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69 lines
1.4 KiB
69 lines
1.4 KiB
////
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Included in:
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- user-manual: Extensions: Preprocessor example
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////
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Purpose::
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Skim off front matter from the top of the document that gets used by site generators like Jekyll and Awestruct.
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.sample-with-front-matter.adoc
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```
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---
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tags: [announcement, website]
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---
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= Document Title
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content
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[subs="attributes,specialcharacters"]
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.Captured front matter
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....
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---
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{front-matter}
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---
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....
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```
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.FrontMatterPreprocessor
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```ruby
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require 'asciidoctor'
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require 'asciidoctor/extensions'
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class FrontMatterPreprocessor < Asciidoctor::Extensions::Preprocessor
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def process document, reader
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lines = reader.lines # get raw lines
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return reader if lines.empty?
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front_matter = []
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if lines.first.chomp == '---'
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original_lines = lines.dup
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lines.shift
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while !lines.empty? && lines.first.chomp != '---'
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front_matter << lines.shift
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end
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if (first = lines.first).nil? || first.chomp != '---'
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lines = original_lines
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else
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lines.shift
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document.attributes['front-matter'] = front_matter.join.chomp
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# advance the reader by the number of lines taken
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(front_matter.length + 2).times { reader.advance }
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end
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end
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reader
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end
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end
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```
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.Usage
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```ruby
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Asciidoctor::Extensions.register do
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preprocessor FrontMatterPreprocessor
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end
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Asciidoctor.convert_file 'sample-with-front-matter.adoc', :safe => :safe
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```
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