Class: SXP::Reader::CommonLisp

Inherits:
Basic show all
Defined in:
lib/sxp/reader/common_lisp.rb

Overview

A Common Lisp S-expressions parser.

See Also:

  • https:/wwwhttps:/www.cshttps:/www.cs.cmuhttps:/www.cs.cmu.edu/Groups/AI/html/cltl/clm/node14https:/www.cs.cmu.edu/Groups/AI/html/cltl/clm/node14.html

Constant Summary collapse

OPTIONS = 
{nil: false, t: true, quote: :quote, function: :function}
DECIMAL = 
/^[+-]?(\d*)?\.\d*$/
INTEGER_BASE_2 = 
/^[+-]?[01]+$/
INTEGER_BASE_8 = 
/^[+-]?[0-7]+$/
INTEGER_BASE_10 = 
/^[+-]?\d+$/
INTEGER_BASE_16 = 
/^[+-]?[\da-z]+$/i
RATIONAL = 
/^([+-]?\d+)\/(\d+)$/
CHARACTERS =

Escape characters, used in the form ‘#Backspace`. Case is treated insensitively

See Also:

  • SXP::Reader::CommonLisp.https:/wwwhttps:/www.cshttps:/www.cs.cmuhttps:/www.cs.cmu.edu/Groups/AI/html/cltl/clm/node22https:/www.cs.cmu.edu/Groups/AI/html/cltl/clm/node22.html
{
  'newline'   => "\n",
  'space'     => " ",
  'backspace' => "\b",   # \010 BS
  'tab'       => "\t",   # \011 HT
  'linefeed'  => "\n",   # \012 LF
  'page'      => "\f",   # \014 FF
  'return'    => "\r",   # \015 CR
  'rubout'    => "\x7F", # \177 DEL
}

Constants inherited from Basic

Basic::ATOM, Basic::INTEGER, Basic::LPARENS, Basic::RPARENS

Instance Attribute Summary

Attributes inherited from SXP::Reader

#input, #options

Instance Method Summary collapse

Methods inherited from Basic

#read_literal, #read_string

Methods inherited from SXP::Reader

#each, read, #read, read_all, #read_all, read_file, #read_files, #read_integer, #read_list, #read_literal, #read_string, read_url

Constructor Details

#initialize(input, **options, &block) ⇒ CommonLisp

Initializes the reader.

Parameters:

Options Hash (**options):

  • :nil (Object) — default: false
  • :t (Object) — default: true
  • :quote (Object) — default: :quote
  • :function (Object) — default: :function 


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# File 'lib/sxp/reader/common_lisp.rb', line 42

def initialize(input, **options, &block)
  super(input, **OPTIONS.merge(options), &block)
end

Instance Method Details

#read_atom ⇒ Object

Based on Basic#read_atom, but adds ‘t’ and ‘nil’ atoms.

Returns:



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# File 'lib/sxp/reader/common_lisp.rb', line 75

def read_atom
  case buffer = read_literal
    when '.'      then buffer.to_sym
    when RATIONAL then Rational($1.to_i, $2.to_i)
    when DECIMAL  then Float(buffer) # FIXME?
    when INTEGER  then Integer(buffer)
    when /^t$/i   then true
    when /^nil$/i then nil
    else buffer.to_sym
  end
end

#read_character ⇒ String

Read characters sequences like ‘#backspace`. Otherwise, reads a single character. Requires the ability to put eroneously read characters back in the input stream

Returns:

See Also:

  • SXP::Reader::CommonLisp.https:/wwwhttps:/www.cshttps:/www.cs.cmuhttps:/www.cs.cmu.edu/Groups/AI/html/cltl/clm/node22https:/www.cs.cmu.edu/Groups/AI/html/cltl/clm/node22.html


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# File 'lib/sxp/reader/common_lisp.rb', line 136

def read_character
  lit = read_literal

  return " " if lit.empty? && peek_char == " "
  CHARACTERS.fetch(lit.downcase) do |string|
    # Return just the first character
    unread(string[1..-1])
    string[0,1]
  end
end

#read_function ⇒ Array

Reads ‘#’mapcar` forms.

Returns:



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# File 'lib/sxp/reader/common_lisp.rb', line 125

def read_function
  [options[:function] || :function, read]
end

#read_quote ⇒ Array

Reads ‘’foobar` forms.

Returns:



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# File 'lib/sxp/reader/common_lisp.rb', line 116

def read_quote
  skip_char # "'"
  [options[:quote] || :quote, read.tap {|s| s.quote_style = :squote if s.is_a?(String)}]
end

#read_sharp ⇒ Object

Returns:



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# File 'lib/sxp/reader/common_lisp.rb', line 59

def read_sharp
  skip_char # '#'
  case char = read_char
    when ?b, ?B  then read_integer(2)
    when ?o, ?O  then read_integer(8)
    when ?x, ?X  then read_integer(16)
    when ?\\     then read_character
    when ?(      then read_vector
    when ?'      then read_function
    else raise Error, "invalid sharp-sign read syntax: ##{char.chr}"
  end
end

#read_symbol(delimiter = nil) ⇒ Symbol

Returns:



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# File 'lib/sxp/reader/common_lisp.rb', line 89

def read_symbol(delimiter = nil)
  buffer = ""
  skip_char # '|'
  until delimiter === peek_char
    buffer <<
      case char = read_char
        when ?\\ then read_char
        else char
      end
  end
  skip_char # '|'
  buffer.to_sym
end

#read_token ⇒ Object

Returns:



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# File 'lib/sxp/reader/common_lisp.rb', line 48

def read_token
  case peek_char
    when ?#  then [:atom, read_sharp]
    when ?|  then [:atom, read_symbol(?|)]
    when ?'  then [:atom, read_quote]
    else super
  end
end

#read_vector ⇒ Array

Reads ‘#(1 2 3)` forms.

Returns:



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# File 'lib/sxp/reader/common_lisp.rb', line 107

def read_vector
  list = read_list(')')
  Vector.[](*list)
end

#skip_comments ⇒ void

This method returns an undefined value.



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# File 'lib/sxp/reader/common_lisp.rb', line 149

def skip_comments
  until eof?
    case (char = peek_char).chr
      when /\s+/ then skip_char
      when /;/   then skip_line
      else break
    end
  end
end