1. Gonzales AST — Abstract Syntax Tree

If you don't know what AST is, first read [article at Wikipedia] (http://en.wikipedia.org/wiki/Abstract_syntax_tree).

In general Gonzales AST looks like this:

['stylesheet',
  ['atrules', ..],
  ['s', ' '],
  ['commentML', 'sample'],
  ['ruleset',
    ['selector', ..]],
    ['block', ..]]

Known issues

operator / unary — rather artificial division, in addition unary is misnamed. Utilities working with AST may need to handle both types of nodes instead of one.

raw — currently raw contains unparsed progid IE. In the future it makes sense to parse that parts in full AST.

2. Node structure

Node is a JavaScript array of the following type:

['token type', <- required
 <content>]    <- optional

Content can be other nodes or CSS source.

In case needInfo parameter was true, the node includes info object.
It contains token's index number and token's line number:

[{ ln: ln, tn: tn }, <- info object
 'token type',       <- required
 <content>]          <- optional

3. Node types

In alphabetical order.

arguments

Mixin's arguments.
Valid only for scss syntax.
Can be any number of:

string,
ident,
vhash,
variable,
number,
declaration,

wraped with braces, mixed with spaces and separated with commas.

(10)

↓

['arguments',
  ['number', '10']]

atkeyword

@-rule identifier.

@font-face

↓

['atkeyword',
  ['ident', 'font-face']]

atruleb

Block @-rule.

Consists of:

atkeyword (@-rule identifier),
rule, and
block.

@test x y {p:v}

↓

['atruleb',
  ['atkeyword',
    ['ident', 'test']],
  ['s', ' '],
  ['ident', 'x'],
  ['s', ' '],
  ['ident', 'y'],
  ['s', ' '],
  ['block',
    ['declaration',
      ['property',
        ['ident', 'p']],
      ['propertyDelim'],
      ['value',
        ['ident', 'v']]]]]

atruler, atrulerq, atrulers

@-rule with a ruleset.

Consists of:

atkeyword (@-rule identifier),
rule, and
styles set.

@media x y {s{p:v}}

↓

['atruler',
  ['atkeyword',
    ['ident', 'media']],
  ['atrulerq',
    ['s', ' '],
    ['ident', 'x'],
    ['s', ' '],
    ['ident', 'y'],
    ['s', ' ']],
  ['atrulers',
    ['ruleset',
      ['selector',
        ['simpleselector',
          ['ident', 's']]],
      ['block',
        ['declaration',
          ['property',
            ['ident', 'p']],
          ['propertyDelim'],
          ['value',
            ['ident', 'v']]]]]]]

atrules

Single-line @-rule.

Consists of:

atkeyword (@-rule identifier), and
rule.

@import url('/css/styles.css')

↓

['atrules',
  ['atkeyword',
    ['ident', 'import']],
  ['s', ' '],
  ['uri',
    ['string', ''/css/styles.css'']]]

attrib

Attribute selector.

[a='b']

↓

['attrib',
  ['ident', 'a'],
  ['attrselector', '='],
  ['string', ''b'']]

attrselector

Attribute selector operator: =, ~=, ^=, $=, *=, |=.

[a='b']

↓

['attrib',
  ['ident', 'a'],
  ['attrselector', '='],
  ['string', ''b'']]

block

Part of the style in braces: {...}.
For *.sass files — code that will be compiled to a block.

{ color: red }

↓

['block',
  ['s', ' '],
  ['declaration',
    ['property',
      ['ident', 'color']],
    ['propertyDelim'],
    ['value',
      ['s', ' '],
      ['ident', 'red'],
      ['s', ' ']]]]

braces

Braces and their content.

()
(1)

↓

['braces', '(', ')']
['braces', '(', ')',
  ['number', '1']]

class

Class.

.abc

↓

['class',
  ['ident', 'abc']]

combinator

Combinator: +, >, ~.

x+y { .. }

↓

['simpleselector',
  ['ident', 'x'],
  ['combinator', '+'],
  ['ident', 'y']]

commentML

Multi-line comment.

/* test */

↓

['commentML', ' test ']

commentSL

Single-line comment. Valid for less, scss and sass.

// comment

↓

['commentSL', ' comment']

condition

Condition. Valid for less, scss and sass.

@if nani == panda

↓

['condition',
  ['atkeyword',
    ['ident', 'if']],
  ['s', ' '],
  ['ident', 'nani'],
  ['s', ' '],
  ['operator', '='],
  ['operator', '='],
  ['s', ' '],
  ['ident', 'panda']]

declaration

Property/value pair.

Consists of:

property,
propertyDelim and
value

mixed with spaces and comments.

color: red

↓

['declaration',
  ['property',
    ['ident', 'color']],
  ['propertyDelim'],
  ['value',
    ['s', ' '],
    ['ident', 'red']]]

declDelim

Declaration delimiter in block: \n for sass, ; for other syntaxes.

x {a: b; c: d}

↓

['block',
  ['declaration',
    ['property',
      ['ident', 'a']],
    ['propertyDelim'],
    ['value',
      ['s', ' '],
      ['ident', 'b']]],
  ['declDelim'],
  ['s', ' '],
  ['declaration',
    ['property',
      ['ident', 'c']],
    ['propertyDelim'],
    ['value',
      ['s', ' '],
      ['ident', 'd']]]]

default

!default keyword. Valid only for scss and syntax.

a: b !default

↓

['declaration',
  ['property',
    ['ident', 'a']],
  ['propertyDelim'],
  ['value',
    ['s', ' '],
    ['ident', 'b'],
    ['s', ' '],
    ['default']]]

delim

Simple selector delimiter in selector: ,.

x,y{ .. }

↓

['selector',
  ['simpleselector',
    ['ident', 'x']],
  ['delim'],
  ['simpleselector',
    ['ident', 'y']]]

dimension

Number with dimension unit.

10px

↓

['dimension',
  ['number', '10'],
  ['ident', 'px']]

escapedString

Escaped string.
Valid only for less.

~"ms:alwaysHasItsOwnSyntax.For.@{what}()"

↓

['escapedString', '"ms:alwaysHasItsOwnSyntax.For.@{what}()"']]

filter, filterv, progid

Node to store IE filter.

Consists of:

property (property name),
filterv (contents), and
progid (progid itself).

filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(src='a.png',sizingMethod='scale')

↓

['filter',
  ['property',
    ['ident', 'filter']],
  ['propertyDelim'],
  ['filterv',
    ['progid',
      ['raw', 'progid:DXImageTransform.Microsoft.AlphaImageLoader(src='a.png',sizingMethod='scale')']]]]

function, functionBody

Function.

Consists of:

ident (function name), and
functionBody (function body).

color: rgb(255,0,0)

↓

['declaration',
  ['property',
    ['ident', 'color']],
  ['propertyDelim'],
  ['value',
    ['s', ' '],
    ['function',
      ['ident', 'rgb'],
      ['functionBody',
        ['number', '255'],
        ['operator', ','],
        ['number', '0'],
        ['operator', ','],
        ['number', '0']]]]]

functionExpression

Node to store expression.

left:expression(document.body.offsetWidth+1)

↓

['declaration',
  ['property',
    ['ident', 'left']],
  ['propertyDelim'],
  ['value',
    ['functionExpression', 'document.body.offsetWidth+1']]]

ident

Identifiers or names.

In atkeyword:

@import ..;

↓

['atkeyword',
  ['ident', 'import']]

In class:

.abc

↓

['class',
  ['ident', 'abc']]

In dimension:

10px

↓

['dimension',
  ['number', '10'],
  ['ident', 'px']]

important

!important keyword.

a: b !important

↓

['declaration',
  ['property',
    ['ident', 'a']],
  ['propertyDelim'],
  ['value',
    ['s', ' '],
    ['ident', 'b'],
    ['s', ' '],
    ['important']]]

include

Included mixin.

For scss and sass:

@include nani

↓

['include',
  ['atkeyword',
    ['ident', 'include']],
  ['s', ' '],
  ['simpleselector',
    ['ident', 'nani']]]

For less:

.nani(2px)

↓

['include',
  ['class',
    ['ident', 'nani']],
  ['arguments',
    ['dimension',
      ['number', '2'],
      ['ident', 'px']]]]

interpolatedVariable

Interpolated variable.

For scss and sass:

#{$nani}

↓

['interpolatedVariable',
  ['ident', 'nani']]

For less:

@{nani}

↓

['interpolatedVariable',
  ['ident', 'nani']]

loop

Valid only for scss and sass.

@while 1 > 2 {a{p:v}}

↓

['loop',
  ['atkeyword',
    ['ident', 'while']],
  ['s', ' '],
  ['number', '1'],
  ['s', ' '],
  ['operator', '>'],
  ['s', ' '],
  ['number', '2'],
  ['s', ' '],
  ['block',
    ['ruleset',
      ['selector',
        ['simpleselector',
          ['ident', 'a']]],
      ['block',
        ['declaration',
          ['property',
            ['ident', 'p']],
          ['propertyDelim'],
          ['value',
            ['ident', 'v']]]]]]]

mixin

For scss and sass:

@mixin nani {color:tomato}

↓

['mixin',
  ['atkeyword',
    ['ident', 'mixin']],
  ['s', ' '],
  ['ident', 'nani'],
  ['s', ' '],
  ['block',
    ['declaration',
      ['property',
        ['ident', 'color']],
      ['propertyDelim'],
      ['value',
        ['ident', 'tomato']]]]]

For less:

.nani (@color) {color:@color}

↓

['mixin',
  ['class',
    ['ident', 'nani']],
  ['s', ' '],
  ['arguments',
    ['variable',
      ['ident', 'color']]],
  ['s', ' '],
  ['block',
    ['declaration',
      ['property',
        ['ident', 'color']],
      ['propertyDelim'],
      ['value',
        ['variable',
          ['ident', 'color']]]]]]

namespace

Namespace sign in simpleselector.

*|E { .. }

↓

['simpleselector',
  ['ident', '*'],
  ['namespace'],
  ['ident', 'E']]

nth

Numbers and identifiers in nthselector.

:nth-child(2n+1)

↓

['nthselector',
  ['ident', 'nth-child'],
  ['nth', '2n'],
  ['unary', '+'],
  ['nth', '1']]

nthselector

:nth- pseudo-classes.

It consists of a pseudo-class ident and content.

:nth-last-child(+3n-2)

↓

['nthselector',
  ['ident', 'nth-last-child'],
  ['unary', '+'],
  ['nth', '3n'],
  ['unary', '-'],
  ['nth', '2']]

number

Number.

10
12.34

↓

['number', '10']
['number', '12.34']

operator

Operator: /, ,, :, =.

test(x,y)

↓

['function',
  ['ident', 'test'],
  ['functionBody',
    ['ident', 'x'],
    ['operator', ','],
    ['ident', 'y']]]

parentselector

Valid only for less, scss and sass.

&.nani

↓

['parentselector'],
['class',
  ['ident', 'nani']]

percentage

Number with percent sign.

10%

↓

['percentage',
  ['number', '10']]

placeholder

Placeholder.
Valid only for scss and sass.

%button

↓

['placeholder',
  ['ident', 'button']]

property

CSS property.

top:0
$color: tomato

↓

['declaration',
  ['property',
    ['ident', 'top']],
  ['propertyDelim'],
  ['value',
    ['number', '0']]]


['declaration',
  ['property',
    ['variable', 'color']],
  ['propertyDelim'],
  ['value',
    ['ident', 'tomato']]]

propertyDelim

Delimiter : between property and value.

color: tomato

↓

['declaration',
  ['property',
    ['ident', 'color']],
  ['propertyDelim'],
  ['value',
    ['s', ' '],
    ['ident', 'tomato']]]

Sass allows you to put : before property:

:color tomato

↓

['declaration',
  ['propertyDelim'],
  ['property',
    ['ident', 'color'],
    ['s', ' ']],
  ['value',
    ['ident', 'tomato']]]

pseudoc

Pseudo-class.

test:visited

↓

['simpleselector',
  ['ident', 'test'],
  ['pseudoc',
    ['ident', 'visited']]]

pseudoe

Pseudo-element.

p::first-line

↓

['simpleselector',
  ['ident', 'p'],
  ['pseudoe',
    ['ident', 'first-line']]]

raw

Unparsed parts of the style. Refers to a specific browser specific extensions, usually IE filter.

progid:DXImageTransform.Microsoft.AlphaImageLoader(src='a.png',sizingMethod='scale')

↓

['progid',
  ['raw', 'progid:DXImageTransform.Microsoft.AlphaImageLoader(src='a.png',sizingMethod='scale')']]]]

ruleset

A set of rules with selectors.

Consists of:

selector (selector), and
block (a set of rules).

x, y {p:v}

↓

['ruleset',
  ['selector',
    ['simpleselector',
      ['ident', 'x']],
    ['delim'],
    ['simpleselector',
      ['s', ' '],
      ['ident', 'y'],
      ['s', ' ']]],
  ['block',
    ['declaration',
      ['property',
        ['ident', 'p']],
      ['propertyDelim'],
      ['value',
        ['ident', 'v']]]]]

s

Whitespace: space, \t, \n, \r.

/*a*/  /*b*/

↓

['commentML', 'a'],
['s', '  '],
['commentML', 'b']

selector

Node to store simpleselector groups.

x, y, [a=b] { .. }

↓

['selector',
  ['simpleselector',
    ['ident', 'x']],
  ['delim'],
  ['simpleselector',
    ['s', ' '],
    ['ident', 'y']],
  ['delim'],
  ['simpleselector',
    ['s', ' '],
    ['attrib',
      ['ident', 'a'],
      ['attrselector', '='],
      ['ident', 'b']],
    ['s', ' ']]]

shash

Hexadecimal number in simpleselector.

.. #FFF .. { .. }

↓

['shash', 'FFF']

simpleselector

Sets of selectors between a commas.

x, y+z { .. }

↓

['selector',
  ['simpleselector',
    ['ident', 'x']],
  ['delim'],
  ['simpleselector',
    ['s', ' '],
    ['ident', 'y'],
    ['combinator', '+'],
    ['ident', 'z'],
    ['s', ' ']]]

string

String wraped with single or double quotes.

'test'
"test"

↓

['string', ''test'']
['string', '"test"']

stylesheet

Style. The root node of AST.

Can consist of:

rulesets (sets of rules with selectors),
@-rules,
whitespaces,
single-line comments,
multi-line comments.

@import "x.png"; /*sample*/ x{p:v}

↓

['stylesheet',
  ['atrules',
    ['atkeyword',
      ['ident', 'import']],
    ['s', ' '],
    ['string', '"x.png"']],
  ['s', ' '],
  ['commentML', 'sample'],
  ['s', ' '],
  ['ruleset',
    ['selector',
      ['simpleselector',
        ['ident', 'x']]],
    ['block',
      ['declaration',
        ['property',
          ['ident', 'p']],
        ['propertyDelim'],
        ['value',
          ['ident', 'v']]]]]]

unary

Unary (or arithmetical) sign: +, -.

nth-last-child(3n+0)

↓

['nthselector',
  ['ident', 'nth-last-child'],
  ['nth', '3n'],
  ['unary', '+'],
  ['nth', '0']]

unknown

Node to store invalid (or unknown) parts of the style, that parser can extract and continue on.

// invalid

↓

['stylesheet',
  ['unknown', '// invalid']]

uri

URI.

@import url('/css/styles.css')

↓

['atrules',
  ['atkeyword',
    ['ident', 'import']],
  ['s', ' '],
  ['uri',
    ['string', ''/css/styles.css'']]]

value

Value of a property.

color: tomato

↓

['declaration',
  ['property',
    ['ident', 'color']],
  ['propertyDelim'],
  ['value',
    ['s', ' '],
    ['ident', 'tomato']]]

variable

Valid for less, scss and sass.

Sass:

$color

↓

['variable',
  ['ident', 'color']]

LESS:

@color
@@foo

↓

['variable',
  ['ident', 'color']]

['variable',
  ['variable',
    ['ident', 'foo']]]

variableslist

Valid for less, scss and sass.

Sass:

$arguments...

↓

['variableslist',
  ['variable',
    ['ident', 'arguments']]]

LESS:

@rest...

↓

['variableslist',
  ['variable',
    ['ident', 'rest']]]

vhash

Hexadecimal number in value.

.. { ..: #FFF }

↓

['vhash', 'FFF']

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AST-Description.md

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1. Gonzales AST — Abstract Syntax Tree

Known issues

2. Node structure

3. Node types

arguments

atkeyword

atruleb

atruler, atrulerq, atrulers

atrules

attrib

attrselector

block

braces

class

combinator

commentML

commentSL

condition

declaration

declDelim

default

delim

dimension

escapedString

filter, filterv, progid

function, functionBody

functionExpression

ident

important

include

interpolatedVariable

loop

mixin

namespace

nth

nthselector

number

operator

parentselector

percentage

placeholder

property

propertyDelim

pseudoc

pseudoe

raw

ruleset

s

selector

shash

simpleselector

string

stylesheet

unary

unknown

uri

value

variable

variableslist

vhash