Parse strings

lib/chervil/ast.rb

   require "chervil/ast/application"
   require "chervil/ast/identifier"
   require "chervil/ast/number"
+  require "chervil/ast/string"
 end

lib/chervil/ast/string.rb

+module Chervil::AST
+  class String
+    attr_reader :value
+
+    def initialize(value)
+      @value = value
+    end
+
+    def ==(other)
+      @value == other.value
+    end
+  end
+end

lib/chervil/parser.rb

 module Chervil
-  class Parser
-    def initialize(lexer)
+  class Parser def initialize(lexer)
       @lexer = lexer
       @tree = Array.new
       @current_token = @lexer.get_next_token
     end
 
     def expr
-      if @current_token.type == :number
+      if [:string, :number].include?(@current_token.type)
         constant
       elsif @current_token.type == :identifier
         identifier
       when :number
         token = eat(:number)
         AST::Number.new(token.value.to_f)
+      when :string
+        token = eat(:string)
+        AST::String.new(token.value)
       end
     end
 

spec/parser_spec.rb

       expect(parse('1').first).to eq(AST::Number.new(1.0))
     end
 
+    it 'parses a string' do
+      expect(parse('"hello world"').first).to eq(AST::String.new('hello world'))
+    end
+
     it 'parses an identifier' do
       expect(parse('+').first).to eq(AST::Identifier.new('+'))
     end