266 | kind = k; |
| 267 | return true; |
| 268 | } |
| 269 | } |
| 270 | |
| 271 | return false; |
| 272 | } |
| 273 | |
| 274 | private static bool RemainingStartsWith(ReadOnlySpan<char> s, int i, string sep) |
| 275 | { |
| 276 | if (sep.Length == 0 || i + sep.Length > s.Length) |
| 277 | return false; |
| 278 | return s.Slice(i, sep.Length).SequenceEqual(sep.AsSpan()); |
| 279 | } |
| 280 | } |
| 281 | |