Differential D16055 Diff 38631 src/utils/PhutilProseDifferenceEngine.php

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src/utils/PhutilProseDifferenceEngine.php

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				<?php

				final class PhutilProseDifferenceEngine extends Phobject {

				public function getDiff($u, $v) {
				$diff = id(new PhutilProseDiff());

				$this->buildDiff($diff, $u, $v, 1);
				$diff->reorderParts();

				return $diff;
				}

				private function buildDiff(PhutilProseDiff $diff, $u, $v, $level) {
				if ($level == 4) {
				$diff->addPart('-', $u);
				$diff->addPart('+', $v);
				return;
				}

				$u_parts = $this->splitCorpus($u, $level);
				$v_parts = $this->splitCorpus($v, $level);

				$matrix = id(new PhutilEditDistanceMatrix())
				->setSequences($u_parts, $v_parts)
				->setComputeString(true);

				$u_pos = 0;
				$v_pos = 0;

				$edits = $matrix->getEditString();
				$edits_length = strlen($edits);

				for ($ii = 0; $ii < $edits_length; $ii++) {
				$c = $edits[$ii];
				if ($c == 's') {
				$diff->addPart('=', $u_parts[$u_pos]);
				$u_pos++;
				$v_pos++;
				} else if ($c == 'd') {
				$diff->addPart('-', $u_parts[$u_pos]);
				$u_pos++;
				} else if ($c == 'i') {
				$diff->addPart('+', $v_parts[$v_pos]);
				$v_pos++;
				} else if ($c == 'x') {
				$this->buildDiff($diff, $u_parts[$u_pos], $v_parts[$v_pos], $level + 1);
				$u_pos++;
				$v_pos++;
				} else {
				throw new Exception(
				pht(
				'Unexpected character ("%s") in edit string.',
				$c));
				}
				}
				}

				private function splitCorpus($corpus, $level) {
				switch ($level) {
				case 1:
				// Level 1: Split into sentences.
				$expr = '/([\n,!;?\.]+)/';
				break;
				case 2:
				// Level 2: Split into words.
				$expr = '/(\s+)/';
				break;
				case 3:
				// Level 3: Split into characters.
				return phutil_utf8v_combined($corpus);
				}

				$pieces = preg_split($expr, $corpus, -1, PREG_SPLIT_DELIM_CAPTURE);
				return $this->stitchPieces($pieces);
				}

				private function stitchPieces(array $pieces) {
				$results = array();
				$count = count($pieces);
				for ($ii = 0; $ii < $count; $ii += 2) {
				$result = $pieces[$ii];
				if ($ii + 1 < $count) {
				$result .= $pieces[$ii + 1];
				}
				$results[] = $result;
				}

				return $results;
				}

				}