Report NullPointerException when we try to construct a regular expression

lib/regexp.cc

Index: lib/regexp.cc
===================================================================
--- lib/regexp.cc	(revision 713)
+++ lib/regexp.cc	(working copy)
@@ -5,6 +5,7 @@
 #include "vm/bootstrap_natives.h"
 
 #include "vm/assert.h"
+#include "vm/dart_entry.h"
 #include "vm/exceptions.h"
 #include "vm/native_entry.h"
 #include "vm/object.h"
@@ -13,9 +14,18 @@
 
 namespace dart {
 
+static void CheckAndThrowExceptionIfNull(const Instance& obj) {
+  if (obj.IsNull()) {
+    GrowableArray<const Object*> args;
+    Exceptions::ThrowByType(Exceptions::kNullPointer, args);
+  }
+}
+
+
 DEFINE_NATIVE_ENTRY(JSSyntaxRegExp_factory, 4) {
   ASSERT(TypeArguments::CheckedHandle(arguments->At(0)).IsNull());
   const String& pattern = String::CheckedHandle(arguments->At(1));
+  CheckAndThrowExceptionIfNull(pattern);
   const Instance& handle_multi_line = Instance::CheckedHandle(arguments->At(2));
   const Instance& handle_ignore_case =
       Instance::CheckedHandle(arguments->At(3));
@@ -29,6 +39,7 @@
 
 DEFINE_NATIVE_ENTRY(JSSyntaxRegExp_getPattern, 1) {
   const JSRegExp& regexp = JSRegExp::CheckedHandle(arguments->At(0));
+  ASSERT(!regexp.IsNull());
   const String& result = String::Handle(regexp.pattern());
   arguments->SetReturn(result);
 }
@@ -36,6 +47,7 @@
 
 DEFINE_NATIVE_ENTRY(JSSyntaxRegExp_multiLine, 1) {
   const JSRegExp& regexp = JSRegExp::CheckedHandle(arguments->At(0));
+  ASSERT(!regexp.IsNull());
   const Bool& result = Bool::Handle(Bool::Get(regexp.is_multi_line()));
   arguments->SetReturn(result);
 }
@@ -43,6 +55,7 @@
 
 DEFINE_NATIVE_ENTRY(JSSyntaxRegExp_ignoreCase, 1) {
   const JSRegExp& regexp = JSRegExp::CheckedHandle(arguments->At(0));
+  ASSERT(!regexp.IsNull());
   const Bool& result = Bool::Handle(Bool::Get(regexp.is_ignore_case()));
   arguments->SetReturn(result);
 }
@@ -50,6 +63,7 @@
 
 DEFINE_NATIVE_ENTRY(JSSyntaxRegExp_getGroupCount, 1) {
   const JSRegExp& regexp = JSRegExp::CheckedHandle(arguments->At(0));
+  ASSERT(!regexp.IsNull());
   if (regexp.is_initialized()) {
     const Smi& result = Smi::Handle(regexp.num_bracket_expressions());
     arguments->SetReturn(result);
@@ -67,7 +81,9 @@
 
 DEFINE_NATIVE_ENTRY(JSSyntaxRegExp_ExecuteMatch, 3) {
   const JSRegExp& regexp = JSRegExp::CheckedHandle(arguments->At(0));
+  ASSERT(!regexp.IsNull());
   const String& str = String::CheckedHandle(arguments->At(1));
+  CheckAndThrowExceptionIfNull(str);

[turnidge, 2011/10/27 17:08:19]

I just wanted to point out that by putting the check in the C++ code instead of
the dart code, we will miss out on the chance to eliminate the null check in
cases where the compiler knows that str is non-null -- for example, if it has
just been allocated.  Not sure how much this matters though.

[siva, 2011/10/28 06:14:43]

Doing null pointer checks and throwing NullPointerException in dart code seems
weird as it is supposed to happen through a call to noSuchMethod.
I am trying to see if it would be possible to access str in dart code and
trigger a call to noSuchMethod, probably for another CL.

On 2011/10/27 17:08:19, turnidge wrote:

   const Smi& start_index = Smi::CheckedHandle(arguments->At(2));
   const Array& result =
       Array::Handle(Jscre::Execute(regexp, str, start_index.Value()));