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Add a more robust representation of selectors #20

Closed
5 tasks done
philss opened this issue Sep 4, 2015 · 4 comments
Closed
5 tasks done

Add a more robust representation of selectors #20

philss opened this issue Sep 4, 2015 · 4 comments
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Feature Help wanted
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1.0

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@philss
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philss commented Sep 4, 2015

The current implementation does not allow searching for elements using a multi selector, like a.some-class or .some-class.another-class. This is because it is coupled to the idea of one search per selector at time. This means that I can't search a "tag" and a "class" in the same element at the same time.

We need to provide a basic infrastructure to be able to search using groups of selectors.
This could bring a huge flexibility to Floki, since it's would be possible to truly simulates the "jQuery" selector (actually simulates Sizzle, the jQuery query selector engine).

Examples of queries to support:

  • Floki.find("a.foo")
  • Floki.find(".foo.bar")
  • Floki.find(".foo[data-js=bar]")
  • Floki.find("a.foo[data='baz.html']")
  • Floki.find("a b.foo")

The following examples can be implemented as well, but since depends on a more robust representation of the HTML tree, it should be implemented in the future:

  • Floki.find("a + b") (matches b followed by a)
  • Floki.find("a > b") (matches b that is right in the first level of children of a)
  • Floki.find("a:first-child") (matchesawhena` is the first child of its parent)

This issue is related to #18
@philss philss added this to the 1.0 milestone Sep 4, 2015
@edmz
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edmz commented Sep 4, 2015

Just curious, in you experience, is Floki.find("a + b") harder to implement than Floki.find("a.foo")?

@philss
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philss commented Sep 4, 2015

@edmz I think it's harder because for the Floki.find("a + b") we need to have the concept of "parent" selector, and a "parent lookup". Today it's possible to perform a descending search using Floki.find("a b"), but this is easier because we only lookup elements inside the previous selector.

Floki.find("a.foo") would require a multiple match in the same element, making it easier than the previous example since we don't need to check the "position", or parent/child element, of the target element inside the HTML tree.

@philss
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philss commented Sep 12, 2015

Just to let you know: I'm working on this. It's getting shape and I should have a working version soon.

philss added a commit that referenced this issue Sep 17, 2015
@philss
Add a robust representation of selectors
62e24ff 
This is a huge refactor in the `Floki.find/2` function that enables more
complex searches using a mix of selectors. You can mix selectors
like you would normally do in other tools like jQuery or to apply rules
using CSS selectors.

Examples of queries now supported:
- "a.foo"
- ".foo.bar"
- ".baz[data='something']"
- "[title][href$='.html']"
- "a b.foo c"

To archive this, it was necessary to write a tokenizer and a parser for
the inputted selector. It's quite easy to understand after read this
article by Andrea Leopardi (@whatyouhide) about tokenizing and parsing
in Elixir:
http://andrealeopardi.com/posts/tokenizing-and-parsing-in-elixir-using-leex-and-yecc/

The tokenizer partially covers the specs of CSS3 selectors, that you can
find at http://www.w3.org/TR/css3-selectors/

Knowning issues:
- There is no support for pseudo-selectors;
- The only combinator supported is descendant combinator;
- If there is a group of selectors in the same query, and two selectors
  matches the same node, this node will appear twice in the resultant
  list.

Closes #18 and #20.
@philss philss mentioned this issue Sep 17, 2015
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@philss
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philss commented Sep 17, 2015

The merge of #22 closes this issue. I will open new issues related to the selectors that are missing.

@philss philss closed this as completed Sep 17, 2015
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