Fix & enable irept pretty-printer

Author: JohnDumbell

scripts/pretty-printers/gdb/pretty_printers.py

@@ -70,7 +70,12 @@ def find_type(type, name):
 
 
 class IrepPrettyPrinter:
-    "Print an irept"
+    """
+    Print an irept.
+
+    This is an array GDB type as everything in the tree is key->value, so it
+    works better than doing a map type with individual key/value entries.
+    """
 
     def __init__(self, val):
         self.val = val["data"].referenced_value()
@@ -82,31 +87,42 @@ def to_string(self):
             return "Exception pretty printing irept"
 
     def children(self):
+        """
+        This method tells the pretty-printer what children this object can
+        return. Because we've stated this is a array then we've also stated that
+        irept is a container that holds other values.
+
+        This makes things awkward because some ireps are not actually containers
+        of children but values themselves. It's hard to represent that, so instead
+        we return a single child with the value of the node.
+        """
+
         sub = self.val["sub"]
-        count = 0
+        sub_count = 0
         item = sub["_M_impl"]["_M_start"]
         finish = sub["_M_impl"]["_M_finish"]
         while item != finish:
-            yield "sub %d key" % count, "sub[%d]" % count
-            yield "sub %d value" % count, item.dereference()
-            count += 1
+            # The name is just the index, as that's all we have.
+            yield "%d" % sub_count, item.dereference()
+            sub_count += 1
             item += 1
 
         named_sub = self.val["named_sub"]
         size = named_sub["_M_t"]["_M_impl"]["_M_node_count"]
         node = named_sub["_M_t"]["_M_impl"]["_M_header"]["_M_left"]
-        count = 0
-        while count != size:
+        named_sub_count = 0
+        while named_sub_count != size:
             rep_type = find_type(named_sub.type, "_Rep_type")
             link_type = find_type(rep_type, "_Link_type")
             node_type = link_type.strip_typedefs()
             current = node.cast(node_type).dereference()
             addr_type = current.type.template_argument(0).pointer()
             result = current["_M_storage"]["_M_storage"].address.cast(addr_type).dereference()
-            yield "named_sub %d key" % count, "named_sub[\"%s\"]" % deconstruct_dstring(result["first"])[1].replace("\"", "\\\"")
-            yield "named_sub %d value" % count, result["second"]
-            count += 1
-            if count < size:
+
+            # Return (name_of_named_sub, value)
+            yield "%s" % deconstruct_dstring(result["first"])[1].replace("\"", "\\\""), result["second"]
+            named_sub_count += 1
+            if named_sub_count < size:
                 # Get the next node
                 right = node.dereference()["_M_right"]
                 if right:
@@ -125,8 +141,14 @@ def children(self):
                     if node.dereference()["_M_right"] != parent:
                         node = parent
 
+        # If we have no children it means we're actually a value node, so
+        # return the value of the node and a throw-away second value.
+        if sub_count == 0 and named_sub_count == 0:
+            yield (self.to_string(), self.val)
+
+
     def display_hint(self):
-        return "map"
+        return "array"
 
 
 class InstructionPrettyPrinter:
@@ -154,5 +176,7 @@ def load_cbmc_printers():
     # it should be applied too, third is the class that should be called to pretty-print that type.
     printers.add_printer("dstringt", "^(?:dstringt|irep_idt)", DStringPrettyPrinter)
     printers.add_printer("instructiont", "^goto_programt::instructiont", InstructionPrettyPrinter)
+    printers.add_printer("irept", "^irept", IrepPrettyPrinter)
+
     # We aren't associating with a particular object file, so pass in None instead of gdb.current_objfile()
     gdb.printing.register_pretty_printer(None, printers, replace=True)