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Contents
module SXP; class Reader
##
# A basic S-expression parser.
class Basic < Reader
LPARENS = [?(]
RPARENS = [?)]
ATOM = /^[^\s()]+/
RATIONAL = /^([+-]?\d+)\/(\d+)$/
DECIMAL = /^[+-]?(\d*)?\.\d*$/
INTEGER = /^[+-]?\d+$/
##
# @return [Object]
def read_token
case peek_char
when ?(, ?) then [:list, read_char]
when ?" then [:atom, read_string] #"
else super
end
end
##
# @return [Object]
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)
else buffer.to_sym
end
end
##
# @return [String]
def read_string
buffer = String.new
skip_char # '"'
until peek_char == ?" #"
buffer <<
case char = read_char
when ?\\ then read_character
else char
end
end
skip_char # '"'
buffer
end
##
# @return [String]
def read_character
case char = read_char
when ?b then ?\b
when ?f then ?\f
when ?n then ?\n
when ?r then ?\r
when ?t then ?\t
when ?u then read_chars(4).to_i(16).chr
when ?U then read_chars(8).to_i(16).chr
when ?" then char #"
when ?\\ then char
else char
end
end
##
# @return [String]
def read_literal
grammar = self.class.const_get(:ATOM)
buffer = String.new
buffer << read_char while !eof? && peek_char.chr =~ grammar
buffer
end
end # Basic
end; end # SXP::Reader
Version data entries
10 entries across 10 versions & 1 rubygems