Add support for two arguments to base::BindBlock.

BUG=None

Review URL: https://codereview.chromium.org/148263010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247502 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 32 insertions, 0 deletions

diff --git a/base/mac/bind_objc_block.h b/base/mac/bind_objc_block.h
index 75da437..9deb2d2 100644
--- a/base/mac/bind_objc_block.h
+++ b/base/mac/bind_objc_block.h
@@ -14,7 +14,13 @@
 // BindBlock builds a callback from an Objective-C block. Example usages:
 //
 // Closure closure = BindBlock(^{DoSomething();});
+//
 // Callback<int(void)> callback = BindBlock(^{return 42;});
+//
+// Callback<void(const std::string&, const std::string&)> callback =
+//     BindBlock(^(const std::string& arg0, const std::string& arg1) {
+//         ...
+//     });
 
 namespace base {
 
@@ -33,6 +39,12 @@ R RunBlock(base::mac::ScopedBlock<R(^)(A1)> block, A1 a) {
   return extracted_block(a);
 }
 
+template<typename R, typename A1, typename A2>
+R RunBlock(base::mac::ScopedBlock<R(^)(A1, A2)> block, A1 a, A2 b) {
+  R(^extracted_block)(A1, A2) = block.get();
+  return extracted_block(a, b);
+}
+
 }  // namespace internal
 
 // Construct a callback with no argument from an objective-C block.
@@ -49,6 +61,13 @@ base::Callback<R(A1)> BindBlock(R(^block)(A1)) {
                     base::mac::ScopedBlock<R(^)(A1)>(Block_copy(block)));
 }
 
+// Construct a callback with two arguments from an objective-C block.
+template<typename R, typename A1, typename A2>
+base::Callback<R(A1, A2)> BindBlock(R(^block)(A1, A2)) {
+  return base::Bind(&base::internal::RunBlock<R, A1, A2>,
+                    base::mac::ScopedBlock<R(^)(A1, A2)>(Block_copy(block)));
+}
+
 }  // namespace base
 
 #endif  // BASE_MAC_BIND_OBJC_BLOCK_H_
diff --git a/base/mac/bind_objc_block_unittest.mm b/base/mac/bind_objc_block_unittest.mm
index a4bcd76..c72fd4a 100644
--- a/base/mac/bind_objc_block_unittest.mm
+++ b/base/mac/bind_objc_block_unittest.mm
@@ -4,6 +4,8 @@
 
 #import "base/mac/bind_objc_block.h"
 
+#include <string>
+
 #include "base/callback.h"
 #include "base/bind.h"
 #include "base/callback_helpers.h"
@@ -51,4 +53,15 @@ TEST(BindObjcBlockTest, TestArgument) {
   EXPECT_EQ(kArgument + 1, c.Run(kArgument));
 }
 
+TEST(BindObjcBlockTest, TestTwoArguments) {
+  std::string result;
+  std::string* ptr = &result;
+  base::Callback<void(const std::string&, const std::string&)> c =
+      base::BindBlock(^(const std::string& a, const std::string& b) {
+          *ptr = a + b;
+      });
+  c.Run("forty", "two");
+  EXPECT_EQ(result, "fortytwo");
+}
+
 }  // namespace