* lib/date/delta.rb: merged from date4. [experimental]

* lib/date/delta/parser.*: ditto.

	* lib/date.rb: followed the above changes.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@24567 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,11 @@
+Mon Aug 17 08:31:56 2009  Tadayoshi Funaba  <tadf@dotrb.org>
+
+	* lib/date/delta.rb: merged from date4.  [experimental]
+
+	* lib/date/delta/parser.*: ditto.
+
+	* lib/date.rb: followed the above changes.
+
 Mon Aug 17 08:19:03 2009  Tadayoshi Funaba  <tadf@dotrb.org>
 
 	* lib/date/format.rb (strptime): removed \v; since \s includes \v.

lib/date.rb

@@ -194,6 +194,7 @@
 #     puts secs_to_new_year()
 
 require 'date/format'
+require 'date/delta'
 
 # Class representing a date.
 #
@@ -1336,6 +1337,9 @@ class Date
   def + (n)
     case n
     when Numeric; return self.class.new!(@ajd + n, @of, @sg)
+    when Delta
+      d = n.__send__(:delta)
+      return (self >> d.imag) + d.real
     end
     raise TypeError, 'expected numeric'
   end
@@ -1352,8 +1356,11 @@ class Date
     case x
     when Numeric; return self.class.new!(@ajd - x, @of, @sg)
     when Date;    return @ajd - x.ajd
+    when Delta
+      d = x.__send__(:delta)
+      return (self << d.imag) - d.real
     end
-    raise TypeError, 'expected numeric or date'
+    raise TypeError, 'expected numeric'
   end
 
   # Compare this date with another date.
@@ -1371,6 +1378,12 @@ class Date
     case other
     when Numeric; return @ajd <=> other
     when Date;    return @ajd <=> other.ajd
+    else
+      begin
+        l, r = other.coerce(self)
+        return l <=> r
+      rescue NoMethodError
+      end
     end
     nil
   end
@@ -1385,6 +1398,9 @@ class Date
     case other
     when Numeric; return jd == other
     when Date;    return jd == other.jd
+    else
+      l, r = other.coerce(self)
+      return l === r
     end
     false
   end

lib/date/delta.rb

@@ -0,0 +1,400 @@
+# delta.rb: Written by Tadayoshi Funaba 2004-2009
+
+require 'date'
+require 'date/delta/parser'
+
+class Date
+
+  class Delta
+
+    include Comparable
+
+    UNIT_PREFIXES = {
+      'yotta'      => Rational(10**24),
+      'zetta'      => Rational(10**21),
+      'exa'        => Rational(10**18),
+      'peta'       => Rational(10**15),
+      'tera'       => Rational(10**12),
+      'giga'       => Rational(10**9),
+      'mega'       => Rational(10**6),
+      'kilo'       => Rational(10**3),
+      'hecto'      => Rational(10**2),
+      'deca'       => Rational(10**1),
+      'deka'       => Rational(10**1),
+      'deci'       => Rational(1, 10**1),
+      'centi'      => Rational(1, 10**2),
+      'milli'      => Rational(1, 10**3),
+      'decimilli'  => Rational(1, 10**4),
+      'centimilli' => Rational(1, 10**5),
+      'micro'      => Rational(1, 10**6),
+      'nano'       => Rational(1, 10**9),
+      'millimicro' => Rational(1, 10**9),
+      'pico'       => Rational(1, 10**12),
+      'micromicro' => Rational(1, 10**12),
+      'femto'      => Rational(1, 10**15),
+      'atto'       => Rational(1, 10**18),
+      'zepto'      => Rational(1, 10**21),
+      'yocto'      => Rational(1, 10**24)
+    }
+
+    IUNITS = {
+      'year'       => Complex(0, 12),
+      'month'      => Complex(0, 1)
+    }
+
+    RUNITS = {
+      'day'        => Rational(1),
+      'week'       => Rational(7),
+      'sennight'   => Rational(7),
+      'fortnight'  => Rational(14),
+      'hour'       => Rational(1, 24),
+      'minute'     => Rational(1, 1440),
+      'second'     => Rational(1, 86400)
+    }
+
+    UNIT_PREFIXES.each do |k, v|
+      RUNITS[k + 'second'] = v * RUNITS['second']
+    end
+
+    remove_const :UNIT_PREFIXES
+
+    UNITS = {}
+
+    IUNITS.each do |k, v|
+      UNITS[k] = v
+    end
+
+    RUNITS.each do |k, v|
+      UNITS[k] = v
+    end
+
+    UNITS4KEY = {}
+
+    UNITS.each do |k, v|
+      UNITS4KEY[k] = UNITS4KEY[k + 's'] = v
+    end
+
+    UNITS4KEY['y'] = UNITS4KEY['years']
+    UNITS4KEY['yr'] = UNITS4KEY['years']
+    UNITS4KEY['yrs'] = UNITS4KEY['years']
+    UNITS4KEY['m'] = UNITS4KEY['months']
+    UNITS4KEY['mo'] = UNITS4KEY['months']
+    UNITS4KEY['mon'] = UNITS4KEY['months']
+    UNITS4KEY['mnth'] = UNITS4KEY['months']
+    UNITS4KEY['mnths'] = UNITS4KEY['months']
+    UNITS4KEY['w'] = UNITS4KEY['weeks']
+    UNITS4KEY['wk'] = UNITS4KEY['weeks']
+    UNITS4KEY['d'] = UNITS4KEY['days']
+    UNITS4KEY['dy'] = UNITS4KEY['days']
+    UNITS4KEY['dys'] = UNITS4KEY['days']
+    UNITS4KEY['h'] = UNITS4KEY['hours']
+    UNITS4KEY['hr'] = UNITS4KEY['hours']
+    UNITS4KEY['hrs'] = UNITS4KEY['hours']
+    UNITS4KEY['min'] = UNITS4KEY['minutes']
+    UNITS4KEY['mins'] = UNITS4KEY['minutes']
+    UNITS4KEY['s'] = UNITS4KEY['seconds']
+    UNITS4KEY['sec'] = UNITS4KEY['seconds']
+    UNITS4KEY['secs'] = UNITS4KEY['seconds']
+    UNITS4KEY['ms'] = UNITS4KEY['milliseconds']
+    UNITS4KEY['msec'] = UNITS4KEY['milliseconds']
+    UNITS4KEY['msecs'] = UNITS4KEY['milliseconds']
+    UNITS4KEY['milli'] = UNITS4KEY['milliseconds']
+    UNITS4KEY['us'] = UNITS4KEY['microseconds']
+    UNITS4KEY['usec'] = UNITS4KEY['microseconds']
+    UNITS4KEY['usecs'] = UNITS4KEY['microseconds']
+    UNITS4KEY['micro'] = UNITS4KEY['microseconds']
+    UNITS4KEY['ns'] = UNITS4KEY['nanoseconds']
+    UNITS4KEY['nsec'] = UNITS4KEY['nanoseconds']
+    UNITS4KEY['nsecs'] = UNITS4KEY['nanoseconds']
+    UNITS4KEY['nano'] = UNITS4KEY['nanoseconds']
+
+    def self.delta_to_dhms(delta)
+      fr = delta.imag.abs
+      y,   fr = fr.divmod(12)
+      m,   fr = fr.divmod(1)
+
+      if delta.imag < 0
+	y = -y
+	m = -m
+      end
+
+      fr = delta.real.abs
+      ss,  fr = fr.divmod(SECONDS_IN_DAY) # 4p
+      d,   ss = ss.divmod(86400)
+      h,   ss = ss.divmod(3600)
+      min, s  = ss.divmod(60)
+
+      if delta.real < 0
+	d = -d
+	h = -h
+	min = -min
+	s = -s
+      end
+
+      return y, m, d, h, min, s, fr
+    end
+
+    def self.dhms_to_delta(y, m, d, h, min, s, fr)
+      fr = 0 if fr == 0
+      Complex(0, y.to_i * 12 + m.to_i) +
+	Rational(d * 86400 + h * 3600 + min * 60 + (s + fr), 86400) # 4p
+    end
+
+    def initialize(delta)
+      @delta = delta
+      @__ca__ = {}
+    end
+
+    class << self; alias_method :new!, :new end
+
+    def self.new(arg=0, h=0, min=0, s=0)
+      if Hash === arg
+	d = Complex(0)
+	arg.each do |k, v|
+	  k = k.to_s.downcase
+	  unless UNITS4KEY[k]
+	    raise ArgumentError, "unknown keyword #{k}"
+	  end
+	  d += v * UNITS4KEY[k]
+	end
+      else
+	d = dhms_to_delta(0, 0, arg, h, min, s, 0)
+      end
+      new!(d)
+    end
+
+    UNITS.each_key do |k|
+      module_eval <<-"end;"
+	def self.#{k}s(n=1)
+	  new(:d=>n * UNITS['#{k}'])
+	end
+      end;
+    end
+
+    class << self; alias_method :mins, :minutes end
+    class << self; alias_method :secs, :seconds end
+
+    def self.parse(str)
+      d = begin (@@pa ||= Parser.new).parse(str)
+	  rescue Racc::ParseError
+	    raise ArgumentError, 'syntax error'
+	  end
+      new!(d)
+    end
+
+    def self.diff(d1, d2) new(d1.ajd - d2.ajd) end
+
+    class << self
+
+      def once(*ids) # :nodoc: -- restricted
+	for id in ids
+	  module_eval <<-"end;"
+	    alias_method :__#{id.object_id}__, :#{id.to_s}
+	    private :__#{id.object_id}__
+	    def #{id.to_s}(*args)
+	      @__ca__[#{id.object_id}] ||= __#{id.object_id}__(*args)
+	    end
+	  end;
+        end
+      end
+
+      private :once
+
+    end
+
+    def dhms() self.class.delta_to_dhms(@delta) end
+
+    once :dhms
+
+    def delta() @delta end
+
+    protected :delta
+
+    def years() dhms[0] end
+    def months() dhms[1] end
+    def days() dhms[2] end
+    def hours() dhms[3] end
+    def minutes() dhms[4] end
+    def seconds() dhms[5] end
+    def second_fractions() dhms[6] end
+
+    alias_method :mins, :minutes
+    alias_method :secs, :seconds
+    alias_method :sec_fractions, :second_fractions
+
+    RUNITS.each_key do |k|
+      module_eval <<-"end;"
+	def in_#{k}s(u=1)
+	  if @delta.imag != 0
+	    raise ArgumentError, "#{k}: #{self} has month"
+	  end
+	  @delta.real / (u * RUNITS['#{k}'])
+	end
+      end;
+    end
+
+    alias_method :in_mins, :in_minutes
+    alias_method :in_secs, :in_seconds
+
+    def zero?() @delta.zero? end
+    def nonzero?() unless zero? then self end end
+
+    def integer? () @delta.imag == 0 && @delta.real.integer? end
+
+    def -@ () self.class.new!(-@delta) end
+    def +@ () self.class.new!(+@delta) end
+
+    def dx_addsub(m, n)
+      case n
+      when Numeric; return self.class.new!(@delta.__send__(m, n))
+      when Delta; return self.class.new!(@delta.__send__(m, n.delta))
+      else
+	l, r = n.coerce(self)
+	return l.__send__(m, r)
+      end
+    end
+
+    private :dx_addsub
+
+    def + (n) dx_addsub(:+, n) end
+    def - (n) dx_addsub(:-, n) end
+
+    def dx_muldiv(m, n)
+      case n
+      when Numeric
+	return self.class.new!(@delta.__send__(m, n))
+      else
+	l, r = n.coerce(self)
+	return l.__send__(m, r)
+      end
+    end
+
+    private :dx_muldiv
+
+    def * (n) dx_muldiv(:*, n) end
+    def / (n) dx_muldiv(:/, n) end
+
+    def dx_conv1(m, n)
+      if @delta.imag != 0
+	raise ArgumentError, "#{m}: #{self} has month"
+      end
+      case n
+      when Numeric
+	return self.class.new!(Complex(@delta.real.__send__(m, n), 0))
+      else
+	l, r = n.coerce(self)
+	return l.__send__(m, r)
+      end
+    end
+
+    private :dx_conv1
+
+    def % (n) dx_conv1(:%, n) end
+
+    def div(n) dx_conv1(:div, n) end
+    def modulo(n) dx_conv1(:modulo, n) end
+    def divmod(n) [div(n), modulo(n)] end
+
+    def quotient(n)
+      if @delta.imag != 0
+	raise ArgumentError, "quotient: #{self} has month"
+      end
+      case n
+      when Numeric
+	return self.class.new!(Complex((@delta.real / n).truncate))
+      else
+	l, r = n.coerce(self)
+	return l.__send__(m, r)
+      end
+    end
+
+    def remainder(n) dx_conv1(:remainder, n) end
+    def quotrem(n) [quotient(n), remainder(n)] end
+
+    def ** (n) dx_conv1(:**, n) end
+    def quo(n) dx_muldiv(:quo, n) end
+
+    def <=> (other)
+      if @delta.imag != 0
+	raise ArgumentError, "<=>: #{self} has month"
+      end
+      case other
+      when Numeric; return @delta.real <=> other
+      when Delta;   return @delta.real <=> other.delta.real
+      else
+	begin
+	  l, r = other.coerce(self)
+	  return l <=> r
+	rescue NoMethodError
+	end
+      end
+      nil
+    end
+
+    def == (other)
+      case other
+      when Numeric; return @delta == other
+      when Delta;   return @delta == other
+      else
+	begin
+	  l, r = other.coerce(self)
+	  return l == r
+	rescue NoMethodError
+	end
+      end
+      nil
+    end
+
+    def coerce(other)
+      case other
+      when Numeric; return other, @delta
+      else
+	super
+      end
+    end
+
+    def eql? (other) Delta === other && self == other end
+    def hash() @delta.hash end
+
+    def dx_conv0(m)
+      if @delta.imag != 0
+	raise ArgumentError, "#{m}: #{self} has month"
+      end
+      @delta.real.__send__(m)
+    end
+
+    private :dx_conv0
+
+    def abs() dx_conv0(:abs) end
+
+    def ceil() dx_conv0(:ceil) end
+    def floor() dx_conv0(:floor) end
+    def round() dx_conv0(:round) end
+    def truncate() dx_conv0(:truncate) end
+
+    def to_i() dx_conv0(:to_i) end
+    def to_f() dx_conv0(:to_f) end
+    def to_r() dx_conv0(:to_r) end
+
+    alias_method :to_int, :to_i
+
+    def inspect() format('#<%s: %s (%s)>', self.class, to_s, @delta) end
+
+    def to_s
+      format(%(%s(%dd %.02d:%02d'%02d"%03d)%s(%dy %dm)), # '
+	     if @delta.real < 0 then '-' else '+' end,
+	     days.abs, hours.abs, mins.abs, secs.abs, sec_fractions.abs * 1000,
+	     if @delta.imag < 0 then '-' else '+' end,
+	     years.abs, months.abs)
+    end
+
+    def marshal_dump() @delta end
+
+    def marshal_load(a)
+      @delta = a
+      @__ca__ = {}
+    end
+
+  end
+
+end

lib/date/delta/parser.rb

@@ -0,0 +1,301 @@
+#
+# DO NOT MODIFY!!!!
+# This file is automatically generated by racc 1.4.5
+# from racc grammer file "parser.ry".
+#
+
+require 'racc/parser'
+
+
+class Date
+
+  class Delta
+
+    class Parser < Racc::Parser
+
+module_eval <<'..end parser.ry modeval..id43bff5dec9', 'parser.ry', 42
+
+  def lookup(str)
+    t = str.downcase
+    k = UNITS4KEY[t]
+    return [:UNIT, k] if k
+    return [:AND, nil] if t == 'and'
+    return [:UNKNOWNWORD, nil]
+  end
+
+  def parse(str)
+    @q = []
+    until str.empty?
+      case str
+      when /\A\s+/
+      when /\AP(\d+y)?(\d+m)?(\d+d)?t?(\d+h)?(\d+m)?(\d+s)?(\d+w)?/i
+	y, m, d, h, min, s, w =
+	  [$1, $2, $3, $4, $5, $6, $7].collect{|x| x.to_i}
+	y *= UNITS4KEY['years']
+	m *= UNITS4KEY['months']
+	d *= UNITS4KEY['days']
+	h *= UNITS4KEY['hours']
+	min *= UNITS4KEY['minutes']
+	s *= UNITS4KEY['seconds']
+	w *= UNITS4KEY['weeks']
+	@q.push [:DURATION, y + m + d + h + min + s + w]
+      when /\A\d+/
+	@q.push [:DIGITS, $&.to_i]
+      when /\A[a-z]+/i
+	@q.push lookup($&)
+      when /\A.|\n/
+	@q.push [$&, $&]
+      end
+      str = $'
+    end
+    @q.push [false, false]
+    do_parse
+  end
+
+  def next_token
+    @q.shift
+  end
+
+..end parser.ry modeval..id43bff5dec9
+
+##### racc 1.4.5 generates ###
+
+racc_reduce_table = [
+ 0, 0, :racc_error,
+ 1, 16, :_reduce_none,
+ 1, 17, :_reduce_none,
+ 1, 17, :_reduce_none,
+ 3, 17, :_reduce_4,
+ 3, 17, :_reduce_5,
+ 3, 17, :_reduce_6,
+ 3, 17, :_reduce_7,
+ 3, 17, :_reduce_8,
+ 3, 17, :_reduce_9,
+ 3, 17, :_reduce_10,
+ 2, 17, :_reduce_11,
+ 2, 17, :_reduce_12,
+ 3, 17, :_reduce_13,
+ 2, 18, :_reduce_14,
+ 0, 20, :_reduce_15,
+ 1, 20, :_reduce_none,
+ 1, 19, :_reduce_none ]
+
+racc_reduce_n = 18
+
+racc_shift_n = 32
+
+racc_action_table = [
+    13,    14,    15,    16,    17,    18,    19,     4,    27,    23,
+     8,     9,     1,     4,    25,     2,     8,     9,     1,     4,
+    24,     2,     8,     9,     1,     4,    21,     2,     8,     9,
+     1,     4,    11,     2,     8,     9,     1,     4,    26,     2,
+     8,     9,     1,     4,   nil,     2,     8,     9,     1,     4,
+   nil,     2,     8,     9,     1,   nil,   nil,     2,    13,    14,
+    15,    16,    17,    18,    19,    13,    14,    15,    13,    14,
+    15,    13,    14,    15,    13,    14,    15 ]
+
+racc_action_check = [
+    10,    10,    10,    10,    10,    10,    10,    17,    15,    10,
+    17,    17,    17,    18,    13,    17,    18,    18,    18,     4,
+    11,    18,     4,     4,     4,     1,     9,     4,     1,     1,
+     1,     8,     3,     1,     8,     8,     8,    19,    14,     8,
+    19,    19,    19,     0,   nil,    19,     0,     0,     0,    16,
+   nil,     0,    16,    16,    16,   nil,   nil,    16,     5,     5,
+     5,     5,     5,     5,     5,    30,    30,    30,    28,    28,
+    28,    29,    29,    29,    31,    31,    31 ]
+
+racc_action_pointer = [
+    37,    19,   nil,    32,    13,    55,   nil,   nil,    25,    13,
+    -3,    20,   nil,     4,    28,    -2,    43,     1,     7,    31,
+   nil,   nil,   nil,   nil,   nil,   nil,   nil,   nil,    65,    68,
+    62,    71 ]
+
+racc_action_default = [
+   -18,   -18,   -17,   -18,   -18,    -1,    -2,    -3,   -18,   -15,
+   -18,   -18,   -12,   -18,   -18,   -18,   -18,   -18,   -18,   -18,
+   -11,   -16,   -14,   -13,    32,   -10,    -8,    -9,    -4,    -5,
+    -6,    -7 ]
+
+racc_goto_table = [
+     5,    10,     3,    22,    12,   nil,   nil,   nil,    20,   nil,
+   nil,   nil,   nil,   nil,   nil,   nil,    28,    29,    30,    31 ]
+
+racc_goto_check = [
+     2,     2,     1,     5,     2,   nil,   nil,   nil,     2,   nil,
+   nil,   nil,   nil,   nil,   nil,   nil,     2,     2,     2,     2 ]
+
+racc_goto_pointer = [
+   nil,     2,     0,   nil,   nil,    -6 ]
+
+racc_goto_default = [
+   nil,   nil,   nil,     6,     7,   nil ]
+
+racc_token_table = {
+ false => 0,
+ Object.new => 1,
+ :UNARY => 2,
+ "^" => 3,
+ "*" => 4,
+ "/" => 5,
+ "+" => 6,
+ "," => 7,
+ :AND => 8,
+ "-" => 9,
+ :DIGITS => 10,
+ "(" => 11,
+ ")" => 12,
+ :UNIT => 13,
+ :DURATION => 14 }
+
+racc_use_result_var = true
+
+racc_nt_base = 15
+
+Racc_arg = [
+ racc_action_table,
+ racc_action_check,
+ racc_action_default,
+ racc_action_pointer,
+ racc_goto_table,
+ racc_goto_check,
+ racc_goto_default,
+ racc_goto_pointer,
+ racc_nt_base,
+ racc_reduce_table,
+ racc_token_table,
+ racc_shift_n,
+ racc_reduce_n,
+ racc_use_result_var ]
+
+Racc_token_to_s_table = [
+'$end',
+'error',
+'UNARY',
+'"^"',
+'"*"',
+'"/"',
+'"+"',
+'","',
+'AND',
+'"-"',
+'DIGITS',
+'"("',
+'")"',
+'UNIT',
+'DURATION',
+'$start',
+'stmt',
+'expr',
+'time',
+'iso',
+'unit']
+
+Racc_debug_parser = false
+
+##### racc system variables end #####
+
+ # reduce 0 omitted
+
+ # reduce 1 omitted
+
+ # reduce 2 omitted
+
+ # reduce 3 omitted
+
+module_eval <<'.,.,', 'parser.ry', 18
+  def _reduce_4( val, _values, result )
+result += val[2]
+   result
+  end
+.,.,
+
+module_eval <<'.,.,', 'parser.ry', 19
+  def _reduce_5( val, _values, result )
+result += val[2]
+   result
+  end
+.,.,
+
+module_eval <<'.,.,', 'parser.ry', 20
+  def _reduce_6( val, _values, result )
+result += val[2]
+   result
+  end
+.,.,
+
+module_eval <<'.,.,', 'parser.ry', 21
+  def _reduce_7( val, _values, result )
+result -= val[2]
+   result
+  end
+.,.,
+
+module_eval <<'.,.,', 'parser.ry', 22
+  def _reduce_8( val, _values, result )
+result *= val[2]
+   result
+  end
+.,.,
+
+module_eval <<'.,.,', 'parser.ry', 23
+  def _reduce_9( val, _values, result )
+result /= val[2]
+   result
+  end
+.,.,
+
+module_eval <<'.,.,', 'parser.ry', 24
+  def _reduce_10( val, _values, result )
+result **= val[2]
+   result
+  end
+.,.,
+
+module_eval <<'.,.,', 'parser.ry', 25
+  def _reduce_11( val, _values, result )
+result = -val[1]
+   result
+  end
+.,.,
+
+module_eval <<'.,.,', 'parser.ry', 26
+  def _reduce_12( val, _values, result )
+result = +val[1]
+   result
+  end
+.,.,
+
+module_eval <<'.,.,', 'parser.ry', 27
+  def _reduce_13( val, _values, result )
+result =  val[1]
+   result
+  end
+.,.,
+
+module_eval <<'.,.,', 'parser.ry', 30
+  def _reduce_14( val, _values, result )
+result = val[0] * val[1]
+   result
+  end
+.,.,
+
+module_eval <<'.,.,', 'parser.ry', 33
+  def _reduce_15( val, _values, result )
+result = 1
+   result
+  end
+.,.,
+
+ # reduce 16 omitted
+
+ # reduce 17 omitted
+
+ def _reduce_none( val, _values, result )
+  result
+ end
+
+    end   # class Parser
+
+  end   # class Delta
+
+end   # class Date

lib/date/delta/parser.ry

@@ -0,0 +1,84 @@
+# parser.ry: Written by Tadayoshi Funaba 2006,2008,2009 -*- ruby -*-
+
+class Date::Delta::Parser
+
+  prechigh
+    nonassoc UNARY
+    left '^'
+    left '*' '/'
+    left '+' ',' AND '-'
+  preclow
+
+  rule
+
+  stmt	: expr
+	;
+
+  expr	: time
+	| iso
+	| expr '+' expr   {result += val[2]}
+	| expr ',' expr   {result += val[2]}
+	| expr AND expr   {result += val[2]}
+	| expr '-' expr   {result -= val[2]}
+	| expr '*' DIGITS {result *= val[2]}
+	| expr '/' DIGITS {result /= val[2]}
+	| expr '^' DIGITS {result **= val[2]}
+	| '-' expr =UNARY {result = -val[1]}
+	| '+' expr =UNARY {result = +val[1]}
+	| '(' expr ')'    {result =  val[1]}
+	;
+
+  time	: DIGITS unit {result = val[0] * val[1]}
+	;
+
+  unit	: {result = 1} | UNIT
+	;
+
+  iso	: DURATION
+	;
+
+---- header ----
+---- inner ----
+
+  def lookup(str)
+    t = str.downcase
+    k = UNITS4KEY[t]
+    return [:UNIT, k] if k
+    return [:AND, nil] if t == 'and'
+    return [:UNKNOWNWORD, nil]
+  end
+
+  def parse(str)
+    @q = []
+    until str.empty?
+      case str
+      when /\A\s+/
+      when /\AP(\d+y)?(\d+m)?(\d+d)?t?(\d+h)?(\d+m)?(\d+s)?(\d+w)?/i
+	y, m, d, h, min, s, w =
+	  [$1, $2, $3, $4, $5, $6, $7].collect{|x| x.to_i}
+	y *= UNITS4KEY['years']
+	m *= UNITS4KEY['months']
+	d *= UNITS4KEY['days']
+	h *= UNITS4KEY['hours']
+	min *= UNITS4KEY['minutes']
+	s *= UNITS4KEY['seconds']
+	w *= UNITS4KEY['weeks']
+	@q.push [:DURATION, y + m + d + h + min + s + w]
+      when /\A\d+/
+	@q.push [:DIGITS, $&.to_i]
+      when /\A[a-z]+/i
+	@q.push lookup($&)
+      when /\A.|\n/
+	@q.push [$&, $&]
+      end
+      str = $'
+    end
+    @q.push [false, false]
+    do_parse
+  end
+
+  def next_token
+    @q.shift
+  end
+
+---- footer ----