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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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