regexp Reference

Use regular expressions to process input

regexp

Examples

Discussion

With regexp, it's possible to use PERL-compatible regular expressions to parse or make substitutions within symbols and lists. The argument is a symbol that sets the RE, as does the 're' command in the left inlet. the 'substitute' command passes a symbol to be used in substitutions - if no symbol is present, it removes the previous one. Any other symbol or list in the left inlet is treated as the subject string, and is processed according to those parameters. The middle outlet reports a list of the instances where the RE matched portions of the subject string. If the RE contains parentheses, they are treated as backreferences, and the center-left outlet puts them into a list upon every match within the subject string. If a 'substitute' string has been set, the leftmost output returns the subject string with necessary substitutions. (n.b. substitute strings may contain back references, of the form %n)

Arguments

expression [symbol]

Optional

A regular expression may be used as an argument to set the regular expression (see above for regular expression formatting and metacharacter information).

substitution [symbol]

Optional

An optional second argument will set the substitution string.

Attributes

re [symbol]

The word re, followed by a PERL-compatible regular expression, sets the regular expression rules to be used when parsing or making substitutions within any symbol or list input.

If a regular expression contains spaces, it must be enclosed within double quotes when specified using the re message or as a typed-in argument to the regexp object.

Regular expressions use the following form and syntax:

[...] defines a 'class' of characters. any of the characters within it may be matched. several special symbols may also appear within it:

...-... specifies a range (within ASCII codes)

\\d specifies a decimal digit (\\D specifies a non-decimal digit). Note that double backslashes must be used -- Max erases single backslashes.

\\s specifies white space (\\S specifies non-white space). Note that double backslashes must be used -- Max erases single backslashes.

\\w specifies an alphanumeric (\\W specifies a nonalphanumeric). Note that double backslashes must be used -- Max erases single backslashes.

^... specifies a complement of

...* appears zero times

...+ appears at least once

...? appears once or not at all

(...) specifies a backreference that may be referred to in a substitution string such as %n, where n is the position of the parenthesis in left-to-right order.

substitute [symbol]

The word substitute, followed by a symbol, passes a symbol to be used in substitutions. If the word substitute is not followed by a symbol, the previous substitution symbol is removed.

Note: If you need to output a % followed by a number in any substitution string, you should use %%, so that the % is not read as a backreference.

tosymbol [int]

The word tosymbol, followed by a zero or one, toggles the output behavior of the regexp object. When enabled, output from the left outlet of the object will be a single symbol. When disabled, output from the left outlet of the object will consist of a list of individual elements.

Common Box Attributes

Messages

int

Arguments

subject-string [int]
Any int received in the regexp object's inlet is treated as the subject string to be processed according to the regular expression and symbol substitutions provided.

float

Arguments

subject-string [float]
Any float received in the regexp object's inlet is treated as the subject string to be processed according to the regular expression and symbol substitutions provided.

list

Arguments

subject-string [list]
Any symbol or list received in the regexp object's inlet (not matching the object's attributes) is treated as the subject string to be processed according to the regular expression and symbol substitutions provided.

anything

Arguments

subject-string [list]
Performs the same function as a list message.

Output

symbol or list

Out left outlet: If a substitute string has been set using the substitute message, the input list or symbol is sent out the left outlet with any required substitutions (n.b. substitute strings may contain back references, of the form %n).

Out center-left outlet: If the regular expressions contains parentheses, they are treated as backreferences. The middle outlet reports the backreferences upon every match within the subject string, and outputs them in the form of a list.

Out center outlet: The rightmost outlet reports a list of the instances where the regular expression matched portions of the subject string.

Out center-right outlet: The rightmost outlet passes the original input, in the case that not match occurs.

Out right outlet: The rightmost outlet is used to report the values of the object's attributes.

See Also

Name Description
fromsymbol
key
keyup
message
spell
tosymbol