Patchwork [Chris,Moller] Re: [tools-team] 11874 Vector pretty-printer chokes on bit-vectors

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Submitter Tom Tromey
Date Aug. 16, 2010, 6:39 p.m.
Message ID <m3k4nqmmfu.fsf@fleche.redhat.com>
Download mbox | patch
Permalink /patch/61826/
State New
Headers show

Comments

Tom Tromey - Aug. 16, 2010, 6:39 p.m.
I am checking this in.

This specializes the std::vector printer to handle std::vector<bool>,
which are represented differently.  This is gdb PR 11874; I'll fix up
the ChangeLog entry to mention that.
On 08/13/10 17:57, Tom Tromey wrote:
> Chris>  +                return ('[%d]' % count, obit)
>
> It seems like it might be nicer to only print the set bits, something
> like bitset.
>    

If it's a sparse vector, yeah, you're right.  But it's probably more 
trouble than it's worth to figure that out and do different things 
depending, and, on average, it probably dumps more chares to print the 
indices of the '1's than to print all of the bits.

>
> Chris>  +            return ('%s<bool>  of length %d, capacity %d'
> Chris>  +                    % (self.typename, int (length), int (capacity)))
>
> Doesn't self.typename already include the<bool>?
>    

No.  typename comes from a string in the dictionary entry for 
std::vector<.*> and is the same regardless of the template argument.
Tom

Patch

Index: python/libstdcxx/v6/printers.py
===================================================================
--- python/libstdcxx/v6/printers.py	(revision 163221)
+++ python/libstdcxx/v6/printers.py	(working copy)
@@ -153,37 +153,71 @@ 
     "Print a std::vector"
 
     class _iterator:
-        def __init__ (self, start, finish):
-            self.item = start
-            self.finish = finish
+        def __init__ (self, start, finish, bitvec):
+            self.bitvec = bitvec
+            if bitvec:
+                self.item   = start['_M_p']
+                self.so     = start['_M_offset']
+                self.finish = finish['_M_p']
+                self.fo     = finish['_M_offset']
+                itype = self.item.dereference().type
+                self.isize = 8 * itype.sizeof
+            else:
+                self.item = start
+                self.finish = finish
             self.count = 0
 
         def __iter__(self):
             return self
 
         def next(self):
-            if self.item == self.finish:
-                raise StopIteration
             count = self.count
             self.count = self.count + 1
-            elt = self.item.dereference()
-            self.item = self.item + 1
-            return ('[%d]' % count, elt)
+            if self.bitvec:
+                if self.item == self.finish and self.so >= self.fo:
+                    raise StopIteration
+                elt = self.item.dereference()
+                obit = 1 if elt & (1 << self.so) else 0
+                self.so = self.so + 1
+                if self.so >= self.isize:
+                    self.item = self.item + 1
+                    self.so = 0
+                return ('[%d]' % count, obit)
+            else:
+                if self.item == self.finish:
+                    raise StopIteration
+                elt = self.item.dereference()
+                self.item = self.item + 1
+                return ('[%d]' % count, elt)
 
     def __init__(self, typename, val):
         self.typename = typename
         self.val = val
+        self.is_bool = val.type.template_argument(0).code  == gdb.TYPE_CODE_BOOL
 
     def children(self):
         return self._iterator(self.val['_M_impl']['_M_start'],
-                              self.val['_M_impl']['_M_finish'])
+                              self.val['_M_impl']['_M_finish'],
+                              self.is_bool)
 
     def to_string(self):
         start = self.val['_M_impl']['_M_start']
         finish = self.val['_M_impl']['_M_finish']
         end = self.val['_M_impl']['_M_end_of_storage']
-        return ('%s of length %d, capacity %d'
-                % (self.typename, int (finish - start), int (end - start)))
+        if self.is_bool:
+            start = self.val['_M_impl']['_M_start']['_M_p']
+            so    = self.val['_M_impl']['_M_start']['_M_offset']
+            finish = self.val['_M_impl']['_M_finish']['_M_p']
+            fo     = self.val['_M_impl']['_M_finish']['_M_offset']
+            itype = start.dereference().type
+            bl = 8 * itype.sizeof
+            length   = (bl - so) + bl * ((finish - start) - 1) + fo
+            capacity = bl * (end - start)
+            return ('%s<bool> of length %d, capacity %d'
+                    % (self.typename, int (length), int (capacity)))
+        else:
+            return ('%s of length %d, capacity %d'
+                    % (self.typename, int (finish - start), int (end - start)))
 
     def display_hint(self):
         return 'array'
Index: ChangeLog
===================================================================
--- ChangeLog	(revision 163221)
+++ ChangeLog	(working copy)
@@ -1,3 +1,8 @@ 
+2010-08-13  Chris Moller  <cmoller@redhat.com>
+
+	* python/libstdcxx/v6/printers.py (StdVectorPrinter): Added stuff
+	to handle pretty-printing of std::vector<bool>.
+
 2010-08-12  Kostya Serebryany <kcc@google.com>
 	    Paolo Carlini  <paolo.carlini@oracle.com>