RubyとParsletで算術演算のパーサを作った - Ill-documented Grimoire :: Blog
はじめに Ruby用のパーサジェネレータ、Parslet というものを見つけたので、 簡単な練習として算術演算のパーサを作ってみました。 加減乗除と剰余算・累乗（+-*/%^）、および括弧を使った数式の文字列を入力して、値を浮動小数点数で計算できます。 Parsletの基本的な使い方は Get Started が参考になりました。 方針 パーサで文字列をHashとArrayの組み合わせに分割 パース結果からASTを構築 ASTを評価 パーサ まず、Parslet::Parserクラスを継承して、パースを行うクラスを用意します。 ルールはBNFの様に記述することができます。 Parsletの仕組みとして、パースされた結果はHashとArrayの組み合わせとして出力されます。 class Parser < Parslet::Parser #ルールを指定する rule(:lparen) { st
Parsing JSON the hard way
This article was written by Aaron Patterson, a Ruby developer living in Seattle, WA. He’s been having fun writing Ruby for the past 7 years, and hopes to share his love of Ruby with you. Hey everybody! I hope you’re having a great day today! The sun has peeked out of the clouds for a bit today, so I’m doing great! In this article, we’re going to be looking at some compiler tools for use with Ruby.
Writing an S-Expression parser in Ruby
Note: because these articles usually contain inline code examples it is highly likely that they will not display properly in your feed reader. To see this article as it was originally written please visit: http://thingsaaronmade.com/blog/writing-an-s-expression-parser-in-ruby.html S-Expressions are a very versatile syntax for defining data structures and program code that are used by most Lisp-der
Issue 6.1: Parsing JSON the hard way - Practicing Ruby
Welcome to Practicing Ruby! We produce delightful lessons for Rubyists every two weeks. To support our efforts, become a paid subscriber today! This article was written by Aaron Patterson, a Ruby developer living in Seattle, WA. He's been having fun writing Ruby for the past 7 years, and hopes to share his love of Ruby with you. Hey everybody! I hope you're having a great day today! The sun has pe
zerowidth positive lookahead | Parsing TOML in Ruby with Parslet
This is part 1 of 4. Part 2 - Annotating a TOML Parse Tree Part 3 - Transforming a TOML Parse Tree Part 4 - Displaying Errors in a TOML Document toml-parslet on GitHub. Last night, in a fit of YAML-induced pique, Tom Preston-Werner created the spec for “Tom’s Obvious Minimal Language”, or TOML. It’s a simple text-based file format, similar to INI files, and this presents us with the opportunity to
Issue 6.1: Parsing JSON the hard way - Practicing Ruby
Welcome to Practicing Ruby! Support reader-focused and reader-funded indie publishing by becoming a paid subscriber today. This article was written by Aaron Patterson, a Ruby developer living in Seattle, WA. He's been having fun writing Ruby for the past 7 years, and hopes to share his love of Ruby with you. Hey everybody! I hope you're having a great day today! The sun has peeked out of the cloud
演算子優先順位構文解析器 - Tociyuki::Diary
「富豪的 CLOSURE 計算結果使い捨て型シフト還元解析おもちゃ」は、プログラミング言語用の構文解析器で使うのには向いていません。どちらかというと、左再帰があるテキスト処理やデータ処理の構文解析器に使えないものかと考えています。 ところで、プログラミング言語で上向き構文解析したい箇所と言えば、左再帰になっている二項演算子式の生成規則がまっさきに思い浮かびます。他は下向き構文解析向けの部分が大半です。それならば、下向き用の定番、再帰下降型解析器の中に上向き構文解析器を組み込めると何かと便利でしょう。そのような用途に、演算子優先順位構文解析器 (Operator-precedence parser) がうってつけです。yacc/bison のように優先順位と左結号か右結合かを指定するだけで望みのままに二項演算子を利用できる解析器を、再帰下降型構文解析器へシームレスに組み込むことができるように
The Start of a Long Journey: How Ruby Parses and Compiles Your Code - Pat Shaughnessy
The Start of a Long Journey: How Ruby Parses and Compiles Your Code This is an excerpt from the beginning of an eBook I’m writing this Summer called “Ruby Under a Microscope.” My goal is to teach you how Ruby works internally without assuming you know anything about the C programming language. If you’re interested in Ruby internals you can sign up here and I’ll send you an email when the eBook is
Ruby Library Report 【第 6 回】 正規表現と構文解析
『るびま』は、Ruby に関する技術記事はもちろんのこと、Rubyist へのインタビューやエッセイ、その他をお届けするウェブ雑誌です。 Rubyist Magazine について 『Rubyist Magazine』、略して『るびま』は、日本 Ruby の会の有志による Rubyist の Rubyist による、Rubyist とそうでない人のためのウェブ雑誌です。 最新号 Rubyist Magazine 0058 号 バックナンバー Rubyist Magazine 0058 号 RubyKaigi 2018 直前特集号 Rubyist Magazine 0057 号 RubyKaigi 2017 直前特集号 Rubyist Magazine 0056 号 Rubyist Magazine 0055 号 Rubyist Magazine 0054 号 東京 Ruby 会議 11 直
Writing Parsers in Ruby using Treetop
Ruby Weekly is a weekly newsletter covering the latest Ruby and Rails news. Treetop is one of the most underrated, yet powerful, Ruby libraries out there. If you want to write a parser, it kicks ass. The only problem is unless you're into reading up about and playing with parsers, it's not always obvious how to get going with them, or Treetop in particular. Luckily Aaron Gough, Toronto-based Ruby
Introducing Koi - A language that teaches the basics of language implementation
Note: because these articles usually contain inline code examples it is highly likely that they will not display properly in your feed reader. To see this article as it was originally written please visit: http://thingsaaronmade.com/blog/introducing-koi.html Several months ago I started on a quest to learn more about how programming languages work internally. Today I am releasing my first programm
http://treetop.rubyforge.org/
Treetop is a language for describing languages. Combining the elegance of Ruby with cutting-edge parsing expression grammars, it helps you analyze syntax with revolutionarily ease. sudo gem install treetop Intuitive Grammar Specifications Parsing expression grammars (PEGs) are simple to write and easy to maintain. They are a simple but powerful generalization of regular expressions that are easie
Dhaka
Introduction Dhaka is a set of tools for generating lexers and LALR(1) parsers for context-free grammars. It is written solely in Ruby with no native extensions and no dependencies. Its primary aim is to be easy to adapt and use for common parsing tasks. For example, if you need to parse and evaluate arithmetic or some other expression language with nested constructs in your Ruby application you m
字下げ依存構文の解析 - 再帰の反復blog
Python、Haskell、YAMLのように行頭の字下げが文法構造に影響を与えるような構文を、字下げ依存構文(indentation-sensitive syntax)と呼ぶことにする。 Peter J. Landin「The Next 700 Programming Languages」(pdf)では、字下げ依存構文のための規則をオフサイドルールと呼んでいる(6節(3))。 そこでは 句の最初のシンボルをちょうど含んだ右下象限が、句全体を含んでいなければならない。 と説明している。 つまり <first symbol>-------------------------------------> ---------------------------------------------------> --------------------------------------------
parslet - About
require 'parslet' include Parslet # Constructs a parser using a Parser Expression Grammar parser = str('"') >> ( str('\\').ignore >> any | str('"').absent? >> any ).repeat.as(:string) >> str('"') result = parser.parse %Q("this is a valid \\"string\\"") result # => {:string=>"this is a valid \"string\""@1} A small Ruby library for constructing parsers in the PEG (Parsing Expression Grammar) fashion
A quick intro to writing a parser with Treetop
Note: because these articles usually contain inline code examples it is highly likely that they will not display properly in your feed reader. To see this article as it was originally written please visit: http://thingsaaronmade.com/blog/a-quick-intro-to-writing-a-parser-using-treetop.html Treetop is a Ruby library that allows you to create parsers easily by describing them using a Parsing Express
rukansai-38-3-ujihisa, ruby kansai rubykansai on USTREAM. Conference
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再帰下降パーサーの練習 - komamitsu.log
