Skip to content

Functions

Jump to bottom
ReFreezed edited this page Apr 24, 2021 · 27 revisions

Utility Functions

a

html = a( url [, label=prettyUrl(url) ] )

Create a simple HTML <a> element.

ceil

n = ceil( n )

Alias for math.ceil().

chooseExistingFile

path = chooseExistingFile( pathWithoutExtension, extensions )

Return the path of an existing file with any of the specified extensions. Returns nil if no file exists.

chooseExistingImage

path = chooseExistingImage( pathWithoutExtension )

Return the path of an existing image file with any of the specified extensions. Returns nil if no image file exists.

Short form for chooseExistingFile(pathWithoutExtension, IMAGE_EXTENSIONS).

cssPrefix

css = cssPrefix( property, value )

Quick and dirty way of adding vendor-specific prefixes to a CSS property. Example:

local css = cssPrefix("flex", "auto")
-- css is "-ms-flex: auto; -moz-flex: auto; -webkit-flex: auto; flex: auto;"

date

string = date( format [, time=now ] )

Alias for os.date(). (See the C docs for date format.)

entities

html = entities( text )

Encode HTML entities, e.g. < to &lt;.

errorf

errorf( [ level=1, ] format, ... )

Trigger an error with a formatted message.

Short form for error(F(format, ...), level).

F

string = F( format, ... )

Alias for string.format().

fileExists

bool = fileExists( path )

Check if a file exists in the content folder.

fileExistsInOutput

bool = fileExistsInOutput( path [, skipRewriting=false ] )

Check if a file exists in the output folder, optionally without the usual rewriting of the path.

files

paths = files( folder, [ onlyFilenames=false, ] filenamePattern )
paths = files( folder, [ onlyFilenames=false, ] fileExtensionArray )
paths = files( folder, [ onlyFilenames=false, ] filterFunction )

Get a list of files in a folder inside the content folder. Examples:

local function dogFilter(filename)
	if filename:find"dog" then
		return true
	end
end

local imagePaths  = files("/images", IMAGE_EXTENSIONS)
local psFilePaths = files("/resources/misc", "%.psd$")
local dogPaths    = files("/animal-files", dogFilter)

find

item, index = find( array, attribute, value )

Get the item in the array whose attribute is value. Returns nil if no item is found.

findAll

items = findAll( array, attribute, value )

Get all items in the array whose attribute is value.

floor

n = floor( n )

Alias for math.floor().

formatTemplate

template = formatTemplate( format, valueTable )

Quick and dirty formatting of a template, presumably before using generateFromTemplate(). This replaces all instances of :key: with the corresponding field from valueTable. Example:

local template = formatTemplate(
	[[
		{{
		page.title  = :title:
		page.layout = "awesome"
		}}

		My dog likes :thing:.
		Other dogs probably like :thing: too!
	]],
	{
		title = F("%q", "Timmie the Dog"), -- Remember, :title: is in the code block.
		thing = "bones",
	}
)
generateFromTemplate("dogs/info.md", template)

Also see toLua().

generatorMeta

html = generatorMeta( [ hideVersion=false ] )

Generate HTML generator meta tag (e.g. <meta name="generator" content="LuaWebGen 1.0.0">). This tag makes it possible to track how many websites use this generator, which is cool! This should be placed in the <head> element.

getBasename

basename = getBasename( filename )

Get the filename without the extension. Example:

local basename = getBasename"blog/my-post.html"
print(basename) -- "my-post"

getCompleteOutputPath

pathInCwd = getCompleteOutputPath( path )

Get the final (possibly rewritten) path for any file path. Example:

local path = "/images/dog.png"
local pathInCwd = getCompleteOutputPath(path)
print(pathInCwd) -- "output/images/dog.png"

Note: The returned path is relative to current working directory, which is always the site root folder. The LuaWebGen API generally only handle paths relative to the content folder - the return value from getCompleteOutputPath() is an exception.

getExtension

extension = getExtension( path )

Get the extension part of a path or filename.

getFilename

filename = getFilename( path )

Get the filename part of a path.

getImageDimensions

width, height = getImageDimensions( path )

Get the width and height of an image. Returns nil and a message on error.

getKeys

keys = getKeys( table )

Get the keys from a table.

img

html = img( url [, alt="", title ] )
html = img( url [, alt="", useAltAsTitle=false ] )

Create a simple HTML <img> element.

indexOf

index = indexOf( array, value )

Get the index of a value in an array. Returns nil if the value was not found.

ipairsr

for index, value in ipairsr( array ) do

Iterate backwards through an array.

isAny

bool = isAny( valueToCompare, value1, value2, ... )
bool = isAny( valueToCompare, arrayOfValues )

Compare a value against a set of values.

markdown

html = markdown( markdownText )

Convert markdown to HTML.

max

n = max( n1, n2, ... )

Alias for math.max().

min

n = min( n1, n2, ... )

Alias for math.min().

newStringBuilder

stringBuilder = newStringBuilder( )

Create a handy string builder object, like so:

local b = newStringBuilder()

-- Add things.
b('<img src="icon.png">') -- One argument adds a plain value.
b(42) -- The one argument can be any value.
b('<h1>%s</h1>', entities(page.title)) -- Multiple arguments act like string.format() .

-- Get the contents.
local html = b() -- No arguments returns the concatenated string.

now

datetime = now( )

Get the current date and time as a datetime string.

pairsSorted

for key, value in pairsSorted( table ) do

Like pairs(), iterate over the fields of a table, but in alphabetic order of the keys. Note that the function does not detect additions or removals of table fields during the iteration.

prettyUrl

text = prettyUrl( url )

Make a URL look nice for displaying as text. Example:

local url   = "https://www.animals.com/dogs/"
local label = prettyUrl(url) -- "animals.com/dogs"

echof('<a href="%s">%s</a>', url, label)

Also see a().

printf

printf( format, ... )

Short form for print(F(format, ...)).

printfOnce

printfOnce( format, ... )

Print a formatted message only once. Meant for preventing too much spam in the console/log.

printOnce

printOnce( ... )

Print value(s) only once. Meant for preventing too much spam in the console/log.

removeItem

removeItem( array, value1, ... )

Remove one or more values from an array. Does not remove duplicate values.

round

number = round( number )

Round a number.

sortNatural

array = sortNatural( array [, attribute ] )

Naturally sort an array of strings. If the array contains tables you can sort by a specific attribute instead.

split

parts = split( string, separatorPattern [, startIndex=1, plain=false ] )

Split a string by a pattern. Example:

local dogs = split("Fido,Grumpy,The Destroyer", ",")

thumb

html = thumb( imagePath, thumbWidth [, thumbHeight ] [, isLink=false ] )

Create a thumbnail from an image. At least one of thumbWidth or thumbHeight must be a positive number. Example:

{{thumb("/images/gorillaz-fan-art.png", 400, 400, true) -- Max size is 400x400. }}
{{thumb("/images/a-big-tree.gif", 512, true)            -- Max width is 512.    }}
{{thumb("/images/1000-clown-cars.jpg", 0, 350, false)   -- Max height is 350.   }}

toDatetime

datetime = toDatetime( time )

Convert a time number to a datetime string.

toLua

luaString = toLua( value )

Convert any value to Lua code. Useful e.g. when sending tables to layouts. Example:

local credits = {
	{what="Fabric", who="Soft Inc."},
	{what="Paint",  who="Bob Bobson Co."},
}

local template = formatTemplate(
	[[
		{{
		page.title = :title:
		P.creditsInPageFooter = :credits:
		}}

		Experience the best carpets around!
	]],
	{
		title   = toLua("Carpets"),
		credits = toLua(credits),
	}
)

generateFromTemplate("products/carpets.md", template)

toTime

time = toTime( datetime )

Convert a datetime to a normal time number value that standard libraries understand. Example:

local time = toTime(page.publishDate)
local publishYear = os.date("%Y", time)

trim

string = trim( string )

Remove surrounding whitespace from a string.

trimNewlines

string = trimNewlines( string )

Remove surrounding newlines from a string.

url

encodedString = url( urlString )

Percent-encode a URL (spaces become %20 etc.).

Note: url() does not encode HTML entities, like ampersand, thus does not produce valid HTML:

local src  = url"/thumb.php?size=200&name=Hello world!"
local html = F('<img src="%s">', entities(src)) -- Correct.
local html = F('<img src="%s">', src) -- Incorrect.

urlAbs

encodedString = urlAbs( urlString )

Same as url() but also prepends site.baseUrl to relative URLs, making them absolute.

urlExists

urlExists( url )

Check that a file for the URL exists. Useful e.g. as a sanity check after moving a bunch of pages (that now should have aliases). See validateUrls() for multiple URL checks. Example:

function config.validate()
	local url = "/old-folder/my-post/"
	if not urlExists(url) then
		error("Page is missing: "..url)
	end
end

urlize

urlPart = urlize( string )

Make a string look like a URL. Useful e.g. when converting page titles to URL slugs.

urlize("Hello, big world!") -- "hello-big-world"

validateUrls

validateUrls( urls )

Check that files for multiple URLs exist, and trigger an error if any don't exist. Useful e.g. as a sanity check after moving a bunch of pages (that now should have aliases). See urlExists() for single URL checks. Example:

function config.validate()
	validateUrls{
		"/old-folder/my-post/",
		"/work-in-progress/dog.png",
	}
end

warning

warning( message )

Prints a big warning message to the console. Nothing else happens.

warningOnce

warningOnce( message )

Prints a big warning message to the console once only. Nothing else happens.

Context-Specific Functions

There are currently 3 contexts where code can run:

echo

echo( string )

Output a string from a template. HTML entities are encoded automatically. Available in templates. Also, see echoRaw().

Note: This function is used under the hood and it's often not necessary to call it manually. For example, these rows do the same thing:

{{date"%Y"}}
{{echo(date"%Y")}}

echof

echof( format, ... )

Short form for echo(F(format, ...)).

echofRaw

echofRaw( format, ... )

Short form for echoRaw(F(format, ...)).

echoRaw

echoRaw( string )

Like echo(), output a string from a template, except HTML entities don't become encoded in this string. Available in templates.

echo   ("a < b") -- Output is "a &lt; b"
echoRaw("a < b") -- Output is "a < b"

Note: In templates, if echo isn't used then HTML entities are sometimes encoded and sometimes not - LuaWebGen tries to be smart about it:

{{"<br>"}}            -- Output is "<br>"
{{"Foo <br>"}}        -- Output is "Foo &lt;br&gt;"

{{echo"<br>"}}        -- Output is "&lt;br&gt;"
{{echo"Foo <br>"}}    -- Output is "Foo &lt;br&gt;"

{{echoRaw"<br>"}}     -- Output is "<br>"
{{echoRaw"Foo <br>"}} -- Output is "Foo <br>"

generateFromTemplate

page = generateFromTemplate( path, templateString )

Generate a page from a template. Available in config.before() and config.after(). Example:

local path     = "/dogs/fido.md"
local template = "# Fido\n\nFido is fluffy!"
local page     = generateFromTemplate(path, template)
printf("We generated page '%s'.", page.url)

include

html = include( filename )

Get a HTML template from the layouts folder. Available in templates. Note: Exclude the extension from the filename (e.g. include("footer")).

isCurrentUrl

bool = isCurrentUrl( url )

Check if the relative URL of the current page is url. Example:

{{if isCurrentUrl"/blog/last-post/"}}
You've reached the end!
{{end}}

isCurrentUrlBelow

bool = isCurrentUrlBelow( urlPrefix )

Check if the relative URL of the current page starts with urlPrefix. Example:

{{local class =  isCurrentUrlBelow"/blog/" and "current" or ""}}

<a href="/blog/" class="{{class}}">Blog</a>

lock

lock( )

Prevent further changes to page properties, such as page.isDraft and page.publishDate. This allows the current page to be referenced elsewhere even during it's generation. Also see config.autoLockPages. Example:

{{
page.title = "Cute Kittens"
lock()
page.title = "Sly Turtles" -- Error!
}}

outputRaw

outputRaw( path, contents )

Output any data to a file. Available in config.before() and config.after(). Example:

outputRaw("/docs/versions.txt", "Version 1\nReleased: 2002-10-16\n")

preserveRaw

preserveRaw( path )

Prevent a previously outputted raw file from being cleaned out after the site generation is done. This function makes it possible to not having to call outputRaw() every time the site builds which could decrease build time. Available in config.before() and config.after().

Note: This functionality is automatically used for all raw files in the content folder.

subpages

pages = subpages( [ allowCurrentPageToBeIncluded=false ] )

Recursively get all pages in the current folder and below, sorted by page.publishDate. Intended for index pages, but can be used anywhere. Available in templates. Example:

# Blog Archive

{{fori page in subpages()}}
- [{{page.publishDate}} {{page.title}}]({{page.permalink}})
{{end}}

Note: Two pages in the same folder cannot normally request all subpages - that would result in an infinite loop as LuaWebGen tries to generate all subpages before returning a list of them. However, you can solve this by calling lock() in all relevant pages, or enable config.autoLockPages. This will prevent further changes to essential page information (such as page.isDraft or page.publishDate) and thus allowing the page to be referenced elsewhere even during it's generation.

Another possible solution is to generate at least one of those two pages in config.after().

Topics

Clone this wiki locally