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A pegjs grammar to convert css selectors to their respective xpath selector. Try it online http://pegjs.majda.cz/online.
Now also with weights.
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/** | |
Parses css selectors to their respective xpath expressions. | |
TODO: | |
- pseudo classes | |
for calculation of weight of the selectors, see | |
http://aktuell.de.selfhtml.org/archiv/doku/8.1.1/css/formate/kaskade.htm#spezifitaet | |
**/ | |
start | |
= selectors | |
name = | |
a:[a-zA-Z_]b:[a-zA-Z0-9-_]* { | |
return a + b.join(""); | |
} | |
space = " " | |
whitespace = [ \t\n\r] | |
selectors | |
= fss:firstSelectors* fs:firstSelector { | |
return fss.concat(fs); | |
} | |
firstSelectors | |
= fs:firstSelector whitespace* "," whitespace* { | |
return fs; | |
} | |
firstSelector | |
= s:selector { | |
return { | |
xpath: "//" + s.xpath, | |
weight: s.weight | |
} | |
} | |
selector | |
= e:element c:chain s:selector { | |
return { | |
xpath: e.xpath + c + s.xpath, | |
weight: [e.weight[0] + s.weight[0], e.weight[1] + s.weight[1], e.weight[2] + s.weight[2]] | |
} | |
} / e:element | |
chain | |
= adjacentSelector / childSelector / descentSelector | |
adjacentSelector | |
= space* "+" space* { | |
return "/following-sibling::" | |
} | |
childSelector | |
= space* ">" space* { | |
return "/" | |
} | |
descentSelector | |
= space+ { | |
return "//" | |
} | |
element | |
= elementSelector / idSelector / classSelector | |
idSelector | |
= id:id { | |
return { | |
xpath: "node()" + id.xpath, | |
weight: [1, 0, 0] | |
} | |
} | |
classSelector | |
= c:classList { | |
return { | |
xpath: "node()" + c.xpath, | |
weight: c.weight | |
} | |
} | |
classList | |
= c:class+ { | |
return { | |
xpath: "[" + c.join(" and ") + "]", | |
weight: [0, c.length, 0] | |
} | |
} | |
class | |
= "." n:name { | |
return "contains(concat(' ', normalize-space(@class), ' '), ' " + n +" ')"; | |
} | |
id | |
= "#" n:name { | |
return { | |
xpath: "[@id='" + n + "']", | |
weight: 1 | |
} | |
} | |
elementSelector | |
= tag:(universalElement / typeElement) id:(id / attributeSelector)? c:classList? { | |
return { | |
xpath: (tag.xpath || "") + (id.xpath || "") + (c.xpath || ""), | |
weight: [id ? id.weight : 0, c ? c.weight[1] : 0, tag.weight[2]] | |
} | |
} | |
universalElement | |
= "*" { | |
return { | |
xpath: "node()", | |
weight: [0, 0, 0] | |
} | |
} | |
typeElement | |
= n:name { | |
return { | |
xpath: n, | |
weight: [0, 0, 1] | |
}; | |
} | |
attributeSelector | |
= "[" a:( listAttribute / equalAttribute / hasAttribute ) "]" { | |
return { | |
xpath: "[" + a + "]", | |
weight: 0 | |
} | |
} | |
hasAttribute | |
= n:name { | |
return "@" + n; | |
} | |
listAttribute | |
= name:name "~=" v:("'" [^']+ "'" / '"' [^"]+ '"') { | |
return "contains(@" + name + ", '" + v[1].join("") + "')"; | |
} | |
equalAttribute | |
= name:name "=" v:("'" [^']+ "'" / '"' [^"]+ '"') { | |
return "@" + name + "='" + v[1].join("") + "'"; | |
} |
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