ComparisonCompactor
In questo esempio andremo a realizzare e rifattorizzare un comparatore di stringhe. Date due stringhe differenti, come abc e abbc, mostra la differenza generando una stringa del tipo: "expected: {ab[]c} but was: {ab[b]c}".
Substring
<?php
/**
* @param string $str
* @param int $start
* @param int|null $end
* @return false|string
*/
function substring(string $str, int $start, int $end = null)
{
if ($end !== null) {
return substr($str, $start, $end - $start);
}
return substr($str, $start);
}ComparisonCompactor (prima del refactoring)
<?php
include_once('Substring.php');
class ComparisonCompactorOriginal
{
private const ELLIPSIS = '...';
private const DELTA_START = '[';
private const DELTA_END = ']';
/** @var int */
private $_contextLength;
/** @var string|null */
private $_expected;
/** @var string|null */
private $_actual;
/** @var int */
private $_prefix;
/** @var int */
private $_suffix;
/**
* ComparisonCompactorOriginal constructor.
* @param int $contextLength
* @param string|null $expected
* @param string|null $actual
*/
public function __construct(int $contextLength, ?string $expected, ?string $actual)
{
$this->_contextLength = $contextLength;
$this->_expected = $expected;
$this->_actual = $actual;
}
/**
* @param string|null $message
* @return string
*/
public function compact(string $message = null): string
{
if ($this->_expected === null || $this->_actual === null || $this->areStringsEqual()) {
return trim(sprintf('%s expected: {%s} but was: {%s}', $message, $this->_expected, $this->_actual));
}
$this->findCommonPrefix();
$this->findCommonSuffix();
$expected = $this->compactString($this->_expected);
$actual = $this->compactString($this->_actual);
return trim(sprintf('%s expected: {%s} but was: {%s}', $message, $expected, $actual));
}
/**
* @param string $source
* @return string
*/
private function compactString(string $source): string
{
$result =
self::DELTA_START .
substring($source, $this->_prefix, strlen($source) - $this->_suffix + 1) .
self::DELTA_END;
if ($this->_prefix > 0) {
$result = $this->computeCommonPrefix() . $result;
}
if ($this->_suffix > 0) {
$result = $result . $this->computeCommonSuffix();
}
return $result;
}
/**
* @return void
*/
private function findCommonPrefix(): void
{
$this->_prefix = 0;
$end = min(strlen($this->_expected), strlen($this->_actual));
for (; $this->_prefix < $end; $this->_prefix++) {
if ($this->_expected[$this->_prefix] !== $this->_actual[$this->_prefix]) {
break;
}
}
}
/**
* @return void
*/
private function findCommonSuffix(): void
{
$expectedSuffix = strlen($this->_expected) - 1;
$actualSuffix = strlen($this->_actual) - 1;
for (; $actualSuffix >= $this->_prefix && $expectedSuffix >= $this->_prefix; $actualSuffix--, $expectedSuffix--) {
if ($this->_expected[$expectedSuffix] !== $this->_actual[$actualSuffix]) {
break;
}
}
$this->_suffix = strlen($this->_expected) - $expectedSuffix;
}
/**
* @return string
*/
private function computeCommonPrefix(): string
{
return
($this->_prefix > $this->_contextLength ? self::ELLIPSIS : '') .
(substring($this->_expected, max(0, $this->_prefix - $this->_contextLength), $this->_prefix));
}
/**
* @return string
*/
private function computeCommonSuffix(): string
{
$end = min(strlen($this->_expected) - $this->_suffix + 1 + $this->_contextLength, strlen($this->_expected));
return
(substring($this->_expected, strlen($this->_expected) - $this->_suffix + 1, $end)) .
(strlen($this->_expected) - $this->_suffix + 1 < strlen($this->_expected) - $this->_contextLength ? self::ELLIPSIS : '');
}
/**
* @return bool
*/
private function areStringsEqual(): bool
{
return $this->_expected === $this->_actual;
}
}ComparisonCompactor (dopo il refactoring)
<?php
include_once('Substring.php');
class ComparisonCompactorFinal
{
private const ELLIPSIS = '...';
private const DELTA_START = '[';
private const DELTA_END = ']';
/** @var int */
private $contextLength;
/** @var string|null */
private $expected;
/** @var string|null */
private $actual;
/** @var int */
private $prefixLength;
/** @var int */
private $suffixLength;
/**
* ComparisonCompactorFinal constructor.
* @param int $contextLength
* @param string|null $expected
* @param string|null $actual
*/
public function __construct(int $contextLength, ?string $expected, ?string $actual)
{
$this->contextLength = $contextLength;
$this->expected = $expected;
$this->actual = $actual;
}
/**
* @param string|null $message
* @return string
*/
public function formatCompactedComparison(string $message = null): string
{
$compactExpected = $this->expected;
$compactActual = $this->actual;
if ($this->shouldBeCompacted()) {
$this->findCommonPrefixAndSuffix();
$compactExpected = $this->compact($this->expected);
$compactActual = $this->compact($this->actual);
}
return trim(sprintf('%s expected: {%s} but was: {%s}', $message, $compactExpected, $compactActual));
}
/**
* @return bool
*/
private function shouldBeCompacted(): bool
{
return !$this->shouldNotBeCompacted();
}
/**
* @return bool
*/
private function shouldNotBeCompacted(): bool
{
return $this->expected === null || $this->actual === null || $this->expected === $this->actual;
}
/**
* @return void
*/
private function findCommonPrefixAndSuffix(): void
{
$this->findCommonPrefix();
$this->suffixLength = 0;
for (; !$this->suffixOverlapsPrefix(); $this->suffixLength++) {
if ($this->charFromEnd($this->expected) !== $this->charFromEnd($this->actual)) {
break;
}
}
}
/**
* @return void
*/
private function findCommonPrefix(): void
{
$this->prefixLength = 0;
$end = min(strlen($this->expected), strlen($this->actual));
for (; $this->prefixLength < $end; $this->prefixLength++) {
if ($this->expected[$this->prefixLength] !== $this->actual[$this->prefixLength]) {
break;
}
}
}
/**
* @return bool
*/
private function suffixOverlapsPrefix(): bool
{
return (
strlen($this->actual) - $this->suffixLength <= $this->prefixLength ||
strlen($this->expected) - $this->suffixLength <= $this->prefixLength
);
}
/**
* @param string $s
* @return string
*/
private function charFromEnd(string $s): string
{
return $s[strlen($s) - $this->suffixLength - 1];
}
/**
* @param string $s
* @return string
*/
private function compact(string $s): string
{
return (
$this->startEllipsis() .
$this->startContext() .
self::DELTA_START .
$this->delta($s) .
self::DELTA_END .
$this->endContext() .
$this->endEllipsis()
);
}
/**
* @return string
*/
private function startEllipsis(): string
{
return $this->prefixLength > $this->contextLength ? self::ELLIPSIS : '';
}
/**
* @return string
*/
private function startContext(): string
{
$contextStart = max(0, $this->prefixLength - $this->contextLength);
$contextEnd = $this->prefixLength;
return substring($this->expected, $contextStart, $contextEnd);
}
/**
* @param string $s
* @return string
*/
private function delta(string $s): string
{
$deltaStart = $this->prefixLength;
$deltaEnd = strlen($s) - $this->suffixLength;
return substring($s, $deltaStart, $deltaEnd);
}
/**
* @return string
*/
private function endContext(): string
{
$contextStart = strlen($this->expected) - $this->suffixLength;
$contextEnd = min($contextStart + $this->contextLength, strlen($this->expected));
return substring($this->expected, $contextStart, $contextEnd);
}
/**
* @return string
*/
private function endEllipsis(): string
{
return $this->suffixLength > $this->contextLength ? self::ELLIPSIS : '';
}
}Index
<?php
include_once('ComparisonCompactorOriginal.php');
include_once('ComparisonCompactorFinal.php');
$contextLength = 2;
$expected = 'abc';
$actual = 'abbc';
$comparisonOriginal = new ComparisonCompactorOriginal($contextLength, $expected, $actual);
print_r(nl2br('<b>Original: </b>' . PHP_EOL . $comparisonOriginal->compact()));
print_r(nl2br(PHP_EOL . PHP_EOL));
$comparisonFinal = new ComparisonCompactorFinal($contextLength, $expected, $actual);
print_r(nl2br('<b> Final: </b>' . PHP_EOL . $comparisonFinal->formatCompactedComparison()));Last updated