Add two new pretty-printer methods
This adds two new pretty-printer methods, to support random access to
children. The methods are implemented for the no-op array printer,
and DAP is updated to use this.
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
index 2aaf101..5e88fd0 100644
--- a/gdb/doc/python.texi
+++ b/gdb/doc/python.texi
@@ -1828,6 +1828,22 @@
If the result is not one of these types, an exception is raised.
@end defun
+@defun pretty_printer.num_children ()
+This is not a basic method, so @value{GDBN} will only ever call it for
+objects derived from @code{gdb.ValuePrinter}.
+
+If available, this method should return the number of children.
+@code{None} may be returned if the number can't readily be computed.
+@end defun
+
+@defun pretty_printer.child (n)
+This is not a basic method, so @value{GDBN} will only ever call it for
+objects derived from @code{gdb.ValuePrinter}.
+
+If available, this method should return the child value indicated by
+@var{n}. Indices start at zero.
+@end defun
+
@value{GDBN} provides a function which can be used to look up the
default pretty-printer for a @code{gdb.Value}:
diff --git a/gdb/python/lib/gdb/dap/varref.py b/gdb/python/lib/gdb/dap/varref.py
index c1e5ba8..764a829 100644
--- a/gdb/python/lib/gdb/dap/varref.py
+++ b/gdb/python/lib/gdb/dap/varref.py
@@ -151,9 +151,9 @@
# This discards all laziness. This could be improved
# slightly by lazily evaluating children, but because this
# code also generally needs to know the number of
- # children, it probably wouldn't help much. A real fix
- # would require an update to gdb's pretty-printer protocol
- # (though of course that is probably also inadvisable).
+ # children, it probably wouldn't help much. Note that
+ # this is only needed with legacy (non-ValuePrinter)
+ # printers.
self.child_cache = list(self.printer.children())
return self.child_cache
@@ -161,9 +161,12 @@
if self.count is None:
return None
if self.count == -1:
- if hasattr(self.printer, "num_children"):
- num_children = self.printer.num_children
- else:
+ num_children = None
+ if isinstance(self.printer, gdb.ValuePrinter) and hasattr(
+ self.printer, "num_children"
+ ):
+ num_children = self.printer.num_children()
+ if num_children is None:
num_children = len(self.cache_children())
self.count = num_children
return self.count
@@ -193,7 +196,12 @@
@in_gdb_thread
def fetch_one_child(self, idx):
- return self.cache_children()[idx]
+ if isinstance(self.printer, gdb.ValuePrinter) and hasattr(
+ self.printer, "child"
+ ):
+ return self.printer.child(idx)
+ else:
+ return self.cache_children()[idx]
@in_gdb_thread
diff --git a/gdb/python/lib/gdb/printing.py b/gdb/python/lib/gdb/printing.py
index 21afa4d..0bbe2cb 100644
--- a/gdb/python/lib/gdb/printing.py
+++ b/gdb/python/lib/gdb/printing.py
@@ -285,11 +285,16 @@
def __init__(self, value):
self.__value = value
- self.num_children = 1
def to_string(self):
return self.__value.format_string(deref_refs=False)
+ def num_children(self):
+ return 1
+
+ def child(self, i):
+ return "value", self.__value.referenced_value()
+
def children(self):
yield "value", self.__value.referenced_value()
@@ -313,9 +318,6 @@
e_values = itertools.takewhile(lambda x: x.enumval <= high, e_values)
low = 0
high = len(list(e_values)) - 1
- # This is a convenience to the DAP code and perhaps other
- # users.
- self.num_children = high - low + 1
self.__low = low
self.__high = high
@@ -325,6 +327,12 @@
def display_hint(self):
return "array"
+ def num_children(self):
+ return self.__high - self.__low + 1
+
+ def child(self, i):
+ return (self.__low + i, self.__value[self.__low + i])
+
def children(self):
for i in range(self.__low, self.__high + 1):
yield (i, self.__value[i])
