Implement Function.prototype.toMethod.

test/mjsunit/harmony/toMethod.js

+// Copyright 2013 the V8 project authors. All rights reserved.
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+// modification, are permitted provided that the following conditions are
+// met:
+//
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+//     * Redistributions in binary form must reproduce the above
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+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+// Flags: --harmony-classes --allow-natives-syntax
+
+
+(function ToMethodSingleClass() {
+  function f(x) {
+    var a = [0, 1, 2]
+    return a[x];
+  }
+
+  function ClassD() { }
+
+  assertEquals(1, f(1));
+  var g = f.toMethod(ClassD.prototype);
+  assertEquals(1, g(1));
+  assertEquals(undefined, f[%HomeObjectSymbol()]);
+  assertEquals(ClassD.prototype, g[%HomeObjectSymbol()]);
+}());
+
+
+(function ToMethodClassHierarchy() {
+  function f(x) {
+    return function g(y)  { x++; return x + y; };
+  }
+
+  function Base() {}
+  function Derived() { }
+  Derived.prototype = Object.create(Base.prototype);
+
+  var q = f(0);
+  assertEquals(2, q(1));
+  assertEquals(3, q(1));
+  var g = q.toMethod(Derived.prototype);
+  assertFalse(g === q);
+  assertEquals(4, g(1));
+  assertEquals(5, q(1));
+}());
+
+
+(function ToMethodErrorCases() {
+  var sFun = Function.prototype.toMethod;
+  assertThrows(function() { sFun.call({}); }, TypeError);
+  assertThrows(function() { sFun.call({}, {}); }, TypeError);
+  function f(){};
+  assertThrows(function() { f.toMethod(1); }, TypeError);
+}());
+
+
+(function ToMethodPrototypeChain() {
+  var o = {};
+  var o1 = {};
+  function f() { }
+
+  function g() { }
+
+  var fMeth = f.toMethod(o);
+  assertEquals(o, fMeth[%HomeObjectSymbol()]);
+  g.__proto__ = fMeth;
+  assertEquals(undefined, g[%HomeObjectSymbol()]);
+  var gMeth = g.toMethod(o1);
+  assertEquals(fMeth, gMeth.__proto__);
+  assertEquals(o1, gMeth[%HomeObjectSymbol()]);
+}());
+
+
+(function ToMethodBoundFunction() {
+  var o = {};
+  var p = {};
+
+
+  function f(x, y, z) {

[Toon Verwaest, 2014/08/18 14:15:35]

Add flag "called = false" on the outside, and set it to true on the inside, to
ensure the method is even called.

[Dmitry Lomov (no reviews), 2014/08/19 20:02:48]

Checking return value instead.

+    assertEquals(o, this);
+    assertEquals(1, x);
+    assertEquals(2, y);
+    assertEquals(3, z);
+  }
+
+  var fBound = f.bind(o, 1, 2, 3);
+  var fMeth = fBound.toMethod(p);
+  fMeth();
+  fMeth.call(p);
+}());

[Toon Verwaest, 2014/08/18 14:15:35]

What about tests for rebinding a method, given that those are just JSFunctions
too? (This is API is a bit weird imho...)

[Dmitry Lomov (no reviews), 2014/08/19 20:02:48]

Done.