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Code Issues Releases Wiki Activity

Add "PhutilProseDiff" classes to "phabricator/"

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Summary: Depends on D20836. Ref T13414. Ref T13425. Ref T13395. Move these to "phabricator/" before trying to improve the high-level diff engine in prose diffs.

Test Plan: Ran "arc liberate", looked at a prose diff (no behavioral change).

Maniphest Tasks: T13425, T13414, T13395

Differential Revision: https://secure.phabricator.com/D20838
This commit is contained in:
epriestley 2019-09-25 14:37:20 -07:00
parent 281598d65c
commit 9d884f144f
4 changed files with 752 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
src/__phutil_library_map__.php
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@ -5599,6 +5599,9 @@ phutil_register_library_map(array(
'PhutilOAuthAuthAdapter' => 'applications/auth/adapter/PhutilOAuthAuthAdapter.php', 'PhutilOAuthAuthAdapter' => 'applications/auth/adapter/PhutilOAuthAuthAdapter.php',
'PhutilPHPCodeSnippetContextFreeGrammar' => 'infrastructure/lipsum/code/PhutilPHPCodeSnippetContextFreeGrammar.php', 'PhutilPHPCodeSnippetContextFreeGrammar' => 'infrastructure/lipsum/code/PhutilPHPCodeSnippetContextFreeGrammar.php',
'PhutilPhabricatorAuthAdapter' => 'applications/auth/adapter/PhutilPhabricatorAuthAdapter.php', 'PhutilPhabricatorAuthAdapter' => 'applications/auth/adapter/PhutilPhabricatorAuthAdapter.php',
'PhutilProseDiff' => 'infrastructure/diff/prose/PhutilProseDiff.php',
'PhutilProseDiffTestCase' => 'infrastructure/diff/prose/__tests__/PhutilProseDiffTestCase.php',
'PhutilProseDifferenceEngine' => 'infrastructure/diff/prose/PhutilProseDifferenceEngine.php',
'PhutilQsprintfInterface' => 'infrastructure/storage/xsprintf/PhutilQsprintfInterface.php', 'PhutilQsprintfInterface' => 'infrastructure/storage/xsprintf/PhutilQsprintfInterface.php',
'PhutilQueryString' => 'infrastructure/storage/xsprintf/PhutilQueryString.php', 'PhutilQueryString' => 'infrastructure/storage/xsprintf/PhutilQueryString.php',
'PhutilRealNameContextFreeGrammar' => 'infrastructure/lipsum/PhutilRealNameContextFreeGrammar.php', 'PhutilRealNameContextFreeGrammar' => 'infrastructure/lipsum/PhutilRealNameContextFreeGrammar.php',
@ -12398,6 +12401,9 @@ phutil_register_library_map(array(
'PhutilOAuthAuthAdapter' => 'PhutilAuthAdapter', 'PhutilOAuthAuthAdapter' => 'PhutilAuthAdapter',
'PhutilPHPCodeSnippetContextFreeGrammar' => 'PhutilCLikeCodeSnippetContextFreeGrammar', 'PhutilPHPCodeSnippetContextFreeGrammar' => 'PhutilCLikeCodeSnippetContextFreeGrammar',
'PhutilPhabricatorAuthAdapter' => 'PhutilOAuthAuthAdapter', 'PhutilPhabricatorAuthAdapter' => 'PhutilOAuthAuthAdapter',
'PhutilProseDiff' => 'Phobject',
'PhutilProseDiffTestCase' => 'PhutilTestCase',
'PhutilProseDifferenceEngine' => 'Phobject',
'PhutilQueryString' => 'Phobject', 'PhutilQueryString' => 'Phobject',
'PhutilRealNameContextFreeGrammar' => 'PhutilContextFreeGrammar', 'PhutilRealNameContextFreeGrammar' => 'PhutilContextFreeGrammar',
'PhutilRemarkupAnchorRule' => 'PhutilRemarkupRule', 'PhutilRemarkupAnchorRule' => 'PhutilRemarkupRule',

292
src/infrastructure/diff/prose/PhutilProseDiff.php Normal file
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@ -0,0 +1,292 @@
<?php
final class PhutilProseDiff extends Phobject {
private $parts = array();
public function addPart($type, $text) {
$this->parts[] = array(
'type' => $type,
'text' => $text,
);
return $this;
}
public function getParts() {
return $this->parts;
}
/**
* Get diff parts, but replace large blocks of unchanged text with "."
* parts representing missing context.
*/
public function getSummaryParts() {
$parts = $this->getParts();
$head_key = head_key($parts);
$last_key = last_key($parts);
$results = array();
foreach ($parts as $key => $part) {
$is_head = ($key == $head_key);
$is_last = ($key == $last_key);
switch ($part['type']) {
case '=':
$pieces = $this->splitTextForSummary($part['text']);
if ($is_head || $is_last) {
$need = 2;
} else {
$need = 3;
}
// We don't have enough pieces to omit anything, so just continue.
if (count($pieces) < $need) {
$results[] = $part;
break;
}
if (!$is_head) {
$results[] = array(
'type' => '=',
'text' => head($pieces),
);
}
$results[] = array(
'type' => '.',
'text' => null,
);
if (!$is_last) {
$results[] = array(
'type' => '=',
'text' => last($pieces),
);
}
break;
default:
$results[] = $part;
break;
}
}
return $results;
}
public function reorderParts() {
// Reorder sequences of removed and added sections to put all the "-"
// parts together first, then all the "+" parts together. This produces
// a more human-readable result than intermingling them.
$o_run = array();
$n_run = array();
$result = array();
foreach ($this->parts as $part) {
$type = $part['type'];
switch ($type) {
case '-':
$o_run[] = $part;
break;
case '+':
$n_run[] = $part;
break;
default:
if ($o_run || $n_run) {
foreach ($this->combineRuns($o_run, $n_run) as $merged_part) {
$result[] = $merged_part;
}
$o_run = array();
$n_run = array();
}
$result[] = $part;
break;
}
}
if ($o_run || $n_run) {
foreach ($this->combineRuns($o_run, $n_run) as $part) {
$result[] = $part;
}
}
// Now, combine consecuitive runs of the same type of change (like a
// series of "-" parts) into a single run.
$combined = array();
$last = null;
$last_text = null;
foreach ($result as $part) {
$type = $part['type'];
if ($last !== $type) {
if ($last !== null) {
$combined[] = array(
'type' => $last,
'text' => $last_text,
);
}
$last_text = null;
$last = $type;
}
$last_text .= $part['text'];
}
if ($last_text !== null) {
$combined[] = array(
'type' => $last,
'text' => $last_text,
);
}
$this->parts = $combined;
return $this;
}
private function combineRuns($o_run, $n_run) {
$o_merge = $this->mergeParts($o_run);
$n_merge = $this->mergeParts($n_run);
// When removed and added blocks share a prefix or suffix, we sometimes
// want to count it as unchanged (for example, if it is whitespace) but
// sometimes want to count it as changed (for example, if it is a word
// suffix like "ing"). Find common prefixes and suffixes of these layout
// characters and emit them as "=" (unchanged) blocks.
$layout_characters = array(
' ' => true,
"\n" => true,
'.' => true,
'!' => true,
',' => true,
'?' => true,
']' => true,
'[' => true,
'(' => true,
')' => true,
'<' => true,
'>' => true,
);
$o_text = $o_merge['text'];
$n_text = $n_merge['text'];
$o_len = strlen($o_text);
$n_len = strlen($n_text);
$min_len = min($o_len, $n_len);
$prefix_len = 0;
for ($pos = 0; $pos < $min_len; $pos++) {
$o = $o_text[$pos];
$n = $n_text[$pos];
if ($o !== $n) {
break;
}
if (empty($layout_characters[$o])) {
break;
}
$prefix_len++;
}
$suffix_len = 0;
for ($pos = 0; $pos < ($min_len - $prefix_len); $pos++) {
$o = $o_text[$o_len - ($pos + 1)];
$n = $n_text[$n_len - ($pos + 1)];
if ($o !== $n) {
break;
}
if (empty($layout_characters[$o])) {
break;
}
$suffix_len++;
}
$results = array();
if ($prefix_len) {
$results[] = array(
'type' => '=',
'text' => substr($o_text, 0, $prefix_len),
);
}
if ($prefix_len < $o_len) {
$results[] = array(
'type' => '-',
'text' => substr(
$o_text,
$prefix_len,
$o_len - $prefix_len - $suffix_len),
);
}
if ($prefix_len < $n_len) {
$results[] = array(
'type' => '+',
'text' => substr(
$n_text,
$prefix_len,
$n_len - $prefix_len - $suffix_len),
);
}
if ($suffix_len) {
$results[] = array(
'type' => '=',
'text' => substr($o_text, -$suffix_len),
);
}
return $results;
}
private function mergeParts(array $parts) {
$text = '';
$type = null;
foreach ($parts as $part) {
$part_type = $part['type'];
if ($type === null) {
$type = $part_type;
}
if ($type !== $part_type) {
throw new Exception(pht('Can not merge parts of dissimilar types!'));
}
$text .= $part['text'];
}
return array(
'type' => $type,
'text' => $text,
);
}
private function splitTextForSummary($text) {
$matches = null;
$ok = preg_match('/^(\n*[^\n]+)\n/', $text, $matches);
if (!$ok) {
return array($text);
}
$head = $matches[1];
$text = substr($text, strlen($head));
$ok = preg_match('/\n([^\n]+\n*)\z/', $text, $matches);
if (!$ok) {
return array($text);
}
$last = $matches[1];
$text = substr($text, 0, -strlen($last));
if (!strlen(trim($text))) {
return array($head, $last);
} else {
return array($head, $text, $last);
}
}
}

209
src/infrastructure/diff/prose/PhutilProseDifferenceEngine.php Normal file
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@ -0,0 +1,209 @@
<?php
final class PhutilProseDifferenceEngine extends Phobject {
public function getDiff($u, $v) {
return $this->buildDiff($u, $v, 0);
}
private function buildDiff($u, $v, $level) {
$u_parts = $this->splitCorpus($u, $level);
$v_parts = $this->splitCorpus($v, $level);
$matrix = id(new PhutilEditDistanceMatrix())
->setMaximumLength(128)
->setSequences($u_parts, $v_parts)
->setComputeString(true);
// For word-level and character-level changes, smooth the output string
// to reduce the choppiness of the diff.
if ($level > 1) {
$matrix->setApplySmoothing(PhutilEditDistanceMatrix::SMOOTHING_FULL);
}
$u_pos = 0;
$v_pos = 0;
$edits = $matrix->getEditString();
$edits_length = strlen($edits);
$diff = new PhutilProseDiff();
for ($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') {
$diff->addPart('-', $u_parts[$u_pos]);
$diff->addPart('+', $v_parts[$v_pos]);
$u_pos++;
$v_pos++;
} else {
throw new Exception(
pht(
'Unexpected character ("%s") in edit string.',
$c));
}
}
$diff->reorderParts();
// If we just built a character-level diff, we're all done and do not
// need to go any deeper.
if ($level == 3) {
return $diff;
}
$blocks = array();
$block = null;
foreach ($diff->getParts() as $part) {
$type = $part['type'];
$text = $part['text'];
switch ($type) {
case '=':
if ($block) {
$blocks[] = $block;
$block = null;
}
$blocks[] = array(
'type' => $type,
'text' => $text,
);
break;
case '-':
if (!$block) {
$block = array(
'type' => '!',
'old' => '',
'new' => '',
);
}
$block['old'] .= $text;
break;
case '+':
if (!$block) {
$block = array(
'type' => '!',
'old' => '',
'new' => '',
);
}
$block['new'] .= $text;
break;
}
}
if ($block) {
$blocks[] = $block;
}
$result = new PhutilProseDiff();
foreach ($blocks as $block) {
$type = $block['type'];
if ($type == '=') {
$result->addPart('=', $block['text']);
} else {
$old = $block['old'];
$new = $block['new'];
if (!strlen($old) && !strlen($new)) {
// Nothing to do.
} else if (!strlen($old)) {
$result->addPart('+', $new);
} else if (!strlen($new)) {
$result->addPart('-', $old);
} else {
if ($matrix->didReachMaximumLength()) {
// If this text was too big to diff, don't try to subdivide it.
$result->addPart('-', $old);
$result->addPart('+', $new);
} else {
$subdiff = $this->buildDiff(
$old,
$new,
$level + 1);
foreach ($subdiff->getParts() as $part) {
$result->addPart($part['type'], $part['text']);
}
}
}
}
}
$result->reorderParts();
return $result;
}
private function splitCorpus($corpus, $level) {
switch ($level) {
case 0:
// Level 0: Split into paragraphs.
$expr = '/([\n]+)/';
break;
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, $level);
}
private function stitchPieces(array $pieces, $level) {
$results = array();
$count = count($pieces);
for ($ii = 0; $ii < $count; $ii += 2) {
$result = $pieces[$ii];
if ($ii + 1 < $count) {
$result .= $pieces[$ii + 1];
}
if ($level < 2) {
// Split pieces into separate text and whitespace sections: make one
// piece out of all the whitespace at the beginning, one piece out of
// all the actual text in the middle, and one piece out of all the
// whitespace at the end.
$matches = null;
preg_match('/^(\s*)(.*?)(\s*)\z/', $result, $matches);
if (strlen($matches[1])) {
$results[] = $matches[1];
}
if (strlen($matches[2])) {
$results[] = $matches[2];
}
if (strlen($matches[3])) {
$results[] = $matches[3];
}
} else {
$results[] = $result;
}
}
// If the input ended with a delimiter, we can get an empty final piece.
// Just discard it.
if (last($results) == '') {
array_pop($results);
}
return $results;
}
}

245
src/infrastructure/diff/prose/__tests__/PhutilProseDiffTestCase.php Normal file
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@ -0,0 +1,245 @@
<?php
final class PhutilProseDiffTestCase extends PhutilTestCase {
public function testProseDiffsDistance() {
$this->assertProseParts(
'',
'',
array(),
pht('Empty'));
$this->assertProseParts(
"xxx\nyyy",
"xxx\nzzz\nyyy",
array(
"= xxx\n",
"+ zzz\n",
'= yyy',
),
pht('Add Paragraph'));
$this->assertProseParts(
"xxx\nzzz\nyyy",
"xxx\nyyy",
array(
"= xxx\n",
"- zzz\n",
'= yyy',
),
pht('Remove Paragraph'));
// Without smoothing, the alogorithm identifies that "shark" and "cat"
// both contain the letter "a" and tries to express this as a very
// fine-grained edit which replaces "sh" with "c" and then "rk" with "t".
// This is technically correct, but it is much easier for human viewers to
// parse if we smooth this into a single removal and a single addition.
$this->assertProseParts(
'They say the shark has nine lives.',
'They say the cat has nine lives.',
array(
'= They say the ',
'- shark',
'+ cat',
'= has nine lives.',
),
pht('"Shark/cat" word edit smoothenss.'));
$this->assertProseParts(
'Rising quickly, she says',
'Rising quickly, she remarks:',
array(
'= Rising quickly, she ',
'- says',
'+ remarks:',
),
pht('"Says/remarks" word edit smoothenss.'));
$this->assertProseParts(
'See screenshots',
'Viewed video files',
array(
'- See screenshots',
'+ Viewed video files',
),
pht('Complete paragraph rewrite.'));
$this->assertProseParts(
'xaaax',
'xbbbx',
array(
'- xaaax',
'+ xbbbx',
),
pht('Whole word rewrite with common prefix and suffix.'));
$this->assertProseParts(
' aaa ',
' bbb ',
array(
'= ',
'- aaa',
'+ bbb',
'= ',
),
pht('Whole word rewrite with whitespace prefix and suffix.'));
$this->assertSummaryProseParts(
"a\nb\nc\nd\ne\nf\ng\nh\n",
"a\nb\nc\nd\nX\nf\ng\nh\n",
array(
'.',
"= d\n",
'- e',
'+ X',
"= \nf",
'.',
),
pht('Summary diff with middle change.'));
$this->assertSummaryProseParts(
"a\nb\nc\nd\ne\nf\ng\nh\n",
"X\nb\nc\nd\ne\nf\ng\nh\n",
array(
'- a',
'+ X',
"= \nb",
'.',
),
pht('Summary diff with head change.'));
$this->assertSummaryProseParts(
"a\nb\nc\nd\ne\nf\ng\nh\n",
"a\nb\nc\nd\ne\nf\ng\nX\n",
array(
'.',
"= g\n",
'- h',
'+ X',
"= \n",
),
pht('Summary diff with last change.'));
$this->assertProseParts(
'aaa aaa aaa aaa, bbb bbb bbb bbb.',
"aaa aaa aaa aaa, bbb bbb bbb bbb.\n\n- ccc ccc ccc",
array(
'= aaa aaa aaa aaa, bbb bbb bbb bbb.',
"+ \n\n- ccc ccc ccc",
),
pht('Diff with new trailing content.'));
$this->assertProseParts(
'aaa aaa aaa aaa, bbb bbb bbb bbb.',
'aaa aaa aaa aaa bbb bbb bbb bbb.',
array(
'= aaa aaa aaa aaa',
'- ,',
'= bbb bbb bbb bbb.',
),
pht('Diff with a removed comma.'));
$this->assertProseParts(
'aaa aaa aaa aaa, bbb bbb bbb bbb.',
"aaa aaa aaa aaa bbb bbb bbb bbb.\n\n- ccc ccc ccc!",
array(
'= aaa aaa aaa aaa',
'- ,',
'= bbb bbb bbb bbb.',
"+ \n\n- ccc ccc ccc!",
),
pht('Diff with a removed comma and new trailing content.'));
$this->assertProseParts(
'[ ] Walnuts',
'[X] Walnuts',
array(
'= [',
'- ',
'+ X',
'= ] Walnuts',
),
pht('Diff adding a tickmark to a checkbox list.'));
$this->assertProseParts(
'[[ ./week49 ]]',
'[[ ./week50 ]]',
array(
'= [[ ./week',
'- 49',
'+ 50',
'= ]]',
),
pht('Diff changing a remarkup wiki link target.'));
// Create a large corpus with many sentences and paragraphs.
$large_paragraph = 'xyz. ';
$large_paragraph = str_repeat($large_paragraph, 50);
$large_paragraph = rtrim($large_paragraph);
$large_corpus = $large_paragraph."\n\n";
$large_corpus = str_repeat($large_corpus, 50);
$large_corpus = rtrim($large_corpus);
$this->assertProseParts(
$large_corpus,
"aaa\n\n".$large_corpus."\n\nzzz",
array(
"+ aaa\n\n",
'= '.$large_corpus,
"+ \n\nzzz",
),
pht('Adding initial and final lines to a large corpus.'));
}
private function assertProseParts($old, $new, array $expect_parts, $label) {
$engine = new PhutilProseDifferenceEngine();
$diff = $engine->getDiff($old, $new);
$parts = $diff->getParts();
$this->assertParts($expect_parts, $parts, $label);
}
private function assertSummaryProseParts(
$old,
$new,
array $expect_parts,
$label) {
$engine = new PhutilProseDifferenceEngine();
$diff = $engine->getDiff($old, $new);
$parts = $diff->getSummaryParts();
$this->assertParts($expect_parts, $parts, $label);
}
private function assertParts(
array $expect,
array $actual_parts,
$label) {
$actual = array();
foreach ($actual_parts as $actual_part) {
$type = $actual_part['type'];
$text = $actual_part['text'];
switch ($type) {
case '.':
$actual[] = $type;
break;
default:
$actual[] = "{$type} {$text}";
break;
}
}
$this->assertEqual($expect, $actual, $label);
}
}