mojom: Add associative arrays to the mojom language.

mojo/public/cpp/bindings/string.h

Index: mojo/public/cpp/bindings/string.h
diff --git a/mojo/public/cpp/bindings/string.h b/mojo/public/cpp/bindings/string.h
index cd7db26e8230a8f1fa1df62822e3d972bb60e571..fcc4739f252dec4c3c210515d3e856babb3ca28c 100644
--- a/mojo/public/cpp/bindings/string.h
+++ b/mojo/public/cpp/bindings/string.h
@@ -40,6 +40,11 @@ class String {
     return TypeConverter<U, String>::Convert(*this);
   }
 
+  String& operator=(const mojo::String& str) {

[yzshen1, 2014/09/27 00:01:58]

Do you also want to add a copy constructor?

[Elliot Glaysher, 2014/10/02 19:54:03]

Done.

+    value_ = str.value_;
+    is_null_ = str.is_null_;
+    return *this;
+  }
   String& operator=(const std::string& str) {
     value_ = str;
     is_null_ = false;
@@ -110,6 +115,19 @@ inline std::ostream& operator<<(std::ostream& out, const String& s) {
   return out << s.get();
 }
 
+inline bool operator<(const String& a, const String& b) {
+  // TODO(erg): This needs a test.
+  if (a.is_null() && !b.is_null()) {
+    // The null string is less than a non-NULL string.
+    return true;
+  } else if (a.is_null() || b.is_null()) {
+    // in all other cases where A or B is NULL, |a| is not less than |b|.
+    return false;
+  }
+
+  return a.get() < b.get();
+}
+
 // TODO(darin): Add similar variants of operator<,<=,>,>=
 
 template <>