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libphutil/src/markup/engine/PhutilRemarkupEngine.php
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PhutilRemarkupEngine.php
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<?php
final class PhutilRemarkupEngine extends PhutilMarkupEngine {
const MODE_DEFAULT = 0;
const MODE_TEXT = 1;
const MAX_CHILD_DEPTH = 32;
private $blockRules = array();
private $config = array();
private $mode;
private $metadata = array();
private $states = array();
private $postprocessRules = array();
public function setConfig($key, $value) {
$this->config[$key] = $value;
return $this;
}
public function getConfig($key, $default = null) {
return idx($this->config, $key, $default);
}
public function setMode($mode) {
$this->mode = $mode;
return $this;
}
public function isTextMode() {
return $this->mode & self::MODE_TEXT;
}
public function setBlockRules(array $rules) {
assert_instances_of($rules, 'PhutilRemarkupEngineBlockRule');
$rules = msort($rules, 'getPriority');
$this->blockRules = $rules;
foreach ($this->blockRules as $rule) {
$rule->setEngine($this);
}
$post_rules = array();
foreach ($this->blockRules as $block_rule) {
foreach ($block_rule->getMarkupRules() as $rule) {
$key = $rule->getPostprocessKey();
if ($key !== null) {
$post_rules[$key] = $rule;
}
}
}
$this->postprocessRules = $post_rules;
return $this;
}
public function getTextMetadata($key, $default = null) {
if (isset($this->metadata[$key])) {
return $this->metadata[$key];
}
return idx($this->metadata, $key, $default);
}
public function setTextMetadata($key, $value) {
$this->metadata[$key] = $value;
return $this;
}
public function storeText($text) {
if ($this->isTextMode()) {
$text = phutil_safe_html($text);
}
return $this->storage->store($text);
}
public function overwriteStoredText($token, $new_text) {
if ($this->isTextMode()) {
$new_text = phutil_safe_html($new_text);
}
$this->storage->overwrite($token, $new_text);
return $this;
}
public function markupText($text) {
return $this->postprocessText($this->preprocessText($text));
}
public function pushState($state) {
if (empty($this->states[$state])) {
$this->states[$state] = 0;
}
$this->states[$state]++;
return $this;
}
public function popState($state) {
if (empty($this->states[$state])) {
throw new Exception("State '{$state}' pushed more than popped!");
}
$this->states[$state]--;
if (!$this->states[$state]) {
unset($this->states[$state]);
}
return $this;
}
public function getState($state) {
return !empty($this->states[$state]);
}
public function preprocessText($text) {
$this->metadata = array();
$this->storage = new PhutilRemarkupBlockStorage();
$blocks = $this->splitTextIntoBlocks($text);
$output = array();
foreach ($blocks as $block) {
$output[] = $this->markupBlock($block);
}
$output = $this->flattenOutput($output);
$map = $this->storage->getMap();
unset($this->storage);
$metadata = $this->metadata;
return array(
'output' => $output,
'storage' => $map,
'metadata' => $metadata,
);
}
private function splitTextIntoBlocks($text, $depth = 0) {
// Apply basic block and paragraph normalization to the text. NOTE: We don't
// strip trailing whitespace because it is semantic in some contexts,
// notably inlined diffs that the author intends to show as a code block.
$text = phutil_split_lines($text, true);
$block_rules = $this->blockRules;
$blocks = array();
$cursor = 0;
$prev_block = array();
while (isset($text[$cursor])) {
$starting_cursor = $cursor;
foreach ($block_rules as $block_rule) {
$num_lines = $block_rule->getMatchingLineCount($text, $cursor);
if ($num_lines) {
if ($blocks) {
$prev_block = last($blocks);
}
$curr_block = array(
'start' => $cursor,
'num_lines' => $num_lines,
'rule' => $block_rule,
'is_empty' => self::isEmptyBlock($text, $cursor, $num_lines),
'children' => array(),
);
if ($prev_block
&& self::shouldMergeBlocks($text, $prev_block, $curr_block)) {
$blocks[last_key($blocks)]['num_lines'] += $curr_block['num_lines'];
$blocks[last_key($blocks)]['is_empty'] =
$blocks[last_key($blocks)]['is_empty'] && $curr_block['is_empty'];
} else {
$blocks[] = $curr_block;
}
$cursor += $num_lines;
break;
}
}
if ($starting_cursor === $cursor) {
throw new Exception('Block in text did not match any block rule.');
}
}
foreach ($blocks as $key => $block) {
$lines = array_slice($text, $block['start'], $block['num_lines']);
$blocks[$key]['text'] = implode('', $lines);
}
// Stop splitting child blocks apart if we get too deep. This arrests
// any blocks which have looping child rules, and stops the stack from
// exploding if someone writes a hilarious comment with 5,000 levels of
// quoted text.
if ($depth < self::MAX_CHILD_DEPTH) {
foreach ($blocks as $key => $block) {
$rule = $block['rule'];
if (!$rule->supportsChildBlocks()) {
continue;
}
list($parent_text, $child_text) = $rule->extractChildText(
$block['text']);
$blocks[$key]['text'] = $parent_text;
$blocks[$key]['children'] = $this->splitTextIntoBlocks(
$child_text,
$depth + 1);
}
}
return $blocks;
}
private function markupBlock(array $block) {
$children = array();
foreach ($block['children'] as $child) {
$children[] = $this->markupBlock($child);
}
if ($children) {
$children = $this->flattenOutput($children);
} else {
$children = null;
}
return $block['rule']->markupText($block['text'], $children);
}
private function flattenOutput(array $output) {
if ($this->isTextMode()) {
$output = implode("\n\n", $output)."\n";
} else {
$output = phutil_implode_html("\n\n", $output);
}
return $output;
}
private static function shouldMergeBlocks($text, $prev_block, $curr_block) {
$block_rules = ipull(array($prev_block, $curr_block), 'rule');
$default_rule = 'PhutilRemarkupEngineRemarkupDefaultBlockRule';
try {
assert_instances_of($block_rules, $default_rule);
// If the last block was empty keep merging
if ($prev_block['is_empty']) {
return true;
}
// If this line is blank keep merging
if ($curr_block['is_empty']) {
return true;
}
// If the current line and the last line have content, keep merging
if (strlen(trim($text[$curr_block['start'] - 1]))) {
if (strlen(trim($text[$curr_block['start']]))) {
return true;
}
}
} catch (Exception $e) {
}
return false;
}
private static function isEmptyBlock($text, $start, $num_lines) {
for ($cursor = $start; $cursor < $start + $num_lines; $cursor++) {
if (strlen(trim($text[$cursor]))) {
return false;
}
}
return true;
}
public function postprocessText(array $dict) {
$this->metadata = idx($dict, 'metadata', array());
$this->storage = new PhutilRemarkupBlockStorage();
$this->storage->setMap(idx($dict, 'storage', array()));
foreach ($this->blockRules as $block_rule) {
$block_rule->postprocess();
}
foreach ($this->postprocessRules as $rule) {
$rule->didMarkupText();
}
return $this->restoreText(idx($dict, 'output'), $this->isTextMode());
}
public function restoreText($text) {
return $this->storage->restore($text, $this->isTextMode());
}
}
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