Class: TPPlus::Scanner

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

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Scanner

Returns a new instance of Scanner.



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# File 'lib/tp_plus/scanner.rb', line 3

def initialize
end

Instance Method Details

#isDigit?(ch) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/tp_plus/scanner.rb', line 30

def isDigit?(ch)
  return false if ch == -1

  case ch
  when '0','1','2','3','4','5','6','7','8','9'
    return true
  else
    return false
  end
end

#isLetter?(ch) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/tp_plus/scanner.rb', line 41

def isLetter?(ch)
  return false if ch == -1

  case ch
  when 'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z',
       'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z',
       '_'
    return true
  else
    return false
  end
end

#next ⇒ Object 



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# File 'lib/tp_plus/scanner.rb', line 16

def next
  if @rdOffset < @src.length
    @offset = @rdOffset
    @ch = @src[@rdOffset]
    if @ch == "\n"
      @lineno += 1
    end
    @rdOffset += 1
  else
    @offset = @src.length
    @ch = -1
  end
end

#next_token ⇒ Object

return token



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# File 'lib/tp_plus/scanner.rb', line 131

def next_token
  self.skipWhitespace

  tok = nil
  lit = ""
  ch = @ch

  if isLetter?(ch)
    lit = self.scanIdentifier
    if @ch == '['
      tok = TPPlus::Token.lookup_data(lit)
    elsif lit == "DIV"
      tok = :DIV
    else
      # keywords are longer than 1 char, avoid lookup otherwise
      if lit.length > 1
        if @prevDot
          case lit
          when "gp1","gp2","gp3","gp4","gp5"
            tok = :GROUP
          else
            tok = TPPlus::Token.lookup(lit)
          end
        else
          tok = TPPlus::Token.lookup(lit)
        end
      else
        tok = :WORD
      end
    end
  elsif isDigit?(ch)
    tok, lit = self.scanNumber
  else
    self.next # always make progress
    case ch
    when -1
      return nil
    when '='
      if @ch == '='
        tok = :EEQUAL
        self.next
      else
        tok = :EQUAL
      end
    when ':'
      if @ch == "="
        tok = :ASSIGN
        self.next
      else
        tok = :COLON
      end
    when "<"
      if @ch == "="
        tok = :LTE
        self.next
      elsif @ch == ">"
        tok = :NOTEQUAL
        self.next
      else
        tok = :LT
      end
    when ">"
      if @ch == "="
        tok = :GTE
        self.next
      else
        tok = :GT
      end
    when "+"
      tok = :PLUS
    when "-"
      tok = :MINUS
    when "*"
      tok = :STAR
    when "/"
      tok = :SLASH
    when "&"
      if @ch == "&"
        tok = :AND
        self.next
      elsif isLetter?(@ch)
        tok = :ADDRESS
        lit = self.scanIdentifier
      else
        tok = :ILLEGAL
      end
    when "|"
      if @ch == "|"
        tok = :OR
        self.next
      else
        tok = :ILLEGAL
      end
    when "%"
      tok = :MOD
    when ";"
      tok = :SEMICOLON
    when "."
      if self.isDigit?(@ch)
        tok, lit = self.scanReal
      else
        tok = :DOT
      end
    when "!"
      if @ch == "="
        tok = :NOTEQUAL
        self.next
      else
        tok = :BANG
      end
    when "\"", "'"
      tok = :STRING
      lit = self.scanString(ch)
    when "#"
      tok = :COMMENT
      lit = self.scanComment
    when "@"
      tok = :LABEL
      lit = self.scanLabel
    when '('
      tok = :LPAREN
    when ')'
      tok = :RPAREN
    when ','
      tok = :COMMA
    when '['
      tok = :LBRACK
    when ']'
      tok = :RBRACK
    when '{'
      tok = :LBRACE
    when '}'
      tok = :RBRACE
    when "\n"
      tok = :NEWLINE
    else
      tok = :ILLEGAL
      lit = ch
    end
  end

  if tok == :DOT
    @prevDot = true
  else
    @prevDot = false
  end

  return [tok, lit]
end

#scan_setup(src) ⇒ Object 



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# File 'lib/tp_plus/scanner.rb', line 6

def scan_setup(src)
  @src = src
  @lineno = 1
  @ch = " "
  @offset = 0
  @rdOffset = 0
  @prevDot = false # for groups
  self.next
end

#scanComment ⇒ Object 



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# File 'lib/tp_plus/scanner.rb', line 100

def scanComment
  offs = @offset-1 # opening # already consumed
  while @ch != "\n" && @ch != -1
    self.next
  end

  return @src[offs,(@offset-offs)]
end

#scanIdentifier ⇒ Object 



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# File 'lib/tp_plus/scanner.rb', line 60

def scanIdentifier
  offs = @offset
  while isLetter?(@ch) || isDigit?(@ch)
    self.next
  end

  # allow one ? or ! at end
  if @ch == '?' || @ch == '!'
    self.next
  end

  return @src[offs,(@offset-offs)]
end

#scanLabel ⇒ Object 



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# File 'lib/tp_plus/scanner.rb', line 121

def scanLabel
  offs = @offset
  while self.isLetter?(@ch)
    self.next
  end

  return @src[offs, (@offset-offs)]
end

#scanNumber ⇒ Object 



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# File 'lib/tp_plus/scanner.rb', line 83

def scanNumber
  offs = @offset
  while self.isDigit?(@ch)
    self.next
  end
  if @ch == '.'
    self.next
    while self.isDigit?(@ch)
      self.next
    end

    return [:REAL, @src[offs,(@offset-offs)].to_f]
  else
    return [:DIGIT, @src[offs,(@offset-offs)].to_i]
  end
end

#scanReal ⇒ Object 



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# File 'lib/tp_plus/scanner.rb', line 74

def scanReal
  offs = @offset-1
  while self.isDigit?(@ch)
    self.next
  end

  return [:REAL, @src[offs,(@offset-offs)].to_f]
end

#scanString(type) ⇒ Object 



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# File 'lib/tp_plus/scanner.rb', line 109

def scanString(type)
  offs = @offset
  while @ch != type && @ch != -1
    self.next
  end

  # consume close
  self.next

  return @src[offs, (@offset-offs-1)] # -1 to remove trailing " or '
end

#skipWhitespace ⇒ Object 



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# File 'lib/tp_plus/scanner.rb', line 54

def skipWhitespace
  while @ch == ' ' || @ch == "\t" || @ch == "\r"
    self.next
  end
end