Add a --element-count option to the expression command

This option evaluates an expression and, if the result is of pointer type, treats it as if it was an array of that many elements and displays such elements

This has a couple subtle points but is mostly as straightforward as it sounds

Add a parray N <expr> alias for this new mode

Also, extend the --object-description mode to do the moral equivalent of the above but display each element in --object-description mode
Add a poarray N <expr> alias for this

llvm-svn: 267372

14 files changed, 294 insertions, 13 deletions

diff --git a/lldb/include/lldb/DataFormatters/DumpValueObjectOptions.h b/lldb/include/lldb/DataFormatters/DumpValueObjectOptions.h
index f65ee7b9584..e90bd1bcadc 100644
--- a/lldb/include/lldb/DataFormatters/DumpValueObjectOptions.h
+++ b/lldb/include/lldb/DataFormatters/DumpValueObjectOptions.h
@@ -152,6 +152,9 @@ public:
 
     DumpValueObjectOptions&
     SetRevealEmptyAggregates (bool reveal = true);
+    
+    DumpValueObjectOptions&
+    SetElementCount (uint32_t element_count = 0);
 
 public:
     uint32_t m_max_depth = UINT32_MAX;
@@ -163,6 +166,7 @@ public:
     lldb::LanguageType m_varformat_language = lldb::eLanguageTypeUnknown;
     PointerDepth m_max_ptr_depth;
     DeclPrintingHelper m_decl_printing_helper;
+    uint32_t m_element_count = 0;
     bool m_use_synthetic : 1;
     bool m_scope_already_checked : 1;
     bool m_flat_output : 1;
diff --git a/lldb/include/lldb/DataFormatters/ValueObjectPrinter.h b/lldb/include/lldb/DataFormatters/ValueObjectPrinter.h
index 23d7ee2edf5..c7591b01968 100644
--- a/lldb/include/lldb/DataFormatters/ValueObjectPrinter.h
+++ b/lldb/include/lldb/DataFormatters/ValueObjectPrinter.h
@@ -153,6 +153,10 @@ protected:
     void
     PrintChildrenPostamble (bool print_dotdotdot);
     
+    lldb::ValueObjectSP
+    GenerateChild (ValueObject* synth_valobj,
+                   size_t idx);
+    
     void
     PrintChild (lldb::ValueObjectSP child_sp,
                 const DumpValueObjectOptions::PointerDepth& curr_ptr_depth);
diff --git a/lldb/include/lldb/Interpreter/OptionGroupValueObjectDisplay.h b/lldb/include/lldb/Interpreter/OptionGroupValueObjectDisplay.h
index 53c8550da81..86e4c1662e6 100644
--- a/lldb/include/lldb/Interpreter/OptionGroupValueObjectDisplay.h
+++ b/lldb/include/lldb/Interpreter/OptionGroupValueObjectDisplay.h
@@ -77,6 +77,7 @@ public:
     uint32_t no_summary_depth;
     uint32_t max_depth;
     uint32_t ptr_depth;
+    uint32_t elem_count;
     lldb::DynamicValueType use_dynamic;
 };
 
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/parray/Makefile b/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/parray/Makefile
new file mode 100644
index 00000000000..314f1cb2f07
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/parray/Makefile
@@ -0,0 +1,5 @@
+LEVEL = ../../../make
+
+CXX_SOURCES := main.cpp
+
+include $(LEVEL)/Makefile.rules
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/parray/TestPrintArray.py b/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/parray/TestPrintArray.py
new file mode 100644
index 00000000000..700b7418118
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/parray/TestPrintArray.py
@@ -0,0 +1,70 @@
+"""
+Test lldb data formatter subsystem.
+"""
+
+from __future__ import print_function
+
+
+
+import datetime
+import os, time
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+class PrintArrayTestCase(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    def test_print_array(self):
+        """Test that expr -Z works"""
+        self.build()
+        self.printarray_data_formatter_commands()
+
+    def setUp(self):
+        # Call super's setUp().
+        TestBase.setUp(self)
+        # Find the line number to break at.
+        self.line = line_number('main.cpp', 'break here')
+
+    def printarray_data_formatter_commands(self):
+        """Test that expr -Z works"""
+        self.runCmd("file a.out", CURRENT_EXECUTABLE_SET)
+
+        lldbutil.run_break_set_by_file_and_line (self, "main.cpp", self.line, num_expected_locations=1, loc_exact=True)
+
+        self.runCmd("run", RUN_SUCCEEDED)
+
+        # The stop reason of the thread should be breakpoint.
+        self.expect("thread list", STOPPED_DUE_TO_BREAKPOINT,
+            substrs = ['stopped',
+                       'stop reason = breakpoint'])
+
+        # This is the function to remove the custom formats in order to have a
+        # clean slate for the next test case.
+        def cleanup():
+            self.runCmd('type format clear', check=False)
+            self.runCmd('type summary clear', check=False)
+            self.runCmd('type synth clear', check=False)
+
+        # Execute the cleanup function during test case tear down.
+        self.addTearDownHook(cleanup)
+        
+        self.expect('expr --element-count 3 -- data', substrs=['[0] = 1', '[1] = 3', '[2] = 5'])
+        self.expect('expr data', substrs=['int *', '$', '0x'])
+        self.expect('expr -f binary --element-count 0 -- data', substrs=['int *', '$', '0b'])
+        self.expect('expr -f hex --element-count 3 -- data', substrs=['[0] = 0x', '1', '[1] = 0x', '3', '[2] = 0x', '5'])
+        self.expect('expr -f binary --element-count 2 -- data', substrs=['int *', '$', '0x', '[0] = 0b', '1', '[1] = 0b', '11'])
+        self.expect('parray 3 data', substrs=['[0] = 1', '[1] = 3', '[2] = 5'])
+        self.expect('parray `1 + 1 + 1` data', substrs=['[0] = 1', '[1] = 3', '[2] = 5'])
+        self.expect('parray `data[1]` data', substrs=['[0] = 1', '[1] = 3', '[2] = 5'])
+        self.expect('parray/x 3 data', substrs=['[0] = 0x', '1', '[1] = 0x', '3', '[2] = 0x', '5'])
+        self.expect('parray/x `data[1]` data', substrs=['[0] = 0x', '1', '[1] = 0x', '3', '[2] = 0x', '5'])
+
+        # check error conditions
+        self.expect('expr --element-count 10 -- 123', error=True, substrs=['expression cannot be used with --element-count as it does not refer to a pointer'])
+        self.expect('expr --element-count 10 -- (void*)123', error=True, substrs=['expression cannot be used with --element-count as it refers to a pointer to void'])
+        self.expect('parray data', error=True, substrs=["invalid element count 'data'"])
+        self.expect('parray data data', error=True, substrs=["invalid element count 'data'"])
+        self.expect('parray', error=True, substrs=['Not enough arguments provided'])
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/parray/main.cpp b/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/parray/main.cpp
new file mode 100644
index 00000000000..b2d6309947a
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/parray/main.cpp
@@ -0,0 +1,29 @@
+//===-- main.cpp -------------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include <functional>
+#include <stdlib.h>
+
+template<typename ElemType>
+ElemType* alloc(size_t count, std::function<ElemType(size_t)> get)
+{
+  ElemType *elems = new ElemType[count];
+  for(size_t i = 0; i < count; i++)
+    elems[i] = get(i);
+  return elems;
+}
+
+int main (int argc, const char * argv[])
+{
+  int* data = alloc<int>(5, [] (size_t idx) -> int {
+    return 2 * idx + 1;
+  });
+  return 0; // break here
+}
+
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/poarray/Makefile b/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/poarray/Makefile
new file mode 100644
index 00000000000..261658b10ae
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/poarray/Makefile
@@ -0,0 +1,9 @@
+LEVEL = ../../../make
+
+OBJCXX_SOURCES := main.mm
+
+CFLAGS_EXTRAS += -w
+
+include $(LEVEL)/Makefile.rules
+
+LDFLAGS += -framework Foundation
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/poarray/TestPrintObjectArray.py b/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/poarray/TestPrintObjectArray.py
new file mode 100644
index 00000000000..7eb26a56986
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/poarray/TestPrintObjectArray.py
@@ -0,0 +1,60 @@
+"""
+Test lldb data formatter subsystem.
+"""
+
+from __future__ import print_function
+
+
+
+import datetime
+import os, time
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+class PrintObjectArrayTestCase(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    @skipUnlessDarwin
+    def test_print_array(self):
+        """Test that expr -O -Z works"""
+        self.build()
+        self.printarray_data_formatter_commands()
+
+    def setUp(self):
+        # Call super's setUp().
+        TestBase.setUp(self)
+        # Find the line number to break at.
+        self.line = line_number('main.mm', 'break here')
+
+    def printarray_data_formatter_commands(self):
+        """Test that expr -O -Z works"""
+        self.runCmd("file a.out", CURRENT_EXECUTABLE_SET)
+
+        lldbutil.run_break_set_by_file_and_line (self, "main.mm", self.line, num_expected_locations=1, loc_exact=True)
+
+        self.runCmd("run", RUN_SUCCEEDED)
+
+        # The stop reason of the thread should be breakpoint.
+        self.expect("thread list", STOPPED_DUE_TO_BREAKPOINT,
+            substrs = ['stopped',
+                       'stop reason = breakpoint'])
+
+        # This is the function to remove the custom formats in order to have a
+        # clean slate for the next test case.
+        def cleanup():
+            self.runCmd('type format clear', check=False)
+            self.runCmd('type summary clear', check=False)
+            self.runCmd('type synth clear', check=False)
+
+        # Execute the cleanup function during test case tear down.
+        self.addTearDownHook(cleanup)
+
+        self.expect('expr --element-count 3 --object-description -- objects', substrs=['3735928559', '4276993775', '3203398366', 'Hello', 'World', 'Two =', '1 ='])
+        self.expect('poarray 3 objects', substrs=['3735928559', '4276993775', '3203398366', 'Hello', 'World', 'Two =', '1 ='])
+        self.expect('expr --element-count 3 --object-description --description-verbosity=full -- objects', substrs=['[0] =', '3735928559', '4276993775', '3203398366', '[1] =', 'Hello', 'World', '[2] =', 'Two =', '1 ='])
+        self.expect('parray 3 objects', substrs=['[0] = 0x', '[1] = 0x', '[2] = 0x'])
+        self.expect('expr --element-count 3 -d run -- objects', substrs=['3 elements', '2 elements', '2 key/value pairs'])
+        self.expect('expr --element-count 3 -d run --ptr-depth=1 -- objects', substrs=['3 elements', '2 elements', '2 key/value pairs', '3735928559', '4276993775', '3203398366', '"Hello"', '"World"'])
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/poarray/main.mm b/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/poarray/main.mm
new file mode 100644
index 00000000000..9ef61e6a73f
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/poarray/main.mm
@@ -0,0 +1,30 @@
+//===-- main.cpp -------------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#import <Foundation/Foundation.h>
+
+struct ThreeObjects
+{
+  id one;
+  id two;
+  id three;
+};
+
+int main()
+{
+  NSArray *array1 = @[@0xDEADBEEF, @0xFEEDBEEF, @0xBEEFFADE];
+  NSArray *array2 = @[@"Hello", @"World"];
+  NSDictionary *dictionary = @{@1: array2, @"Two": array2};
+  ThreeObjects *tobjects = new ThreeObjects();
+  tobjects->one = array1;
+  tobjects->two = array2;
+  tobjects->three = dictionary;
+  id* objects = (id*)tobjects;
+  return 0; // break here
+}
diff --git a/lldb/source/Commands/CommandObjectExpression.cpp b/lldb/source/Commands/CommandObjectExpression.cpp
index 25a88449c52..431b3d4ff88 100644
--- a/lldb/source/Commands/CommandObjectExpression.cpp
+++ b/lldb/source/Commands/CommandObjectExpression.cpp
@@ -282,6 +282,18 @@ CommandObjectExpression::GetOptions ()
     return &m_option_group;
 }
 
+static lldb_private::Error
+CanBeUsedForElementCountPrinting (ValueObject& valobj)
+{
+    CompilerType type(valobj.GetCompilerType());
+    CompilerType pointee;
+    if (!type.IsPointerType(&pointee))
+        return Error("as it does not refer to a pointer");
+    if (pointee.IsVoidType())
+        return Error("as it refers to a pointer to void");
+    return Error();
+}
+
 bool
 CommandObjectExpression::EvaluateExpression(const char *expr,
                                             Stream *output_stream,
@@ -356,6 +368,17 @@ CommandObjectExpression::EvaluateExpression(const char *expr,
                     if (format != eFormatDefault)
                         result_valobj_sp->SetFormat (format);
 
+                    if (m_varobj_options.elem_count > 0)
+                    {
+                        Error error(CanBeUsedForElementCountPrinting(*result_valobj_sp));
+                        if (error.Fail())
+                        {
+                            result->AppendErrorWithFormat("expression cannot be used with --element-count %s\n", error.AsCString(""));
+                            result->SetStatus(eReturnStatusFailed);
+                            return false;
+                        }
+                    }
+
                     DumpValueObjectOptions options(m_varobj_options.GetAsDumpOptions(m_command_options.m_verbosity,format));
                     options.SetVariableFormatDisplayLanguage(result_valobj_sp->GetPreferredDisplayLanguage());
 
diff --git a/lldb/source/DataFormatters/DumpValueObjectOptions.cpp b/lldb/source/DataFormatters/DumpValueObjectOptions.cpp
index f3de1257bb8..e1f5320feee 100644
--- a/lldb/source/DataFormatters/DumpValueObjectOptions.cpp
+++ b/lldb/source/DataFormatters/DumpValueObjectOptions.cpp
@@ -242,4 +242,10 @@ DumpValueObjectOptions::SetRevealEmptyAggregates (bool reveal)
     m_reveal_empty_aggregates = reveal;
     return *this;
 }
-                                
+
+DumpValueObjectOptions&
+DumpValueObjectOptions::SetElementCount (uint32_t element_count)
+{
+    m_element_count = element_count;
+    return *this;
+}
diff --git a/lldb/source/DataFormatters/ValueObjectPrinter.cpp b/lldb/source/DataFormatters/ValueObjectPrinter.cpp
index 04c29128354..167afca7fbb 100644
--- a/lldb/source/DataFormatters/ValueObjectPrinter.cpp
+++ b/lldb/source/DataFormatters/ValueObjectPrinter.cpp
@@ -416,11 +416,12 @@ ValueObjectPrinter::GetValueSummaryError (std::string& value,
                                           std::string& summary,
                                           std::string& error)
 {
-    if (m_options.m_format != eFormatDefault && m_options.m_format != m_valobj->GetFormat())
-    {
-        m_valobj->GetValueAsCString(m_options.m_format,
-                                    value);
-    }
+    lldb::Format format = m_options.m_format;
+    // if I am printing synthetized elements, apply the format to those elements only
+    if (m_options.m_element_count > 0)
+        m_valobj->GetValueAsCString(lldb::eFormatDefault, value);
+    else if (format != eFormatDefault && format != m_valobj->GetFormat())
+        m_valobj->GetValueAsCString(format, value);
     else
     {
         const char* val_cstr = m_valobj->GetValueAsCString();
@@ -514,7 +515,7 @@ ValueObjectPrinter::PrintObjectDescriptionIfNeeded (bool value_printed,
     if (ShouldPrintValueObject())
     {
         // let's avoid the overly verbose no description error for a nil thing
-        if (m_options.m_use_objc && !IsNil() && !IsUninitialized())
+        if (m_options.m_use_objc && !IsNil() && !IsUninitialized() && (m_options.m_element_count == 0))
         {
             if (!m_options.m_hide_value || !m_options.m_hide_name)
                 m_stream->Printf(" ");
@@ -587,6 +588,11 @@ ValueObjectPrinter::ShouldPrintChildren (bool is_failed_description,
     if (is_uninit)
         return false;
     
+    // if the user has specified an element count, always print children
+    // as it is explicit user demand being honored
+    if (m_options.m_element_count > 0)
+        return true;
+    
     TypeSummaryImpl* entry = GetSummaryFormatter();
     
     if (m_options.m_use_objc)
@@ -667,18 +673,22 @@ void
 ValueObjectPrinter::PrintChild (ValueObjectSP child_sp,
                                 const DumpValueObjectOptions::PointerDepth& curr_ptr_depth)
 {
+    const uint32_t consumed_depth = (m_options.m_element_count == 0) ? 1 : 0;
+    const bool does_consume_ptr_depth = ((IsPtr() && m_options.m_element_count == 0) || IsRef());
+
     DumpValueObjectOptions child_options(m_options);
     child_options.SetFormat(m_options.m_format).SetSummary().SetRootValueObjectName();
     child_options.SetScopeChecked(true).SetHideName(m_options.m_hide_name).SetHideValue(m_options.m_hide_value)
-    .SetOmitSummaryDepth(child_options.m_omit_summary_depth > 1 ? child_options.m_omit_summary_depth - 1 : 0);
+    .SetOmitSummaryDepth(child_options.m_omit_summary_depth > 1 ? child_options.m_omit_summary_depth - consumed_depth : 0)
+    .SetElementCount(0);
     
     if (child_sp.get())
     {
         ValueObjectPrinter child_printer(child_sp.get(),
                                          m_stream,
                                          child_options,
-                                         (IsPtr() || IsRef()) ? --curr_ptr_depth : curr_ptr_depth,
-                                         m_curr_depth + 1,
+                                         does_consume_ptr_depth ? --curr_ptr_depth : curr_ptr_depth,
+                                         m_curr_depth + consumed_depth,
                                          m_printed_instance_pointers);
         child_printer.PrintValueObject();
     }
@@ -689,6 +699,9 @@ ValueObjectPrinter::GetMaxNumChildrenToPrint (bool& print_dotdotdot)
 {
     ValueObject* synth_m_valobj = GetValueObjectForChildrenGeneration();
     
+    if (m_options.m_element_count > 0)
+        return m_options.m_element_count;
+    
     size_t num_children = synth_m_valobj->GetNumChildren();
     print_dotdotdot = false;
     if (num_children)
@@ -743,6 +756,21 @@ ValueObjectPrinter::ShouldPrintEmptyBrackets (bool value_printed,
     return true;
 }
 
+ValueObjectSP
+ValueObjectPrinter::GenerateChild (ValueObject* synth_valobj, size_t idx)
+{
+    if (m_options.m_element_count > 0)
+    {
+        // if generating pointer-as-array children, use GetSyntheticArrayMember
+        return synth_valobj->GetSyntheticArrayMember(idx, true);
+    }
+    else
+    {
+        // otherwise, do the usual thing
+        return synth_valobj->GetChildAtIndex(idx, true);
+    }
+}
+
 void
 ValueObjectPrinter::PrintChildren (bool value_printed,
                                    bool summary_printed,
@@ -758,8 +786,7 @@ ValueObjectPrinter::PrintChildren (bool value_printed,
         
         for (size_t idx=0; idx<num_children; ++idx)
         {
-            ValueObjectSP child_sp(synth_m_valobj->GetChildAtIndex(idx, true));
-            if (child_sp)
+            if (ValueObjectSP child_sp = GenerateChild(synth_m_valobj, idx))
             {
                 if (!any_children_printed)
                 {
@@ -866,6 +893,7 @@ ValueObjectPrinter::PrintChildrenIfNeeded (bool value_printed,
                           m_options.m_show_types ||
                           !m_options.m_allow_oneliner_mode ||
                           m_options.m_flat_output ||
+                          (m_options.m_element_count > 0) ||
                           m_options.m_show_location) ? false : DataVisualization::ShouldPrintAsOneLiner(*m_valobj);
     bool is_instance_ptr = IsInstancePointer();
     uint64_t instance_ptr_value = LLDB_INVALID_ADDRESS;
diff --git a/lldb/source/Interpreter/CommandInterpreter.cpp b/lldb/source/Interpreter/CommandInterpreter.cpp
index b28c44a5272..bf6cded4e92 100644
--- a/lldb/source/Interpreter/CommandInterpreter.cpp
+++ b/lldb/source/Interpreter/CommandInterpreter.cpp
@@ -348,6 +348,8 @@ CommandInterpreter::Initialize ()
             po->SetHelp("Evaluate an expression in the current program context, using user defined variables and variables currently in scope, and display the result of evaluation in a language-specific manner.");
             po->SetHelpLong("");
         }
+        AddAlias("parray", cmd_obj_sp, "--element-count %1 --")->SetHelpLong("");
+        AddAlias("poarray", cmd_obj_sp, "--object-description --element-count %1 --")->SetHelpLong("");
     }
     
     cmd_obj_sp = GetCommandSPExact ("process kill", false);
diff --git a/lldb/source/Interpreter/OptionGroupValueObjectDisplay.cpp b/lldb/source/Interpreter/OptionGroupValueObjectDisplay.cpp
index bbd966859c3..c30a978d957 100644
--- a/lldb/source/Interpreter/OptionGroupValueObjectDisplay.cpp
+++ b/lldb/source/Interpreter/OptionGroupValueObjectDisplay.cpp
@@ -44,7 +44,8 @@ g_option_table[] =
     { LLDB_OPT_SET_1, false, "no-summary-depth",   'Y', OptionParser::eOptionalArgument, nullptr, nullptr, 0, eArgTypeCount,     "Set the depth at which omitting summary information stops (default is 1)."},
     { LLDB_OPT_SET_1, false, "raw-output",         'R', OptionParser::eNoArgument,       nullptr, nullptr, 0, eArgTypeNone,      "Don't use formatting options."},
     { LLDB_OPT_SET_1, false, "show-all-children",  'A', OptionParser::eNoArgument,       nullptr, nullptr, 0, eArgTypeNone,      "Ignore the upper bound on the number of children to show."},
-    { LLDB_OPT_SET_1, false, "validate",           'V',  OptionParser::eRequiredArgument, nullptr, nullptr, 0, eArgTypeBoolean,   "Show results of type validators."},
+    { LLDB_OPT_SET_1, false, "validate",           'V',  OptionParser::eRequiredArgument, nullptr, nullptr,0, eArgTypeBoolean,   "Show results of type validators."},
+    { LLDB_OPT_SET_1, false, "element-count",      'Z', OptionParser::eRequiredArgument, nullptr, nullptr, 0, eArgTypeCount,     "Treat the result of the expression as if its type is an array of this many values."},
     { 0, false, nullptr, 0, 0, nullptr, nullptr, 0, eArgTypeNone, nullptr }
 };
 
@@ -92,6 +93,12 @@ OptionGroupValueObjectDisplay::SetOptionValue (CommandInterpreter &interpreter,
             if (!success)
                 error.SetErrorStringWithFormat("invalid max depth '%s'", option_arg);
             break;
+
+        case 'Z':
+            elem_count = StringConvert::ToUInt32 (option_arg, UINT32_MAX, 0, &success);
+            if (!success)
+                error.SetErrorStringWithFormat("invalid element count '%s'", option_arg);
+            break;
             
         case 'P':
             ptr_depth = StringConvert::ToUInt32 (option_arg, 0, 0, &success);
@@ -141,6 +148,7 @@ OptionGroupValueObjectDisplay::OptionParsingStarting (CommandInterpreter &interp
     use_objc          = false;
     max_depth         = UINT32_MAX;
     ptr_depth         = 0;
+    elem_count        = 0;
     use_synth         = true;
     be_raw            = false;
     ignore_cap        = false;
@@ -187,6 +195,8 @@ OptionGroupValueObjectDisplay::GetAsDumpOptions (LanguageRuntimeDescriptionDispl
         options.SetRawDisplay();
     
     options.SetRunValidator(run_validator);
+    
+    options.SetElementCount(elem_count);
 
     return options;
 }