85 lines
3.2 KiB
Elixir
85 lines
3.2 KiB
Elixir
defmodule Readability.Sanitizer do
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@moduledoc """
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Clean an element of all tags of type "tag" if they look fishy.
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"Fishy" is an algorithm based on content length, classnames, link density, number of images & embeds, etc.
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"""
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alias Readability.Helper
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alias Readability.Candidate
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alias Readability.Candidate.Scoring
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@type html_tree :: tuple | list
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@doc """
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Sanitizes article html tree
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"""
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@spec sanitize(html_tree, [Candidate.t], list) :: html_tree
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def sanitize(html_tree, candidates, opts \\ []) do
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html_tree = html_tree
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|> Helper.remove_tag(&clean_headline_tag?(&1))
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|> Helper.remove_tag(&clean_unlikely_tag?(&1))
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|> Helper.remove_tag(&clean_empty_p?(&1))
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if opts[:clean_conditionally] do
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html_tree |> Helper.remove_tag(conditionally_cleaing_fn(candidates))
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else
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html_tree
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end
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end
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defp conditionally_cleaing_fn(candidates) do
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fn({tag, attrs, _} = tree) ->
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if Enum.any?(["table", "ul", "div"], &(&1 == tag)) do
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weight = Scoring.class_weight(attrs)
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same_tree = candidates
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|> Enum.find(%Candidate{}, &(&1.html_tree == tree))
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list? = tag == "ul"
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cond do
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weight + same_tree.score < 0
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-> true
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length(Regex.scan(~r/\,/, Floki.text(tree))) < 10 ->
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# If there are not very many commas, and the number of
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# non-paragraph elements is more than paragraphs or other
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# ominous signs, remove the element.
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p_len = tree |> Floki.find("p") |> length
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img_len = tree |> Floki.find("img") |> length
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li_len = tree |> Floki.find("li") |> length
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input_len = tree |> Floki.find("input") |> length
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embed_len = tree
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|> Floki.find("embed")
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|> Enum.reject(&(&1 =~ Readability.regexes(:video)))
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|> length
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link_density = Scoring.calc_link_density(tree)
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conent_len = Helper.text_length(tree)
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img_len > p_len # too many image
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|| (!list? && li_len > p_len) # more <li>s than <p>s
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|| input_len > (p_len / 3) # less than 3x <p>s than <input>s
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|| (!list? && conent_len < Readability.regexes(:min_text_length) && img_len != 1) # too short a content length without a single image
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|| (weight < 25 && link_density > 0.2) # too many links for its weight (#{weight})
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|| (weight >= 25 && link_density > 0.5) # too many links for its weight (#{weight})
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|| ((embed_len == 1 && conent_len < 75) || embed_len > 1) # <embed>s with too short a content length, or too many <embed>s
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true -> false
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end
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end
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end
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end
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defp clean_headline_tag?({tag, attrs, _} = html_tree) do
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tag =~ ~r/^h\d{1}$/
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&& (Scoring.class_weight(attrs) < 0 || Scoring.calc_link_density(html_tree) > 0.33)
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end
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defp clean_unlikely_tag?({tag, attrs, _}) do
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attrs_str = attrs |> Enum.map(&(elem(&1, 1))) |> Enum.join("")
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tag =~ ~r/form|object|iframe|embed/ && !(attrs_str =~ Readability.regexes(:video))
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end
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defp clean_empty_p?({tag, _, _} = html_tree) do
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tag == "p" && Helper.text_length(html_tree) == 0
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end
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end
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