wan24-Core 1.25.0

wan24-Core

This core library contains some .NET extensions and boiler plate avoiding helpers. It's designed as core library for a long running process and optimized for that purpose. The code tries to cache agressive whereever it's possible. Types are designed to be thread-safe, if they're likely to be accessed reading/writing from multiple threads (if it's their nature). However, if it's not sure that a types nature is to manage multithreaded access, performance goes before thread safety.

It started as a slender extension method collection and growed up to a larger core utility until today. It's possible that some specialized parts will be splitted into separate libraries in the future, if the core library is getting too big - but the namespace will stay the same.

Some key features:

• Bootstrapping
• Disposable base class for disposable types, which supports asynchronous disposing
  • Dispose attribute for fields/properties which should be disposed automatic when disposing
• CancellationOnDispose cancels a cancellation token when an object is being disposed (or another given cancellation token ws canceled)
• Cancellations combines multiple cancellation tokens into one
• Type helper (type loading)
• Secure byte and char array, which clears its contents when disposing
• Pool rented array as disposable object (which optionally clears its contents when disposing; for byte/char arrays just like the Secure*Array)
• Asynchronous API helper
  • Asynchronous fluent API helper
• Byte array extensions
  • Endian conversion
  • Bit-converter (endian-safe)
  • UTF-8/16/32 (little endian) string decoding
  • Clearing
• Dictionary extensions
  • Merge with string key prefix
  • Merge a list with the index as key (and an optional key prefix)
• Char array extensions
  • Clearing
• Array helper extensions
  • Offset/length validation
• Array pool extensions
  • Renting a cleared array
• Enumerable extensions
  • Combine enumerables
  • Chunk enumerables
• Reflection extensions
  • Automatic parameter extension when invoking a method (with DI support)
  • Synchronous/asynchronous method invokation
  • Automatic constructor invokation using a given parameter set (with DI support)
  • Nullability detection
  • Get property getter/setter delegates
  • Get cached field/property/method info
• Cache for field/property/method info and custom attributes
• Delegate extensions
  • Delegate list invokation (with or without return values, with DI support)
  • Asynchronous delegate list invokation (with or without return values, with DI support)
• Task extensions
  • Result getting of a generic task
  • Asynchronous task list awaiting
  • Shortcuts for await configurations
  • Shortcuts for starting a function as long running task
  • Shortcuts for starting a function as task with fair execution by the scheduler
  • Add a cancellation token to a task (which can cancel the task awaiter)
• DI helper
  • Service provider adoption
  • DI object factory delegates
  • Asynchronous DI object factory delegates
• Enumeration extensions
  • Get enumeration value display string from DisplayTextAttribute or using ToString (fallback)
  • Determine if all, any or which flags are contained in an enumeration value
  • Remove flags of a mixed enumeration value
  • Get only flags of a mixed enumeration value
  • Value validation
• Number extensions
  • Determine if a type is a number
  • Determine if a number type is unsigned
  • Bit-converter (endian-safe)
  • Determine if a number (or any IComparable) is within a range
• Numeric bitwise extensions
• Collection extensions
  • Add a range of items
• JSON helper
  • Exchangeable JSON encoder/decoder delegates (using System.Text.Json per default)
• JSON extensions
  • Encode an object
  • Decode from a type
  • Decode a string
• Object extensions
  • Type conversion
  • Determine if a value is within a list of values
• String extensions
  • Get UTF-8/16/32 bytes (little endian)
  • Parsing
• Generic helper
  • Determine if two generic values are equal
  • Determine if a value is null
  • Determine if a value is default
  • Determine if a value is null or default
• DateTime extensions
  • Determine if a time is within a range
  • Determine if a time matches a reference time plus/minus an offset
  • Apply an offset to a time base on a reference time
• TimeSpanHelper
  • Update a timeout
• Queue worker (for actions and/or items)
• Parallel queue worker (for actions and/or items)
• ParallelAsync implementation
  • ForEachAsync with an asynchronous or synchronous input source
  • FilterAsync with an asynchronous or synchronous input source and item filter
  • Filter for synchronous parallel filtering
• Base class for a hosted worker, which implements the IHostedService interface (timed or permanent running)
• EventThrottle for throttling event handler calls
• ProcessThrottle for throttling a processing channel
• OrderedDictionary<tKey, tValue> is used for working with indexed key/value pairs
• Timeout will count down and raise an event, if not reset before reaching the timeout
• ILogger support
• IChangeToken support using ChangeCallback
• Hierarchic configuration using OverrideableConfig
• Cancellation token awaiter
• ObjectPool for pooling objects (DisposableObjectPool for disposable types), and BlockingObjectPool for a strict pool capacity limit
• (Blocking)StreamPool, PooledMemoryStream, PooledTempFileStream and PooledTempStream (hosts written data in memory first)
• ResetEvent for (a)synchronous event waiting
• LazyValue<T>, DisposableLazyValue<T>, AsyncDisposableLazyValue<T> and TimeoutValue<T> for lazy and timeout value serving
• ObjectLockManager<T> for asynchronous and awaitable object locking
• Bitmap for working with bits
• DisposableWrapper<T> for wrapping any (not disposable?) object with the IDisposable and IAsyncDisposable interface using custom dispose actions during runtime
• DisposableAdapter for adopting the IDisposableObject interface from a type which can't extend the DisposableBase type
• Generic object extenions for validating method arguments
• CLI arguments interpreter
• Runtime configuration from CLI arguments
• Fast byte to string and string to byte encoding/decoding (using an URI friendly charset, faster and smaller results than base64 encoding; charset is customizable; encoded data integrity can be validated without decoding; including extensions for numeric type encoding/decoding)
• Collecting periodical statistical values
• Streams
  • StreamBase as base class which implements some disposing logic
  • WrapperStream wraps a base stream and provides LeaveOpen
  • PartialStream wraps a part of a base stream (read-only)
  • LengthLimitedStream ensures a maximum stream length (only writing)
  • MemoryPoolStream uses an ArrayPool<byte> for storing written data
  • ThrottledStream throttles reading/writing troughput
  • TimeoutStream can timeout async reading/writing methods
  • BlockingBufferStream for writing to / reading from a buffer blocked
  • HubStream for forwarding writing operations to multiple target streams
  • LimitedStream limits reading/writing/seeking capabilities of a stream
  • ZeroStream reads zero bytes and writes to nowhere
  • CountingStream counts red/written bytes
  • PauseableStream is a stream which can temporary pause reading/writing
  • EnumerableStream streams an enumerable/enumerator
  • CombinedStream combines multiple streams into one stream (read-only)
  • SynchronizedStream synchronizes IO and seeking
  • RandomStream reads random bytes into the given buffers
• Named mutex helper
  • GlobalLock for a synchronous context
  • GlobalLockAsync for an asynchronous context
• Retry helper which supports timeout, delay and cancellation
• Asynchronous event
• Stream extensions
  • Get the number of remaining bytes until the streams end
  • Copy a part of a stream to another stream
  • Generic seek
  • Write N zero bytes
  • Write N random bytes
  • Create stream chunks
• Checksum implementation in ChecksumExtensions and ChecksumTransform

How to get it

This library is available as NuGet package "wan24-Core".

Bootstrapping

The Bootstrapper.Async method calls all static methods having the BootstrapperAttribute. In order to be able to find the methods, it's required to add the BootstrapperAttribute to the assembly.

You may also ad the BootstrapperAttribute to a type and/or the bootstrapper method, in case the assembly contains multiple of them. In the assembly attribute you need to set ScanClasses and/or ScanMethods to true in order to perform a deep scanning during bootstrapping for performance reasons.

The bootstrapper methods may consume parameters which are available from the DI helper. The method may be synchronous or asynchronous. The method can't be defined in a generic class, and it can't be generic itself.

[assembly:Bootstrapper(typeof(YourBootstrapper),nameof(YourBootstrapper.BootstrapperMethod))]

public static class YourBootstrapper
{
    public static async Task BootstrapperMethod()
    {
        // Perform your bootstrapping here
    }
}

// Call the bootstrapper somewhere in your apps initialization code
await Bootstrap.Async();

The BootstrapperAttribute can be initialized with a numeric priority. The bootstrapper will order the found bootstrapping methods by priority, where the one with the highest number will be executed first (assembly and type priorities count, too). At last there's a assembly location, type and method name sorting. Bootstrapper methods will be executed sequential.

If you give a type and a method name to the assembly BootstrapperAttribute, you won't need to add the attribute to the type and the method.

During bootstrapping, the cancellation token which was given to the Bootstrap.Async method, can be injected to a bootstrappers method parameters.

After that bootstrapping was done, the Bootstrap.AsyncBootstrapper will be called. At last the Bootstrap.OnBootstrap event will be raised.

During bootstrapping the Bootstrap.IsBooting property is true. After bootstrapping the Bootstrap.DidBoot property is true.

The bootstrapper will load all referenced assemblies. If you load an assembly later, it'll be bootstrapped automatic and added to the TypeHelper singleton instance.

Type helper

If you use the TypeHelper.AddTypes method, the unknown assemblies of the added types will be added as searchable assemblies automatic.

You may attach to the TypeHelper.OnLoadType event for handling requests more dynamic.

The TypeHelper.GetType method will try Type.GetType first and fall back to the helper, if no type was found.

DI helper

In order to make DI (dependency injection) working, you need to

• set a DiHelper.ServiceProvider and/or
• add DiHelper.(Async)ObjectFactories

The DiHelper.GetDiObjectAsync method will try to resolve the request synchronous, first. But the DiHelper.GetDiObject won't try asynchronous object factories.

Mixed enumeration value

A mixed enumeration contains X bits enumeration values, and Y bits flags:

[Flags]
public enum MixedEnum : int
{
    None = 0,
    Value1 = 1,
    Value2 = 2,
    Value3 = 3,
    ...
    Flag1 = 1 << 8,
    Flag2 = 1 << 9,
    FLAGS = Flag1 | Flag2 // Required to identify flags
}

The FLAGS value helps these extension methods to handle flag values:

MixedEnum value = MixedEnum.Value1 | MixedEnum.Flag1,
    valueOnly = value.RemoveFlags(),// == MixedEnum.Value1
    flagsOnly = value.OnlyFlags();// == MixedEnum.Flag1

Unsafe code

The library uses unsafe code. If you don't want/need that, you can compile the library with the NO_UNSAFE compiler constant to disable any unsafe operation. Remember to unset the unsafe compiler option, too!

Disposable base class

The DisposableBase implements the IDisposable and IAsyncDisposable interfaces. It provides some helpers and events, and also the DisposeAttribute, which can be applied to fields and properties which you wish to dispose automatic when disposing.

When your type derives from the DisposableBase, you'll need to implement the abstract Dispose method:

protected override Dispose(bool disposing)
{
    // Your dispose logic here
}

There are measures to avoid that this method is being called twice.

To implement custom asynchronous disposing:

protected override async Task DisposeCore()
{
    // Your dispose logic here
}

In order to make the DisposeAttribute working, you have to call the protected method DisposeAttributes or DisposeAttributesAsync.

The IsDisposing property value will be true as soon as the disposing process started, and it will never become false again. The IsDisposed property value will be true as soon as the disposing process did finish.

TIP: Use the DisposableBase<T> base type, if you plan to use the DisposeAttribute! This base class will cache the fields/properties once on initialization to get rid of the reflection overhead which DisposableBase requires for this feature.

NOTE: The DisposeAttribute can be applied to byte[] and char[], too, which will simply call the Clear extension method on disposing. Another IEnumerable will be enumerated for disposable items (recursing!).

Queue worker

using QueueWorker worker = new();
await worker.EnqueueAsync((ct) =>
{
    // Do any background action here
});

The QueueWorker class can be extended as you need it.

The ParallelQueueWorker requires a number of threads in the constructor, which defines the degree of parallelism, in which enqueued tasks will be processed.

Queue item worker

using QueueItemWorker<ItemType> worker = new();
await worker.EnqueueAsync(new ItemType());

The QueueItemWorker<T> class can be extended as you need it.

The ParallelItemQueueWorker<T> requires a number of threads in the constructor, which defines the degree of parallelism, in which enqueued items will be processed.

ParallelAsync

Using the .NET parallel implementation it's not possible to invoke asynchronous item handlers. For this you can use the ParallelAsync.ForEachAsync method, which uses a parallel item queue worker in the background for asynchronous processing.

Hosted worker

public class YourHostedWorker : HostedWorkerBase
{
    public YourHostedWorker() : base() { }

    protected override async Task WorkerAsync()
    {
        // Perform the service actions here
    }
}

The hosted worker implements the IHostedService interface and can be extended as you need it.

Timed hosted worker

public class YourHostedWorker : TimedHostedWorkerBase
{
    public YourHostedWorker() : base(interval: 500) { }

    protected override async Task WorkerAsync()
    {
        // Perform the service actions here
    }
}

This example uses a 500ms timer. Based on the defined timer type, the interval will be processed in different ways:

• Default: Next worker run is now plus the interval (used by default)
• Exact: Next worker run is now plus the interval minus the processing duration (used, if the start time of the processing is important)
• ExactCatchingUp: As Exact, but catching up missing processing runs without delay, if a worker run duration exceeds the interval (used, if the number of worker runs is important)

Using the SetTimerAsync method you can change the timer settings at any time. If you give the nextRun parameter, you may set a fixed next run time (which won't effect the given interval, but just force the service to run at a specific time for the next time).

NOTE: The nextRun parameter will also force the service to (re)start!

By setting the property RunOnce to true, the service will stop after running the worker once. In combination with the SetTimerAsync parameter nextRun you can execute the worker at a specific time once.

The hosted worker implements the IHostedService interface and can be extended as you need it.

EventThrottle

public class YourType : DisposableBase
{
    protected readonly YourEventThrottle EventThrottle;

    public YourType() : base() => EventThrottle = new(this);

    // This method will raise the OnEvent
    public void AnyMethod()
    {
        RaiseOnEventThrottled();
    }

    protected override Dispose(bool disposing) => EventThrottle.Dispose();

    // Delegate for OnEvent
    public delegate void YourTypeEvent_Delegate();
    // Event to throttle
    public event YourTypeEvent_Delegate? OnEvent;
    // Raise the OnEvent using the event throttle
    protected void RaiseOnEventThrottled() => EventThrottle.Raise();
    // Finally let the event handlers process the event
    protected void RaiseOnEvent() => OnEvent?.Invoke();

    // Event throttle implementation
    public class YourEventThrottle : EventThrottle
    {
        // Throttle the event handling down to max. one handling per 300ms
        public YourEventThrottle(YourType instance) : base(timeout: 300) => Instance = instance;

        public YourType Instance { get; }

        protected override HandleEvent(DateTime raised, int raisedCount)
        {
            Instance.RaiseOnEvent();
        }
    }
}

If AnyMethod is being called, the event will be forwarded to the event throttle, which decides to throttle or raise the event. If AnyMethod was called three times within 300ms, the first call will be executed in realtime, while the 2nd and the 3rd call will be sqashed and executed once 300ms after the 1st call was processed.

This example assumes you're working with a real event - but you may throttle any event (which may not be a real event) using throttling logic.

ProcessThrottle

public class YourProcessThrottle : ProcessThrottle
{
    // Throttle to processing one object per second
    public YourProcessThrottle() : base(limit: 1, timeout: 1000) { }

    // Processing API using a timeout
    public async Task<int> ProcessAsync(Memory<bool> items, TimeSpan timeout)
        => await ProcessAsync(items.Length, (count) => 
        {
            await Task.Yield();
            Span<bool> toProcess = items.Span[..count];
            items = items[count..];
            // Process toProcess
        }, timeout);

    // Processing API using a cancellation token
    public async Task<int> ProcessAsync(Memory<bool> items, CancellationToken token = default)
        => await ProcessAsync(items.Length, (count) => 
        {
            await Task.Yield();
            Span<bool> toProcess = items.Span[..count];
            items = items[count..];
            // Process toProcess
        }, token);
}

The example will throttle the processing to a maximum of one object per second. Multiple threads may call ProcessAsync concurrent - processing will be organized thread-safe.

The return value of ProcessAsync is the number of objects processed until timeout or canceled.

The processing delegate shouldn't care about the timeout or if canceled and just process the given number of objects.

NOTE: A usage gap will slide the throttling timer. Example:

The timeout was set to 3 objects per 100ms. Now processing goes like this:

• First processed object on 0ms will activate the throttling timeout
• Next processed object on 10ms will increase the object throttling counter
• Next processed object on 110ms will reset the throttling timeout and counter (the usage gap of 100ms does exceed the timeout)
• Next 2 processed objects on 120ms will activate the throttle
• Next object will have to wait until the throttle was released
• The throttle will be released on 210ms, which allows the last object to be processed now

In short words: The throttle timer will not reset in an fixed interval, but the interval starts when processing items.

Change token

Implement by extending ChangeToken:

public class YourObservableType : ChangeToken
{
    public YourObservableType() : base()
    {
        ChangeIdentifier = () => HasChanged;
    }

    public bool HasChanged => ...;// Return if the object was changed

    public void ChangeAction()
    {
        // Perform changes
        InvokeCallbacks();
    }
}

Or by using a ChangeToken instance:

public class YourObservableType : IChangeToken
{
    public readonly ChangeToken ChangeToken;

    public YourObservableType() => ChangeToken = new(() => HasChanged);

    public bool HasChanged => ...;// Return if the object was changed

    public void ChangeAction()
    {
        // Perform changes
        ChangeToken.InvokeCallbacks();
    }

    // Implement the IChangeToken interface using our ChangeToken instance

    bool IChangeToken.HasChanged => ChangeToken.HasChanged;

    bool IChangeToken.ActiveChangeCallbacks => ChangeToken.ActiveChangeCallbacks;

    IDisposable IChangeToken.RegisterChangeCallback(Action<object?> callback, object? state)
        => ChangeToken.RegisterChangeCallback(callback, state);
}

Hierarchic configuration

Assume this configuration hierarchy:

Level	Description
1	Default values
2	User values (can override default values)
3	Administrator values (can override default/user values)

In code:

public sealed class Config : OverrideableConfig<Config>
{
    public Config() : base()
    {
        SubConfig = new(this, new(this));// User values
        InitProperties();
    }

    private Config(Config parent, Config? sub = null) : base(parent)
    {
        if(sub != null)
        {
            SubConfig = sub;
            sub.ParentConfig = this;
            sub.SubConfig = new(sub);// Administrator values
        }
        InitProperties();
    }

    // A configuration value
    public ConfigOption<string, Config> AnyValue { get; private set; } = null!;

    private void InitProperties()
    {
        AnyValue = ParentConfig == null 
            // The master option has a default value
            ? new(this, nameof(AnyValue), canBeOverridden: true, "default")
            // No default value for a sub-option
            : new(this, nameof(AnyValue));
    }
}

Config config = new(),
    user = config.SubConfig,
    admin = user.SubConfig;

CAUTION: There's no endless-recursion protection for the ParentConfig or the SubConfig properties!

Now users are able to override default values, and administrators are able to override default and/or user values:

// Still the default value
Assert.AreEqual("default", config.AnyValue.FinalValue);

// User overrides the default value
user.AnyValue.Value = "user";
Assert.AreEqual("default", config.AnyValue.Value);
Assert.AreEqual("user", config.AnyValue.FinalValue);

// Administrator overrides the user value
admin.AnyValue.Value = "admin";
Assert.AreEqual("admin", config.AnyValue.FinalValue);

// User can't override the administrator value (but still store his own value 
// in case the administrator would unset his value)
user.AnyValue.Value = "test";
Assert.AreEqual("admin", config.AnyValue.FinalValue);
Assert.AreEqual("test", user.AnyValue.Value);

NOTE: Setting an option value is thread-safe.

It's also possible to flip the hierarchy:

Level	Description
1	Default values
2	Administrator values (can define user visible and optional not overrideable values)
3	User values (can override overrideable values)

Using this hierarchy an administrator could also allow or deny overriding values at any time, for example.

The hierarchy depth isn't limited.

Object locking

The ObjectLockManager<T> helps locking any object during an asynchronous operation:

ObjectLock ol = await ObjectLockManager<AnyType>.Shared.LockAsync(anyObjectKey);
// A 2nd call to ObjectLockManager<AnyType>.Shared.LockAsync would block until the lock was released
await ol.RunTaskAsync(Task.Run(async () => 
{
    // Perform the asynchronous operation here
}));
// ol is disposed already, 'cause the asynchronous operation source task was awaited
// The next ObjectLockManager<AnyType>.Shared.LockAsync call will be processed now, if any
await ol.Task;// To throw any exception during performing the asynchronous operation

If AnyType implements the IObjectKey interface, it can be given to the ObjectLockManager<T> methods as object argument.

NOTE: ObjectLock will dispose itself as soon as RunTaskAsync has been called, and the given task was completed.

CLI arguments interpreter

There a just a few rules:

1. A flag starts with a single dash
2. A key for a value (list) starts with a double dash
3. Keys/values can be quoted using single or double quotes
4. Escape character is the backslash (only applicable in quoted values)
5. A quoted value must be escaped for JSON decoding, a backslash must be double escaped
6. Double quotes in a quoted value must be escaped always

Example:

"-flag" --key 'value1' value2 --key -value3 '--key2' "value"

For appending the value -value3 to the value list of key, the value needs to be added with another --key key identifier, 'cause it starts with a dash and could be misinterpreted as a flag (which would result in a parser error).

A CLI app called with these arguments could interpret them easy using the CliArguments class:

CliArguments cliArgs = new(args);
Assert.IsTrue(cliArgs["flag"]);
Assert.AreEqual(3, cliArgs.All("key").Count);
Assert.AreEqual("value", cliArgs.Single("key2"));

A -- (double dash) may be interpreted as an empty key name or a flag with the name -, based on if a value, which doesn't start with a dash, is following. Examples:

• --: - flag
• -- -: - flag (-- and - are both interpreted as double - flag (double flags will be combined))
• -- value: Empty key with the value value
• -- -key: - and key flags

Keyless arguments will be stored in the KeyLessArguments list - example:

CliArguments ca = CliArguments.Parse("value1 -flag value2 --key value3");
Assert.AreEqual(2, ca.KeyLessArguments.Count);
Assert.AreEqual("value1", ca.KeyLessArguments[0]);
Assert.AreEqual("value2", ca.KeyLessArguments[1]);
Assert.IsTrue(ca["flag"]);
Assert.IsTrue(ca["key", true]);

Fast byte ↔ string encoding/decoding

base64 is supported everywhere, but it's (relative) slow and produces too much overhead, and uses also URI unfriendly characters. In addition it's also not easy to validate base64, or to determine the encoded/decoded value length.

To fix all of these problems, the ByteEncoding class implements a fast encoding, which uses only characters 0-9, a-z, A-Z, dash and underscore and produces less overhead than base64. The encoded/decoded value length can be calculated in advance, and it's fast and easy to detect errors in the encoded data without having to decode it, first.

// In case you want to use a prepared output buffer
int encodedLen = anyByteArray.GetEncodedLength();

// Encoding
char[] encoded = anyByteArray.Encode();

// In case you want to use a prepared output buffer
int decodedLen = encoded.GetDecodedlength();

// Decoding
byte[] decoded = encoded.Decode();

Using extensions numeric values can be en-/decoded on the fly, too. The special EncodeNumberCompact extension methods determine the smallest value matching numeric type before encoding (use DecodeCompactNumber with the original numeric type as generic argument for decoding).

NOTE: Encoding an empty array results in an empty string. Encoding 0 results in an empty string, too. Nothing encodes to nothing and decodes to nothing, too.

If required, the used encoding character map can be customized. You may use any 64 characters long map with unique items.

String parser

Using the Parse extension method for a string, you can parse placeholders into a string and modify the output using (customizable) parser functions:

Dictionary<string, string> data = new()
{
    {"name", "value"}
};
Assert.AreEqual("value", "%{name}".Parse(data));

You may setup the default parser data in StringExtensions.ParserEnvironment. The given parser data will override defaults.

You can execute as many parser functions on the output as required, separated using ::

%{input:func1:func2(param1,param2,...):func3():...}

The first optional segment is always a parser data variable name (if not used, the sequence starts with a : to indicate a function call). A function may or may not have parameters. The result of a function will be provided for the next function. Available functions:

Function	Syntax	Usage
sub	%{input:sub([offset/length](,[length]))}	extracts a sub-string
left	%{input:left([length])}	takes X characters from the left
right	%{input:right([length])}	takes X characters from the right
trim	%{input:trim}	removes white-spaces from the value
discard	%{input:discard}	no parameters, discards the current output
escape_html	%{input:escape_html}	escapes the value for use within HTML
escape_json	%{input:escape_json}	escapes the value for use within double quotes (double quotes will be trimmed from the JSON result!)
escape_uri	%{input:escape_uri}	escapes the value for use within an URI
set	%{input:set([name])} sets the current output as parser variable with the given name
var	%{:var([name])} gets a parser data variable value
item	%{:item([index],[item/name](,[item](,...)))} gets an item from a list (if using a variable name, its value will be splitted using pipe)
prepend	%{input:prepend([string])}	prepends a string
append	%{input:append([string])}	appends a string
insert	%{input:insert([index],[string])}	inserts a string at an index
remove	%{input:remove([offset/length](,[length]))}	removes a part (from the left)
concat	%{:concat([string],[string](,[string](...))}	concatenates strings
join	%{:join([separator],[string],[string](,...))}	joins strings
math	%{:math([operator],[value1],[value2](,...))}	performs math
rx	%{:rx([group_index]],[name/pattern])}	exchanges the parser regular expression and content group index for the next parser operations (the next round)
format	%{input:format([format])}	to format a numeric value
str_format	%{input:str_format(([value1](,...))} to format the string value
insert_item	%{input:insert_item([index],[items_name])}	to insert an item (items will be splitted by pipe)
remove_item	%{input:remove_item([index])}	to remove an item (items will be splitted by pipe)
sort	%{input:sort((desc))}	to sort items
foreach	%{input:foreach([name])}	to parse a parser data value for each item (will be stored in _item)
if	%{input:if([name](,[name]))}	to parse a parser data value, if the value is 1 (else parse the second given parser data value)
split	%{input:split(prefix)}	to split items by pipe and set them as parser data using the prefix and appending the zero based item index
range	%{:range([start],[count])}	to create a numeric range
dummy	%{:dummy(...)}	does nothing (may be used as comment)

Available math operators:

Operator	Function
+	Summarize
-	Substract
*	Multiply
/	Divide
%	Modulo
a	Average
i	Minimum
x	Maximum
r	Round (2nd value is the number of decimals)
f	Floor
c	Ceiling
p	Y power of X (double conversion will be applied)
=	Equality (0 is not equal, 1 if equal)
<	Lower than (0 is not lower, 1 if lower)
>	Greater than (0 is not greater, 1 if greater)
s	Change the sign

Numbers are written in invariant culture float style. decimal will be used as number format.

To create a custom parser function:

StringExtensions["func_name"] = (context) => 
{
    // Work with the StringParserContext and return the value to use or set context.Error for error handling
    return context.Value;
};

Example:

StringExtensions["upper"] = (context) => context.Value.ToUpper();

Dictionary<string, string> data = new()
{
    {"name", "value"}
};
Assert.AreEqual("VALUE", "%{name:upper}".Parse(data));

CAUTION: A placeholder must produce the same result, if it occurs repeated! A repeated placeholder won't be parsed more than once, but being replaced with the result of the first parsed placeholder.

Example:

Dictionary<string, string> data = new()
{
    {"name", "value"}
};
string tmpl = "%{name}%{name:len:set(name):discard}%{name}";
Assert.AreEqual("valuevalue", tmpl.Parse(data));

From the logic value5 would be expected. To get value5, finally, you'll have to modify the template:

%{name}%{name:len:set(name):discard}%{name:dummy}

TIP: Almost all function parameters may be parser data variable names, too, if they have a $ prefix. To support that, use the TryGetData method of the StringParserContext, if a parameter value starts with $.

TIP: To ensure having all required parameters, use the EnsureValidParameterCount of the StringParserContext. The method allows you to define a number of allowed parameter counts (including zero) and produces a common error message, if the function call syntax is wrong.

TIP: A custom parser function may change the parser regular expression and content group by changing Rx and RxGroup.

The string parser works recursive. To avoid an endless recursion, the default parsing round count limit is 3. The current parsing round is accessable trough the parser data _round. If a parser function parses a template, the called parser will work in the current parsing round context and respect the limit, too. Youmay set another default limit in StringExtensions.ParserMaxRounds.

The default behavior for errors is to throw an exception. If error throwing was disabled, in case of an error a placeholder will stay in clear text, and a function will return the unaltered value.

You may modify the placeholder declaration by setting another regular expression to StringExtensions.RxParser. Group $1 must contain the whole placeholder, while group $2 is required to contain the inner placeholder contents (like variable name, function calls, parameters, etc.). There's no way to customize the inner placeholder content syntax at present. You may also give a custom regular expression to the Parse extension method, if you want an isolated parsing. You can modify the inner content group index by setting StringExtensions.RxParserGroup or giving rxGroup to the Parse methods.

CAUTION: Be careful with customized parser functions: A mistake could let a manipulated string harm your computer!

Retry helper

RetryInfo<object> result = await RetryHelper.TryActionAsync(
    async (currentTry, cancellation) => 
    {
        // Perform any critical action which may throw or timeout and return a value (or not)
    },
    maxNumberOfTries: 3,
    timeout: TimeSpan.FromSeconds(30),
    delay: TimeSpan.FromSeconds(3)
    );

// This will throw an exception, if failed, or return the action delegate return value, if succeed
object returnValue = result.ThrowIfFailed();

TryAction* will try to execute an action for a maximum of N times, optional having a total timeout, and optional performing a delay after a failed try. The given action delegate may also return a value, which you can then find in the RetryInfo<T>.Result property, if Succeed is true.

The RetryInfo<T> object contains some runtime informations:

• Start, done time and total runtime
• Number of tries processed (a timeout or cancellation may throw before the action is being called)
• Catched exceptions during tries
• If succeed, cancelled or timeout
• The action delegate return value (if any)

NOTE: There's also a synchronous TryAction method, which supports timeout and cancellation also.

Asynchronous events

// Example type using an asynchronous event
public class YourType
{
    public readonly AsyncEvent<YourType, EventArgs> OnYourEvent;

    public YourType() => OnYourEvent = new(this);

    public async Task RaiseOnYourEventAsync()
        => await ((IAsyncEvent<YourType, EventArgs>)OnYourEvent).RaiseEventAsync();
}

// An example asynchronous event listener
async Task eventListener(YourType sender, EventArgs e, CancellationToken ct)
{
    ...
}

// Attach to the event and raise it
YourType obj = new();
Assert.IsFalse(obj.OnYourEvent);
obj.OnYourEvent.Listen(eventListener);
Assert.IsTrue(obj.OnYourEvent);
await obj.RaiseOnYourEventAsync();

// Detach the event listener
obj.OnYourEvent.Detach(eventListener);
Assert.IsFalse(obj.OnYourEvent);

An AsyncEvent<tSender, tArgs> instance will only export public event informations and functions like adding/removing event handlers, and if event handlers are present. For raising the event, you need to use the RaiseEventAsync methods which are available from the IAsyncEvent<tSender, tArgs> interface.

Timeout, cancellation, synchronous and asynchronous event handlers are supported. The AsyncEvent<tSender, tArgs> is designed to be thread-safe, while multiple threads are allowed to raise the event in parallel.

Checksum

ChecksumExtensions and ChecksumTransform allow generating a checksum:

byte[] data = ...,
    moreData = ...,
    checksum = data.CreateChecksum();
moreData.UpdateChecksum(checksum);

The default checksum length is 8 bytes and needs to be a power of two, if being customized. If you need a numeric value from the checksum bytes:

ulong numericChecksum = checksum.AsSpan().ToULong();

The algorithm uses XOR to modify the checksum bytes, which are zero by default. If the input data is only zero, the checksum will stay at zero. If you use the same input data for a 2nd time, the checksum will be equal to the one from the 1st time.

The ChecksumTransform is a HashAlgorithm and can be used as every .NET implemented hash algorithm (even it's not a hash, but only a checksum!):

byte[] checksum = ChecksumTransform.HashData(data);

You may register the checksum algorithm as "Checksum" using the Register method:

ChecksumTransform.Register();