Scan parens

lib/chervil.rb

@@ -1,5 +1,3 @@
-require "chervil/version"
-
-module Chervil
-  # Your code goes here...
-end
+require 'chervil/lexer'
+require 'chervil/token'
+require 'chervil/version'

lib/chervil/lexer.rb

@@ -0,0 +1,35 @@
+module Chervil
+  class Lexer
+    def initialize(source)
+      @source = source
+      @position = 0
+    end
+
+    def current_char
+      @source[@position]
+    end
+
+    def advance
+      @position += 1
+    end
+
+    def get_next_token
+      case current_char
+      when '('
+        advance
+        Token.new(:lparen, "(")
+      when ')'
+        advance
+        Token.new(:rparen, ")")
+      end
+    end
+
+    def tokenize
+      tokens = Array.new
+      until @position == @source.size
+        tokens << get_next_token
+      end
+      tokens
+    end
+  end
+end

lib/chervil/token.rb

@@ -0,0 +1,15 @@
+module Chervil
+  class Token
+    attr_reader :type
+    attr_reader :value
+
+    def initialize(type, value)
+      @type = type
+      @value = value
+    end
+
+    def ==(other)
+      @type == other.type && @value == other.value
+    end
+  end
+end

package-lock.json

@@ -0,0 +1,23 @@
+{
+  "name": "chervil",
+  "version": "1.0.0",
+  "lockfileVersion": 1,
+  "requires": true,
+  "dependencies": {
+    "@prettier/plugin-ruby": {
+      "version": "0.6.2",
+      "resolved": "https://registry.npmjs.org/@prettier/plugin-ruby/-/plugin-ruby-0.6.2.tgz",
+      "integrity": "sha512-wTZ+Vrrxg6JwdrA23t+vUz+oaXcPeBCGmpCGKFeKQc7ls1+NOoZ7SLjYcf5ttxnNxFlIX2D4H74yhCEwX/HetQ==",
+      "dev": true,
+      "requires": {
+        "prettier": "^1.16.4"
+      }
+    },
+    "prettier": {
+      "version": "1.16.4",
+      "resolved": "https://registry.npmjs.org/prettier/-/prettier-1.16.4.tgz",
+      "integrity": "sha512-ZzWuos7TI5CKUeQAtFd6Zhm2s6EpAD/ZLApIhsF9pRvRtM1RFo61dM/4MSRUA0SuLugA/zgrZD8m0BaY46Og7g==",
+      "dev": true
+    }
+  }
+}

package.json

@@ -0,0 +1,9 @@
+{
+  "scripts": {
+    "format": "prettier --write **/*.rb"
+  },
+  "devDependencies": {
+    "@prettier/plugin-ruby": "^0.6.2",
+    "prettier": "^1.16.4"
+  }
+}

spec/lexer_spec.rb

@@ -0,0 +1,9 @@
+module Chervil
+  RSpec.describe Lexer do
+    it 'lexes parens' do
+      expect(Lexer.new('()').tokenize).to eq(
+        [Token.new(:lparen, '('), Token.new(:rparen, ')')]
+      )
+    end
+  end
+end

spec/spec_helper.rb

@@ -1,9 +1,10 @@
-require "bundler/setup"
-require "chervil"
+require 'bundler/setup'
+require 'chervil'
 
 RSpec.configure do |config|
   # Enable flags like --only-failures and --next-failure
-  config.example_status_persistence_file_path = ".rspec_status"
+  config.example_status_persistence_file_path =
+    '.rspec_status'
 
   # Disable RSpec exposing methods globally on `Module` and `main`
   config.disable_monkey_patching!