Migrate the parser for cases to a separate class (ForNeVeR#100)

src/WpfMath/Parsers/MatrixCommandParser.cs

@@ -0,0 +1,29 @@
+using WpfMath.Atoms;
+using WpfMath.Exceptions;
+
+namespace WpfMath.Parsers
+{
+    /// <summary>A parser for matrix-like constructs.</summary>
+    internal class MatrixCommandParser : ICommandParser
+    {
+        public CommandProcessingResult ProcessCommand(CommandContext context)
+        {
+            var position = context.ArgumentsStartPosition;
+            var source = context.CommandSource;
+
+            if (position == source.Length)
+                throw new TexParseException("illegal end!");
+
+            var matrixSource = TexFormulaParser.ReadElement(source, ref position);
+
+            var cells = context.Parser.GetMatrixData(context.Formula, matrixSource);
+            var matrix = new MatrixAtom(matrixSource, cells, MatrixCellAlignment.Left);
+            var atom = new FencedAtom(
+                matrixSource,
+                matrix,
+                TexFormulaParser.GetDelimiterSymbol("lbrace", null),
+                null);
+            return new CommandProcessingResult(atom, position);
+        }
+    }
+}

src/WpfMath/Parsers/StandardCommands.cs

@@ -23,6 +23,7 @@ public CommandProcessingResult ProcessCommand(CommandContext context)
 
         public static IReadOnlyDictionary<string, ICommandParser> Dictionary = new Dictionary<string, ICommandParser>
         {
+            ["cases"] = new MatrixCommandParser(),
             ["underline"] = new UnderlineCommand()
         };
     }

src/WpfMath/TexFormulaParser.cs

@@ -34,7 +34,6 @@ public class TexFormulaParser
         /// </summary>
         private static readonly HashSet<string> embeddedCommands = new HashSet<string>
         {
-            "cases",
             "color",
             "colorbox",
             "frac",
@@ -343,23 +342,6 @@ private Atom ProcessCommand(
             SourceSpan source;
             switch (command)
             {
-                case "cases":
-                    {
-                        if (position == value.Length)
-                            throw new TexParseException("illegal end!");
-                        SkipWhiteSpace(value, ref position);
-
-                        var matrixsource = ReadElement(value, ref position);
-
-                        var cells = GetMatrixData(formula, matrixsource);
-                        var matrix = new MatrixAtom(matrixsource, cells, MatrixCellAlignment.Left);
-                        return new FencedAtom(
-                            matrixsource,
-                            matrix,
-                            GetDelimiterSymbol("lbrace", null),
-                            null);
-                    }
-
                 case "frac":
                     {
                         var numeratorFormula = this.Parse(ReadElement(value, ref position), formula.TextStyle);
@@ -511,7 +493,8 @@ private Atom ProcessCommand(
         /// Retrives the cells of a matrix from a given source.
         /// </summary>
         /// <param name="matrixsource">The source to retrieve the 2D-Array of atoms from.</param>
-        private List<List<Atom>> GetMatrixData(TexFormula formula, SourceSpan matrixsource)
+        // TODO[F]: Remove this method completely, shouldn't be internal
+        internal List<List<Atom>> GetMatrixData(TexFormula formula, SourceSpan matrixsource)
         {
             // rowindent: how many characters the next row should skip for its sourcespan to start
             var rowdata = new List<List<(StringBuilder builder, int rowindent)>>