/// <summary>
/// Returns a parser which runs the current parser and applies a selector function.
/// The selector function receives a <see cref="ReadOnlySpan{TToken}"/> as its first argument, and the result of the current parser as its second argument.
/// The <see cref="ReadOnlySpan{TToken}"/> represents the sequence of input tokens which were consumed by the parser.
///
/// This allows you to write "pattern"-style parsers which match a sequence of tokens and return a view of the part of the input stream which they matched.
/// </summary>
/// <param name="selector">
/// A selector function which computes a result of type <typeparamref name="U"/>.
/// The arguments of the selector function are a <see cref="ReadOnlySpan{TToken}"/> containing the sequence of input tokens which were consumed by this parser,
/// and the result of this parser.
/// </param>
/// <typeparam name="U">The result type</typeparam>
/// <returns>A parser which runs the current parser and applies a selector function.</returns>
public Parser <TToken, U> MapWithInput <U>(ReadOnlySpanFunc <TToken, T, U> selector)
{
if (selector == null)
{
throw new ArgumentNullException(nameof(selector));
}
return(new MapWithInputParser <U>(this, selector));
}
/// <summary>
/// 读取当前只读片段。
/// </summary>
/// <param name="size">当前字节数。</param>
/// <param name="func">转换函数。</param>
/// <returns>返回读取结果。</returns>
public TResult ReadBuffer <TResult>(int size, ReadOnlySpanFunc <byte, TResult> func)
{
var buffer = _sequence.Slice(Start, size);
Start = _sequence.GetPosition(size, Start);
if (buffer.First.Length == size)
{
return(func(buffer.First.Span));
}
Span <byte> bytes = stackalloc byte[size];
buffer.CopyTo(bytes);
return(func(bytes));
}
public MapWithInputParser(Parser <TToken, T> parser, ReadOnlySpanFunc <TToken, T, U> selector)
{
_parser = parser;
_selector = selector;
}
/// <summary>
/// Returns a parser which runs the current parser and applies a selector function.
/// The selector function receives a <see cref="ReadOnlySpan{TToken}"/> as its first argument, and the result of the current parser as its second argument.
/// The <see cref="ReadOnlySpan{TToken}"/> represents the sequence of input tokens which were consumed by the parser.
///
/// This allows you to write "pattern"-style parsers which match a sequence of tokens and return a view of the part of the input stream which they matched.
///
/// This function is an alternative name for <see cref="MapWithInput"/>.
/// </summary>
/// <param name="selector">
/// A selector function which computes a result of type <typeparamref name="U"/>.
/// The arguments of the selector function are a <see cref="ReadOnlySpan{TToken}"/> containing the sequence of input tokens which were consumed by this parser,
/// and the result of this parser.
/// </param>
/// <typeparam name="U">The result type</typeparam>
/// <returns>A parser which runs the current parser and applies a selector function.</returns>
public Parser <TToken, U> Slice <U>(ReadOnlySpanFunc <TToken, T, U> selector)
=> this.MapWithInput(selector);