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419 lines
11 KiB
JavaScript
419 lines
11 KiB
JavaScript
// CSS Grammar
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// ===========
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//
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// Based on grammar from CSS 2.1 specification [1] (including the errata [2]).
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// Generated parser builds a syntax tree composed of nested JavaScript objects,
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// vaguely inspired by CSS DOM [3]. The CSS DOM itself wasn't used as it is not
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// expressive enough (e.g. selectors are reflected as text, not structured
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// objects) and somewhat cumbersome.
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//
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// Limitations:
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//
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// * Many errors which should be recovered from according to the specification
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// (e.g. malformed declarations or unexpected end of stylesheet) are fatal.
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// This is a result of straightforward rewrite of the CSS grammar to PEG.js.
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//
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// [1] http://www.w3.org/TR/2011/REC-CSS2-20110607
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// [2] http://www.w3.org/Style/css2-updates/REC-CSS2-20110607-errata.html
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// [3] http://www.w3.org/TR/DOM-Level-2-Style/css.html
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{
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function extractOptional(optional, index) {
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return optional ? optional[index] : null;
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}
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function extractList(list, index) {
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return list.map(function(element) { return element[index]; });
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}
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function buildList(head, tail, index) {
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return [head].concat(extractList(tail, index))
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.filter(function(element) { return element !== null; });
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}
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function buildExpression(head, tail) {
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return tail.reduce(function(result, element) {
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return {
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type: "Expression",
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operator: element[0],
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left: result,
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right: element[1]
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};
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}, head);
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}
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}
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start
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= stylesheet:stylesheet comment* { return stylesheet; }
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// ----- G.1 Grammar -----
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stylesheet
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= charset:(CHARSET_SYM STRING ";")? (S / CDO / CDC)*
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imports:(import (CDO S* / CDC S*)*)*
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rules:((ruleset / media / page) (CDO S* / CDC S*)*)*
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{
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return {
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type: "StyleSheet",
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charset: extractOptional(charset, 1),
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imports: extractList(imports, 0),
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rules: extractList(rules, 0)
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};
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}
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import
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= IMPORT_SYM S* href:(STRING / URI) S* media:media_list? ";" S* {
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return {
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type: "ImportRule",
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href: href,
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media: media !== null ? media : []
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};
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}
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media
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= MEDIA_SYM S* media:media_list "{" S* rules:ruleset* "}" S* {
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return {
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type: "MediaRule",
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media: media,
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rules: rules
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};
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}
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media_list
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= head:medium tail:("," S* medium)* { return buildList(head, tail, 2); }
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medium
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= name:IDENT S* { return name; }
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page
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= PAGE_SYM S* selector:pseudo_page?
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"{" S*
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declarationsHead:declaration?
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declarationsTail:(";" S* declaration?)*
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"}" S*
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{
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return {
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type: "PageRule",
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selector: selector,
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declarations: buildList(declarationsHead, declarationsTail, 2)
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};
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}
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pseudo_page
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= ":" value:IDENT S* { return { type: "PseudoSelector", value: value }; }
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operator
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= "/" S* { return "/"; }
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/ "," S* { return ","; }
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combinator
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= "+" S* { return "+"; }
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/ ">" S* { return ">"; }
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property
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= name:IDENT S* { return name; }
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ruleset
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= selectorsHead:selector
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selectorsTail:("," S* selector)*
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"{" S*
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declarationsHead:declaration?
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declarationsTail:(";" S* declaration?)*
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"}" S*
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{
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return {
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type: "RuleSet",
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selectors: buildList(selectorsHead, selectorsTail, 2),
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declarations: buildList(declarationsHead, declarationsTail, 2)
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};
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}
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selector
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= left:simple_selector S* combinator:combinator right:selector {
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return {
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type: "Selector",
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combinator: combinator,
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left: left,
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right: right
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};
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}
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/ left:simple_selector S+ right:selector {
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return {
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type: "Selector",
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combinator: " ",
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left: left,
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right: right
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};
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}
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/ selector:simple_selector S* { return selector; }
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simple_selector
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= element:element_name qualifiers:(id / class / attrib / pseudo)* {
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return {
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type: "SimpleSelector",
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element: element,
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qualifiers: qualifiers
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};
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}
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/ qualifiers:(id / class / attrib / pseudo)+ {
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return {
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type: "SimpleSelector",
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element: "*",
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qualifiers: qualifiers
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};
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}
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id
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= id:HASH { return { type: "IDSelector", id: id }; }
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class
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= "." class_:IDENT { return { type: "ClassSelector", "class": class_ }; }
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element_name
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= IDENT
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/ "*"
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attrib
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= "[" S*
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attribute:IDENT S*
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operatorAndValue:(("=" / INCLUDES / DASHMATCH) S* (IDENT / STRING) S*)?
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"]"
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{
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return {
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type: "AttributeSelector",
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attribute: attribute,
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operator: extractOptional(operatorAndValue, 0),
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value: extractOptional(operatorAndValue, 2)
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};
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}
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pseudo
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= ":"
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value:(
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name:FUNCTION S* params:(IDENT S*)? ")" {
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return {
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type: "Function",
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name: name,
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params: params !== null ? [params[0]] : []
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};
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}
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/ IDENT
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)
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{ return { type: "PseudoSelector", value: value }; }
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declaration
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= name:property ':' S* value:expr prio:prio? {
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return {
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type: "Declaration",
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name: name,
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value: value,
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important: prio !== null
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};
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}
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prio
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= IMPORTANT_SYM S*
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expr
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= head:term tail:(operator? term)* { return buildExpression(head, tail); }
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term
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= quantity:(PERCENTAGE / LENGTH / EMS / EXS / ANGLE / TIME / FREQ / NUMBER)
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S*
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{
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return {
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type: "Quantity",
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value: quantity.value,
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unit: quantity.unit
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};
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}
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/ value:STRING S* { return { type: "String", value: value }; }
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/ value:URI S* { return { type: "URI", value: value }; }
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/ function
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/ hexcolor
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/ value:IDENT S* { return { type: "Ident", value: value }; }
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function
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= name:FUNCTION S* params:expr ")" S* {
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return { type: "Function", name: name, params: params };
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}
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hexcolor
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= value:HASH S* { return { type: "Hexcolor", value: value }; }
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// ----- G.2 Lexical scanner -----
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// Macros
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h
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= [0-9a-f]i
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nonascii
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= [\x80-\uFFFF]
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unicode
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= "\\" digits:$(h h? h? h? h? h?) ("\r\n" / [ \t\r\n\f])? {
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return String.fromCharCode(parseInt(digits, 16));
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}
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escape
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= unicode
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/ "\\" ch:[^\r\n\f0-9a-f]i { return ch; }
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nmstart
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= [_a-z]i
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/ nonascii
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/ escape
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nmchar
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= [_a-z0-9-]i
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/ nonascii
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/ escape
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string1
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= '"' chars:([^\n\r\f\\"] / "\\" nl:nl { return ""; } / escape)* '"' {
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return chars.join("");
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}
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string2
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= "'" chars:([^\n\r\f\\'] / "\\" nl:nl { return ""; } / escape)* "'" {
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return chars.join("");
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}
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comment
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= "/*" [^*]* "*"+ ([^/*] [^*]* "*"+)* "/"
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ident
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= prefix:$"-"? start:nmstart chars:nmchar* {
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return prefix + start + chars.join("");
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}
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name
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= chars:nmchar+ { return chars.join(""); }
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num
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= [+-]? ([0-9]* "." [0-9]+ / [0-9]+) ("e" [+-]? [0-9]+)? {
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return parseFloat(text());
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}
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string
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= string1
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/ string2
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url
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= chars:([!#$%&*-\[\]-~] / nonascii / escape)* { return chars.join(""); }
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s
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= [ \t\r\n\f]+
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w
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= s?
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nl
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= "\n"
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/ "\r\n"
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/ "\r"
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/ "\f"
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A = "a"i / "\\" "0"? "0"? "0"? "0"? [\x41\x61] ("\r\n" / [ \t\r\n\f])? { return "a"; }
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C = "c"i / "\\" "0"? "0"? "0"? "0"? [\x43\x63] ("\r\n" / [ \t\r\n\f])? { return "c"; }
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D = "d"i / "\\" "0"? "0"? "0"? "0"? [\x44\x64] ("\r\n" / [ \t\r\n\f])? { return "d"; }
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E = "e"i / "\\" "0"? "0"? "0"? "0"? [\x45\x65] ("\r\n" / [ \t\r\n\f])? { return "e"; }
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G = "g"i / "\\" "0"? "0"? "0"? "0"? [\x47\x67] ("\r\n" / [ \t\r\n\f])? / "\\g"i { return "g"; }
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H = "h"i / "\\" "0"? "0"? "0"? "0"? [\x48\x68] ("\r\n" / [ \t\r\n\f])? / "\\h"i { return "h"; }
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I = "i"i / "\\" "0"? "0"? "0"? "0"? [\x49\x69] ("\r\n" / [ \t\r\n\f])? / "\\i"i { return "i"; }
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K = "k"i / "\\" "0"? "0"? "0"? "0"? [\x4b\x6b] ("\r\n" / [ \t\r\n\f])? / "\\k"i { return "k"; }
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L = "l"i / "\\" "0"? "0"? "0"? "0"? [\x4c\x6c] ("\r\n" / [ \t\r\n\f])? / "\\l"i { return "l"; }
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M = "m"i / "\\" "0"? "0"? "0"? "0"? [\x4d\x6d] ("\r\n" / [ \t\r\n\f])? / "\\m"i { return "m"; }
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N = "n"i / "\\" "0"? "0"? "0"? "0"? [\x4e\x6e] ("\r\n" / [ \t\r\n\f])? / "\\n"i { return "n"; }
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O = "o"i / "\\" "0"? "0"? "0"? "0"? [\x4f\x6f] ("\r\n" / [ \t\r\n\f])? / "\\o"i { return "o"; }
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P = "p"i / "\\" "0"? "0"? "0"? "0"? [\x50\x70] ("\r\n" / [ \t\r\n\f])? / "\\p"i { return "p"; }
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R = "r"i / "\\" "0"? "0"? "0"? "0"? [\x52\x72] ("\r\n" / [ \t\r\n\f])? / "\\r"i { return "r"; }
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S_ = "s"i / "\\" "0"? "0"? "0"? "0"? [\x53\x73] ("\r\n" / [ \t\r\n\f])? / "\\s"i { return "s"; }
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T = "t"i / "\\" "0"? "0"? "0"? "0"? [\x54\x74] ("\r\n" / [ \t\r\n\f])? / "\\t"i { return "t"; }
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U = "u"i / "\\" "0"? "0"? "0"? "0"? [\x55\x75] ("\r\n" / [ \t\r\n\f])? / "\\u"i { return "u"; }
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X = "x"i / "\\" "0"? "0"? "0"? "0"? [\x58\x78] ("\r\n" / [ \t\r\n\f])? / "\\x"i { return "x"; }
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Z = "z"i / "\\" "0"? "0"? "0"? "0"? [\x5a\x7a] ("\r\n" / [ \t\r\n\f])? / "\\z"i { return "z"; }
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// Tokens
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S "whitespace"
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= comment* s
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CDO "<!--"
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= comment* "<!--"
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CDC "-->"
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= comment* "-->"
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INCLUDES "~="
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= comment* "~="
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DASHMATCH "|="
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= comment* "|="
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STRING "string"
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= comment* string:string { return string; }
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IDENT "identifier"
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= comment* ident:ident { return ident; }
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HASH "hash"
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= comment* "#" name:name { return "#" + name; }
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IMPORT_SYM "@import"
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= comment* "@" I M P O R T
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PAGE_SYM "@page"
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= comment* "@" P A G E
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MEDIA_SYM "@media"
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= comment* "@" M E D I A
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CHARSET_SYM "@charset"
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= comment* "@charset "
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// We use |s| instead of |w| here to avoid infinite recursion.
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IMPORTANT_SYM "!important"
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= comment* "!" (s / comment)* I M P O R T A N T
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EMS "length"
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= comment* value:num E M { return { value: value, unit: "em" }; }
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EXS "length"
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= comment* value:num E X { return { value: value, unit: "ex" }; }
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LENGTH "length"
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= comment* value:num P X { return { value: value, unit: "px" }; }
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/ comment* value:num C M { return { value: value, unit: "cm" }; }
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/ comment* value:num M M { return { value: value, unit: "mm" }; }
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/ comment* value:num I N { return { value: value, unit: "in" }; }
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/ comment* value:num P T { return { value: value, unit: "pt" }; }
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/ comment* value:num P C { return { value: value, unit: "pc" }; }
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ANGLE "angle"
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= comment* value:num D E G { return { value: value, unit: "deg" }; }
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/ comment* value:num R A D { return { value: value, unit: "rad" }; }
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/ comment* value:num G R A D { return { value: value, unit: "grad" }; }
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TIME "time"
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= comment* value:num M S_ { return { value: value, unit: "ms" }; }
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/ comment* value:num S_ { return { value: value, unit: "s" }; }
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FREQ "frequency"
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= comment* value:num H Z { return { value: value, unit: "hz" }; }
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/ comment* value:num K H Z { return { value: value, unit: "kh" }; }
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PERCENTAGE "percentage"
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= comment* value:num "%" { return { value: value, unit: "%" }; }
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NUMBER "number"
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= comment* value:num { return { value: value, unit: null }; }
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URI "uri"
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= comment* U R L "("i w url:string w ")" { return url; }
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/ comment* U R L "("i w url:url w ")" { return url; }
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FUNCTION "function"
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= comment* name:ident "(" { return name; }
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