Add dataformatter for NSDecimalNumber

[JDevlieghere]

Summary

This patch adds a data formatter for NSDecimalNumber. The latter is a Foundation object used for representing and performing arithmetic on base-10 numbers that bridges to Decimal.

[aprantl]

source/Plugins/Language/ObjC/Cocoa.cpp

462

Side note: It would be slightly faster/elegant to use a StringRef instead of the char* for the comparisons.

639

Since the whole structure is one packed bitfield, an alternative implementation would be to read all 16b at once and memcpy to a local variable bitfield and let the compiler do the unpacking; that might be shorter. This version seems fine, too.

[davide]

I didn't check whether the representation was correct (although it looks lo). The structure of the patch looks fine to me, thanks for adding the comments :)

[jingham]

This looks fine to me. Nothing in the TypeSummaryOptions is relevant to printing these numbers, so it's correct to ignore them.

packages/Python/lldbsuite/test/functionalities/data-formatter/data-formatter-objc/TestDataFormatterObjC.py

def nsnumber_data_formatter_commands(self):
         self.assertTrue(i128_handled_correctly, "Expected valid output for int128_t; got " + output)
 
         self.expect('frame variable num_at1 num_at2 num_at3 num_at4',
                     substrs=['(NSNumber *) num_at1 = ', ' (int)12',
                              '(NSNumber *) num_at2 = ', ' (int)-12',
                              '(NSNumber *) num_at3 = ', ' (double)12.5',
                              '(NSNumber *) num_at4 = ', ' (double)-12.5'])
 
+    def nsdecimalnumber_data_formatter_commands(self):
+        self.expect('frame variable decimal_number decimal_neg_number decimal_one decimal_zero decimal_nan',
+                    substrs=['(NSDecimalNumber *) decimal_number = ', '123456 x 10^-10',
+                             '(NSDecimalNumber *) decimal_neg_number = ', '-123456 x 10^10',
+                             '(NSDecimalNumber *) decimal_one = ', '1 x 10^0',
+                             '(NSDecimalNumber *) decimal_zero = ', '0',
+                             '(NSDecimalNumber *) decimal_nan = ', 'NaN'])
+
     def nscontainers_data_formatter_commands(self):
         self.expect(
             'frame variable newArray newDictionary newMutableDictionary cfarray_ref mutable_array_ref',
             substrs=[
                 '(NSArray *) newArray = ',
                 '@"50 elements"',
                 '(NSDictionary *) newDictionary = ',
                 ' 12 key/value pairs',

packages/Python/lldbsuite/test/functionalities/data-formatter/data-formatter-objc/main.m

[object2 doIncrementByInt:3];
       NSNumber* num8_Y = [NSNumber numberWithBool:YES];
       NSNumber* num8_N = [NSNumber numberWithBool:NO];
       NSNumber* num9 = [NSNumber numberWithShort:0x1E8480];
       NSNumber* num_at1 = @12;
       NSNumber* num_at2 = @-12;
       NSNumber* num_at3 = @12.5;
       NSNumber* num_at4 = @-12.5;
 
-    NSDecimalNumber* decimal_one = [NSDecimalNumber one];
+      NSDecimalNumber* decimal_number = [NSDecimalNumber decimalNumberWithMantissa:123456 exponent:-10 isNegative:NO];
+      NSDecimalNumber* decimal_number_neg = [NSDecimalNumber decimalNumberWithMantissa:123456 exponent:10 isNegative:YES];
+      NSDecimalNumber* decimal_one = [NSDecimalNumber one];
+      NSDecimalNumber* decimal_zero = [NSDecimalNumber zero];
+      NSDecimalNumber* decimal_nan = [NSDecimalNumber notANumber];
 
       NSString *str0 = [num6 stringValue];
 
       NSString *str1 = [NSString stringWithCString:"A rather short ASCII NSString object is here" encoding:NSASCIIStringEncoding];
 
       NSString *str2 = [NSString stringWithUTF8String:"A rather short UTF8 NSString object is here"];
 
       NSString *str3 = @"A string made with the at sign is here";

source/Plugins/Language/ObjC/Cocoa.h

 
 template <bool needs_at>
 bool NSDataSummaryProvider(ValueObject &valobj, Stream &stream,
                            const TypeSummaryOptions &options);
 
 bool NSNumberSummaryProvider(ValueObject &valobj, Stream &stream,
                              const TypeSummaryOptions &options);
 
+bool NSDecimalNumberSummaryProvider(ValueObject &valobj, Stream &stream,
+                             const TypeSummaryOptions &options);
+
 bool NSNotificationSummaryProvider(ValueObject &valobj, Stream &stream,
                                    const TypeSummaryOptions &options);
 
 bool NSTimeZoneSummaryProvider(ValueObject &valobj, Stream &stream,
                                const TypeSummaryOptions &options);
 
 bool NSMachPortSummaryProvider(ValueObject &valobj, Stream &stream,
                                const TypeSummaryOptions &options);

source/Plugins/Language/ObjC/Cocoa.cpp

bool lldb_private::formatters::NSNumberSummaryProvider(
   const char *class_name = descriptor->GetClassName().GetCString();
 
   if (!class_name || !*class_name)
     return false;
 
   if (!strcmp(class_name, "__NSCFBoolean"))
     return ObjCBooleanSummaryProvider(valobj, stream, options);
 
+  if (!strcmp(class_name, "NSDecimalNumber"))
+    return NSDecimalNumberSummaryProvider(valobj, stream, options);
+
   if (!strcmp(class_name, "NSNumber") || !strcmp(class_name, "__NSCFNumber")) {
     uint64_t value = 0;
     uint64_t i_bits = 0;
     if (descriptor->GetTaggedPointerInfo(&i_bits, &value)) {
       switch (i_bits) {
       case 0:
         NSNumber_FormatChar(valobj, stream, (char)value, options.GetLanguage());
         break;
if (descriptor->GetTaggedPointerInfo(&i_bits, &value)) {
       }
       return success;
     }
   }
 
   return false;
 }
 
+bool lldb_private::formatters::NSDecimalNumberSummaryProvider(
+    ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
+  ProcessSP process_sp = valobj.GetProcessSP();
+  if (!process_sp)
+    return false;
+
+  lldb::addr_t valobj_addr = valobj.GetValueAsUnsigned(0);
+  uint32_t ptr_size = process_sp->GetAddressByteSize();
+
+  Status error;
+  int8_t exponent = process_sp->ReadUnsignedIntegerFromMemory(
+      valobj_addr + ptr_size, 1, 0, error);
+  if (error.Fail())
+    return false;
+
+  uint8_t length_and_negative = process_sp->ReadUnsignedIntegerFromMemory(
+      valobj_addr + ptr_size + 1, 1, 0, error);
+  if (error.Fail())
+    return false;
+
+  // Fifth bit marks negativity.
+  const bool is_negative = (length_and_negative >> 4) & 1;
+
+  // Zero length and negative means NaN.
+  uint8_t length = length_and_negative & 0xf;
+  const bool is_nan = is_negative && (length == 0);
+
+  if (is_nan) {
+    stream.Printf("NaN");
+    return true;
+  }
+
+  if (length == 0) {
+    stream.Printf("0");
+    return true;
+  }
+
+  uint64_t mantissa = process_sp->ReadUnsignedIntegerFromMemory(
+      valobj_addr + ptr_size + 4, 8, 0, error);
+  if (error.Fail())
+    return false;
+
+  if (is_negative)
+    stream.Printf("-");
+
+  stream.Printf("%" PRIu64 " x 10^%" PRIi8, mantissa, exponent);
+  return true;
+}
+
 bool lldb_private::formatters::NSURLSummaryProvider(
     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
   ProcessSP process_sp = valobj.GetProcessSP();
   if (!process_sp)
     return false;
 
   ObjCLanguageRuntime *runtime =
       (ObjCLanguageRuntime *)process_sp->GetLanguageRuntime(

source/Plugins/Language/ObjC/ObjCLanguage.cpp

AddCXXSummary(
       objc_category_sp, lldb_private::formatters::NSNumberSummaryProvider,
       "NSNumber summary provider", ConstString("__NSCFNumber"), appkit_flags);
   AddCXXSummary(
       objc_category_sp, lldb_private::formatters::NSNumberSummaryProvider,
       "NSNumber summary provider", ConstString("NSCFBoolean"), appkit_flags);
   AddCXXSummary(
       objc_category_sp, lldb_private::formatters::NSNumberSummaryProvider,
       "NSNumber summary provider", ConstString("NSCFNumber"), appkit_flags);
+  AddCXXSummary(objc_category_sp,
+                lldb_private::formatters::NSNumberSummaryProvider,
+                "NSDecimalNumber summary provider",
+                ConstString("NSDecimalNumber"), appkit_flags);
 
   AddCXXSummary(objc_category_sp,
                 lldb_private::formatters::NSURLSummaryProvider,
                 "NSURL summary provider", ConstString("NSURL"), appkit_flags);
   AddCXXSummary(
       objc_category_sp, lldb_private::formatters::NSURLSummaryProvider,
       "NSURL summary provider", ConstString("CFURLRef"), appkit_flags);