Embedding Lua - ReFreezed/LuaWebGen GitHub Wiki

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Code Blocks

Lua can be embedded in .html, .md and .css files by default. A block of code exists between {{ and }}, which can be literally anywhere in the file (even inside HTML comment tags). Code is not context sensitive, other than what type of file it is in (e.g. HTML entities may get encoded in .html and .md files, but not in .css files).

<h1>Questions for year {{ os.date("%Y") }}</h1>
<section>
	{{
	echoRaw("<h2>")
	echo("Is 5 < 9 still true?")
	echoRaw("</h2>")
	}}
</section>

There are two main kinds of code blocks: Those that output (or "echo") a value, and those that just contain code to run.

If the block contains a value expression then the result is echoed:

<p>86 + 47 = {{ 86 + 47 }}</p>
<p>My name is {{ getMyName() .. " the 3rd" }}</p>
<p>Random double-digit number: {{
	math.random( -- Code can span multiple lines.
		10, 99
	)
}}</p>
{{ nil --[[ Nil values don't echo anything. ]] }}
{{ print("Hello!") --[[ The print function returns nothing, so nothing is echoed here either. ]] }}

Under the hood, {{valueExpression}} calls echoSmart().

Otherwise, the code just runs:

<p>
	Have you seen
	{{
	print("Just counting to 4...")
	for i = 1, 4 do
		print(i)
	end
	}}
	the cat?
</p>

There is a third special kind of block that can be used for outputting percent-encoded URLs. The block should contain a relative or absolute URL (without quotes or anything else). These three blocks are equal:

<a href="{{ /blog/2008/smörgåsbord/ }}">The Grand Smörgåsbord</a>
<a href="{{ url('/blog/2008/smörgåsbord/') }}">The Grand Smörgåsbord</a>
<a href="{{ echo(url('/blog/2008/smörgåsbord/')) }}">The Grand Smörgåsbord</a>

Whitespace around code blocks can be trimmed away by putting * inside the block near {{ or }}:

A {{  echo("B")  }} C   This results in "A B C"
A {{* echo("B") *}} C   This results in "ABC"
A {{* echo("B")  }} C   This results in "AB C"

Control Structures

Control structures in templates behave pretty much like in normal Lua, but here are some additions. To use a "templateified" control structure put the keyword right after {{:

Normal if:
{{
if foo == "bar" then
	echo("Foo is bar!")
end
}}

Templateified if:
{{ if foo == "bar" }}
Foo is bar!
{{ end }}

{{   if   foo   ==   "bar"   }}
Extra spaces are fine.
{{   end   }}

for / fori

Templateified for statements have several simplified versions:

{{ for 3 }}
- Loop forwards from 1 to 3: {{ i }}
{{ end }}

{{ for < 3 }}
- Loop backwards from 3 to 1: {{ i }}
{{ end }}

fori is a new keyword here and implies it's an ipairs() loop.

{{ fori dog in data.dogs }}
- {{ i }}: {{ dog.name }}
{{ end }}

{{ fori data.dogs }}
- {{ i }}: {{ it.name }}
{{ end }}

fori also supports < for looping backwards.

{{ fori < data.dogs }}
- {{ i }}: {{ it.name }}
{{ end }}

Header Code Block

A code block at the top of the page is commonly used as a place for setting page properties. Example:

{{
page.title  = "Cool Dogs"
page.date   = "1999-06-29 15:00"
page.layout = "minimal"
}}

## Golder Retriever
Blah blah blah.

## Jack Russel Terrier
Blah blah blah.
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