35 lines
904 B
Ruby
35 lines
904 B
Ruby
# frozen_string_literal: true
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module Banzai
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module Filter
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class FrontMatterFilter < HTML::Pipeline::Filter
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DELIM_LANG = {
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'---' => 'yaml',
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'+++' => 'toml',
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';;;' => 'json'
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}.freeze
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DELIM = Regexp.union(DELIM_LANG.keys)
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PATTERN = %r{
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\A(?:[^\r\n]*coding:[^\r\n]*)? # optional encoding line
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\s*
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^(?<delim>#{DELIM})[ \t]*(?<lang>\S*) # opening front matter marker (optional language specifier)
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\s*
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^(?<front_matter>.*?) # front matter (not greedy)
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\s*
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^\k<delim> # closing front matter marker
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\s*
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}mx
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def call
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html.sub(PATTERN) do |_match|
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lang = $~[:lang].presence || DELIM_LANG[$~[:delim]]
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["```#{lang}", $~[:front_matter], "```", "\n"].join("\n")
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end
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end
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end
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end
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end
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