Use Regex - Revision history

Nmingott at 22:41, 4 May 2025

2025-05-04T22:41:32Z

← Older revision		Revision as of 22:41, 4 May 2025
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	rex subexpression: 3. " => '34' "		rex subexpression: 3. " => '34' "
	</syntaxhighlight>		</syntaxhighlight>
	"

	* Observe well that the matching substrings are stored into the Regex object.		* Observe well that the matching substrings are stored into the Regex object.

Nmingott: syntax hilight

2025-05-04T22:40:50Z

syntax hilight

← Older revision		Revision as of 22:40, 4 May 2025
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	* First things first, to work with Regexp you need to load the appropriate package		* First things first, to work with Regexp you need to load the appropriate package
			<syntaxhighlight lang="smalltalk">

	Feature require: 'Regex'.		Feature require: 'Regex'.
			</syntaxhighlight>

	* Important, '''matchesRegex''' tries to match a full string, if you want to scan for a substring use '''search: .'''		* Important, '''matchesRegex''' tries to match a full string, if you want to scan for a substring use '''search: .'''
	* Does the string match a regex?		* Does the string match a regex?
			<syntaxhighlight lang="smalltalk">

	'hello123' matchesRegex: 'he'. " => false "		'hello123' matchesRegex: 'he'. " => false "
	'hello123' matchesRegex: 'he.*'. " => true "		'hello123' matchesRegex: 'he.*'. " => true "
			</syntaxhighlight>

	* Find all occurrences of a regex		* Find all occurrences of a regex
			<syntaxhighlight lang="smalltalk">

	' 2019-08-01T00:00:00+00:00' allRegexMatches: '\d+'.		' 2019-08-01T00:00:00+00:00' allRegexMatches: '\d+'.
	" => an OrderedCollection('2019' '08' '01' '00' '00' '00' '00' '00') "		" => an OrderedCollection('2019' '08' '01' '00' '00' '00' '00' '00') "
			</syntaxhighlight>

	* '''Split''' a string, classic applications: CSV parsing, get a list of words from a sentence.		* '''Split''' a string, classic applications: CSV parsing, get a list of words from a sentence.
			<syntaxhighlight lang="smalltalk">

	',' asRegex split: '123,c1,12.4 , Foo bar, baz'.		',' asRegex split: '123,c1,12.4 , Foo bar, baz'.
	" => an OrderedCollection('123' 'c1' '12.4 ' ' Foo bar' ' baz') "		" => an OrderedCollection('123' 'c1' '12.4 ' ' Foo bar' ' baz') "
			</syntaxhighlight>

	* '''Substitute''' each regex match with a given string		* '''Substitute''' each regex match with a given string
			<syntaxhighlight lang="smalltalk">

	'ab cd ab' copyWithRegex: '(a\|b)+' matchesReplacedWith: 'foo' .		'ab cd ab' copyWithRegex: '(a\|b)+' matchesReplacedWith: 'foo' .
	" => 'foo cd foo' "		" => 'foo cd foo' "
			</syntaxhighlight>

	* '''Substitute''' each regex match with the '''result of Block value'''		* '''Substitute''' each regex match with the '''result of Block value'''
			<syntaxhighlight lang="smalltalk">

	'ab cd ab' copyWithRegex: '(a\|b)+' matchesTranslatedUsing: [:each \| each asUppercase] .		'ab cd ab' copyWithRegex: '(a\|b)+' matchesTranslatedUsing: [:each \| each asUppercase] .
	" => 'AB cd AB' "		" => 'AB cd AB' "
			</syntaxhighlight>

	* '''Grouping''' in regex		* '''Grouping''' in regex
			<syntaxhighlight lang="smalltalk">

	str _ 'Today is 05-Aug, it is about 09:34, and we are near Verona. ' .		str := 'Today is 05-Aug, it is about 09:34, and we are near Verona. ' .
	rex _ '(\d+)\:(\d+)' asRegex .		rex := '(\d+)\:(\d+)' asRegex .
	rex class. " => RxMatcher "		rex class. " => RxMatcher "
	rex search: str. " => true # true, a match has been found. "		rex search: str. " => true # true, a match has been found. "
	rex subexpressionCount. " => 3 # number of elements matched. "		rex subexpressionCount. " => 3 # number of elements matched. "
	rex subexpression: 1. " => '09:34' # first element is always the whole match. "		rex subexpression: 1. " => '09:34' # first element is always the whole match. "
	rex subexpression: 2. " => '09' # then there are groups... "		rex subexpression: 2. " => '09' # then there are groups... "
	rex subexpression: 3. " => '34' "		rex subexpression: 3. " => '34' "
			</syntaxhighlight>
			"

	* Observe well that the matching substrings are stored into the Regex object.		* Observe well that the matching substrings are stored into the Regex object.

Nmingott: imported material

2025-05-04T20:11:47Z

imported material

New page

Regex is large subject. For the moment I am going to put here just a list of examples.

* First things first, to work with Regexp you need to load the appropriate package

Feature require: 'Regex'.

* Important, '''matchesRegex''' tries to match a full string, if you want to scan for a substring use '''search: .'''
* Does the string match a regex?

'hello123' matchesRegex: 'he'. " => false "
'hello123' matchesRegex: 'he.*'. " => true "

* Find all occurrences of a regex

' 2019-08-01T00:00:00+00:00' allRegexMatches: '\d+'.
" => an OrderedCollection('2019' '08' '01' '00' '00' '00' '00' '00') "

* '''Split''' a string, classic applications: CSV parsing, get a list of words from a sentence.

',' asRegex split: '123,c1,12.4 , Foo bar, baz'.
" => an OrderedCollection('123' 'c1' '12.4 ' ' Foo bar' ' baz') "

* '''Substitute''' each regex match with a given string

'ab cd ab' copyWithRegex: '(a|b)+' matchesReplacedWith: 'foo' .
" => 'foo cd foo' "

* '''Substitute''' each regex match with the '''result of Block value'''

'ab cd ab' copyWithRegex: '(a|b)+' matchesTranslatedUsing: [:each | each asUppercase] .
" => 'AB cd AB' "

* '''Grouping''' in regex

str _ 'Today is 05-Aug, it is about 09:34, and we are near Verona. ' .
rex _ '(\d+)\:(\d+)' asRegex .
rex class. " => RxMatcher "
rex search: str. " => true # true, a match has been found. "
rex subexpressionCount. " => 3 # number of elements matched. "
rex subexpression: 1. " => '09:34' # first element is always the whole match. "
rex subexpression: 2. " => '09' # then there are groups... "
rex subexpression: 3. " => '34' "

* Observe well that the matching substrings are stored into the Regex object.

----Dr. Nicola Mingotti updated this on 06-Sep-2021. Examples were run in a Cuis a bit older than Cuis5.0-4834.image.