Finding File Names

Regex Arguments in Expressions

if(!matches(value,"[\\p{Alnum}\\p{Space}]+"

),error('Please only enter alpha numeric characters')

Checks whether any characters are not (!) alphanumeric characters or spaces. If any are not, matches() will evaluate to 1, and the error message will be presented. The + is a greedy quantifier, so it can match more than once. This means value can contain as many alphanumeric characters or spaces as it likes, so long as it does not contain anything else.

$xml = replaceAll($xml, "<sc_tower_torqueing/type><id.*?<name>", "<type>"),
$xml = replaceAll($xml, "</name></sc_tower_torqueing/type>", "</type>"),

The first line matches text with the pattern:

•  sc_tower_torqueing/type><id.
• followed by
  • any character, indicated by the wildcard * 
  • however many times it appears, indicated by ?
• followed by the text <name> to finish.

Any matching pattern is changed to the text <type>. 

The second line matches the exact text </name></sc_tower_torqueing/type> and changes any occurrence to “</type>". As the exact text is known, this does not require a regex.

Escaping Special Characters 

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special special

In a regex, some characters, called meta-characters, have special meanings. For example quote marks “ mark the the start and end of a string; see Regular expression metacharacters for a full list and their functions. To use a meta-character as if it is a normal character, use an escape character so that the regex can ignore its special meaning.

For example, the following regex shows some characters are escaped and some are not.

replaceAll(JSON Code,"[^\\p{Space}0-9A-Za-z!:\\\"%&\\[*()\\],-/_\\\\{}\\.]","")

This regex checks text to make sure it does not contain any unusual characters by defining a list of allowed characters:

• paragraph end marks: \\p 
• spaces: {​Space}
• numbers 0-9: ​0-9
• uppercase or lowercase alphabetic characters: A-Za-z
• other characters: ! : % & * ( ) , - / _ { }
• special characters, preceded by backslashes to escape them: " [ ] \ .

Characters with special meaning are:

• quotes and square brackets: “[ and ]"indicate the start and the end of the string 
• caret ^ means NOT, so match anything that is NOT in the following list.

This regex ignores any of the allowed characters. If it finds any character not in the list, it replaces them with nothing, indicated by "". 

For information about escaping characters in PhixFlow expressions, rather than in a regex, see Text Expressions and Escape Characters.

Groups and Capturing 

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capture capture

Capturing groups are numbered by counting their opening parentheses from left to right. For example,  ((A)(B(C))) contains 4 groups:

Group zero always stands for the entire regex.

During a match, each sub-sequence of the input sequence that matches a group is saved. The captured sub-sequence may be used later in the regex, via a back reference. In PhixFlow, a back reference has the format $n, where n is the number of the capturing group; replaceFirst for some examples.

The captured input associated with a group is always the sub-sequence that the group most recently matched. If a group is evaluated a second time because of a quantifier, then any previously captured value is retained if the second evaluation fails. For example, matching the string "aba" against the regex (a(b)?)+ leaves group two set to "b". All captured input is discarded at the beginning of each match.

Groups beginning with (? are pure, non-capturing groups that do not capture text and do not count towards the group total.

Character Constructs 

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construct construct

The following table shows the different characters and what they match.