52 lines
1.5 KiB
Ruby
52 lines
1.5 KiB
Ruby
# frozen_string_literal: true
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require 'uri'
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# Generated HTML is transformed back to GFM by:
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# - app/assets/javascripts/behaviors/markdown/marks/math.js
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# - app/assets/javascripts/behaviors/markdown/nodes/code_block.js
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module Banzai
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module Filter
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# HTML filter that adds class="code math" and removes the dollar sign in $`2+2`$.
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#
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class MathFilter < HTML::Pipeline::Filter
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# Attribute indicating inline or display math.
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STYLE_ATTRIBUTE = 'data-math-style'.freeze
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# Class used for tagging elements that should be rendered
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TAG_CLASS = 'js-render-math'.freeze
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INLINE_CLASSES = "code math #{TAG_CLASS}".freeze
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DOLLAR_SIGN = '$'.freeze
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def call
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doc.css('code').each do |code|
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closing = code.next
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opening = code.previous
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# We need a sibling before and after.
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# They should end and start with $ respectively.
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if closing && opening &&
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closing.text? && opening.text? &&
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closing.content.first == DOLLAR_SIGN &&
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opening.content.last == DOLLAR_SIGN
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code[:class] = INLINE_CLASSES
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code[STYLE_ATTRIBUTE] = 'inline'
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closing.content = closing.content[1..-1]
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opening.content = opening.content[0..-2]
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end
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end
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doc.css('pre.code.math').each do |el|
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el[STYLE_ATTRIBUTE] = 'display'
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el[:class] += " #{TAG_CLASS}"
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end
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doc
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end
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end
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end
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end
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