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Add SplitCallbackIterator
Tiny, but useful, spin-off from the SplitIterator, the SplitCallbackIterator looks ready for commit as well (documentation and one test case from it).
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‎SplitCallbackIterator.php

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<?php
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require_once("SplitIterator.php");
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/**
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* An {@see IteratorIterator} that splits another iterator into
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* multiple iterators based on the decision of a callback.
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*
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* This class is a concrete implementation of a {@see SplitIterator}
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* that only differs in the way the decision on the split is called:
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* While a {@see SplitIterator} needs to be subclassed, this version
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* takes a callback function from the outside.
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*
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* Otherwise the documentation for {@see SplitIterator} applies.
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*
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* A code example that splits a text into paragraphs at empty lines
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* and formats them as simple HTML:
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*
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* <code>
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* // The input is an Iterator over text lines, with
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* // empty lines as markers for paragraph boundaries
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* $lines = new ArrayIterator(array(
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* "This is the",
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* "first paragraph.",
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* "",
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* "And this is",
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* "the second",
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* "one."
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* ));
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*
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* // We just need a function that returns TRUE for empty lines
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* $split = function ($key, $line) { return $line == ""; };
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*
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* // And apply this function to split up the original Iterator
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* // into multiple iterators (one per paragraph)
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* $paragraphs = new SplitCallbackIterator($lines, $split);
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*
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* // Now we can iterate over paragraphs and their lines
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* // already in two nested loops
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* foreach($paragraphs as $paragraph) {
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* print "<p>";
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* foreach($paragraph as $line)
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* print $line." ";
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* print "<\\p>";
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* }
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* </code>
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*
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* @author Beat Vontobel
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* @since 2015-05-20
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* @package MeteoNews\phplib
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* @subpackage Iterators
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*
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* @see SplitIterator
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*/
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class SplitCallbackIterator extends SplitIterator {
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private $needsSplitCallback;
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/**
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* Create a new splitting iterator based on an inner iterator and a
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* callback for the split decision.
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*
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* The callback function gets called for every item in the inner
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* iterator, with each item's key and value as the two arguments. So
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* an example callback could look as follows:
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*
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* <code>
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* function needsSplit($key, $currentItem) {
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* return ... ? TRUE : FALSE;
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* }
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* </code>
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*
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* If the callback returns TRUE, a split is initiated for the given
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* item.
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*
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* @param Traversable The iterator to be split into multiple
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* iterators.
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*
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* @param callable The callback for the split decision.
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*/
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public function __construct(Traversable $innerIterator, callable $needsSplitCallback) {
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$this->needsSplitCallback = $needsSplitCallback;
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parent::__construct($innerIterator);
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}
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final public function needsSplit($key, $value) {
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$callback = $this->needsSplitCallback;
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return $callback($key, $value);
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}
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}
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?>

‎tests/SplitCallbackIterator_000.phpt

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--TEST--
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SplitCallbackIterator: Automatic smoke test (syntax, warnings, silence)
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--FILE--
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<?php
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$source = FALSE;
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$output = FALSE;
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$global_vars = array();
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$cr_okay = FALSE;
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$source = file_get_contents("SplitCallbackIterator.php");
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$lines = preg_split('/(\\x0a|\\x0d)+/', $source, 0, PREG_SPLIT_NO_EMPTY);
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if(preg_match('/\?>\s*$/', $source))
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echo "SplitCallbackIterator has closing PHP tag at end\n";
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else
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echo "SplitCallbackIterator is missing closing PHP tag at end\n";
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if(file_exists(preg_replace("|[^/]+$|", "DOS_LINE_ENDINGS", "SplitCallbackIterator"))) {
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// Check for a consistent use of only CRLF if a "DOS_LINE_ENDINGS" marker
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// file exists in the containing folder
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$cr_okay = (preg_match_all('/\x0d\x0a/', $source) == preg_match_all('/\x0d/', $source)
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&& preg_match_all('/\x0d\x0a/', $source) == preg_match_all('/\x0a/', $source));
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} else {
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// Otherwise (normal situation) any CR character is treated as a bug
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$cr_okay = !preg_match('/\x0d/', $source);
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}
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if($cr_okay)
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echo "SplitCallbackIterator does not contain CR characters (or is consistent and in a folder marked with DOS_LINE_ENDINGS)\n";
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else
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echo "SplitCallbackIterator does contain CR characters (and is not consistent or not in a folder marked with DOS_LINE_ENDINGS)\n";
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$global_vars = array_keys($GLOBALS);
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ob_start();
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require_once("SplitCallbackIterator.php");
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$output = ob_get_contents();
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ob_end_clean();
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if($output === "")
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echo "Parsing of SplitCallbackIterator was silent\n";
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else
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echo "Parsing of SplitCallbackIterator was not silent:\n$output";
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// XXX: Currently, we have these exceptions of global variables being added...
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$global_vars = array_merge($global_vars,
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array('db_host', 'db_user', 'db_pass', 'db_name',
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'memcache_hostconfig',
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'global_script_resources_object'));
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if(count(array_diff(array_keys($GLOBALS), $global_vars)) == 0)
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print "SplitCallbackIterator did not pollute global variable space\n";
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else
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print "SplitCallbackIterator added these variables to global space: ".
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implode(", ", array_diff(array_keys($GLOBALS), $global_vars)).
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"\n";
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$class_defs = array();
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foreach($lines as $line) {
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if(preg_match('/^\s*((abstract)\s+)?(class|interface|trait)\s+([a-z0-9_]+)/i', $line, $matches)) {
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$new_def = "$matches[3] $matches[4]";
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if($matches[3] == 'class'
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&& preg_match('/Exception$/', $matches[4])) {
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foreach($class_defs as $class_def) {
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if(preg_match("/^".preg_replace("/^(trait|interface)/", "class", $class_def)."/", $new_def))
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continue 2;
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}
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}
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$class_defs[] = $new_def;
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}
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}
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if(count($class_defs) <= 1) {
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print "SplitCallbackIterator contains at most one class, interface, or trait (except for Exception classes)\n";
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} else {
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print "SplitCallbackIterator contains multiple classes/interfaces/traits:\n";
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print " ".implode("\n ", $class_defs)."\n";
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}
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?>
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--EXPECT--
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SplitCallbackIterator has closing PHP tag at end
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SplitCallbackIterator does not contain CR characters (or is consistent and in a folder marked with DOS_LINE_ENDINGS)
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Parsing of SplitCallbackIterator was silent
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SplitCallbackIterator did not pollute global variable space
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SplitCallbackIterator contains at most one class, interface, or trait (except for Exception classes)

‎tests/SplitCallbackIterator_001.phpt

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--TEST--
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SplitCallbackIterator: Documentation example
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--FILE--
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<?php
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require_once("SplitCallbackIterator.php");
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$lines = new ArrayIterator(array("First",
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"and second line, and",
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"3rd in 1st paragraph.",
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"",
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"A 2nd paragraph.",
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"",
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"And the final one,",
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"again with two lines."));
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$paragraphs = TestHelpers::pnewdebug("SplitCallbackIterator",
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$lines,
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function ($key, $line) {
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return $line == "";
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});
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foreach($paragraphs as $paragraph) {
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print "<p>\n ";
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foreach($paragraph as $line)
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print $line." ";
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print "\n<\\p>\n";
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}
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?>
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--EXPECT--
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new SplitCallbackIterator(object(ArrayIterator), object(Closure)) returns object(SplitCallbackIterator)
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<p>
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First and second line, and 3rd in 1st paragraph.
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<\p>
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<p>
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A 2nd paragraph.
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<\p>
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<p>
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And the final one, again with two lines.
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<\p>

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