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Buffer utilities

This is a small library implementing simple buffer utilities for dealing with large data sets.

Flushing buffers

Flushing buffers implement buffers with a given size which are automatically flushed using a given handler function when they are full.

You may create an instance as follows. It Takes up to three arguments:

new FlushingBuffer(10, function(data) { /* send data */ });
new FlushingBuffer(10, function(data) { /* send data */ }, function() { return collect(); });

The first argument specifies the buffer size, the second one a handler function which is called each time the buffer is full. It receives the buffer data as argument. The third one is optional and acts as resolver for the underlying data structure to use. If omitted a simple array is used.

New items are added to the buffer using the add()-method. Usually you want the buffer to be flushed a last time, after all data was added, even if it's not full. To achieve this, simply call the flush()-method to manually flush the buffer:

$b = new FlushingBuffer(2, function(data) { /* send data */ });
$b->add(1);
$b->add(2);
$b->add(3);
$b->flush();

You may also specify a key, if you want to replace elements in the buffer at given key.

$b = new FlushingBuffer(2, function(data) { /* send data */ });
$b->add(1, 'key1');
$b->add(2, 'key1');

Of course replacing and existing element does not increase buffer size and therefore does not cause a buffer flush.

Adding multiple items

To add multiple items to the buffer at once, the addMultiple() method can be used. By default keys are not preserved. You can change this by passing true as second parameter.

$b = new FlushingBuffer(2, function(data) { /* send data */ });
$b->addMultiple([1, 2, 3]);

// with preserved keys

$b->addMultiple(['a' => 1, 'b' => 2, 'c' => 3], true);

Filling array keys

To fill multiple keys with the same value, the fillKeys() method can be used:

$b = new FlushingBuffer(2, function(data) { /* send data */ });
$b->fillKeys(['a', 'b', 'c'], 1);

This will add/replace the keys "a", "b" and "c" with the value 1.

Setting values by path

The setPath() method sets a value for the given array path. The path can be specified as string using "dot notation" or as array:

$b = new FlushingBuffer(2, function(data) { /* send data */ });

$b->setPath(['this', 'is', 'a' 'path'], 1);

$b->setPath('this.is.another.path'], 2);

This creates new array levels as needed but only root level items affect the buffer count.

Chunk processors

Chunk processors allow to process an iterable in chunks and return the processed items as generator. They act pretty much like PHP's array_chunk() function except they working with any kind of iterable and returning a generator. Thus they are predestined for processing large data sets.

You may use them like this:

$in = function() { /* input generator code */ };

$generator = (new ChunkProcessor($in, 500, function($chunk) {
    yield /* ... */
}))->consume();

To maintain the keys, the keepKeys argument may be set to true:

$generator = (new ChunkProcessor($in, 500, $processor, null, true))->consume();

Als static method exists, which creates the processor and calls consume() in one step:

$generator = ChunkProcessor::process($in, 500, $processor);