Add JSON text renderer (#1086)

* Add JsonText widget to render highlighted JSON

Closes #1051

src/Spectre.Console/Internal/Extensions/CharExtensions.cs

@@ -0,0 +1,9 @@
+namespace Spectre.Console.Internal;
+
+internal static partial class CharExtensions
+{
+    public static bool IsDigit(this char character, int min = 0)
+    {
+        return char.IsDigit(character) && character >= (char)min;
+    }
+}

src/Spectre.Console/Internal/Extensions/EnumerableExtensions.cs

@@ -0,0 +1,127 @@
+namespace Spectre.Console;
+
+internal static class EnumerableExtensions
+{
+    // List.Reverse clashes with IEnumerable<T>.Reverse, so this method only exists
+    // so we won't have to cast List<T> to IEnumerable<T>.
+    public static IEnumerable<T> ReverseEnumerable<T>(this IEnumerable<T> source)
+    {
+        if (source is null)
+        {
+            throw new ArgumentNullException(nameof(source));
+        }
+
+        return source.Reverse();
+    }
+
+    public static bool None<T>(this IEnumerable<T> source, Func<T, bool> predicate)
+    {
+        return !source.Any(predicate);
+    }
+
+    public static IEnumerable<T> Repeat<T>(this IEnumerable<T> source, int count)
+    {
+        while (count-- > 0)
+        {
+            foreach (var item in source)
+            {
+                yield return item;
+            }
+        }
+    }
+
+    public static int IndexOf<T>(this IEnumerable<T> source, T item)
+        where T : class
+    {
+        var index = 0;
+        foreach (var candidate in source)
+        {
+            if (candidate == item)
+            {
+                return index;
+            }
+
+            index++;
+        }
+
+        return -1;
+    }
+
+    public static int GetCount<T>(this IEnumerable<T> source)
+    {
+        if (source is IList<T> list)
+        {
+            return list.Count;
+        }
+
+        if (source is T[] array)
+        {
+            return array.Length;
+        }
+
+        return source.Count();
+    }
+
+    public static void ForEach<T>(this IEnumerable<T> source, Action<T> action)
+    {
+        foreach (var item in source)
+        {
+            action(item);
+        }
+    }
+
+    public static bool AnyTrue(this IEnumerable<bool> source)
+    {
+        return source.Any(b => b);
+    }
+
+    public static IEnumerable<(int Index, bool First, bool Last, T Item)> Enumerate<T>(this IEnumerable<T> source)
+    {
+        if (source is null)
+        {
+            throw new ArgumentNullException(nameof(source));
+        }
+
+        return Enumerate(source.GetEnumerator());
+    }
+
+    public static IEnumerable<(int Index, bool First, bool Last, T Item)> Enumerate<T>(this IEnumerator<T> source)
+    {
+        if (source is null)
+        {
+            throw new ArgumentNullException(nameof(source));
+        }
+
+        var first = true;
+        var last = !source.MoveNext();
+        T current;
+
+        for (var index = 0; !last; index++)
+        {
+            current = source.Current;
+            last = !source.MoveNext();
+            yield return (index, first, last, current);
+            first = false;
+        }
+    }
+
+    public static IEnumerable<TResult> SelectIndex<T, TResult>(this IEnumerable<T> source, Func<T, int, TResult> func)
+    {
+        return source.Select((value, index) => func(value, index));
+    }
+
+#if !NET6_0_OR_GREATER
+    public static IEnumerable<(TFirst First, TSecond Second)> Zip<TFirst, TSecond>(
+        this IEnumerable<TFirst> source, IEnumerable<TSecond> first)
+    {
+        return source.Zip(first, (first, second) => (first, second));
+    }
+#endif
+
+    public static IEnumerable<(TFirst First, TSecond Second, TThird Third)> ZipThree<TFirst, TSecond, TThird>(
+        this IEnumerable<TFirst> first, IEnumerable<TSecond> second, IEnumerable<TThird> third)
+    {
+        return first.Zip(second, (a, b) => (a, b))
+            .Zip(third, (a, b) => (a.a, a.b, b));
+    }
+}

src/Spectre.Console/Internal/Ratio.cs

@@ -89,7 +89,7 @@ internal static class Ratio
         var totalRemaining = total;
         var result = new List<int>();
 
-        foreach (var (ratio, maximum, value) in ratios.Zip(maximums, values))
+        foreach (var (ratio, maximum, value) in ratios.ZipThree(maximums, values))
         {
             if (ratio != 0 && totalRatio > 0)
             {

src/Spectre.Console/Internal/Text/StringBuffer.cs

@@ -23,11 +23,22 @@ internal sealed class StringBuffer : IDisposable
         _reader.Dispose();
     }
 
+    public char Expect(char character)
+    {
+        var read = Read();
+        if (read != character)
+        {
+            throw new InvalidOperationException($"Expected '{character}', but found '{read}'");
+        }
+
+        return read;
+    }
+
     public char Peek()
     {
         if (Eof)
         {
-            throw new InvalidOperationException("Tried to peek past the end of the text.");
+            return '\0';
         }
 
         return (char)_reader.Peek();
@@ -37,7 +48,7 @@ internal sealed class StringBuffer : IDisposable
     {
         if (Eof)
         {
-            throw new InvalidOperationException("Tried to read past the end of the text.");
+            return '\0';
         }
 
         Position++;