lpp

tiny (80 SLOC) lua preprocessor thing created for personal use

usage

luajit lpp.lua /path/to/file.lpp.lua > output.txt

both lua 5.1 and luajit are supported
.lpp.lua is currently the suggested file extension for lpp files

example

|>! postprocess "remove_empty_lines" <|

|>
  name = "Bob"
  age = 36
<|

Hello! My name is |>! name <|, and my age is |>! age <|. 
I have "|>! -math.huge <|" friends :(.

Some math operations: (age * 36) / 2 = |>! (age * 36) / 2  <|

|>- I'm a comment! |<


Today's lucky number is... |>! math.random(100) <|

Output:

Hello! My name is Bob, and my age is 36.
I have "-inf" friends :(.
Some math operations: (age * 36) / 2 = 648
Today's lucky number is... 60

syntax

wrap your lua code between |> ... <|
returned value gets added to the output
use these to define your globals and functions

inline blocks:

|>! ... <| evaluate a single expression
basically a shorthand for |> return (...) <|
example: |>! 5 * 5 <|

comments:

|>- ... <|
self-explanatory

includes

|>! include "bf_fun.lpp.lua" <|

notice how include(...) is just a normal lua function!

|>! file "data.txt" <|

inserts file without any preprocessing
(again, this is a normal lua function that can be called from anywhere

post-processing

postprocess(...)

adds post-process filter to the queue. runs after the final file is generated

usage:

accepts strings and functions.

|>! postprocess "remove_whitespace" <|
|>! postprocess(postprocess.remove_whitespace) <|
|>! postprocess(function(data)  ... end) <|

strings act as pointers to items in the global postprocess table. they can be defined like so:

postprocess.remove_whitespace = function(data)
  return data:gsub('%s', '')
end

built-in post-processing functions:

• remove_whitespace: removes all whitespace (including line breaks)
• convert_crlf: converts \r\n line endings to \n
• remove_empty_lines: removes all empty lines (lines that don't contain anything)

emit api

_(...) function can be used to write to the file multiple times per block.
it can be useful for loops and conditions.
please note that emit api is incompatible with return values!

emit api example:

|>
  local text = "hello world"
  for i=1,#text do
    _ (text:sub(i,i):byte())
    _ ", "
  end
<|

output: 104, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100,

security

none.