liquid-lua

A lua implementation of liquid for OpenResty platform. [!Build Status](https://travis-ci.org/chenxianyu2015/liquid-lua)

Introduction

Since liquid markup language has no its official language specification document , liquid-lua adopts a classic lexer/parser/interpreter implementation approch and comes up with a strict error mode, which is different from the liquid-ruby approach(regexp tokenizer/tag parser/tag interpreter) with three error modes(lax/warning/strict mode). Due to different implementation approch, liquid-lua will behave differently from liquid-ruby in some cases.i.e., liquid-lua is NOT 100% compatible with liquid-ruby. More detail info about incompatibility between liquid-lua and liquid-ruby will be collected and listed in DIFFERENCE.md . The following components of liquid-lua have been implemented:

• Lexer

• Parser

• Interpreter

• Parser context A component for whitespace control feature.

• Interprerter context A Component exposing lua variable to liquid engine.

• FilterSet A Component exposing lua function to liquid engine. In liquid-ruby it's called Strainer.

• Resourcelimit A simple system resource limit component for liquid engine.

• File system A simple wraper of template source backend (redis/mongo/local file system).

• Lazy A wraper makes a normal lua table behave like lazy hash. In liquid-ruby it's called Drop.

• Nodetab Runtime errors can get the corresponding source text position info from Nodetab. (Linux ELF has a Systab, liquid-lua has a Nodetab.)

Installation

Using OpenResty Package Manager(Recommened)

1. Install OpenResty Package Manager if you haven't yet;

2. Run the following Openesty Package Manager commands to search and install liquid-lua package.

    opm search liquid-lua
    opm get chenxianyu2015/liquid-lua

Manual install

1. Download zip package.

2. Extract liquid.lua directory from zip package.

3. Copy it to your openresty lua lib path.

Usage:

Currently liquid-lua only has a lot of basic and low level components, which are not frendly or easy to use. But it is easy to build frendly interfaces with these components. Here are some examples to show how to use these components.

1. a 'hi tobi' example

       -- require these components
       local Liquid = require 'liquid'
       local Lexer = Liquid.Lexer
       local Parser = Liquid.Parser
       local Interpreter = Liquid.Interpreter
       local InterpreterContext = Liquid.InterpreterContext
       
       -- template to render
       local document = 'hi {{name}}'
       -- variable to render
       local var = {["name"] = "tobi" }
       
       -- dataflow: lexer -> parser -> interpreter
       local lexer = Lexer:new(document)
       local parser = Parser:new(lexer)
       local interpreter = Interpreter:new(parser)
       
       -- the content of result is  'hi tobi'
       local result = interpreter:interpret( InterpreterContext:new(var) )

1. a for-loop example

       -- require these components
       local Liquid = require 'liquid'
       local Lexer = Liquid.Lexer
       local Parser = Liquid.Parser
       local Interpreter = Liquid.Interpreter
       local InterpreterContext = Liquid.InterpreterContext
       
       -- template to render
       local document = '{%for k in num%} {{k}} {% endfor%}'
       -- variable to render
       local var = {["num"] = {5,4,3,2,1} }
       
       -- dataflow: lexer -> parser -> interpreter
       local lexer = Lexer:new(document)
       local parser = Parser:new(lexer)
       local interpreter = Interpreter:new(parser)
       
       -- the content of result is:  5  4  3  2  1
       local result = interpreter:interpret( InterpreterContext:new(var) )

TODO

• More test cases

• Duplicate and dirty code cleanup and refactoring

• Template cache and AST cache component

• More filters

Getting Involved

• Report bugs by posting a description, full stack trace, and all relevant code in a GitHub issue.

Licence

This module is licensed under the BSD license.