E_Mattsan https://blog.hatena.ne.jp/E_Mattsan/ エンジニアのソフトウェア的愛情 https://blog.emattsan.org/ めも Ruby PEG http://treetop.rubyforge.org/index.html https://github.com/nathansobo/treetop calc.tt grammar Arithmetic rule additive multitive r:( op:[+-] multitive )* { def to_i r.elements.reduce(multitive.to_i) do |s, e| s.send(e.op.text_value, e.multitive.to_i) end end } end rule multitive primary r:( op:[*/%]… 190 <iframe src="https://hatenablog-parts.com/embed?url=https%3A%2F%2Fblog.emattsan.org%2Fentry%2F20130815%2F1376576382" title="パーサ、なんどでも - エンジニアのソフトウェア的愛情" class="embed-card embed-blogcard" scrolling="no" frameborder="0" style="display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;"></iframe> Hatena Blog https://hatena.blog 2013-08-15 23:19:42 rich https://blog.emattsan.org/entry/20130815/1376576382 1.0 100%