Introduction

This is a LESS CSS compiler written in C++.

A LESS CSS compiler compiles stylesheets in the LESS format to CSS. Read more on http://lesscss.org/

Differences from the original compiler

By default, this compiler does not apply formatting to the code. The CSS in the output contains no whitespace except where necessary. You can use the -f option to indent the output. If you need it to be more user-readable you can use a CSS formatter. Try CSSTidy: http://csstidy.sourceforge.net/

CSS comments are not included in the output. The purpose of this compiler is to produce the smallest amount of output as possible.

Parentheses are not required in compound values:

border: @width * 2 solid black;

The spin() function produces slightly different results.

There is an imgwidth() and a imgheight() function which can be used with image variables to access their dimensions. e.g.

    img.thumbup {
       content: url(browser/path/to/thumbup.png);
       @image: url('compile/time/path/to/thumbup.png');
       width: imgwidth(@image);
       height: imgheight(@image);
    }

Installation

If compiling from the source checked out with git you first have to run

cmake

To build the compiler just run

make

This searches for a c++ compiler and the libpng and libjpeg libraries. The libraries are not used if not present.

After compiling you will have the binary clessc. You can run make install as root to install the binary.

Usage

To compile the LESS stylesheet stylesheet.less and write the resulting CSS to stylsheet.css run:

clessc stylesheet.less > stylesheet.css

or:

clessc stylesheet.less -o stylesheet.css

To also generate a source map:

clessc stylesheet.less -o stylesheet.css --source-map=stylesheet.map

LESS Support Status

Here follows a list of LESS language features and their support status:

- Variables: yes
  - Default variables (variable overriding): yes
  - Lazy Evaluation: yes
  - Scope: yes
  - Variable interpolation
    - Selectors: yes
    - URLs: yes
    - Import statements: yes
    - Properties: yes
    - Variables: yes
- Nested rules: yes
  - parent selectors `&`: yes
- Nested directives: yes
- Comments: yes
- Importing: yes
  - Import directives: yes
  - File extensions: yes
    - inline: no
- Mixins
  - Selectors in mixins: yes
  - Namespaces: yes
  - Guarded namespaces: no
  - `default()`: no
  - `!important` keyword: no
  - merge: no
    - `+` append with comma: no
    - `+_` append with space: no
- Parametric Mixins
  - Arguments
    - default values: yes
    - separated by commas/semicolons: yes
    - named parameters: yes
    - `@arguments` variable: yes
    - `...` rest variable: yes
    - switch argument: no
  - Return values
    - Variables: yes
    - Mixins: yes
  - Mixin guards: yes
    - `and` keyword: yes
    - multiple conditions with `,`: yes
    - `not` keyword: no
    - `default()`: no
- Detached rulesets: no
    
- Operations
  - Operators (`+-*/`): yes
  - Unit conversion: yes *(1px = 1/96 inch)
  - Escaping: yes
  - Functions: partial
- Extend
  - In ruleset: yes
  - In selector: yes
  - Quote type in attribute selector: no (`[type='identifier']` does not
    match `[type=identifier]`)
  - Extend `all`: yes
  - Attached to interpolated selector: no
  - Match only inside `@media`: no

- Functions
  - `color`: yes
  - `image-size`: no 
  - `image-width`: no
  - `image-height`: no
  - `convert`: yes
  - `data-uri`: no
  - `default`: no
  - `unit`: yes
  - `get-unit`: no
  - `svg-gradient`: no
  - `escape`: yes
  - `e`: yes
  - `%`: no
  - `replace`: no
  - `length` : no
  - `extract`: no
  - `ceil`: yes
  - `floor`: yes
  - `percentage`: yes
  - `round`: yes
  - `sqrt`: yes
  - `abs`: yes
  - `sin`: yes
  - `asin`: yes
  - `cos`: yes
  - `acos`: yes
  - `tan`: yes
  - `atan`: yes
  - `pi`: yes
  - `pow`: yes
  - `mod`: yes
  - `min`: no
  - `max`: no
  - `isnumber`: no
  - `isstring`: no
  - `iscolor`: no
  - `iskeyword`: no
  - `isurl`: no
  - `ispixel`: no
  - `isem`: no
  - `ispercentage`: no
  - `isunit`: no
  - `isruleset`: no
  - `rgb`: yes
  - `rgba`: yes
  - `argb`: yes
  - `hsl`: yes
  - `hsla`: no
  - `hsv`: no
  - `hsva`: no
  - `hue`: yes
  - `saturation`: yes
  - `lightness`: yes
  - `hsvue`: no
  - `hsvsaturation`: no
  - `hsvvalue`: no
  - `red`: yes
  - `green`: yes
  - `blue`: yes
  - `alpha`: yes
  - `luma`: no
  - `luminance`: no
  - `saturate`: yes
  - `desaturate`: yes
  - `lighten`: yes
  - `darken`: yes
  - `fadein`: yes
  - `fadeout`: yes
  - `fade`: no
  - `spin`: yes
  - `mix`: no
  - `tint`: no
  - `shade`: no
  - `greyscale`: no
  - `contrast`: no
  - `multiply`: no
  - `screen`: no
  - `overlay`: no
  - `softlight`: no
  - `hardlight`: no
  - `difference`: no
  - `exclusion`: no
  - `average`: no
  - `negation`: no