Comparable#clamp

* compar.c (cmp_clamp): Introduce Comparable#clamp.  [Feature #10594]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55863 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 34 insertions, 0 deletions

diff --git a/compar.c b/compar.c
index fe0872c4c7..02529c9960 100644
--- a/compar.c
+++ b/compar.c
@@ -174,6 +174,39 @@ cmp_between(VALUE x, VALUE min, VALUE max)
 }
 
 /*
+ *  call-seq:
+ *     obj.clamp(min, max) ->  obj
+ *
+ * Returns <i>min</i> if <i>obj</i> <code><=></code> <i>min</i> is less
+ * than zero, <i>max</i> if <i>obj</i> <code><=></code> <i>max</i> is
+ * greater than zero and <i>obj</i> otherwise.
+ *
+ *     12.clamp(0, 100)         #=> 12
+ *     523.clamp(0, 100)        #=> 100
+ *     -3.123.clamp(0, 100)     #=> 0
+ *
+ *     'd'.clamp('a', 'f')      #=> 'd'
+ *     'z'.clamp('a', 'f')      #=> 'f'
+ */
+
+static VALUE
+cmp_clamp(VALUE x, VALUE min, VALUE max)
+{
+    int c;
+
+    if (cmpint(min, max) > 0) {
+	rb_raise(rb_eArgError, "min argument must be smaller than max argument");
+    }
+
+    c = cmpint(x, min);
+    if (c == 0) return x;
+    if (c < 0) return min;
+    c = cmpint(x, max);
+    if (c > 0) return max;
+    return x;
+}
+
+/*
  *  The <code>Comparable</code> mixin is used by classes whose objects
  *  may be ordered. The class must define the <code><=></code> operator,
  *  which compares the receiver against another object, returning -1, 0,
@@ -225,4 +258,5 @@ Init_Comparable(void)
     rb_define_method(rb_mComparable, "<", cmp_lt, 1);
     rb_define_method(rb_mComparable, "<=", cmp_le, 1);
     rb_define_method(rb_mComparable, "between?", cmp_between, 2);
+    rb_define_method(rb_mComparable, "clamp", cmp_clamp, 2);
 }