PCRE With PHP

PHP Benelux 2015

Transcript

1. PCRE WITH PHP
   @Thomas Weinert
   

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2. ABOUT
   PHP functions and classes
   PCRE syntax
   

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3. WARNING!
   Slides contain a lot of example source
   Most of the examples are really stupid
   

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4. PREG_MATCH()
   Pattern
   Subject
   Matches
   Flags
   Offset
   

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5. PREG_MATCH() EXAMPLE
   preg_match('(a.?)', 'abac', $match);
   var_dump($match);
   array(1) {
   [0]=>
   string(2) "ab"
   }
   

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6. FLAG: PREG_OFFSET_CAPTURE
   preg_match('(a.?)', 'abac', $match, PREG_OFFSET_CAPTURE, 2);
   var_dump($match);
   array(1) {
   [0]=>
   array(2) {
   [0]=>
   string(2) "ac"
   [1]=>
   int(2)
   }
   }
   

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7. OFFSET
   $subject = 'aa ab ac ad';
   $offset = 0;
   $length = strlen($subject);
   while ($offset < $length) {
   if (preg_match('(a.)', $subject, $match, PREG_OFFSET_CAPTURE, $offset)) {
   $offset = $match[0][1] + strlen($match[0][0]);
   var_dump($match[0][0]);
   } else {
   break;
   }
   }
   string(2) "aa"
   string(2) "ab"
   string(2) "ac"
   string(2) "ad"
   

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8. PATTERN
   Delimiter
   Expression
   Modifiers
   /expression/x
   

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9. DELIMITER
   Any non alphanumeric character
   Escaping
   Special meaning
   Brackets
   

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10. DELIMITER: BRACKETS
    preg_match('((one)(two))', 'onetwo', $match);
    var_dump($match);
    array(3) {
    [0]=>
    string(6) "onetwo"
    [1]=>
    string(3) "one"
    [2]=>
    string(3) "two"
    }
    

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11. PATTERN
    String
    Escaping
    $pattern = '(\\\n)';
    $text = <<<'TEXT'
    foo\nbar
    TEXT;
    preg_match($pattern, $text, $match);
    var_dump($pattern, $text, $match);
    string(5) "(\\n)"
    string(8) "foo\nbar"
    array(1) {
    [0]=>
    string(2) "\n"
    }
    

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12. MODIFIERS
    x - PCRE_EXTENDED
    u - PCRE_UTF8
    D - PCRE_DOLLAR_ENDONLY
    s - PCRE_DOTALL
    m - PCRE_MULTILINE
    i - PCRE_CASELESS
    ...
    

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13. PCRE_EXTENDED
    $pattern = <<<'REGEX'
    (^
    (d‐)? # optional country prefix
    (\d{5}) # german zip code
    $)Dix
    REGEX;
    var_dump((bool)preg_match($pattern, 'D‐50670'));
    bool(true)
    

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14. PCRE_UTF8
    (^.*$)u
    Pattern and subject need to be valid UTF-8!
    UTF-8 1 to 4 (5 and 6 are invalid)
    

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15. PCRE_DOLLAR_ENDONLY
    $examples = [
    ["(^\\d+$)", "123"],
    ["(^\\d+$)", "123\n"],
    ["(^\\d+$)D", "123\n"],
    ["(\\A\\d+\\G)", "123\n"]
    ];
    foreach ($examples as $example) {
    var_dump((bool)preg_match($example[0], $example[1], $match));
    }
    bool(true)
    bool(true)
    bool(false)
    bool(false)
    

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16. PCRE_DOTALL
    $examples = [
    ["(^.+$)", "123"],
    ["(^.+$)", "123\n456"],
    ["(^.+$)s", "123\n456"]
    ];
    foreach ($examples as $example) {
    preg_match($example[0], $example[1], $match);
    var_dump($match);
    }
    array(1) {
    [0]=>
    string(3) "123"
    }
    array(0) {
    }
    array(1) {
    [0]=>
    string(7) "123
    456"
    }
    

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17. PCRE_MULTILINE
    $examples = [
    ["(^.+$)", "123"],
    ["(^.+$)", "123\n456"],
    ["(^.+$)m", "123\n456"]
    ];
    foreach ($examples as $example) {
    preg_match($example[0], $example[1], $match);
    var_dump($match);
    }
    array(1) {
    [0]=>
    string(3) "123"
    }
    array(0) {
    }
    array(1) {
    [0]=>
    string(3) "123"
    }
    

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18. PCRE_CASELESS
    $examples = [
    ["(foo)", "foo"],
    ["(foo)", "FOO"],
    ["(foo)i", "FOO"]
    ];
    foreach ($examples as $example) {
    preg_match($example[0], $example[1], $match);
    var_dump($match);
    }
    array(1) {
    [0]=>
    string(3) "foo"
    }
    array(0) {
    }
    array(1) {
    [0]=>
    string(3) "FOO"
    }
    

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19. PREG_MATCH_ALL()
    $subject = 'aa ab ac ad';
    preg_match_all('(a.)', $subject, $match);
    var_dump($match);
    array(1) {
    [0]=>
    array(4) {
    [0]=>
    string(2) "aa"
    [1]=>
    string(2) "ab"
    [2]=>
    string(2) "ac"
    [3]=>
    string(2) "ad"
    }
    }
    

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20. PREG_PATTERN_ORDER
    $subject = 'ab ac';
    preg_match_all('(a(.))', $subject, $match);
    var_dump($match);
    array(2) {
    [0]=>
    array(2) {
    [0]=>
    string(2) "ab"
    [1]=>
    string(2) "ac"
    }
    [1]=>
    array(2) {
    [0]=>
    string(1) "b"
    [1]=>
    string(1) "c"
    }
    }
    

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21. PREG_SET_ORDER
    $subject = 'ab ac';
    preg_match_all('(a(.))', $subject, $match, PREG_SET_ORDER);
    var_dump($match);
    array(2) {
    [0]=>
    array(2) {
    [0]=>
    string(2) "ab"
    [1]=>
    string(1) "b"
    }
    [1]=>
    array(2) {
    [0]=>
    string(2) "ac"
    [1]=>
    string(1) "c"
    }
    }
    

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22. PREG_REPLACE()
    var_dump(
    preg_replace("(')", '"', "'Hello'")
    );
    string(7) ""Hello""
    

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23. ARRAY ARGUMENTS
    var_dump(
    preg_replace(['(\\\r)', '(\\\n)'], ['CR', 'LF'], '\\r and \\n')
    );
    string(9) "CR and LF"
    

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24. REFERENCING SUBPATTERNS
    var_dump(
    preg_replace('(a(.))', 'a#${1}#', 'ab ac')
    );
    string(9) "a#b# a#c#"
    \\1
    $1
    ${1}
    

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25. PREG_REPLACE_CALLBACK()
    No need for modifier "e" (PREG_REPLACE_EVAL)
    var_dump(
    preg_replace_callback(
    '(a(.))',
    function ($match) {
    return strtoupper($match[1]);
    },
    'ab ac'
    )
    );
    string(3) "B C"
    

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26. FUNCTOR
    class Replacer {
    public function __invoke($match) {
    return strtoupper($match[1]);
    }
    }
    var_dump(
    preg_replace_callback(
    '(a(.))',
    new Replacer(),
    'ab ac'
    )
    );
    

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27. PREG_SPLIT()
    $pattern = '(\\R)u';
    $subject = "one\rtwo\n\nthree\r\nfour";
    $match = preg_split($pattern, $subject);
    var_dump($match);
    array(5) {
    [0]=>
    string(3) "one"
    [1]=>
    string(3) "two"
    [2]=>
    string(0) ""
    [3]=>
    string(5) "three"
    [4]=>
    string(4) "four"
    }
    

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28. PREG_SPLIT_NO_EMPTY
    $pattern = '(\\R)u';
    $subject = "one\rtwo\n\nthree\r\nfour";
    $match = preg_split($pattern, $subject, ‐1, PREG_SPLIT_NO_EMPTY);
    var_dump($match);
    array(4) {
    [0]=>
    string(3) "one"
    [1]=>
    string(3) "two"
    [2]=>
    string(5) "three"
    [3]=>
    string(4) "four"
    }
    

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29. PREG_SPLIT_OFFSET_CAPTURE
    $pattern = '(\\R)u';
    $subject = "one\rtwo\n\nthree";
    $flags = PREG_SPLIT_NO_EMPTY | PREG_SPLIT_OFFSET_CAPTURE;
    $match = preg_split($pattern, $subject, ‐1, $flags);
    var_dump($match);
    array(3) {
    [0]=>
    array(2) {
    [0]=>
    string(3) "one"
    [1]=>
    int(0)
    }
    [1]=>
    array(2) {
    [0]=>
    string(3) "two"
    [1]=>
    int(4)
    }
    [2]=>
    array(2) {
    [0]=>
    string(5) "three"
    [1]=>
    int(9)
    }
    }
    

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30. PREG_SPLIT_DELIM_CAPTURE
    $highlights = ['small' => '*', 'short' => '_'];
    $pattern = '((small|short))u';
    $subject = "A small, short example";
    $match = preg_split($pattern, $subject, ‐1, PREG_SPLIT_DELIM_CAPTURE);
    foreach ($match as $part) {
    if (isset($highlights[$part])) {
    echo $highlights[$part], $part, $highlights[$part];
    } else {
    echo $part;
    }
    }
    A *small*, _short_ example
    

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31. PREG_QUOTE()
    var_dump('('.preg_quote('/.*/').')');
    string(8) "(/\.\*/)"
    

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32. REGEXITERATOR
    $data = new ArrayIterator(['aa', 'ab']);
    $iterator = new RegexIterator(
    $data,
    '(.(.))',
    RegexIterator::REPLACE
    );
    $iterator‐>replacement = '$1';
    var_dump(iterator_to_array($iterator));
    array(2) {
    [0] =>
    string(1) "a"
    [1] =>
    string(1) "b"
    }
    

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33. REGEXITERATOR MODES
    MATCH
    GET_MATCH
    ALL_MATCHES
    SPLIT
    REPLACE
    USE_KEY
    

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34. UNICODE
    Modifier u
    All: \X
    Token: \x{A9}
    Category: \p{L}
    Negation: \P{L}, \p{^L}
    Scripts: \p{Hangul}
    Blocks: \p{Arrows}
    

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35. UNICODE EXAMPLE
    $data = <<<'DATA'
    English German
    한국어 日本語
    DATA;
    preg_match_all('(\\pL+)u', $data, $match);
    var_dump($match[0]);
    array(4) {
    [0] =>
    string(7) "English"
    [1] =>
    string(6) "German"
    [2] =>
    string(9) "한국어"
    [3] =>
    string(9) "日本語"
    }
    

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36. NON CATCHING SUBPATTERNS
    preg_match('((?:one)(two))', 'onetwo', $match);
    var_dump($match);
    array(2) {
    [0]=>
    string(6) "onetwo"
    [1]=>
    string(3) "two"
    }
    

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37. SUBPATTERN MODIFIERS
    (?i‐sm)
    $examples = [
    ["((?i)foo)", "FOO"],
    ["((?‐i)foo)i", "FOO"]
    ];
    foreach ($examples as $example) {
    preg_match($example[0], $example[1], $match);
    var_dump($match);
    }
    array(1) {
    [0]=>
    string(3) "FOO"
    }
    array(0) {
    }
    

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38. NAMED SUBPATTERNS
    $pattern = "(^
    (?P\d{4})
    (?:‐(?\d{1,2}))?
    (?:‐(?'day'\d{1,2}))?
    )x";
    preg_match($pattern, "2015‐01‐24", $match);
    var_dump($match);
    array(7) {
    [0]=>
    string(10) "2015‐01‐24"
    ["year"]=>
    string(4) "2015"
    [1]=>
    string(4) "2015"
    ["month"]=>
    string(2) "01"
    [2]=>
    string(2) "01"
    ["day"]=>
    string(2) "24"
    [3]=>
    string(2) "24"
    }
    

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39. PRE-DEFINED SUBROUTINES
    $pattern = "(
    ^
    (?&number)
    (?:\\.(?&number)){3}
    $
    (?(DEFINE)
    (?'number'25[0‐5]|2[1‐4]\d|1\d{2}|\d{1,2})
    )
    )x";
    var_dump((bool)preg_match($pattern, "127.0.0.1", $match));
    var_dump((bool)preg_match($pattern, "355.0.0.1", $match));
    bool(true)
    bool(false)
    

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40. ASSERTIONS
    Look Around
    Look Ahead
    Look Behind
    

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41. LOOK AHEAD
    $examples = [
    ["(h(?=e))", "hello"],
    ["(h(?=e)llo)", "hello"],
    ["(h(?=e).llo)", "hello"]
    ];
    foreach ($examples as $example) {
    preg_match($example[0], $example[1], $match);
    var_dump($match);
    }
    array(1) {
    [0]=>
    string(1) "h"
    }
    array(0) {
    }
    array(1) {
    [0]=>
    string(5) "hello"
    }
    

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42. LOOK AHEAD - NEGATION
    $examples = [
    ["(h(?!e))", "hello"],
    ["(h(?!e))", "hallo"]
    ];
    foreach ($examples as $example) {
    preg_match($example[0], $example[1], $match);
    var_dump($match);
    }
    array(0) {
    }
    array(1) {
    [0]=>
    string(1) "h"
    }
    

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43. LOOK BEHIND
    $examples = [
    ["((?<=h).)", "hello"],
    ["((?];
    foreach ($examples as $example) {
    preg_match($example[0], $example[1], $match);
    var_dump($match);
    }
    array(1) {
    [0]=>
    string(1) "e"
    }
    array(1) {
    [0]=>
    string(1) "h"
    }
    

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44. LOOK BEHIND - ALTERNATIVES
    $examples = [
    ["((?<=e|ha|.{2})l)", "hello"],
    ["((?<=e|ha)l)", "hallo"],
    ["((?<=e|.{2})l)", "hallo"]
    ];
    foreach ($examples as $example) {
    preg_match($example[0], $example[1], $match);
    var_dump($match);
    }
    array(1) {
    [0]=>
    string(1) "l"
    }
    array(1) {
    [0]=>
    string(1) "l"
    }
    array(1) {
    [0]=>
    string(1) "l"
    }
    

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45. LOOK BEHIND - UNKNOWN LENGTH
    preg_match("((?<=.{2,})l)", 'hello', $match);
    Warning: preg_match():
    Compilation failed: lookbehind assertion
    is not fixed length at offset 9 in /tmp... on line 2
    

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46. CONDITIONALS
    $pattern = '((?[\'"])?(?(quote).*?\\k|\\w+))';
    $data = ['foo', '"foo"', "'foo'", 'foo bar', '"foo bar"'];
    foreach ($data as $subject) {
    if (preg_match($pattern, $subject, $match)) {
    echo $match[0], "\n";
    }
    }
    foo
    "foo"
    'foo'
    foo
    "foo bar"
    

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47. RECURSIONS
    $pattern = <<<'PCRE'
    ( \( ( (?>[^()]+) | (?R) )* \) )Ux
    PCRE;
    preg_match_all($pattern, '(ab(cd)ef)(gh)', $match);
    var_dump($match);
    array(2) {
    [0] =>
    array(2) {
    [0] =>
    string(10) "(ab(cd)ef)"
    [1] =>
    string(4) "(gh)"
    }
    [1] =>
    array(2) {
    [0] =>
    string(1) "f"
    [1] =>
    string(1) "h"
    }
    }
    

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48. START OF PATTERN MODIFIERS
    (*UTF), (*UTF8), (*UTF16), (*UTF32)
    (*UTF)(*UCP) = u
    (*CR), (*LF), (*CRLF), (*ANYCRLF), (*ANY)
    (*BSR_ANYCRLF), (*BSR_UNICODE) - \R
    (*LIMIT_MATCH=x), (*LIMIT_RECURSION=d)
    (*NO_AUTO_POSSESS), (*NO_START_OPT)
    (*NOTEMPTY), (*NOTEMPTY_ATSTART)
    

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49. CONTROL VERBS
    (SKIP*)(?!)
    (PRUNE*)
    (THEN*)
    (COMMIT*)
    (ACCEPT*)
    http://perldoc.perl.org/perlre .html#Special-Backtracking-Control-Verbs
    

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50. REGEX101.COM
    

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51. VERSIONS
    PCRE2 10.0 2015-01-05
    PCRE 8.36 2014-09-26
    3V4L.ORG
    PHP7, HHVM >= 3.3: 8.35 2014-04-04
    PHP >= 5.5.10: 8.34 2013-12-15
    

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52. LINKS
    http://www.rexegg.com/
    http://www.regular-expressions.info/
    https://www.regex101.com/
    

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53. THANKS
    

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