Canon/Canon.Console/Services/StringSourceReader.cs

88 lines
1.6 KiB
C#
Raw Permalink Normal View History

using System.Diagnostics.CodeAnalysis;
using Canon.Core.Abstractions;
namespace Canon.Console.Services;
/// <summary>
/// 从字符串中读取源代码
/// </summary>
public sealed class StringSourceReader(string source) : ISourceReader
{
private int _pos = -1;
private uint _lastPos;
public uint Line { get; private set; } = 1;
public uint Pos { get; private set; }
public string FileName => "string";
public char Current
{
get
{
if (_pos == -1)
{
throw new InvalidOperationException("Reader at before the start.");
}
else
{
return source[_pos];
}
}
}
public bool Retract()
{
if (_pos <= 0)
{
return false;
}
_pos -= 1;
if (Current == '\n')
{
Line -= 1;
// TODO: 如果一直回退就完蛋了
Pos = _lastPos;
}
else
{
Pos -= 1;
}
return true;
}
public bool MoveNext()
{
if (_pos >= source.Length - 1)
{
return false;
}
if (_pos != -1 && Current == '\n')
{
Line += 1;
_lastPos = Pos;
Pos = 0;
}
_pos += 1;
Pos += 1;
return true;
}
public bool TryPeekChar([NotNullWhen(true)] out char? c)
{
if (_pos >= source.Length - 1)
{
c = null;
return false;
}
c = source[_pos + 1];
return true;
}
}