Class: Nay::Lexer

Inherits:
Object
  • Object
show all
Defined in:
lib/nay/lexer.rb

Overview

Read in a string and generate Token instances.

Constant Summary collapse

EXPRESSION =

Stack States

:expression
EXPRESSION_LITERAL = 
:expression_literal
CLOSE_EXPRESSION =

Token Types

:close_expression
CONTENT = 
:content
END_EXPRESSION_LITERAL = 
:end_expression_literal
IDENTIFIER = 
:identifier
IGNORE = 
:ignore
OPEN_EXPRESSION = 
:open_expression
OPEN_EXPRESSION_LITERAL = 
:open_expression_literal

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(string) ⇒ Lexer

Returns a new instance of Lexer.



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# File 'lib/nay/lexer.rb', line 24

def initialize(string)
  @scanner = StringScanner.new(string)
  @state   = State.new
end

Instance Attribute Details

#scanner ⇒ Object (readonly)

Returns the value of attribute scanner.



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# File 'lib/nay/lexer.rb', line 22

def scanner
  @scanner
end

#state ⇒ Object (readonly)

Returns the value of attribute state.



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# File 'lib/nay/lexer.rb', line 22

def state
  @state
end

Instance Method Details

#next_token ⇒ Object 



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# File 'lib/nay/lexer.rb', line 37

def next_token
  return nil if scanner.eos?

  case state.current
  when State::DEFAULT
    default
  when EXPRESSION
    expression
  when EXPRESSION_LITERAL
    expression_literal
  end
end

#rest ⇒ Object 



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# File 'lib/nay/lexer.rb', line 29

def rest
  [].tap do |tokens|
    while (token = next_token)
      tokens << token
    end
  end
end