Class: Astrapi::Lexer

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

Constant Summary collapse

IDENT =

.….….….….….….….….….….….…

/\AIDENT/
INT = 
/\AINT/
FLOAT = 
/\AFLOAT/
STRING = 
/\ASTRING/
MODULE =

.….….….….….….….….….….….…

/\Amodule$/
CLASS = 
/\Aclass$/
END_ = 
/\Aend$/
ATTR = 
/\Aattr$/
NEWLINE =

.….….….….….….….….….….….…

/[\n]/
SPACE = 
/[ \t]+/
LPAREN =

.….….….punctuation.….….….….….…

/\A\(/
RPAREN = 
/\A\)/
COMMENT = 
/\A\#(.*)/
ARROW =

.….….….operators.….….….….….…..

/\A\=\>/
LBRACK = 
/\A\[/
RBRACK = 
/\A\]/
LT = 
/\A</
IDENTIFIER =

.….….….literals.….….….….….….

/\A[a-zA-Z]+[a-zA-Z_0-9]*/i

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(str = '') ⇒ Lexer

Returns a new instance of Lexer.



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# File 'lib/lexer.rb', line 61

def initialize str=''
  init(str)
  @suppress_space=true
  @suppress_comment=false
end

Instance Attribute Details

#suppress_comment ⇒ Object

Returns the value of attribute suppress_comment.



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# File 'lib/lexer.rb', line 59

def suppress_comment
  @suppress_comment
end

Instance Method Details

#init(str) ⇒ Object 



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# File 'lib/lexer.rb', line 67

def init str
  @ss=StringScanner.new(str)
  @line=0
end

#next_token ⇒ Object

next token can detect spaces length



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# File 'lib/lexer.rb', line 82

def next_token

  if @ss.bol?
    @line+=1
    @old_pos=@ss.pos
  end

  position=[@line,@ss.pos-@old_pos+1]

  return :eos if @ss.eos?

  case
  when text = @ss.scan(NEWLINE)
    next_token()
  when text = @ss.scan(SPACE)
    next_token()
  when text = @ss.scan(COMMENT)
    next_token()
  when text = @ss.scan(ARROW)
    return Token.new [:arrow,text,position]
  when text = @ss.scan(LT)
    return Token.new [:lt,text,position]
  when text = @ss.scan(LBRACK)
    return Token.new [:lbrack,text,position]
  when text = @ss.scan(RBRACK)
    return Token.new [:rbrack,text,position]
  when text = @ss.scan(IDENTIFIER)
    case
    when value = text.match(IDENT)
      return Token.new [:IDENT,text,position]
    when value = text.match(FLOAT)
      return Token.new [:FLOAT,text,position]
    when value = text.match(INT)
      return Token.new [:INT,text,position]
    when value = text.match(STRING)
      return Token.new [:STRING,text,position]
    when value = text.match(MODULE)
      return Token.new [:module,text,position]
    when value = text.match(CLASS)
      return Token.new [:class,text,position]
    when value = text.match(END_)
      return Token.new [:end,text,position]
    when value = text.match(ATTR)
      return Token.new [:attr,text,position]
    when value = text.match(LPAREN)
      return Token.new [:lparen,text,position]
    when value = text.match(RPAREN)
      return Token.new [:rparen,text,position]
    else
      return Token.new [:identifier,text,position]
    end
  else
    x = @ss.getch
    return Token.new [x, x,position]
  end
end

#tokenize(str) ⇒ Object 



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# File 'lib/lexer.rb', line 72

def tokenize str
  @tokens=[]
  init(str)
  until @ss.eos?
    @tokens << next_token()
  end
  return @tokens[0..-2]
end