Class: Lisp::Tokenizer

Inherits:
Object show all
Defined in:
lib/rubylisp/tokenizer.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(src, absorb_space = true) ⇒ Tokenizer

Returns a new instance of Tokenizer.



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# File 'lib/rubylisp/tokenizer.rb', line 15

def initialize(src, absorb_space=true)
  @absorb_whitespace = absorb_space
  @source = src
  @lookahead_token = nil
  @lookahead_literal = ''
  @eof = false
  @almost_eof = false
  @curent_ch = nil
  @next_ch = nil
  @next_next_ch = nil
  init
end

Instance Attribute Details

#line_number ⇒ Object (readonly)

Returns the value of attribute line_number.



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# File 'lib/rubylisp/tokenizer.rb', line 5

def line_number
  @line_number
end

Class Method Details

.from_file(f) ⇒ Object 



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# File 'lib/rubylisp/tokenizer.rb', line 11

def self.from_file(f)
  self.new(f)
end

.from_string(str, absorb_space = true) ⇒ Object 



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# File 'lib/rubylisp/tokenizer.rb', line 7

def self.from_string(str, absorb_space=true)
  self.new(StringIO.new(str, "r"), absorb_space)
end

Instance Method Details

#advance ⇒ Object 



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# File 'lib/rubylisp/tokenizer.rb', line 29

def advance
  if @source.eof?
    @eof = true
    @almost_eof = true
    @current_ch = nil
    @next_ch = nil
  else
    @current_ch = @source.readchar
    if @source.eof?
      @almost_eof = true
      @next_ch = nil
    else
      @next_ch = @source.readchar
      if @source.eof?
        @next_next_ch = nil
      else
        @next_next_ch = @source.readchar
        @source.ungetc(@next_next_ch)
      end
      @source.ungetc(@next_ch)
    end
  end
end

#almost_eof? ⇒ Boolean

Returns:



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# File 'lib/rubylisp/tokenizer.rb', line 61

def almost_eof?
  @almost_eof
end

#consume_token ⇒ Object 



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# File 'lib/rubylisp/tokenizer.rb', line 311

def consume_token
  @lookahead_token, @lookahead_literal = self.read_next_token
  consume_token if @lookahead_token == :COMMENT
end

#digit?(ch) ⇒ Boolean

Returns:



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# File 'lib/rubylisp/tokenizer.rb', line 73

def digit?(ch)
  ch =~ /[[:digit:]]/
end

#divider?(ch) ⇒ Boolean

Returns:



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# File 'lib/rubylisp/tokenizer.rb', line 192

def divider?(ch)
  ch =~ /[[[:space:]]\(\)\{\}<>\[\]]/
end

#eof? ⇒ Boolean

Returns:



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# File 'lib/rubylisp/tokenizer.rb', line 57

def eof?
  @eof
end

#graph?(ch) ⇒ Boolean

Returns:



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# File 'lib/rubylisp/tokenizer.rb', line 87

def graph?(ch)
  ch =~ /[[:graph:]]/
end

#hex?(ch) ⇒ Boolean

Returns:



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# File 'lib/rubylisp/tokenizer.rb', line 69

def hex?(ch)
  ch =~ /[abcdefABCDEF]/
end

#init ⇒ Object 



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# File 'lib/rubylisp/tokenizer.rb', line 316

def init
  @line_number = 0
  advance
  consume_token
end

#letter?(ch) ⇒ Boolean

Returns:



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# File 'lib/rubylisp/tokenizer.rb', line 65

def letter?(ch)
  ch =~ /[[:alpha:]]/
end

#next_token ⇒ Object 



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# File 'lib/rubylisp/tokenizer.rb', line 53

def next_token
  return @lookahead_token, @lookahead_literal
end

#number?(ch) ⇒ Boolean

Returns:



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# File 'lib/rubylisp/tokenizer.rb', line 77

def number?(ch)
  digit?(ch) || (ch == '-' && digit?(@next_ch))
end

#process_escapes(str) ⇒ Object 



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# File 'lib/rubylisp/tokenizer.rb', line 150

def process_escapes(str)
  i = 0
  processed_str = ""
  while i < str.length
    if str[i] == '\\'
      processed_str << if i < (str.length - 1)
                         i += 1
                         case (str[i])
                         when 'n'
                           "\n"
                         when 't'
                           "\t"
                         when '\\'
                           "\\"
                         else
                           "\\#{str[i]}"
                         end
                       else
                         "\\"
                       end
    else
      processed_str << str[i]
    end
    i += 1
  end
  processed_str
end

#read_character ⇒ Object 



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# File 'lib/rubylisp/tokenizer.rb', line 197

def read_character
  lit = ""
  lit << @current_ch
  advance
  while !eof? && !divider?(@current_ch)
    lit << @current_ch
    advance
  end

  return :CHARACTER, lit
end

#read_next_token ⇒ Object 



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# File 'lib/rubylisp/tokenizer.rb', line 210

def read_next_token
  return :EOF, '' if eof?

  if @absorb_whitespace
    while space?(@current_ch)
      @line_number += 1 if @current_ch == "\n"
      advance
      return :EOF, '' if eof?
    end
  end
  
  if !@absorb_whitespace && space?(@current_ch)
    @line_number += 1 if @current_ch == "\n"
    advance
    return :WHITESPACE, " "
  elsif number?(@current_ch)
    return read_number(false)
  elsif @current_ch == '-' && number?(@next_ch)
    return read_number(false)
  elsif @current_ch == '#' && @next_ch == 'x'
    advance
    advance
    return read_number(true)
  elsif @current_ch == '"'
    advance
    return read_string
  elsif @current_ch == '#' && @next_ch == '\\'
    advance
    advance
    return read_character
  elsif @current_ch == '\'' && @next_ch == '{'
    advance
    advance
    return :QUOTE_LBRACE, "'{"
  elsif @current_ch == '\'' && @next_ch == '#' && @next_next_ch == '('
    advance
    advance
    advance
    return :QUOTE_HASH_LPAREN, "'#("
  elsif @current_ch == '\''
    advance
    return :QUOTE, "'"
  elsif @current_ch == '`'
    advance
    return :BACKQUOTE, "`"
  elsif @current_ch == ',' && @next_ch == '@'
    advance
    advance
    return :COMMAAT, ",@"
  elsif @current_ch == ','
    advance
    return :COMMA, ","
  elsif @current_ch == '('
    advance
    return :LPAREN, "("
  elsif @current_ch == '#' && @next_ch == '('
    advance
    advance
    return :HASH_LPAREN, "#("
  elsif @current_ch == ')'
    advance
    return :RPAREN, ")"
  elsif @current_ch == '{'
    advance
    return :LBRACE, "{"
  elsif @current_ch == '}'
    advance
    return :RBRACE, "}"
  elsif @current_ch == '['
    advance
    return :LBRACKET, "["
  elsif @current_ch == ']'
    advance
    return :RBRACKET, "]"
  elsif @current_ch == '.' && space?(@next_ch)
    advance
    return :PERIOD, "."
  elsif @current_ch == '.' && symbol_character?(@next_ch)
    return read_symbol
    elsif symbol_character?(@current_ch)
      return read_symbol
    elsif @current_ch == '#' && @next_ch == 't'
    advance
    advance
    return :TRUE, "#t"
  elsif @current_ch == '#' && @next_ch == 'f'
    advance
    advance
    return :FALSE, "#f"
  elsif @current_ch == ';'
    lit = ""
    while true
      return :COMMENT, lit if eof? || @current_ch == "\n"
      lit << @current_ch
      advance
    end
  else
    return :ILLEGAL, @current_ch
  end
end

#read_number(hex) ⇒ Object 



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# File 'lib/rubylisp/tokenizer.rb', line 125

def read_number(hex)
  lit = ""
  if @current_ch == '-'
    lit << @current_ch
    advance
  end
  is_float = false
  while !eof? && (digit?(@current_ch) || (hex && hex?(@current_ch)) || (!hex && !is_float && @current_ch == '.'))
    is_float ||= !hex && (@current_ch == '.')
    lit << @current_ch
    advance
  end

  tok = if hex
          :HEXNUMBER
        elsif is_float
          :FLOAT
        else
          :NUMBER
        end

  return tok, lit
end

#read_string ⇒ Object 



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# File 'lib/rubylisp/tokenizer.rb', line 179

def read_string
  lit = ""
  while !eof? && @current_ch != '"'
    lit << @current_ch
    advance
  end

  return :EOF, '' if eof?
  advance
  return :STRING, process_escapes(lit)
end

#read_symbol ⇒ Object 



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# File 'lib/rubylisp/tokenizer.rb', line 96

def read_symbol
  lit = ""
  tok = nil
  if @current_ch == '.'
    lit << @current_ch
    advance
    tok = :FFI_SEND_SYMBOL
  end

  while !eof? && ((@current_ch == '.' && !symbol_character?(@next_ch) && tok.nil?) ||
                  (@current_ch == '/' && symbol_character?(@next_ch)) ||
                  (symbol_character?(@current_ch)))
    tok ||= :FFI_NEW_SYMBOL if @current_ch == '.' && !lit.empty?
    tok = :FFI_STATIC_SYMBOL if @current_ch == '/' && !lit.empty?
    lit << @current_ch
    advance
  end

  tok ||= :SYMBOL
  return tok, case tok
              when :SYMBOL, :FFI_STATIC_SYMBOL
                lit
              when :FFI_SEND_SYMBOL
                lit[1..-1]
              when :FFI_NEW_SYMBOL
                lit[0..-2]
              end
end

#space?(ch) ⇒ Boolean

Returns:



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# File 'lib/rubylisp/tokenizer.rb', line 82

def space?(ch)
  ch =~ /[[:space:]]/
end

#symbol_character?(ch) ⇒ Boolean

Returns:



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# File 'lib/rubylisp/tokenizer.rb', line 92

def symbol_character?(ch)
  graph?(ch) && !("();\"'`|[]{}#,.".include?(ch))
end