ruby - マークダウンのインデントされたコードブロックを解析する

Question

Parslet で記述された文法を使用して Markdown を解析しようとしています。ただし、これまで試したことはすべて再帰でスタックしたため、インデントされたコードブロックを通過できません。それらは次のようになります。

    This is a indented code block.
    Second line.

    Code block continues after blank line.

    There can be any number of chunks, 
    separated by not more than one blank line.

\nこれを解決するために、行 ( を含む) を空白行 ( ) に置き換え、a空白行 ( \n\n) をスペースに置き換える最小限の例を書きましたa aaa aa。

# recurring_group_parser.rb

require 'parslet'
require 'rspec'
require 'parslet/rig/rspec'

class RecurringGroupParser < Parslet::Parser
  root(:block)

  rule :block do
    chunk.repeat(1,3)
  end

  rule :chunk do
    str('a').repeat(1,3) >> space
  end

  rule :space do
    str(' ') | chunk.absent?
  end
end

describe RecurringGroupParser do
  it 'should parse a' do
    is_expected.to parse "a"
  end

  it 'should parse aa' do
    is_expected.to parse "aa"
  end

  it 'should parse aaa' do
    is_expected.to parse "aaa"
  end

  it 'should parse a a' do
    is_expected.to parse "a a"
  end

  it 'should parse aa a' do
    is_expected.to parse "aa a"
  end

  it 'should parse aaa a' do
    is_expected.to parse "aaa a"
  end

  it 'should parse a aa' do
    is_expected.to parse "a aa"
  end

  it 'should parse a aaa' do
    is_expected.to parse "a aaa"
  end

  it 'should parse aa a' do
    is_expected.to parse "aa a"
  end

  it 'should parse aa aa' do
    is_expected.to parse "aa aa"
  end

  it 'should parse aa aaa' do
    is_expected.to parse "aa aaa"
  end

  it 'should parse aaa aa' do
    is_expected.to parse "aaa aa"
  end

  it 'should parse aaa aaa' do
    is_expected.to parse "aaa aaa"
  end

  it 'should parse a a a' do
    is_expected.to parse "a a a"
  end

  it 'should parse aa a a' do
    is_expected.to parse "aa a a"
  end

  it 'should parse aaa a a' do
    is_expected.to parse "aaa a a"
  end

  it 'should parse a aa a' do
    is_expected.to parse "a aa a"
  end

  it 'should parse aa aa a' do
    is_expected.to parse "aa aa a"
  end

  it 'should parse aaa aa a' do
    is_expected.to parse "aaa aa a"
  end

  it 'should parse a aaa a' do
    is_expected.to parse "a aaa a"
  end

  it 'should parse aa aaa a' do
    is_expected.to parse "aa aaa a"
  end

  it 'should parse aaa aaa a' do
    is_expected.to parse "aaa aaa a"
  end

  it 'should parse a a aa' do
    is_expected.to parse "a a aa"
  end

  it 'should parse aa a aa' do
    is_expected.to parse "aa a aa"
  end

  it 'should parse aaa a aa' do
    is_expected.to parse "aaa a aa"
  end

  it 'should parse a aa aa' do
    is_expected.to parse "a aa aa"
  end

  it 'should parse aa aa aa' do
    is_expected.to parse "aa aa aa"
  end

  it 'should parse aaa aa aa' do
    is_expected.to parse "aaa aa aa"
  end

  it 'should parse a aaa aa' do
    is_expected.to parse "a aaa aa"
  end

  it 'should parse aa aaa aa' do
    is_expected.to parse "aa aaa aa"
  end

  it 'should parse aaa aaa aa' do
    is_expected.to parse "aaa aaa aa"
  end

  it 'should parse a a aaa' do
    is_expected.to parse "a a aaa"
  end

  it 'should parse aa a aaa' do
    is_expected.to parse "aa a aaa"
  end

  it 'should parse aaa a aaa' do
    is_expected.to parse "aaa a aaa"
  end

  it 'should parse a aa aaa' do
    is_expected.to parse "a aa aaa"
  end

  it 'should parse aa aa aaa' do
    is_expected.to parse "aa aa aaa"
  end

  it 'should parse aaa aa aaa' do
    is_expected.to parse "aaa aa aaa"
  end

  it 'should parse a aaa aaa' do
    is_expected.to parse "a aaa aaa"
  end

  it 'should parse aa aaa aaa' do
    is_expected.to parse "aa aaa aaa"
  end

  it 'should parse aaa aaa aaa' do
    is_expected.to parse "aaa aaa aaa"
  end
end

ランニングは問題なくrspec recurring_group_parser.rb動作します。改行を元に戻すと、停止します:

# recurring_group_parser.rb

require 'parslet'
require 'rspec'
require 'parslet/rig/rspec'

class RecurringGroupParser < Parslet::Parser
  root(:block)

  rule :block do
    chunk.repeat(1,3)
  end

  rule :chunk do
    line.repeat(1,3) >> blank_line
  end

  rule :line do
    str('a') >> newline
  end

  rule :blank_line do
    newline.repeat(2) | chunk.absent?
  end

  rule :newline do
    str("\n") | any.absent?
  end
end

describe RecurringGroupParser do
  it 'should parse a' do
    is_expected.to parse "a"
  end

  it 'should parse aa' do
    is_expected.to parse "a\na"
  end

  it 'should parse aaa' do
    is_expected.to parse "a\na\na"
  end

  it 'should parse a a' do
    is_expected.to parse "a\n\na"
  end

  it 'should parse aa a' do
    is_expected.to parse "a\na\n\na"
  end

  it 'should parse aaa a' do
    is_expected.to parse "a\naa\n\na"
  end

  it 'should parse a aa' do
    is_expected.to parse "a\n\na\na"
  end

  it 'should parse a aaa' do
    is_expected.to parse "a\n\na\na\na"
  end

  it 'should parse aa a' do
    is_expected.to parse "a\na\n\na"
  end

  it 'should parse aa aa' do
    is_expected.to parse "a\na\n\na\na"
  end

  it 'should parse aa aaa' do
    is_expected.to parse "a\na\n\na\na\na"
  end

  it 'should parse aaa aa' do
    is_expected.to parse "a\naa\n\na\na"
  end

  it 'should parse aaa aaa' do
    is_expected.to parse "a\naa\n\na\na\na"
  end

  it 'should parse a a a' do
    is_expected.to parse "a\n\na\n\na"
  end

  it 'should parse aa a a' do
    is_expected.to parse "a\na\n\na\n\na"
  end

  it 'should parse aaa a a' do
    is_expected.to parse "a\naa\n\na\n\na"
  end

  it 'should parse a aa a' do
    is_expected.to parse "a\n\na\na\n\na"
  end

  it 'should parse aa aa a' do
    is_expected.to parse "a\na\n\na\na\n\na"
  end

  it 'should parse aaa aa a' do
    is_expected.to parse "a\naa\n\na\na\n\na"
  end

  it 'should parse a aaa a' do
    is_expected.to parse "a\n\na\naa\n\na"
  end

  it 'should parse aa aaa a' do
    is_expected.to parse "a\na\n\na\naa\n\na"
  end

  it 'should parse aaa aaa a' do
    is_expected.to parse "a\naa\n\na\naa\n\na"
  end

  it 'should parse a a aa' do
    is_expected.to parse "a\n\na\n\na\na"
  end

  it 'should parse aa a aa' do
    is_expected.to parse "a\na\n\na\n\na\na"
  end

  it 'should parse aaa a aa' do
    is_expected.to parse "a\naa\n\na\n\na\na"
  end

  it 'should parse a aa aa' do
    is_expected.to parse "a\n\na\na\n\na\na"
  end

  it 'should parse aa aa aa' do
    is_expected.to parse "a\na\n\na\na\n\na\na"
  end

  it 'should parse aaa aa aa' do
    is_expected.to parse "a\naa\n\na\na\n\na\na"
  end

  it 'should parse a aaa aa' do
    is_expected.to parse "a\n\na\naa\n\na\na"
  end

  it 'should parse aa aaa aa' do
    is_expected.to parse "a\na\n\na\naa\n\na\na"
  end

  it 'should parse aaa aaa aa' do
    is_expected.to parse "a\naa\n\na\naa\n\na\na"
  end

  it 'should parse a a aaa' do
    is_expected.to parse "a\n\na\n\na\na\na"
  end

  it 'should parse aa a aaa' do
    is_expected.to parse "a\na\n\na\n\na\na\na"
  end

  it 'should parse aaa a aaa' do
    is_expected.to parse "a\naa\n\na\n\na\na\na"
  end

  it 'should parse a aa aaa' do
    is_expected.to parse "a\n\na\na\n\na\na\na"
  end

  it 'should parse aa aa aaa' do
    is_expected.to parse "a\na\n\na\na\n\na\na\na"
  end

  it 'should parse aaa aa aaa' do
    is_expected.to parse "a\naa\n\na\na\n\na\na\na"
  end

  it 'should parse a aaa aaa' do
    is_expected.to parse "a\n\na\naa\n\na\na\na"
  end

  it 'should parse aa aaa aaa' do
    is_expected.to parse "a\na\n\na\naa\n\na\na\na"
  end

  it 'should parse aaa aaa aaa' do
    is_expected.to parse "a\naa\n\na\naa\n\na\na\na"
  end
end

これを単純化するために、行は 1 つのみで構成でき、aインデントされていませんが、後で簡単に変更でき、解析の失敗とは関係ありません。chunk.absent?inrule :blank_lineとany.absent?inの間に衝突があることも確信していますが、rule :newlineこれを修正して再帰を中断する基準を提供する方法がわかりません。どんな助けが欲しい！

score 3 · Accepted Answer

この場合、改行は eof にすることができます。その場合、改行。repeat(2) は繰り返し eof に一致します。「repeat(2,2)」が必要です。これらのバグを見つけやすくすることができます:) ...私のフォークを使用してください。

parslet の fork を使用して、どのようにループしているかを検出できます。ループをキャッチし、何が起こっているかを教えてくれます。通常のパースレットよりも遅いため、本番用の解析に切り替えてください。

この Gemfile を使用します。

source "https://rubygems.org"

gem "parslet" , :git => "https://github.com/NigelThorne/parslet.git"
gem 'rspec'

そして、次の結果が得られます。

 9:23:40.20 > bundle exec rspec parser.rb
FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

Failures:

  1) RecurringGroupParser should parse a
     Failure/Error: is_expected.to parse "a"
     RuntimeError:
       Grammar contains an infinite loop applying 'NEWLINE{2, }' at char position 1
       ...a<-- here
     # ./parser.rb:33:in `block (2 levels) in <top (required)>'

  2) RecurringGroupParser should parse aa
     Failure/Error: is_expected.to parse "a\na"
     RuntimeError:
       Grammar contains an infinite loop applying 'NEWLINE{2, }' at char position 3
       ...a
       a<-- here
     # ./parser.rb:37:in `block (2 levels) in <top (required)>'

  3) RecurringGroupParser should parse aaa
     Failure/Error: is_expected.to parse "a\na\na"
     RuntimeError:
       Grammar contains an infinite loop applying 'NEWLINE{2, }' at char position 5
       ...a
       a
       a<-- here
     # ./parser.rb:41:in `block (2 levels) in <top (required)>'

  4) RecurringGroupParser should parse a a
     Failure/Error: is_expected.to parse "a\n\na"
       expected BLOCK to be able to parse "a\n\na"
     # ./parser.rb:45:in `block (2 levels) in <top (required)>'

  5) RecurringGroupParser should parse aa a
     Failure/Error: is_expected.to parse "a\na\n\na"
       expected BLOCK to be able to parse "a\na\n\na"
     # ./parser.rb:49:in `block (2 levels) in <top (required)>'

  6) RecurringGroupParser should parse aaa a
     Failure/Error: is_expected.to parse "a\naa\n\na"
       expected BLOCK to be able to parse "a\naa\n\na"
     # ./parser.rb:53:in `block (2 levels) in <top (required)>'

  7) RecurringGroupParser should parse a aa
     Failure/Error: is_expected.to parse "a\n\na\na"
       expected BLOCK to be able to parse "a\n\na\na"
     # ./parser.rb:57:in `block (2 levels) in <top (required)>'

  8) RecurringGroupParser should parse a aaa
     Failure/Error: is_expected.to parse "a\n\na\na\na"
       expected BLOCK to be able to parse "a\n\na\na\na"
     # ./parser.rb:61:in `block (2 levels) in <top (required)>'

  9) RecurringGroupParser should parse aa a
     Failure/Error: is_expected.to parse "a\na\n\na"
       expected BLOCK to be able to parse "a\na\n\na"
     # ./parser.rb:65:in `block (2 levels) in <top (required)>'

  10) RecurringGroupParser should parse aa aa
     Failure/Error: is_expected.to parse "a\na\n\na\na"
       expected BLOCK to be able to parse "a\na\n\na\na"
     # ./parser.rb:69:in `block (2 levels) in <top (required)>'

  11) RecurringGroupParser should parse aa aaa
     Failure/Error: is_expected.to parse "a\na\n\na\na\na"
       expected BLOCK to be able to parse "a\na\n\na\na\na"
     # ./parser.rb:73:in `block (2 levels) in <top (required)>'

  12) RecurringGroupParser should parse aaa aa
     Failure/Error: is_expected.to parse "a\naa\n\na\na"
       expected BLOCK to be able to parse "a\naa\n\na\na"
     # ./parser.rb:77:in `block (2 levels) in <top (required)>'

  13) RecurringGroupParser should parse aaa aaa
     Failure/Error: is_expected.to parse "a\naa\n\na\na\na"
       expected BLOCK to be able to parse "a\naa\n\na\na\na"
     # ./parser.rb:81:in `block (2 levels) in <top (required)>'

  14) RecurringGroupParser should parse a a a
     Failure/Error: is_expected.to parse "a\n\na\n\na"
       expected BLOCK to be able to parse "a\n\na\n\na"
     # ./parser.rb:85:in `block (2 levels) in <top (required)>'

  15) RecurringGroupParser should parse aa a a
     Failure/Error: is_expected.to parse "a\na\n\na\n\na"
       expected BLOCK to be able to parse "a\na\n\na\n\na"
     # ./parser.rb:89:in `block (2 levels) in <top (required)>'

  16) RecurringGroupParser should parse aaa a a
     Failure/Error: is_expected.to parse "a\naa\n\na\n\na"
       expected BLOCK to be able to parse "a\naa\n\na\n\na"
     # ./parser.rb:93:in `block (2 levels) in <top (required)>'

  17) RecurringGroupParser should parse a aa a
     Failure/Error: is_expected.to parse "a\n\na\na\n\na"
       expected BLOCK to be able to parse "a\n\na\na\n\na"
     # ./parser.rb:97:in `block (2 levels) in <top (required)>'

  18) RecurringGroupParser should parse aa aa a
     Failure/Error: is_expected.to parse "a\na\n\na\na\n\na"
       expected BLOCK to be able to parse "a\na\n\na\na\n\na"
     # ./parser.rb:101:in `block (2 levels) in <top (required)>'

  19) RecurringGroupParser should parse aaa aa a
     Failure/Error: is_expected.to parse "a\naa\n\na\na\n\na"
       expected BLOCK to be able to parse "a\naa\n\na\na\n\na"
     # ./parser.rb:105:in `block (2 levels) in <top (required)>'

  20) RecurringGroupParser should parse a aaa a
     Failure/Error: is_expected.to parse "a\n\na\naa\n\na"
       expected BLOCK to be able to parse "a\n\na\naa\n\na"
     # ./parser.rb:109:in `block (2 levels) in <top (required)>'

  21) RecurringGroupParser should parse aa aaa a
     Failure/Error: is_expected.to parse "a\na\n\na\naa\n\na"
       expected BLOCK to be able to parse "a\na\n\na\naa\n\na"
     # ./parser.rb:113:in `block (2 levels) in <top (required)>'

  22) RecurringGroupParser should parse aaa aaa a
     Failure/Error: is_expected.to parse "a\naa\n\na\naa\n\na"
       expected BLOCK to be able to parse "a\naa\n\na\naa\n\na"
     # ./parser.rb:117:in `block (2 levels) in <top (required)>'

  23) RecurringGroupParser should parse a a aa
     Failure/Error: is_expected.to parse "a\n\na\n\na\na"
       expected BLOCK to be able to parse "a\n\na\n\na\na"
     # ./parser.rb:121:in `block (2 levels) in <top (required)>'

  24) RecurringGroupParser should parse aa a aa
     Failure/Error: is_expected.to parse "a\na\n\na\n\na\na"
       expected BLOCK to be able to parse "a\na\n\na\n\na\na"
     # ./parser.rb:125:in `block (2 levels) in <top (required)>'

  25) RecurringGroupParser should parse aaa a aa
     Failure/Error: is_expected.to parse "a\naa\n\na\n\na\na"
       expected BLOCK to be able to parse "a\naa\n\na\n\na\na"
     # ./parser.rb:129:in `block (2 levels) in <top (required)>'

  26) RecurringGroupParser should parse a aa aa
     Failure/Error: is_expected.to parse "a\n\na\na\n\na\na"
       expected BLOCK to be able to parse "a\n\na\na\n\na\na"
     # ./parser.rb:133:in `block (2 levels) in <top (required)>'

  27) RecurringGroupParser should parse aa aa aa
     Failure/Error: is_expected.to parse "a\na\n\na\na\n\na\na"
       expected BLOCK to be able to parse "a\na\n\na\na\n\na\na"
     # ./parser.rb:137:in `block (2 levels) in <top (required)>'

  28) RecurringGroupParser should parse aaa aa aa
     Failure/Error: is_expected.to parse "a\naa\n\na\na\n\na\na"
       expected BLOCK to be able to parse "a\naa\n\na\na\n\na\na"
     # ./parser.rb:141:in `block (2 levels) in <top (required)>'

  29) RecurringGroupParser should parse a aaa aa
     Failure/Error: is_expected.to parse "a\n\na\naa\n\na\na"
       expected BLOCK to be able to parse "a\n\na\naa\n\na\na"
     # ./parser.rb:145:in `block (2 levels) in <top (required)>'

  30) RecurringGroupParser should parse aa aaa aa
     Failure/Error: is_expected.to parse "a\na\n\na\naa\n\na\na"
       expected BLOCK to be able to parse "a\na\n\na\naa\n\na\na"
     # ./parser.rb:149:in `block (2 levels) in <top (required)>'

  31) RecurringGroupParser should parse aaa aaa aa
     Failure/Error: is_expected.to parse "a\naa\n\na\naa\n\na\na"
       expected BLOCK to be able to parse "a\naa\n\na\naa\n\na\na"
     # ./parser.rb:153:in `block (2 levels) in <top (required)>'

  32) RecurringGroupParser should parse a a aaa
     Failure/Error: is_expected.to parse "a\n\na\n\na\na\na"
       expected BLOCK to be able to parse "a\n\na\n\na\na\na"
     # ./parser.rb:157:in `block (2 levels) in <top (required)>'

  33) RecurringGroupParser should parse aa a aaa
     Failure/Error: is_expected.to parse "a\na\n\na\n\na\na\na"
       expected BLOCK to be able to parse "a\na\n\na\n\na\na\na"
     # ./parser.rb:161:in `block (2 levels) in <top (required)>'

  34) RecurringGroupParser should parse aaa a aaa
     Failure/Error: is_expected.to parse "a\naa\n\na\n\na\na\na"
       expected BLOCK to be able to parse "a\naa\n\na\n\na\na\na"
     # ./parser.rb:165:in `block (2 levels) in <top (required)>'

  35) RecurringGroupParser should parse a aa aaa
     Failure/Error: is_expected.to parse "a\n\na\na\n\na\na\na"
       expected BLOCK to be able to parse "a\n\na\na\n\na\na\na"
     # ./parser.rb:169:in `block (2 levels) in <top (required)>'

  36) RecurringGroupParser should parse aa aa aaa
     Failure/Error: is_expected.to parse "a\na\n\na\na\n\na\na\na"
       expected BLOCK to be able to parse "a\na\n\na\na\n\na\na\na"
     # ./parser.rb:173:in `block (2 levels) in <top (required)>'

  37) RecurringGroupParser should parse aaa aa aaa
     Failure/Error: is_expected.to parse "a\naa\n\na\na\n\na\na\na"
       expected BLOCK to be able to parse "a\naa\n\na\na\n\na\na\na"
     # ./parser.rb:177:in `block (2 levels) in <top (required)>'

  38) RecurringGroupParser should parse a aaa aaa
     Failure/Error: is_expected.to parse "a\n\na\naa\n\na\na\na"
       expected BLOCK to be able to parse "a\n\na\naa\n\na\na\na"
     # ./parser.rb:181:in `block (2 levels) in <top (required)>'

  39) RecurringGroupParser should parse aa aaa aaa
     Failure/Error: is_expected.to parse "a\na\n\na\naa\n\na\na\na"
       expected BLOCK to be able to parse "a\na\n\na\naa\n\na\na\na"
     # ./parser.rb:185:in `block (2 levels) in <top (required)>'

  40) RecurringGroupParser should parse aaa aaa aaa
     Failure/Error: is_expected.to parse "a\naa\n\na\naa\n\na\na\na"
       expected BLOCK to be able to parse "a\naa\n\na\naa\n\na\na\na"
     # ./parser.rb:189:in `block (2 levels) in <top (required)>'

Finished in 0.01702 seconds (files took 0.26725 seconds to load)
40 examples, 40 failures

Parslet を使用したインデントの解析に関するこの質問を参照してください。

ruby - マークダウンのインデントされたコード ブロックを解析する

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ruby - マークダウンのインデントされたコードブロックを解析する