lustaglue

An extension plugin for Lustache in order to enable custom formatters in expressions such as

{{ variable | filter1 | filter2 | ... | filterN }} 

Installation

Using luarocks:

 luarocks install lustaglue

Or from source:

git clone https://github.com/raygerlabs/lustaglue
cd lustaglue
luarocks make

See the luarock here: https://luarocks.org/modules/raygerlabs/lustaglue

Usage

Definitions

A filter is such an expression that alters the output of the rendering function. A filter can defined using the following syntax:

{{ variable | filter }}

A filter can be applied on the result of another filter such as:

{{ variable | filter1 | filter2 | ... | filterN }}

A filter that has parameters called parametric filter. The syntax is the following:

{{ variable | filter : param1 : param2 : ... : paramN }}

Workflow

local lustache = require "lustache"

local filters = {...}
local lustaglue = require("lustaglue"):new(filters)

local template = {...}
local view = {...}

lustache:render(template, view)

Examples

Simple filters

Given the following filter and view:

local filters = {
  upper = (function(s)
    return string.upper(s)
  end),
}
local view = { name = "John Doe" }

The template

{{ name | upper }}

shall produce:

JOHN DOE

Parametric filters

Given the following filter and view:

local filters = {
  add=(function(a, b)
    return a + b
  end) 
}
local view = {
  ten = 10
}

The template

{{ ten | add: 10 }}

shall produce

20

Expression as parameters

Given the following filter and view:

local filters = {
  add=(function(a, b)
    return a + b
  end) 
}
local view = {
  ten = 10,
  twenty = 20
}

The template

{{ ten | add: twenty }}

shall produce

30

Filter chaining

The filter functions are chainable. Given the following filter and view:

local filters = {
  add=(function(a, b)
    return a + b
  end),
  sum=(function(x, ...)
    return x and x + filters.sum(...) or 0
  end)
}
local view = {
  ten = 10,
  twenty = 20
}

With the following template:

{{ ten | add: -10 }}
{{ ten | add: twenty }}
{{ ten | add: ten | add: twenty | add: 30 | add: 40 | add: 50 }}
{{ ten | sum: 10: 20: 30: 40: 50 }}

And the result will be:

0
30
80
160
160

Quotes

Given the following filter and view:

local filter_functions = {
  concat=(function(a, b)
    return a..b
  end)
}
local view = {
  first_name = "John",
  last_name = "Doe"
}

The template:

{{ first_name | concat: 'ny' }}
{{ first_name | concat: \"ny\" }}
{{ first_name | concat: ' \"Junior\" ' | concat: last_name }}
{{ first_name | concat: \" 'Junior\' \" | concat: last_name }}

shall produce:

Johnny
Johnny
John "Junior" Doe
John 'Junior' Doe