Introduce endless range (a part of #5085)

Co-Authored-By: n4o847 <22975590+n4o847@users.noreply.github.com>
Co-Authored-By: smallkirby <ssmallkirby@gmail.com>

mrbgems/mruby-compiler/core/parse.y

@@ -2118,10 +2118,18 @@ arg             : lhs '=' arg_rhs
                     {
                       $$ = new_dot2(p, $1, $3);
                     }
+                | arg tDOT2
+                    {
+                      $$ = new_dot2(p, $1, new_nil(p));
+                    }
                 | arg tDOT3 arg
                     {
                       $$ = new_dot3(p, $1, $3);
                     }
+                | arg tDOT3
+                    {
+                      $$ = new_dot3(p, $1, new_nil(p));
+                    }
                 | arg '+' arg
                     {
                       $$ = call_bin_op(p, $1, "+", $3);

mrbgems/mruby-range-ext/mrblib/range.rb

@@ -27,10 +27,12 @@ class Range
   end
 
   def max(&block)
-    val = self.first
-    last = self.last
+    val = self.begin
+    last = self.end
     return super if block
 
+    raise RangeError, "cannot get the maximum of endless range" if last.nil?
+
     # fast path for numerics
     if val.kind_of?(Numeric) && last.kind_of?(Numeric)
       raise TypeError if exclude_end? && !last.kind_of?(Fixnum)
@@ -47,9 +49,13 @@ class Range
   end
 
   def min(&block)
-    val = self.first
-    last = self.last
-    return super if block
+    val = self.begin
+    last = self.end
+    if block
+      raise RangeError, "cannot get the minimum of endless range with custom comparison method" if last.nil?
+      return super 
+    end
+    return val if last.nil?
 
     # fast path for numerics
     if val.kind_of?(Numeric) && last.kind_of?(Numeric)

mrbgems/mruby-range-ext/src/range.c

@@ -42,6 +42,9 @@ range_cover(mrb_state *mrb, mrb_value range)
   end = RANGE_END(r);
 
   if (r_le(mrb, beg, val)) {
+    if (mrb_nil_p(end)) {
+      return mrb_true_value();
+    }
     if (RANGE_EXCL(r)) {
       if (r_lt(mrb, val, end))
         return mrb_true_value();
@@ -76,6 +79,11 @@ range_last(mrb_state *mrb, mrb_value range)
 {
   mrb_value num;
   mrb_value array;
+  struct RRange *r = mrb_range_ptr(mrb, range);
+
+  if (mrb_nil_p(RANGE_END(r))) {
+    mrb_raise(mrb, E_RANGE_ERROR, "cannot get the last element of endless range");
+  }
 
   if (mrb_get_args(mrb, "|o", &num) == 0) {
     return mrb_range_end(mrb, range);
@@ -108,6 +116,10 @@ range_size(mrb_state *mrb, mrb_value range)
 
   beg = RANGE_BEG(r);
   end = RANGE_END(r);
+  if ((mrb_fixnum_p(beg) || mrb_float_p(beg)) && mrb_nil_p(end)) {
+    return mrb_float_value(mrb, INFINITY);
+  }
+
   excl = RANGE_EXCL(r);
   if (mrb_fixnum_p(beg)) {
     beg_f = (mrb_float)mrb_fixnum(beg);
@@ -159,6 +171,10 @@ range_size(mrb_state *mrb, mrb_value range)
 
   beg = RANGE_BEG(r);
   end = RANGE_END(r);
+  if (mrb_fixnum_p(beg) && mrb_nil_p(end)) {
+    return mrb_nil_value();
+  }
+
   excl = RANGE_EXCL(r) ? 0 : 1;
 
   if (mrb_fixnum_p(beg) && mrb_fixnum_p(end)) {

mrbgems/mruby-range-ext/test/range.rb

@@ -5,11 +5,16 @@ assert('Range#cover?') do
   assert_true ("a".."z").cover?("c")
   assert_true !("a".."z").cover?("5")
   assert_true ("a".."z").cover?("cc")
+  assert_true ("a"..).cover?("c")
+  assert_false ("a"..).cover?("5")
+  assert_true ("a"..).cover?("cc")
 end
 
 assert('Range#first') do
   assert_equal 10, (10..20).first
   assert_equal [10, 11, 12], (10..20).first(3)
+  assert_equal 10, (10..).first
+  assert_equal [10, 11, 12], (10..).first(3)
 
   skip unless Object.const_defined?(:Float)
   assert_equal [0, 1, 2], (0..Float::INFINITY).first(3)
@@ -18,6 +23,8 @@ end
 assert('Range#last') do
   assert_equal 20, (10..20).last
   assert_equal 20, (10...20).last
+  assert_raise(RangeError) { (10..).last }
+  assert_raise(RangeError) { (10...).last }
   assert_equal [18, 19, 20], (10..20).last(3)
   assert_equal [17, 18, 19], (10...20).last(3)
 end
@@ -26,6 +33,9 @@ assert('Range#size') do
   assert_equal 42, (1..42).size
   assert_equal 41, (1...42).size
   assert_nil ('a'..'z').size
+  assert_nil ('a'..).size
+  
+  assert_nil (1..).size unless Object.const_defined?(:Float)
 
   skip unless Object.const_defined?(:Float)
   assert_equal 6, (1...6.3).size
@@ -33,6 +43,10 @@ assert('Range#size') do
   assert_equal 5, (1.1...6).size
   assert_equal 15, (1.0..15.9).size
   assert_equal Float::INFINITY, (0..Float::INFINITY).size
+
+  assert_equal Float::INFINITY, (1..).size
+  assert_equal Float::INFINITY, (1...).size
+  assert_equal Float::INFINITY, (1.0..).size
 end
 
 assert('Range#max') do
@@ -50,6 +64,10 @@ assert('Range#max') do
   # returns the endpoint when the endpoint equals the start point and the range is inclusive
   assert_equal 5, (5..5).max
 
+  # raises RangeError when called on an endless range
+  assert_raise(RangeError) { (10..).max }
+  assert_raise(RangeError) { (10...).max }
+
   skip unless Object.const_defined?(:Float)
 
   # returns the maximum value in the Float range when called with no arguments
@@ -94,26 +112,31 @@ assert('Range#min') do
   # returns the minimum value in the range when called with no arguments
   assert_equal 1, (1..10).min
   assert_equal 1, (1...10).min
+  assert_equal 1, (1..).min
 
   # returns nil when the start point is greater than the endpoint
   assert_equal nil, (100..10).min
 
   # returns nil when the endpoint equals the start point and the range is exclusive
-  assert_equal nil, (5...5).max
+  assert_equal nil, (5...5).min
 
   # returns the endpoint when the endpoint equals the start point and the range is inclusive
-  assert_equal 5, (5..5).max
+  assert_equal 5, (5..5).min
 
   skip unless Object.const_defined?(:Float)
 
   # returns the minimum value in the Float range when called with no arguments
   assert_equal 303.20, (303.20..908.1111).min
+  assert_equal 1, (1.0..).min
 
   # returns nil when the start point is greater than the endpoint in a Float range
-  assert_equal nil, (3003.20..908.1111).max
+  assert_equal nil, (3003.20..908.1111).min
 end
 
 assert('Range#min given a block') do
+  # raise when called with a block in endless range
+  assert_raise(RangeError) { (1..).min{} }
+
   # passes each pair of values in the range to the block
   acc = []
   (1..10).min do |a, b|

mrbgems/mruby-string-ext/mrblib/string.rb

@@ -444,4 +444,27 @@ class String
     end
     self
   end
+
+  def __upto_endless(&block)
+    return to_enum(:__upto_endless) unless block
+
+    len = self.length
+    # both edges are all digits
+    bi = self.to_i(10)
+    if bi > 0 or bi == "0"*len
+      while true
+        s = bi.to_s
+        s = s.rjust(len, "0") if s.length < len
+        yield s
+        bi += 1
+      end
+      return self
+    end
+    bs = self
+    while true
+      yield bs
+      bs = bs.succ
+    end
+    self
+  end
 end

mrblib/range.rb

@@ -12,8 +12,25 @@ class Range
   def each(&block)
     return to_enum :each unless block
 
-    val = self.first
-    last = self.last
+    val = self.begin
+    last = self.end
+
+    if val.kind_of?(Fixnum) && last.nil?
+      i = val
+      while true
+        block.call(i)
+        i += 1
+      end
+      return self
+    end
+
+    if val.kind_of?(String) && last.nil?
+      if val.respond_to? :__upto_endless
+        return val.__upto_endless(&block)
+      else
+        str_each = true
+      end
+    end
 
     if val.kind_of?(Fixnum) && last.kind_of?(Fixnum) # fixnums are special
       lim = last
@@ -56,6 +73,11 @@ class Range
     h += 1 if self.exclude_end?
     h
   end
+
+  def to_a
+    raise RangeError, "cannot convert endless range to an array" if self.last.nil?
+    super
+  end
 end
 
 ##

src/range.c

@@ -32,6 +32,8 @@ r_check(mrb_state *mrb, mrb_value a, mrb_value b)
     return;
   }
 
+  if (mrb_nil_p(b)) return;
+
   n = mrb_cmp(mrb, a, b);
   if (n == -2) {                /* can not be compared */
     mrb_raise(mrb, E_ARGUMENT_ERROR, "bad value for range");
@@ -212,15 +214,19 @@ range_include(mrb_state *mrb, mrb_value range)
   mrb_value val = mrb_get_arg1(mrb);
   struct RRange *r = mrb_range_ptr(mrb, range);
   mrb_value beg, end;
-  mrb_bool include_p;
 
   beg = RANGE_BEG(r);
   end = RANGE_END(r);
-  include_p = r_le(mrb, beg, val) &&                 /* beg <= val */
-              (RANGE_EXCL(r) ? r_gt(mrb, end, val)   /* end >  val */
-                             : r_ge(mrb, end, val)); /* end >= val */
-
-  return mrb_bool_value(include_p);
+  if (r_le(mrb, beg, val)) {                   /* beg <= val */
+    if (mrb_nil_p(end)) {
+      return mrb_true_value();
+    }
+    if (RANGE_EXCL(r) ? r_gt(mrb, end, val)    /* end >  val */
+                      : r_ge(mrb, end, val)) { /* end >= val */
+      return mrb_true_value();
+    }
+  }
+  return mrb_false_value();
 }
 
 /* 15.2.14.4.12(x) */
@@ -261,10 +267,10 @@ range_inspect(mrb_state *mrb, mrb_value range)
   struct RRange *r = mrb_range_ptr(mrb, range);
 
   str  = mrb_inspect(mrb, RANGE_BEG(r));
-  str2 = mrb_inspect(mrb, RANGE_END(r));
+  if (!mrb_nil_p(RANGE_END(r))) str2 = mrb_inspect(mrb, RANGE_END(r));
   str  = mrb_str_dup(mrb, str);
   mrb_str_cat(mrb, str, "...", RANGE_EXCL(r) ? 3 : 2);
-  mrb_str_cat_str(mrb, str, str2);
+  if (!mrb_nil_p(RANGE_END(r))) mrb_str_cat_str(mrb, str, str2);
 
   return str;
 }
@@ -381,13 +387,15 @@ MRB_API enum mrb_range_beg_len
 mrb_range_beg_len(mrb_state *mrb, mrb_value range, mrb_int *begp, mrb_int *lenp, mrb_int len, mrb_bool trunc)
 {
   mrb_int beg, end;
+  mrb_bool excl;
   struct RRange *r;
 
   if (!mrb_range_p(range)) return MRB_RANGE_TYPE_MISMATCH;
   r = mrb_range_ptr(mrb, range);
 
   beg = mrb_int(mrb, RANGE_BEG(r));
-  end = mrb_int(mrb, RANGE_END(r));
+  end = mrb_nil_p(RANGE_END(r)) ? -1 : mrb_int(mrb, RANGE_END(r));
+  excl = mrb_nil_p(RANGE_END(r)) ? 0 : RANGE_EXCL(r);
 
   if (beg < 0) {
     beg += len;
@@ -400,7 +408,7 @@ mrb_range_beg_len(mrb_state *mrb, mrb_value range, mrb_int *begp, mrb_int *lenp,
   }
 
   if (end < 0) end += len;
-  if (!RANGE_EXCL(r) && (!trunc || end < len)) end++;  /* include end point */
+  if (!excl && (!trunc || end < len)) end++;  /* include end point */
   len = end - beg;
   if (len < 0) len = 0;
 

test/t/array.rb

@@ -57,6 +57,7 @@ assert('Array#[]', '15.2.12.5.4') do
   a = [ "a", "b", "c", "d", "e" ]
   assert_equal(["b", "c"], a[1,2])
   assert_equal(["b", "c", "d"], a[1..-2])
+  assert_equal(["b", "c", "d", "e"], a[1..])
   skip unless Object.const_defined?(:Float)
   assert_equal("b", a[1.1])
 end
@@ -92,6 +93,10 @@ assert('Array#[]=', '15.2.12.5.5') do
   a[2...4] = 6
   assert_equal([1,2,6,5], a)
 
+  a = [1,2,3,4,5]
+  a[2...] = 6
+  assert_equal([1,2,6], a)
+
   # passing self (#3274)
   a = [1,2,3]
   a[1,0] = a

test/t/range.rb

@@ -8,19 +8,30 @@ end
 assert('Range#==', '15.2.14.4.1') do
   assert_true (1..10) == (1..10)
   assert_false (1..10) == (1..100)
+  assert_false (1..10) == (1..)
+
+  assert_true (1..) == (1..nil)
+  assert_true (1..) == (1..)
+  assert_false (1..) == (1...)
+
   skip unless Object.const_defined?(:Float)
   assert_true (1..10) == Range.new(1.0, 10.0)
+
 end
 
 assert('Range#===', '15.2.14.4.2') do
   a = (1..10)
+  b = (1..)
 
   assert_true a === 5
   assert_false a === 20
+  assert_true b === 20
+  assert_false b === 0
 end
 
 assert('Range#begin', '15.2.14.4.3') do
   assert_equal 1, (1..10).begin
+  assert_equal 1, (1..).begin
 end
 
 assert('Range#each', '15.2.14.4.4') do
@@ -28,27 +39,38 @@ assert('Range#each', '15.2.14.4.4') do
   b = 0
   a.each {|i| b += i}
   assert_equal 6, b
+  c = []
+  (1..).each { |i| c << i; break if c.size == 10 }
+  assert_equal [1, 2, 3, 4, 5, 6, 7, 8 ,9, 10], c
 end
 
 assert('Range#end', '15.2.14.4.5') do
   assert_equal 10, (1..10).end
+  assert_nil (1..).end
 end
 
 assert('Range#exclude_end?', '15.2.14.4.6') do
   assert_true (1...10).exclude_end?
   assert_false (1..10).exclude_end?
+  assert_true (1...).exclude_end?
+  assert_false (1..).exclude_end?
 end
 
 assert('Range#first', '15.2.14.4.7') do
   assert_equal 1, (1..10).first
+  assert_equal 1, (1..).first
 end
 
 assert('Range#include?', '15.2.14.4.8') do
   assert_true (1..10).include?(10)
   assert_false (1..10).include?(11)
+  assert_true (1..).include?(10)
+  assert_false (1..).include?(0)
 
   assert_true (1...10).include?(9)
   assert_false (1...10).include?(10)
+  assert_true (1...).include?(10)
+  assert_false (1...).include?(0)
 end
 
 assert('Range#initialize', '15.2.14.4.9') do
@@ -61,17 +83,29 @@ assert('Range#initialize', '15.2.14.4.9') do
   assert_false b.exclude_end?
 
   assert_raise(NameError) { (0..1).__send__(:initialize, 1, 3) }
+
+  c = Range.new(1, nil, true)
+  d = Range.new(1, nil, false)
+
+  assert_equal (1...nil), c
+  assert_true c.exclude_end?
+  assert_equal (1..nil), d
+  assert_false d.exclude_end?
 end
 
 assert('Range#last', '15.2.14.4.10') do
   assert_equal 10, (1..10).last
+  assert_nil (1..).last
 end
 
 assert('Range#member?', '15.2.14.4.11') do
   a = (1..10)
+  b = (1..)
 
   assert_true a.member?(5)
   assert_false a.member?(20)
+  assert_true b.member?(20)
+  assert_false b.member?(0)
 end
 
 assert('Range#to_s', '15.2.14.4.12') do
@@ -79,6 +113,10 @@ assert('Range#to_s', '15.2.14.4.12') do
   assert_equal "0...1", (0...1).to_s
   assert_equal "a..b", ("a".."b").to_s
   assert_equal "a...b", ("a"..."b").to_s
+  assert_equal "0..", (0..).to_s
+  assert_equal "0...", (0...).to_s
+  assert_equal "a..", ("a"..).to_s
+  assert_equal "a...", ("a"...).to_s
 end
 
 assert('Range#inspect', '15.2.14.4.13') do
@@ -86,19 +124,36 @@ assert('Range#inspect', '15.2.14.4.13') do
   assert_equal "0...1", (0...1).inspect
   assert_equal "\"a\"..\"b\"", ("a".."b").inspect
   assert_equal "\"a\"...\"b\"", ("a"..."b").inspect
+  assert_equal "0..", (0..).inspect
+  assert_equal "0...", (0...).inspect
+  assert_equal "\"a\"..", ("a"..).inspect
+  assert_equal "\"a\"...", ("a"...).inspect
 end
 
 assert('Range#eql?', '15.2.14.4.14') do
   assert_true (1..10).eql? (1..10)
   assert_false (1..10).eql? (1..100)
-  assert_false (1..10).eql? (Range.new(1.0, 10.0))
   assert_false (1..10).eql? "1..10"
+  assert_true (1..).eql? (1..)
+  assert_false (1..).eql? (2..)
+  assert_false (1..).eql? "1.."
+  skip unless Object.const_defined?(:Float)
+  assert_false (1..10).eql? (Range.new(1.0, 10.0))
+  assert_false (1..).eql? (Range.new(1.0, nil)) 
 end
 
 assert('Range#initialize_copy', '15.2.14.4.15') do
   assert_raise(NameError) { (0..1).__send__(:initialize_copy, 1..3) }
 end
 
+assert('Range#hash', '15.3.1.3.15') do
+  assert_kind_of(Integer, (1..10).hash)
+  assert_equal (1..10).hash, (1..10).hash
+  assert_not_equal (1..10).hash, (1...10).hash
+  assert_equal (1..).hash, (1..).hash
+  assert_not_equal (1..).hash, (1...).hash
+end
+
 assert('Range#dup') do
   r = (1..3).dup
   assert_equal 1, r.begin
@@ -109,4 +164,15 @@ assert('Range#dup') do
   assert_equal "a", r.begin
   assert_equal "z", r.end
   assert_true r.exclude_end?
+
+  r = (1..).dup
+  assert_equal 1, r.begin
+  assert_nil r.end
+  assert_false r.exclude_end?
+end
+
+assert('Range#to_a') do
+  assert_equal([1, 2, 3, 4, 5], (1..5).to_a)
+  assert_equal([1, 2, 3, 4], (1...5).to_a)
+  assert_raise(RangeError) { (1..).to_a }
 end

test/t/string.rb

@@ -90,6 +90,7 @@ assert('String#[] with Range') do
   h1 = 'abc'[3..4]
   i1 = 'abc'[4..5]
   j1 = 'abcdefghijklmnopqrstuvwxyz'[1..3]
+  k1 = 'abcdefghijklmnopqrstuvwxyz'[-3..]
   a2 = 'abc'[1...0]
   b2 = 'abc'[1...1]
   c2 = 'abc'[1...2]
@@ -100,6 +101,7 @@ assert('String#[] with Range') do
   h2 = 'abc'[3...4]
   i2 = 'abc'[4...5]
   j2 = 'abcdefghijklmnopqrstuvwxyz'[1...3]
+  k2 = 'abcdefghijklmnopqrstuvwxyz'[-3...]
 
   assert_equal '', a1
   assert_equal 'b', b1
@@ -111,6 +113,7 @@ assert('String#[] with Range') do
   assert_equal '', h1
   assert_nil i2
   assert_equal 'bcd', j1
+  assert_equal 'xyz', k1
   assert_equal '', a2
   assert_equal '', b2
   assert_equal 'b', c2
@@ -121,6 +124,7 @@ assert('String#[] with Range') do
   assert_equal '', h2
   assert_nil i2
   assert_equal 'bc', j2
+  assert_equal 'xyz', k2
 end
 
 assert('String#[]=') do