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elvish-re(7) Miscellaneous Information Manual elvish-re(7)

Introduction

The re: module wraps Go’s regexp package. See the Go’s doc for supported regular expression syntax (https://godoc.org/regexp/syntax).

Function usages notations follow the same convention as the builtin module doc.

The following options are supported by multiple functions in this module:

•
&posix=$false: Use POSIX ERE syntax. See also doc (http://godoc.org/regexp#CompilePOSIX) in Go package.
•
&longest=$false: Prefer leftmost-longest match. See also doc (http://godoc.org/regexp#Regexp.Longest) in Go package.
•
&max=-1: If non-negative, limits the maximum number of results.

Functions

re:find {#re:find}

re:find &posix=$false &longest=$false &max=-1 $pattern $source

Find all matches of $pattern in $source.

Each match is represented by a map-like value $m; $m[text], $m[start] and $m[end] are the text, start and end positions (as byte indices into $source) of the match; $m[groups] is a list of submatches for capture groups in the pattern. A submatch has a similar structure to a match, except that it does not have a group key. The entire pattern is an implicit capture group, and it always appears first.

Examples:

~> re:find . ab
▶ [&text=a &start=0 &end=1 &groups=[[&text=a &start=0 &end=1]]]
▶ [&text=b &start=1 &end=2 &groups=[[&text=b &start=1 &end=2]]]
~> re:find '[A-Z]([0-9])' 'A1 B2'
▶ [&text=A1 &start=0 &end=2 &groups=[[&text=A1 &start=0 &end=2] [&text=1 &start=1 &end=2]]]
▶ [&text=B2 &start=3 &end=5 &groups=[[&text=B2 &start=3 &end=5] [&text=2 &start=4 &end=5]]]

re:match {#re:match}

re:match &posix=$false $pattern $source

Determine whether $pattern matches $source. The pattern is not anchored. Examples:

~> re:match . xyz
▶ $true
~> re:match . ''
▶ $false
~> re:match '[a-z]' A
▶ $false

re:quote {#re:quote}

re:quote $string

Quote $string for use in a pattern. Examples:

~> re:quote a.txt
▶ a\.txt
~> re:quote '(*)'
▶ '\(\*\)'

re:replace {#re:replace}

re:replace &posix=$false &longest=$false &literal=$false $pattern $repl $source

Replace all occurrences of $pattern in $source with $repl.

The replacement $repl can be any of the following:

•
A string-typed replacement template. The template can use $name or ${name} patterns to refer to capture groups, where name consists of letters, digits and underscores. A purely numeric patterns like $1 refers to the capture group with the corresponding index; other names refer to capture groups named with the (?P<name>...)) syntax.

In the $name form, the name is taken to be as long as possible; $1 is equivalent to ${1x}, not ${1}x; $10 is equivalent to ${10}, not ${1}0.

To insert a literal $, use $$.

•
A function that takes a string argument and outputs a string. For each match, the function is called with the content of the match, and its output is used as the replacement.

If $literal is true, $repl must be a string and is treated literally instead of as a pattern.

Example:

~> re:replace '(ba|z)sh' '${1}SH' 'bash and zsh'
▶ 'baSH and zSH'
~> re:replace '(ba|z)sh' elvish 'bash and zsh rock'
▶ 'elvish and elvish rock'
~> re:replace '(ba|z)sh' {|x| put [&bash=BaSh &zsh=ZsH][$x] } 'bash and zsh'
▶ 'BaSh and ZsH'

re:split {#re:split}

re:split &posix=$false &longest=$false &max=-1 $pattern $source

Split $source, using $pattern as separators. Examples:

~> re:split : /usr/sbin:/usr/bin:/bin
▶ /usr/sbin
▶ /usr/bin
▶ /bin
~> re:split &max=2 : /usr/sbin:/usr/bin:/bin
▶ /usr/sbin
▶ /usr/bin:/bin
August 17, 2022 Elvish 0.18.0