method subst
Documentation for method subst
assembled from the following types:
class Cool
From Cool
(Cool) method subst
Defined as:
method subst(|)
Coerces the invocant to Stringy and calls Str.subst.
class Str
From Str
(Str) method subst
multi method subst(Str: , , *)
Returns the invocant string where $matcher
is replaced by $replacement
(or the original string, if no match was found).
There is an in-place syntactic variant of subst
spelled s/matcher/replacement/
and with adverb following the s
or inside the matcher.
$matcher
can be a Regex, or a literal Str
. Non-Str matcher arguments of type Cool are coerced to Str
for literal matching. If a Regex $matcher
is used, the $/
special variable will be set to Nil
(if no matches occurred), a Match object, or a List of Match objects (if multi-match options like :g
are used).
Literal replacement substitution
my = "Some foo";my = .subst(/foo/, "string"); # gives 'Some string'.=subst(/foo/, "string"); # in-place substitution. $some-string is now 'Some string'
Callable
The replacement can be a Callable in which the current Match object will be placed in the $/
variable, as well as the $_
topic variable. Using a Callable as replacement is how you can refer to any of the captures created in the regex:
# Using capture from $/ variable (the $0 is the first positional capture)say 'abc123defg'.subst(/(\d+)/, );# OUTPUT: «abc before 123 after defg»# Using capture from $/ variable (the $<foo> is a named capture)say 'abc123defg'.subst(/=\d+/, );# OUTPUT: «abc before 123 after defg»# Using WhateverCode to operate on the Match given in $_:say 'abc123defg'.subst(/(\d+)/, "[ " ~ *.flip ~ " ]");# OUTPUT: «abc[ 321 ]defg»# Using a Callable to generate substitution without involving current Match:my = 41;my = "The answer is secret.";say .subst(/secret/, ); # The answer to everything# OUTPUT: «The answer is 42.»
Adverbs
The following adverbs are supported
short | long | meaning |
---|---|---|
:g | :global | tries to match as often as possible |
:nth(Int|Callable|Whatever) | only substitute the nth match; aliases: :st, :nd, :rd, and :th | |
:ss | :samespace | preserves whitespace on substitution |
:ii | :samecase | preserves case on substitution |
:mm | :samemark | preserves character marks (e.g. 'ü' replaced with 'o' will result in 'ö') |
:x(Int|Range|Whatever) | substitute exactly $x matches |
Note that only in the s///
form :ii
implies :i
and :ss
implies :s
. In the method form, the :s
and :i
modifiers must be added to the regex, not the subst
method call.
More Examples
Here are other examples of usage:
my = "Hey foo foo foo";.subst(/foo/, "bar", :g); # global substitution - returns Hey bar bar bar.subst(/foo/, "no subst", :x(0)); # targeted substitution. Number of times to substitute. Returns back unmodified..subst(/foo/, "bar", :x(1)); #replace just the first occurrence..subst(/foo/, "bar", :nth(3)); # replace nth match alone. Replaces the third foo. Returns Hey foo foo bar
The :nth
adverb has readable English-looking variants:
say 'ooooo'.subst: 'o', 'x', :1st; # OUTPUT: «xoooo»say 'ooooo'.subst: 'o', 'x', :2nd; # OUTPUT: «oxooo»say 'ooooo'.subst: 'o', 'x', :3rd; # OUTPUT: «ooxoo»say 'ooooo'.subst: 'o', 'x', :4th; # OUTPUT: «oooxo»