115 lines
4.8 KiB
C#
115 lines
4.8 KiB
C#
using System.Text;
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namespace LehrerApp.Templating;
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public sealed record TemplateRichTextRun(string Text, string? Placeholder, string? Format,
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bool Bold, bool Italic, bool Underline)
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{
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public bool IsPlaceholder => Placeholder is not null;
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}
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public static class TemplateRichText
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{
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public static IReadOnlyList<TemplateRichTextRun> Parse(string source)
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{
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var runs = new List<TemplateRichTextRun>();
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var literal = new StringBuilder();
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var styles = new Stack<char>();
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void Flush()
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{
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if (literal.Length == 0) return;
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AddRun(runs, new(literal.ToString(), null, null,
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styles.Contains('b'), styles.Contains('i'), styles.Contains('u')));
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literal.Clear();
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}
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for (var index = 0; index < source.Length;)
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{
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if (source[index] == '\\' && index + 1 < source.Length
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&& source[index + 1] is '\\' or '[' or '$')
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{ literal.Append(source[index + 1]); index += 2; continue; }
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if (source[index] == '$' && SystemVariables.TryRead(source, index, out var systemLength))
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{
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literal.Append(source, index, systemLength);
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index += systemLength;
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continue;
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}
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if (TryTag(source, index, out var tag, out var closing, out var tagLength))
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{
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Flush();
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if (closing)
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{
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if (styles.Count == 0 || styles.Peek() != tag)
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throw new InvalidDataException($"Rich-Text-Tag [/{tag}] ist nicht passend geöffnet.");
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styles.Pop();
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}
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else styles.Push(tag);
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index += tagLength; continue;
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}
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if (source[index] == '$' && TryPlaceholder(source, index, out var name, out var format, out var length))
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{
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Flush();
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AddRun(runs, new("", name, format,
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styles.Contains('b'), styles.Contains('i'), styles.Contains('u')));
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index += length; continue;
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}
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literal.Append(source[index++]);
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}
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Flush();
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if (styles.Count > 0) throw new InvalidDataException($"Rich-Text-Tag [{styles.Peek()}] wurde nicht geschlossen.");
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return runs;
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}
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public static IReadOnlyList<string> UsedPlaceholders(string source) => Parse(source)
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.Where(x => x.Placeholder is not null).Select(x => x.Placeholder!).Distinct(StringComparer.Ordinal).ToList();
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private static bool TryTag(string source, int index, out char tag, out bool closing, out int length)
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{
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tag = default; closing = false; length = 0;
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if (index + 2 < source.Length && source[index] == '[' && source[index + 2] == ']'
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&& source[index + 1] is 'b' or 'i' or 'u')
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{ tag = source[index + 1]; length = 3; return true; }
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if (index + 3 < source.Length && source[index] == '[' && source[index + 1] == '/'
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&& source[index + 3] == ']' && source[index + 2] is 'b' or 'i' or 'u')
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{ tag = source[index + 2]; closing = true; length = 4; return true; }
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return false;
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}
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private static bool TryPlaceholder(string source, int index, out string name, out string? format, out int length)
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{
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name = ""; format = null; length = 0;
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if (index + 1 >= source.Length) return false;
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if (source[index + 1] == '{')
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{
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var end = source.IndexOf('}', index + 2);
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if (end < 0) throw new InvalidDataException("Platzhalter mit '${' wurde nicht mit '}' geschlossen.");
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var content = source[(index + 2)..end];
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var parts = content.Split('|', 2);
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name = parts[0].Trim(); format = parts.Length == 2 ? parts[1] : null;
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if (name.Length == 0) throw new InvalidDataException("Ein eingebetteter Platzhaltername darf nicht leer sein.");
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length = end - index + 1; return true;
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}
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if (!IsNameStart(source[index + 1])) return false;
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var cursor = index + 2;
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while (cursor < source.Length && IsNamePart(source[cursor])) cursor++;
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name = source[(index + 1)..cursor]; length = cursor - index; return true;
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}
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private static bool IsNameStart(char value) => char.IsLetter(value) || value == '_';
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private static bool IsNamePart(char value) => char.IsLetterOrDigit(value) || value is '_' or '.' or '-';
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private static void AddRun(List<TemplateRichTextRun> runs, TemplateRichTextRun run)
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{
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if (!run.IsPlaceholder && runs.LastOrDefault() is { IsPlaceholder: false } previous
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&& previous.Bold == run.Bold && previous.Italic == run.Italic && previous.Underline == run.Underline)
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runs[^1] = previous with { Text = previous.Text + run.Text };
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else runs.Add(run);
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}
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}
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