Merge pull request #314 from mk3008/313-adding-the-tryreadword-function

Revised text reading class

src/Carbunql/Analysis/CharReader.cs

@@ -1,51 +1,93 @@
-using Cysharp.Text;
+using System.Diagnostics.CodeAnalysis;
 
 namespace Carbunql.Analysis;
 
+/// <summary>
+/// Class that processes text character by character.
+/// Reading can only be done in the forward direction, and it cannot be reversed.
+/// </summary>
 public class CharReader : IDisposable
 {
 	private bool disposedValue;
 
+	/// <summary>
+	/// Constructor for the CharReader class. Initializes a StringReader using the specified text.
+	/// </summary>
+	/// <param name="text">The text to be processed</param>
 	public CharReader(string text)
 	{
-		Text = text;
-		Reader = new StringReader(Text);
+		Reader = new StringReader(text);
 	}
 
-	public string Text { get; init; }
-
 	private StringReader Reader { get; init; }
 
-	protected char? PeekOrDefaultChar()
+	private char? PeekOrDefault()
 	{
 		var i = Reader.Peek();
 		if (i < 0) return null;
 		return (char)i;
 	}
 
-	public char ReadChar()
+	private char Read()
 	{
 		var i = Reader.Read();
 		if (i < 0) throw new EndOfStreamException();
 		return (char)i;
 	}
 
-	public char? ReadCharOrDefault(char expect)
+	/// <summary>
+	/// Reads one character. Returns false if reading is not possible.
+	/// </summary>
+	/// <param name="c">The character that was read</param>
+	/// <returns>True if reading was successful, otherwise false.</returns>
+	public bool TryRead([MaybeNullWhen(false)] out char c)
+	{
+		c = default;
+
+		var i = Reader.Peek();
+		if (i < 0) return false;
+		c = Read();
+		return true;
+	}
+
+	/// <summary>
+	/// Reads one character. Reading is canceled and false is returned if the read character is different from the expected value.
+	/// </summary>
+	/// <param name="expect">The expected value</param>
+	/// <param name="c">The character that was read</param>
+	/// <returns>True if the read character matches the expected value, otherwise false</returns>
+	public bool TryRead(char expect, [MaybeNullWhen(false)] out char c)
 	{
-		var c = PeekOrDefaultChar();
-		if (c == expect) return ReadChar();
-		return null;
+		c = default;
+
+		var i = Reader.Peek();
+		if (i < 0) return false;
+		if ((char)i == expect)
+		{
+			c = Read();
+			return true;
+		}
+		return false;
 	}
 
-	public IEnumerable<char> ReadChars() => ReadChars((_) => true);
+	/// <summary>
+	/// Returns one character at a time until the end.
+	/// </summary>
+	/// <returns>The read character.</returns>
+	public IEnumerable<char> Reads() => Reads((_) => true);
 
-	public IEnumerable<char> ReadChars(Func<char, bool> whileFn)
+	/// <summary>
+	/// Returns one character at a time while the specified condition is met.
+	/// </summary>
+	/// <param name="whileFn">The condition to continue reading</param>
+	/// <returns>The read character.</returns>
+	public IEnumerable<char> Reads(Func<char, bool> whileFn)
 	{
-		var c = PeekOrDefaultChar();
+		var c = PeekOrDefault();
 		while (c != null && whileFn(c.Value))
 		{
-			yield return ReadChar();
-			c = PeekOrDefaultChar();
+			yield return Read();
+			c = PeekOrDefault();
 		}
 	}