Hate waiting for SASS compiling your stylesheets with Compass over 10 seconds everytime? C6 helps you write style sheets with efficiency.

C6 is a SASS 3.2 compatible implementation written in Go. But wait! this is not only to implement SASS, but also to create a new language for better consistency, syntax and performance. And yes, this means we're free to accept new language feature requests.

Setup GOPATH:

source goenv

Setup dependencies:

source goinstall

Run tests:

go test c6
go test -v c6
go test -v c6/ast

To run specific test

go test -run TestParser -x -v c6

C6 project source does not depend on the import path github.com/c9s/c6, therefore the project needs to be built standalone.

The reason of using goenv instead go get is:

If any dependent package API changed on master, everything will be broken when user runs go get. Therefore we control the package dependency we used by using goenv: install packages on specific tag or branch. This is to prevent unexpected results while we need to build stable application for users.

The other reason of not using github.com/c9s/c6 as our import path is:

We host c6 project source code in a private repository, hence the private build process shouldn't depend on github.com/.... The remote import path restricts the flexibility of our build process.

If you need to build your application with c6, you need to clone the repository into your GOPATH manually:

git clone https://github.com/c9s/c6.git vendor/c6
export GOPATH=vendor/c6:$GOPATH

• Lexing

  • @import
  • simple selector.
    • type selector.
    • child selector.
    • attribute selector.
    • adjacent selector.
    • descendant selector.
    • class selector.
    • ID selector.
  • Ruleset
  • Sub-ruleset
  • Interpolation
  • Property name
  • Property value list
  • Nested properties.
  • Comma-separated list
  • Space-separated list
  • @if , @else , @else if
  • @for, from, through statement
  • @while
  • @mixin
  • @mixin with arguments
  • @include
  • Flags: !default, !important, !optional, !global
  • Hex color
  • Functions
  • Vendor prefix properties
  • MS filter. progid:DXImageTransform.Microsoft....
  • Variable names
  • Variable assignment
  • Time unit support. s second, ms ... etc
  • Angle unit support.
  • Resolution unit support.
  • Unicode Range support: https://developer.mozilla.org/en-US/docs/Web/CSS/unicode-range
  • Media Query

• Built-in Functions

  • .... to be listed

• Parser

  • Parse @import
  • Parse Expr
  • Parse Space-Sep List
  • Parse Comma-Sep List
  • Parse Map (tests required)
  • Parse Selector
  • Parse Selector with interpolation
  • Parse RuleSet
  • Parse DeclBlock
  • Parse Variable Assignment Stmt
  • Parse PropertyName
  • Parse PropertyName with interpolation
  • Parse PropertyValue
  • Parse PropertyValue with interpolation
  • Parse conditions
  • Parse @media statement
  • Parse Nested RuleSet
  • Parse Nested Properties
  • Parse options: !default, !global, !optional
  • Parse CSS Hack for different browser (support more syntax sugar for this)
  • Parse @font-face block
  • Parse @if statement
  • Parse @for statement
  • Parse @while statement
  • Parse @mixin statement
  • Parse @include statement
  • Parse @function statement
  • Parse @return statement
  • Parse @extend statement
  • Parse keyword arguments for @function
  • Parse @switch statement
  • Parse @case statement
  • Parse @use statement

• Building AST

  • RuleSet
  • DeclBlock
  • PropertyName
  • PropertyValue
  • Comma-Separated List
  • Space-Separated List
  • Basic Exprs
  • FunctionCall
  • Expr with interpolation
  • Variable statements
  • Built-in color keyword table
  • Hex Color computation
  • Number operation: add, sub, mul, div
  • Length operation: number operation for px, pt, em, rem, cm ...etc
  • Expr evaluation
  • Boolean expression evaluation
  • Media Query conditions
  • @if If Condition
  • @else if If Else If
  • @else else condition
  • @while statement node
  • @function statement node
  • @mixin statement node
  • @include statement node
  • @return statement node
  • @each statement node

• Runtime

  • HSL Color computation
  • Function Call Invoke mech
  • Mixin Include
  • Import

• SASS Built-in Functions

  • RGB functions
    • rgb($red, $green, $blue)
    • rgba($red, $green, $blue, $alpha)
    • red($color)
    • green($color)
    • blue($color)
    • mix($color1, $color2, [$weight])
  • HSL Functions
    • hsl($hue, $saturation, $lightness)
    • hsla($hue, $saturation, $lightness, $alpha)
    • hue($color)
    • saturation($color)
    • lightness($color)
    • adjust-hue($color, $degrees)
    • lighten($color, $amount)
    • darken($color, $amount)
    • saturate($color, $amount)
    • desaturate($color, $amount)
    • grayscale($color)
    • complement($color)
    • invert($color)
  • Opacity Functions
    • alpha($color) / opacity($color)
    • rgba($color, $alpha)
    • opacify($color, $amount) / fade-in($color, $amount)
    • transparentize($color, $amount) / fade-out($color, $amount)
  • Other Color Functions
    • adjust-color($color, [$red], [$green], [$blue], [$hue], [$saturation], [$lightness], [$alpha])
    • scale-color($color, [$red], [$green], [$blue], [$saturation], [$lightness], [$alpha])
    • change-color($color, [$red], [$green], [$blue], [$hue], [$saturation], [$lightness], [$alpha])
    • ie-hex-str($color)
  • String Functions
    • unquote($string)
    • quote($string)
    • str-length($string)
    • str-insert($string, $insert, $index)
    • str-index($string, $substring)
    • str-slice($string, $start-at, [$end-at])
    • to-upper-case($string)
    • to-lower-case($string)
  • Number Functions
    • percentage($number)
    • round($number)
    • ceil($number)
    • floor($number)
    • abs($number)
    • min($numbers…)
    • max($numbers…)
    • random([$limit])
  • List Functions
    • length($list)
    • nth($list, $n)
    • set-nth($list, $n, $value)
    • join($list1, $list2, [$separator])
    • append($list1, $val, [$separator])
    • zip($lists…)
    • index($list, $value)
    • list-separator(#list)
  • Map Functions
    • map-get($map, $key)
    • map-merge($map1, $map2)
    • map-remove($map, $keys…)
    • map-keys($map)
    • map-values($map)
    • map-has-key($map, $key)
    • keywords($args)
  • Selector Functions
    • .... to be expanded ...

• CodeGen

  • CompactCompiler
    • CompileCssImportStmt: @import url(...);
    • CompileRuleSet
    • CompileSelectors
      • CoimpileParentSelector
    • CompileSubRuleSet
    • CompileCommentBlock
    • CompileDeclBlock
    • CompileMediaQuery: @media
    • CompileSupportrQuery: @support
    • CompileFontFace: @support
    • CompileForStmt
    • CompileIfStmt
      • CompileElseIfStmt
    • CompileWhileStmt
    • CompileEachStmt
    • ... list more ast nodes here ...

• Syntax

  • built-in @import-once

The original SASS is written in Ruby and it's really slow, we take 11 seconds to compile the stylesheets of our application, libsass is fast but it does not catch up the ruby sass implementation , and you can't compile them with Compass. Since Go is simple, easy & fast, thus we implement SASS in Go to move faster.

Further, we want to design a new language (ECSS temporarily named) that is compatible with SASS 3.4 or even SASS 4.0 with more powerful features.

SASS Reference http://sass-lang.com/documentation/file.SASS_REFERENCE.html

A feature check list from libsass:

• https://github.com/sass/libsass/releases/tag/3.2.0
• sass/sass#1094

Grammar Ambiguity:

• https://www.facebook.com/cindylinz/posts/10202186527405801?hc_location=ufi
• https://www.facebook.com/yoan.lin/posts/10152968537931715?_rdr

Standards:

• CSS Syntax Module Level 3 http://www.w3.org/TR/css-syntax-3
• CSS 3 Selector http://www.w3.org/TR/css3-selectors/#grouping
• CSS Font http://www.w3.org/TR/css3-fonts/#basic-font-props
• Selectors API http://www.w3.org/TR/selectors-api/
• At-Page Rule http://dev.w3.org/csswg/css-page-3/#at-page-rule
• Railroad diagram https://github.com/tabatkins/railroad-diagrams
• CSS 2.1 Grammar http://www.w3.org/TR/CSS21/grammar.html

SASS/CSS Frameworks, libraries:

• Bourbon http://bourbon.io/
• Marx https://github.com/mblode/marx
• FormHack http://formhack.io/
• Susy http://susy.oddbird.net/
• Gumby http://www.gumbyframework.com/

Articles:

• Logic in media queries - https://css-tricks.com/logic-in-media-queries/

Please open up an issue on GitHub before you put a lot efforts on pull request.

The code submitting to PR must be filtered with gofmt

• Slack: we are on Slack channel #c6, go invite yourself here: https://docs.google.com/forms/d/11KpalZc6AUuQYf7vz531ys0pLEC9csjkC6QyC_hJQEg/viewform

• Our Official Twitter Channel: https://twitter.com/C6SASS

MPL License https://www.mozilla.org/MPL/2.0/

(MPL is like LGPL but with static/dynamic linking exception, which allows you to either dynamic/static link this library without permissions)