Filters

This is a list of filters that are added by StencilSwiftKit on top of the filters already provided by Stencil (which you can find here).

Filter: basename

Get the last component of a path, essentially the filename (and extension).

Input	Output
test.jpg	test.jpg
some/folder/test.jpg	test.jpg
file.txt.png	file.txt.png

Filter: camelToSnakeCase

Transforms text from camelCase to snake_case. The filter accepts an optional boolean parameter:

• true (default): Lowercase each component.
• false: Keep the casing for each component.

Input	Output (true)	Output (false)
SomeCapString	some_cap_string	Some_Cap_String
someCapString	some_cap_string	some_Cap_String
String_With_WoRds	string_with_words	String_With_Wo_Rds
string_wiTH_WOrds	st_ring_with_words	string_wi_TH_W_Ords
URLChooser	url_chooser	URL_Chooser
PLEASE_STOP_SCREAMING	please_stop_screaming	PLEASE_STOP_SCREAMING

Filter: contains

Checks if the string contains given substring - works the same as Swift's String.contains.

Input	Output
Hello el	true
Hi mates! yo	false

Filter: dirname

Remove the last component of a path, essentially returning the path without the filename (and extension).

Input	Output
test.jpg	``
some/folder/test.jpg	some/folder
file.txt.png	``

Filter: escapeReservedKeywords

Checks if the given string matches a reserved Swift keyword. If it does, wrap the string in escape characters (backticks).

Input	Output
hello	hello
self	`self`
Any	`Any`

Filter: hasPrefix

Checks if the string has the given prefix - works the same as Swift's String.hasPrefix.

Input	Output
Hello Hi	false
Hi mates! H	true

Filter: hasSuffix

Checks if the string has the given suffix - works the same as Swift's String.hasSuffix.

Input	Output
Hello llo	true
Hi mates! ?	false

Filter: lowerFirstLetter

Simply lowercases the first character, leaving the other characters untouched.

Input	Output
Hello	hello
PeopleChooser	peopleChooser
Hi There!	hi There!

Filter: lowerFirstWord

Transforms an arbitrary string so that only the first "word" is lowercased.

• If the string starts with only one uppercase character, lowercase that first character.
• If the string starts with multiple uppercase character, lowercase those first characters up to the one before the last uppercase one, but only if the last one is followed by a lowercase character. This allows to support strings beginnng with an acronym, like URL.

Input	Output
PeoplePicker	peoplePicker
URLChooser	urlChooser

Filter: replace

This filter receives at least 2 parameters: a search parameter and a replacement. This filter has a couple of modes that you can specify using an optional mode argument:

• normal (default): Simple find and replace.
• regex: Enables the use of regular expressions in the search parameter.

Input (search, replacement)	Output (normal)	Output (regex)
Hello (l, k)	Hekko	Hekko
Europe (e, a)	Europa	Europa
Hey1World2! (\d, )	Hey1World2!	Hey World !

Filter: snakeToCamelCase

Transforms a string in "snake_case" format into one in "camelCase" format, following the steps below:

• Separate the string in components using the _ as separator.
• For each component, uppercase the first character and do not touch the other characters in the component.
• Join the components again into one string.

If the whole starting "snake_case" string only contained uppercase characters, then each component will be capitalized: uppercase the first character and lowercase the other characters.

This filter accepts an optional boolean parameter that controls the prefixing behaviour:

• false (default): don't remove any empty components.
• true: trim empty components from the beginning of the string

Input	Output (false)	Output (true)
snake_case	SnakeCase	SnakeCase
snAke_case	SnAkeCase	SnAkeCase
SNAKE_CASE	SnakeCase	SnakeCase
__snake_case	__SnakeCase	SnakeCase

Filter: swiftIdentifier

Transforms an arbitrary string into a valid Swift identifier (using only valid characters for a Swift identifier as defined in the Swift language reference). It will apply the following rules:

• Uppercase the first character.
• Prefix with an underscore if the first character is a number.
• Replace invalid characters by an underscore (_).

The list of allowed characters can be found here: https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html

This filter has a couple of modes that you can specify using an optional mode argument:

• valid: Only do the bare minimum for a valid identifier, i.e. the steps mentioned above except uppercasing characters.
• normal (default): apply the steps mentioned above (uppercase first, prefix if needed, replace invalid characters with _).
• pretty: Same as normal, but afterwards it will apply the snakeToCamelCase filter, and other manipulations, for a prettier (but still valid) identifier.

Input	Output (valid)	Output (normal)	Output (pretty)
hello	hello	Hello	Hello
42hello	_42hello	_42hello	_42hello
some$URL	some_URL	Some_URL	SomeURL
25 Ultra Light	_25_Ultra_Light	_25_Ultra_Light	_25UltraLight
26_extra_ultra_light	_26_extra_ultra_light	_26_extra_ultra_light	_26ExtraUltraLight
apples.count	apples_count	Apples_Count	ApplesCount
foo_bar.baz.qux-yay	foo_bar_baz_qux_yay	Foo_bar_Baz_Qux_Yay	FooBarBazQuxYay

Filter: titlecase

Deprecated in favor of upperFirstLetter.

Filter: upperFirstLetter

Simply uppercases the first character, leaving the other characters untouched.

Note that even if very similar, this filter differs from the capitalized filter, which uppercases the first character but also lowercases the remaining characters.

Input	Output
hello	Hello
peopleChooser	PeopleChooser