RSCG – System.Text.RegularExpressions
RSCG – System.Text.RegularExpressions
| name | System.Text.RegularExpressions |
| nuget | https://www.nuget.org/packages/System.Text.RegularExpressions/ |
| link | https://learn.microsoft.com/en-us/dotnet/standard/base-types/regular-expression-source-generators/ |
| author | Microsoft |
Regex compiled
This is how you can use System.Text.RegularExpressions .
The code that you start with is
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>net7.0</TargetFramework>
<ImplicitUsings>enable</ImplicitUsings>
<Nullable>enable</Nullable>
</PropertyGroup>
<PropertyGroup>
<EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
<CompilerGeneratedFilesOutputPath>$(BaseIntermediateOutputPath)\GeneratedX</CompilerGeneratedFilesOutputPath>
</PropertyGroup>
</Project>
The code that you will use is
using Demo; //https://learn.microsoft.com/en-us/dotnet/standard/base-types/regular-expression-source-generators //https://devblogs.microsoft.com/dotnet/regular-expression-improvements-in-dotnet-7/ var x = "Abc"; Console.WriteLine(DemoRegex.EvaluateText(x));
using System.Text.RegularExpressions;
namespace Demo;
public partial class DemoRegex
{
[GeneratedRegex("abc|def", RegexOptions.IgnoreCase, "en-US")]
private static partial Regex AbcOrDefGeneratedRegex();
public static bool EvaluateText(string text)
{
return (AbcOrDefGeneratedRegex().IsMatch(text));
}
}
The code that is generated is
// <auto-generated/>
#nullable enable
#pragma warning disable CS0162 // Unreachable code
#pragma warning disable CS0164 // Unreferenced label
#pragma warning disable CS0219 // Variable assigned but never used
namespace Demo
{
partial class DemoRegex
{
/// <remarks>
/// Pattern explanation:<br/>
/// <code>
/// ○ Match with 2 alternative expressions, atomically.<br/>
/// ○ Match a sequence of expressions.<br/>
/// ○ Match a character in the set [Aa].<br/>
/// ○ Match a character in the set [Bb].<br/>
/// ○ Match a character in the set [Cc].<br/>
/// ○ Match a sequence of expressions.<br/>
/// ○ Match a character in the set [Dd].<br/>
/// ○ Match a character in the set [Ee].<br/>
/// ○ Match a character in the set [Ff].<br/>
/// </code>
/// </remarks>
[global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Text.RegularExpressions.Generator", "7.0.8.17405")]
private static partial global::System.Text.RegularExpressions.Regex AbcOrDefGeneratedRegex() => global::System.Text.RegularExpressions.Generated.AbcOrDefGeneratedRegex_0.Instance;
}
}
namespace System.Text.RegularExpressions.Generated
{
using System;
using System.CodeDom.Compiler;
using System.Collections;
using System.ComponentModel;
using System.Globalization;
using System.Runtime.CompilerServices;
using System.Text.RegularExpressions;
using System.Threading;
/// <summary>Custom <see cref="Regex"/>-derived type for the AbcOrDefGeneratedRegex method.</summary>
[GeneratedCodeAttribute("System.Text.RegularExpressions.Generator", "7.0.8.17405")]
file sealed class AbcOrDefGeneratedRegex_0 : Regex
{
/// <summary>Cached, thread-safe singleton instance.</summary>
internal static readonly AbcOrDefGeneratedRegex_0 Instance = new();
/// <summary>Initializes the instance.</summary>
private AbcOrDefGeneratedRegex_0()
{
base.pattern = "abc|def";
base.roptions = RegexOptions.IgnoreCase;
ValidateMatchTimeout(Utilities.s_defaultTimeout);
base.internalMatchTimeout = Utilities.s_defaultTimeout;
base.factory = new RunnerFactory();
base.capsize = 1;
}
/// <summary>Provides a factory for creating <see cref="RegexRunner"/> instances to be used by methods on <see cref="Regex"/>.</summary>
private sealed class RunnerFactory : RegexRunnerFactory
{
/// <summary>Creates an instance of a <see cref="RegexRunner"/> used by methods on <see cref="Regex"/>.</summary>
protected override RegexRunner CreateInstance() => new Runner();
/// <summary>Provides the runner that contains the custom logic implementing the specified regular expression.</summary>
private sealed class Runner : RegexRunner
{
/// <summary>Scan the <paramref name="inputSpan"/> starting from base.runtextstart for the next match.</summary>
/// <param name="inputSpan">The text being scanned by the regular expression.</param>
protected override void Scan(ReadOnlySpan<char> inputSpan)
{
// Search until we can't find a valid starting position, we find a match, or we reach the end of the input.
while (TryFindNextPossibleStartingPosition(inputSpan) &&
!TryMatchAtCurrentPosition(inputSpan) &&
base.runtextpos != inputSpan.Length)
{
base.runtextpos++;
if (Utilities.s_hasTimeout)
{
base.CheckTimeout();
}
}
}
/// <summary>Search <paramref name="inputSpan"/> starting from base.runtextpos for the next location a match could possibly start.</summary>
/// <param name="inputSpan">The text being scanned by the regular expression.</param>
/// <returns>true if a possible match was found; false if no more matches are possible.</returns>
private bool TryFindNextPossibleStartingPosition(ReadOnlySpan<char> inputSpan)
{
int pos = base.runtextpos;
ulong charMinusLow;
// Any possible match is at least 3 characters.
if (pos <= inputSpan.Length - 3)
{
// The pattern matches a character in the set [CFcf] at index 2.
// Find the next occurrence. If it can't be found, there's no match.
ReadOnlySpan<char> span = inputSpan.Slice(pos);
for (int i = 0; i < span.Length - 2; i++)
{
int indexOfPos = span.Slice(i + 2).IndexOfAny("CFcf");
if (indexOfPos < 0)
{
goto NoMatchFound;
}
i += indexOfPos;
if (((long)((0x9000000090000000UL << (int)(charMinusLow = (uint)span[i] - 'A')) & (charMinusLow - 64)) < 0) &&
((long)((0x9000000090000000UL << (int)(charMinusLow = (uint)span[i + 1] - 'B')) & (charMinusLow - 64)) < 0))
{
base.runtextpos = pos + i;
return true;
}
}
}
// No match found.
NoMatchFound:
base.runtextpos = inputSpan.Length;
return false;
}
/// <summary>Determine whether <paramref name="inputSpan"/> at base.runtextpos is a match for the regular expression.</summary>
/// <param name="inputSpan">The text being scanned by the regular expression.</param>
/// <returns>true if the regular expression matches at the current position; otherwise, false.</returns>
private bool TryMatchAtCurrentPosition(ReadOnlySpan<char> inputSpan)
{
int pos = base.runtextpos;
int matchStart = pos;
ReadOnlySpan<char> slice = inputSpan.Slice(pos);
// Match with 2 alternative expressions, atomically.
{
if (slice.IsEmpty)
{
return false; // The input didn't match.
}
switch (slice[0])
{
case 'A' or 'a':
if ((uint)slice.Length < 3 ||
!slice.Slice(1).StartsWith("bc", StringComparison.OrdinalIgnoreCase)) // Match the string "bc" (ordinal case-insensitive)
{
return false; // The input didn't match.
}
pos += 3;
slice = inputSpan.Slice(pos);
break;
case 'D' or 'd':
if ((uint)slice.Length < 3 ||
!slice.Slice(1).StartsWith("ef", StringComparison.OrdinalIgnoreCase)) // Match the string "ef" (ordinal case-insensitive)
{
return false; // The input didn't match.
}
pos += 3;
slice = inputSpan.Slice(pos);
break;
default:
return false; // The input didn't match.
}
}
// The input matched.
base.runtextpos = pos;
base.Capture(0, matchStart, pos);
return true;
}
}
}
}
/// <summary>Helper methods used by generated <see cref="Regex"/>-derived implementations.</summary>
[GeneratedCodeAttribute("System.Text.RegularExpressions.Generator", "7.0.8.17405")]
file static class Utilities
{
/// <summary>Default timeout value set in <see cref="AppContext"/>, or <see cref="Regex.InfiniteMatchTimeout"/> if none was set.</summary>
internal static readonly TimeSpan s_defaultTimeout = AppContext.GetData("REGEX_DEFAULT_MATCH_TIMEOUT") is TimeSpan timeout ? timeout : Regex.InfiniteMatchTimeout;
/// <summary>Whether <see cref="s_defaultTimeout"/> is non-infinite.</summary>
internal static readonly bool s_hasTimeout = s_defaultTimeout != Timeout.InfiniteTimeSpan;
}
}
Code and pdf at
https://ignatandrei.github.io/RSCG_Examples/v2/docs/System.Text.RegularExpressions
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