Commit 17634d72 authored by Travis Miller's avatar Travis Miller Committed by Douwe Maan

Changed frontmatter filtering to support YAML, JSON, TOML, and arbitrary languages

parent abeeb24c
---
title: Changed frontmatter filtering to support YAML, JSON, TOML, and arbitrary languages
merge_request: 23331
author: Travis Miller
type: changed
# frozen_string_literal: true
module Banzai
module Filter
class FrontMatterFilter < HTML::Pipeline::Filter
DELIM_LANG = {
'---' => 'yaml',
'+++' => 'toml',
';;;' => 'json'
}.freeze
DELIM = Regexp.union(DELIM_LANG.keys)
PATTERN = %r{
\A(?:[^\r\n]*coding:[^\r\n]*)? # optional encoding line
\s*
^(?<delim>#{DELIM})[ \t]*(?<lang>\S*) # opening front matter marker (optional language specifier)
\s*
^(?<front_matter>.*?) # front matter (not greedy)
\s*
^\k<delim> # closing front matter marker
\s*
}mx
def call
html.sub(PATTERN) do |_match|
lang = $~[:lang].presence || DELIM_LANG[$~[:delim]]
["```#{lang}", $~[:front_matter], "```", "\n"].join("\n")
end
end
end
end
end
# frozen_string_literal: true
module Banzai
module Filter
class YamlFrontMatterFilter < HTML::Pipeline::Filter
DELIM = '---'.freeze
# Hat-tip to Middleman: https://git.io/v2e0z
PATTERN = %r{
\A(?:[^\r\n]*coding:[^\r\n]*\r?\n)?
(?<start>#{DELIM})[ ]*\r?\n
(?<frontmatter>.*?)[ ]*\r?\n?
^(?<stop>#{DELIM})[ ]*\r?\n?
\r?\n?
(?<content>.*)
}mx.freeze
def call
match = PATTERN.match(html)
return html unless match
"```yaml\n#{match['frontmatter']}\n```\n\n#{match['content']}"
end
end
end
end
......@@ -5,7 +5,7 @@ module Banzai
class PreProcessPipeline < BasePipeline
def self.filters
FilterArray[
Filter::YamlFrontMatterFilter,
Filter::FrontMatterFilter,
Filter::BlockquoteFenceFilter,
]
end
......
require 'rails_helper'
describe Banzai::Filter::FrontMatterFilter do
include FilterSpecHelper
it 'allows for `encoding:` before the front matter' do
content = <<~MD
# encoding: UTF-8
---
foo: foo
bar: bar
---
# Header
Content
MD
output = filter(content)
expect(output).not_to match 'encoding'
end
it 'converts YAML front matter to a fenced code block' do
content = <<~MD
---
foo: :foo_symbol
bar: :bar_symbol
---
# Header
Content
MD
output = filter(content)
aggregate_failures do
expect(output).not_to include '---'
expect(output).to include "```yaml\nfoo: :foo_symbol\n"
end
end
it 'converts TOML frontmatter to a fenced code block' do
content = <<~MD
+++
foo = :foo_symbol
bar = :bar_symbol
+++
# Header
Content
MD
output = filter(content)
aggregate_failures do
expect(output).not_to include '+++'
expect(output).to include "```toml\nfoo = :foo_symbol\n"
end
end
it 'converts JSON front matter to a fenced code block' do
content = <<~MD
;;;
{
"foo": ":foo_symbol",
"bar": ":bar_symbol"
}
;;;
# Header
Content
MD
output = filter(content)
aggregate_failures do
expect(output).not_to include ';;;'
expect(output).to include "```json\n{\n \"foo\": \":foo_symbol\",\n"
end
end
it 'converts arbitrary front matter to a fenced code block' do
content = <<~MD
---arbitrary
foo = :foo_symbol
bar = :bar_symbol
---
# Header
Content
MD
output = filter(content)
aggregate_failures do
expect(output).not_to include '---arbitrary'
expect(output).to include "```arbitrary\nfoo = :foo_symbol\n"
end
end
context 'on content without front matter' do
it 'returns the content unmodified' do
content = <<~MD
# This is some Markdown
It has no YAML front matter to parse.
MD
expect(filter(content)).to eq content
end
end
context 'on front matter without content' do
it 'converts YAML front matter to a fenced code block' do
content = <<~MD
---
foo: :foo_symbol
bar: :bar_symbol
---
MD
output = filter(content)
aggregate_failures do
expect(output).to eq <<~MD
```yaml
foo: :foo_symbol
bar: :bar_symbol
```
MD
end
end
end
end
require 'rails_helper'
describe Banzai::Filter::YamlFrontMatterFilter do
include FilterSpecHelper
it 'allows for `encoding:` before the frontmatter' do
content = <<-MD.strip_heredoc
# encoding: UTF-8
---
foo: foo
---
# Header
Content
MD
output = filter(content)
expect(output).not_to match 'encoding'
end
it 'converts YAML frontmatter to a fenced code block' do
content = <<-MD.strip_heredoc
---
bar: :bar_symbol
---
# Header
Content
MD
output = filter(content)
aggregate_failures do
expect(output).not_to include '---'
expect(output).to include "```yaml\nbar: :bar_symbol\n```"
end
end
context 'on content without frontmatter' do
it 'returns the content unmodified' do
content = <<-MD.strip_heredoc
# This is some Markdown
It has no YAML frontmatter to parse.
MD
expect(filter(content)).to eq content
end
end
end
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