numeric.c: int_floor

* numeric.c (int_floor): add an optional parameter, digits, as
  well as Integer#round.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54561 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Wed Apr 13 15:47:53 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* numeric.c (int_floor): add an optional parameter, digits, as
+	  well as Integer#round.
+
 Wed Apr 13 14:47:47 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* file.c (Init_File): add alias File.empty? to File.zero?.

numeric.c

@@ -110,6 +110,7 @@ static VALUE fix_rshift(long, unsigned long);
 static VALUE int_pow(long x, unsigned long y);
 static VALUE int_cmp(VALUE x, VALUE y);
 static int int_round_zero_p(VALUE num, int ndigits);
+VALUE rb_int_floor(VALUE num, int ndigits);
 static VALUE flo_truncate(VALUE num);
 static int float_invariant_round(double number, int ndigits, VALUE *num);
 
@@ -1820,6 +1821,28 @@ rb_int_round(VALUE num, int ndigits)
     return n;
 }
 
+VALUE
+rb_int_floor(VALUE num, int ndigits)
+{
+    VALUE f;
+
+    if (int_round_zero_p(num, ndigits))
+	return INT2FIX(0);
+    f = int_pow(10, -ndigits);
+    if (FIXNUM_P(num) && FIXNUM_P(f)) {
+	SIGNED_VALUE x = FIX2LONG(num), y = FIX2LONG(f);
+	int neg = x < 0;
+	if (neg) x = -x + y - 1;
+	x = x / y * y;
+	if (neg) x = -x;
+	return LONG2NUM(x);
+    }
+    if (RB_TYPE_P(f, T_FLOAT)) {
+	/* then int_pow overflow */
+	return INT2FIX(0);
+    }
+    return rb_int_minus(num, rb_int_modulo(num, f));
+}
 
 /*
  *  call-seq:
@@ -4170,6 +4193,37 @@ int_round(int argc, VALUE* argv, VALUE num)
     return rb_int_round(num, ndigits);
 }
 
+/*
+ *  call-seq:
+ *     int.floor([ndigits])  ->  integer or float
+ *
+ *  Returns the largest number less than or equal to +int+ in decimal
+ *  digits (default 0 digits).
+ *
+ *  Precision may be negative.  Returns a floating point number when +ndigits+
+ *  is positive, +self+ for zero, and floor down for negative.
+ *
+ *     1.floor        #=> 1
+ *     1.floor(2)     #=> 1.0
+ *     15.floor(-1)   #=> 10
+ */
+
+static VALUE
+int_floor(int argc, VALUE* argv, VALUE num)
+{
+    int ndigits;
+
+    if (!rb_check_arity(argc, 0, 1)) return num;
+    ndigits = NUM2INT(argv[0]);
+    if (ndigits > 0) {
+	return rb_Float(num);
+    }
+    if (ndigits == 0) {
+	return num;
+    }
+    return rb_int_floor(num, ndigits);
+}
+
 /*
  *  Document-class: ZeroDivisionError
  *
@@ -4340,7 +4394,7 @@ Init_Numeric(void)
     rb_define_method(rb_cInteger, "to_i", int_to_i, 0);
     rb_define_method(rb_cInteger, "to_int", int_to_i, 0);
     rb_define_method(rb_cInteger, "to_f", int_to_f, 0);
-    rb_define_method(rb_cInteger, "floor", int_to_i, 0);
+    rb_define_method(rb_cInteger, "floor", int_floor, -1);
     rb_define_method(rb_cInteger, "ceil", int_to_i, 0);
     rb_define_method(rb_cInteger, "truncate", int_to_i, 0);
     rb_define_method(rb_cInteger, "round", int_round, -1);

test/ruby/test_integer.rb

@@ -199,6 +199,31 @@ class TestInteger < Test::Unit::TestCase
     assert_int_equal(-1111_1111_1111_1111_1111_1111_1111_1110, (-1111_1111_1111_1111_1111_1111_1111_1111).round(-1))
   end
 
+  def test_floor
+    assert_int_equal(11111, 11111.floor)
+    assert_int_equal(11111, 11111.floor(0))
+
+    assert_float_equal(11111.0, 11111.floor(1))
+    assert_float_equal(11111.0, 11111.floor(2))
+
+    assert_int_equal(11110, 11110.floor(-1))
+    assert_int_equal(11110, 11119.floor(-1))
+    assert_int_equal(11100, 11100.floor(-2))
+    assert_int_equal(11100, 11199.floor(-2))
+    assert_int_equal(0, 11111.floor(-5))
+    assert_int_equal(+200, +299.floor(-2))
+    assert_int_equal(+300, +300.floor(-2))
+    assert_int_equal(-300, -299.floor(-2))
+    assert_int_equal(-300, -300.floor(-2))
+    assert_int_equal(+20 * 10**70, (+25 * 10**70).floor(-71))
+    assert_int_equal(-30 * 10**70, (-25 * 10**70).floor(-71))
+    assert_int_equal(+20 * 10**70, (+25 * 10**70 - 1).floor(-71))
+    assert_int_equal(-30 * 10**70, (-25 * 10**70 + 1).floor(-71))
+
+    assert_int_equal(1111_1111_1111_1111_1111_1111_1111_1110, 1111_1111_1111_1111_1111_1111_1111_1111.floor(-1))
+    assert_int_equal(-1111_1111_1111_1111_1111_1111_1111_1120, (-1111_1111_1111_1111_1111_1111_1111_1111).floor(-1))
+  end
+
   def test_bitwise_and_with_integer_mimic_object
     def (obj = Object.new).to_int
       10