Inline compareTo for numbers into min and max.

corelib/src/math.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // Dart core library.
 
 class Math {
   /**
    * Base of the natural logarithms.
    */
@@ skipping 41 matching lines @@
    */
   static int parseInt(String str) => MathNatives.parseInt(str);
 
   /**
    * Parses a [String] representation of a [double], and returns
    * a [double]. Throws a [BadNumberFormatException] if [str] cannot
    * be parsed as a [double].
    */
   static double parseDouble(String str) => MathNatives.parseDouble(str);
 
   static num min(num a, num b) {

[Lasse Reichstein Nielsen, 2012/07/10 07:35:00]

Give it a doc-comment and say how it works (NaN if either value is NaN, -0.0 <
0.0, otherwise int/double with same mathematical value are equal). And that if
they are equal, you return the first argument (but I'd prefer documenting it as
being unspecified which one is returned).

[floitsch, 2012/07/10 17:32:32]

Done.

-    int c = a.compareTo(b);
-    if (c == 0) return a;
-    if (c < 0) {
-      if ((b is double) && b.isNaN()) return b;
-      return a;
+    if (a is num) {
+      // TODO(floitsch): merge this if into the previous one, once dart2js
+      // correctly propagates types for logical ands.
+      if (b is num) {
+        if (a > b) return b;
+        if (a < b) return a;
+        if (b is double) {
+          // Special case for NaN and -0.0. If one argument is NaN return NaN.
+          // [min] must also distinguish between -0.0 and 0.0.
+          if (a is double) {
+            if (a == 0.0) {
+              // a is either 0.0 or -0.0. b is either 0.0, -0.0 or NaN.
+              // The following returns -0.0 if either a or b is -0.0, and it
+              // returns NaN if b is NaN.
+              return (a + b) * a * b;

[Lasse Reichstein Nielsen, 2012/07/10 07:35:00]

This should work even if a or b are not doubles. At least you can remove the 'a
is double' check.
If you inserted it for performance, not correctness, do say so.

[floitsch, 2012/07/10 17:32:32]

I want to return a consistent order when both arguments are equal. Without the
check min(0, 0.0) would return 0.0, but min(1, 1.0) would return 1.

+            }
+          }
+          // Check for NaN and b == -0.0.

[Lasse Reichstein Nielsen, 2012/07/10 07:35:00]

If you didn't check for "a is double" above, then b==NaN would be handled there.

[floitsch, 2012/07/10 17:32:32]

Yes, but then we wouldn't return the left argument.

+          if (a == 0 && b.isNegative() || b != b) return b;
+          return a;
+        }
+        return a;
+      }
+      throw new IllegalArgumentException(b);
     }
-    if ((a is double) && a.isNaN()) return a;
-    return b;
+    throw new IllegalArgumentException(a);
   }
 
   static num max(num a, num b) {
-    // NaNs are handled correctly since the compareTo function always considers
-    // them to be bigger than any other operand.
-    return (a.compareTo(b) < 0) ? b : a;
+    if (a is num) {
+      // TODO(floitsch): merge this if into the previous one, once dart2js
+      // correctly propagates types for logical ands.
+      if (b is num) {
+        if (a > b) return a;
+        if (a < b) return b;
+        if (b is double) {
+          // Special case for NaN and -0.0. If one argument is NaN return NaN.
+          // [max] must also distinguish between -0.0 and 0.0.
+          if (a is double) {
+            if (a == 0.0) {
+              // a is either 0.0 or -0.0. b is either 0.0, -0.0, or NaN.
+              // The following returns 0.0 if either a or b is 0.0, and it
+              // returns NaN if b is NaN.
+              return a + b;
+            }
+          }
+          // Check for NaN.

[Lasse Reichstein Nielsen, 2012/07/10 07:35:00]

Don't we have b.isNaN()? I'd prefer using that, at least for readability.

[floitsch, 2012/07/10 17:32:32]

Done.

+          if (b != b) return b;
+          return a;
+        }
+        // max(-0.0, 0) must return 0.
+        if (b == 0 && a.isNegative()) return b;
+        return a;
+      }
+      throw new IllegalArgumentException(b);
+    }
+    throw new IllegalArgumentException(a);
   }
 
   /**
    * Returns the arc tangent of [a]/[b] with sign according to quadrant.
    */
   static double atan2(num a, num b) => MathNatives.atan2(a, b);
 
   /**
    * If the [exponent] is an integer the result is of the same type as [x].
    * Otherwise it is a [double].
    */
   static num pow(num x, num exponent) => MathNatives.pow(x, exponent);
 
   /**
    * Returns a random double greater than or equal to 0.0 and less
    * than 1.0.
    */
   static double random() => MathNatives.random();
 
   static double sin(num x) => MathNatives.sin(x);
   static double cos(num x) => MathNatives.cos(x);
   static double tan(num x) => MathNatives.tan(x);
   static double acos(num x) => MathNatives.acos(x);
   static double asin(num x) => MathNatives.asin(x);
   static double atan(num x) => MathNatives.atan(x);
   static double sqrt(num x) => MathNatives.sqrt(x);
   static double exp(num x) => MathNatives.exp(x);
   static double log(num x) => MathNatives.log(x);
 }