Implement `String#upto` in Ruby.

Avoid using `mrb_yield` in C code. The function is not recommended.
Because it doesn't work well with fibers.

1 files changed, 73 insertions, 0 deletions

diff --git a/mrbgems/mruby-string-ext/mrblib/string.rb b/mrbgems/mruby-string-ext/mrblib/string.rb
index 39ee57419..27ca30610 100644
--- a/mrbgems/mruby-string-ext/mrblib/string.rb
+++ b/mrbgems/mruby-string-ext/mrblib/string.rb
@@ -386,4 +386,77 @@ class String
     end
     lines
   end
+
+  ##
+  #  call-seq:
+  #     str.upto(other_str, exclusive=false) {|s| block }   -> str
+  #     str.upto(other_str, exclusive=false)                -> an_enumerator
+  #
+  #  Iterates through successive values, starting at <i>str</i> and
+  #  ending at <i>other_str</i> inclusive, passing each value in turn to
+  #  the block. The <code>String#succ</code> method is used to generate
+  #  each value.  If optional second argument exclusive is omitted or is false,
+  #  the last value will be included; otherwise it will be excluded.
+  #
+  #  If no block is given, an enumerator is returned instead.
+  #
+  #     "a8".upto("b6") {|s| print s, ' ' }
+  #     for s in "a8".."b6"
+  #       print s, ' '
+  #     end
+  #
+  #  <em>produces:</em>
+  #
+  #     a8 a9 b0 b1 b2 b3 b4 b5 b6
+  #     a8 a9 b0 b1 b2 b3 b4 b5 b6
+  #
+  #  If <i>str</i> and <i>other_str</i> contains only ascii numeric characters,
+  #  both are recognized as decimal numbers. In addition, the width of
+  #  string (e.g. leading zeros) is handled appropriately.
+  #
+  #     "9".upto("11").to_a   #=> ["9", "10", "11"]
+  #     "25".upto("5").to_a   #=> []
+  #     "07".upto("11").to_a  #=> ["07", "08", "09", "10", "11"]
+  def upto(max, exclusive=false, &block)
+    return to_enum(:upto, max, exclusive) unless block
+    raise TypeError, "no implicit conversion of #{max.class} into String" unless max.kind_of? String
+
+    len = self.length
+    maxlen = max.length
+    # single character
+    if len == 1 and maxlen == 1
+      c = self.ord
+      e = max.ord
+      while c <= e
+        break if exclusive and c == e
+        yield c.chr
+        c += 1
+      end
+      return self
+    end
+    # both edges are all digits
+    bi = self.to_i(10)
+    ei = max.to_i(10)
+    len = self.length
+    if (bi > 0 or bi == "0"*len) and (ei > 0 or ei == "0"*maxlen)
+      while bi <= ei
+        break if exclusive and bi == ei
+        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
+      n = (bs <=> max)
+      break if n > 0
+      break if exclusive and n == 0
+      yield bs
+      break if n == 0
+      bs = bs.succ
+    end
+    self
+  end
 end