[PATCHv2 2/2] Use method children instead of to_string in pretty printers

[Hannes Domani <ssbssa@yahoo.de>]

With '-pretty on' the output is basically the same, but like this the
pointer members can be expanded in the TUI variable windows.

gdb/ChangeLog:

2021-06-04  Hannes Domani  <ssbssa@yahoo.de>

	* gdb-gdb.py.in: Use method children in pretty printers.
---
v2:
- Added ChangeLog.
- Reformatted with black.
---
 gdb/gdb-gdb.py.in | 175 ++++++++++++++++++++--------------------------
 1 file changed, 77 insertions(+), 98 deletions(-)

diff --git a/gdb/gdb-gdb.py.in b/gdb/gdb-gdb.py.in
index af9fcfedc2f..1432d7bbcf8 100644
--- a/gdb/gdb-gdb.py.in
+++ b/gdb/gdb-gdb.py.in
@@ -107,17 +107,13 @@ class StructTypePrettyPrinter:
     def __init__(self, val):
         self.val = val
 
-    def to_string(self):
-        fields = []
-        fields.append("pointer_type = %s" % self.val["pointer_type"])
-        fields.append("reference_type = %s" % self.val["reference_type"])
-        fields.append("chain = %s" % self.val["reference_type"])
-        fields.append(
-            "instance_flags = %s" % TypeFlagsPrinter(self.val["m_instance_flags"])
-        )
-        fields.append("length = %d" % self.val["length"])
-        fields.append("main_type = %s" % self.val["main_type"])
-        return "\n{" + ",\n ".join(fields) + "}"
+    def children(self):
+        for f in self.val.type.fields():
+            name = f.name
+            val = self.val[f]
+            if name == "m_instance_flags":
+                val = str(TypeFlagsPrinter(val))
+            yield name, val
 
 
 class StructMainTypePrettyPrinter:
@@ -142,46 +138,6 @@ class StructMainTypePrettyPrinter:
         ]
         return "|".join(fields)
 
-    def owner_to_string(self):
-        """Return an image of component "owner"."""
-        if self.val["m_flag_objfile_owned"] != 0:
-            return "%s (objfile)" % self.val["m_owner"]["objfile"]
-        else:
-            return "%s (gdbarch)" % self.val["m_owner"]["gdbarch"]
-
-    def struct_field_location_img(self, field_val):
-        """Return an image of the loc component inside the given field
-        gdb.Value.
-        """
-        loc_val = field_val["loc"]
-        loc_kind = str(field_val["loc_kind"])
-        if loc_kind == "FIELD_LOC_KIND_BITPOS":
-            return "bitpos = %d" % loc_val["bitpos"]
-        elif loc_kind == "FIELD_LOC_KIND_ENUMVAL":
-            return "enumval = %d" % loc_val["enumval"]
-        elif loc_kind == "FIELD_LOC_KIND_PHYSADDR":
-            return "physaddr = 0x%x" % loc_val["physaddr"]
-        elif loc_kind == "FIELD_LOC_KIND_PHYSNAME":
-            return "physname = %s" % loc_val["physname"]
-        elif loc_kind == "FIELD_LOC_KIND_DWARF_BLOCK":
-            return "dwarf_block = %s" % loc_val["dwarf_block"]
-        else:
-            return "loc = ??? (unsupported loc_kind value)"
-
-    def struct_field_img(self, fieldno):
-        """Return an image of the main_type field number FIELDNO."""
-        f = self.val["flds_bnds"]["fields"][fieldno]
-        label = "flds_bnds.fields[%d]:" % fieldno
-        if f["artificial"]:
-            label += " (artificial)"
-        fields = []
-        fields.append("name = %s" % f["name"])
-        fields.append("type = %s" % f["m_type"])
-        fields.append("loc_kind = %s" % f["loc_kind"])
-        fields.append("bitsize = %d" % f["bitsize"])
-        fields.append(self.struct_field_location_img(f))
-        return label + "\n" + "  {" + ",\n   ".join(fields) + "}"
-
     def bound_img(self, bound_name):
         """Return an image of the given main_type's bound."""
         bounds = self.val["flds_bnds"]["bounds"].dereference()
@@ -197,17 +153,6 @@ class StructMainTypePrettyPrinter:
                 info.append("upper_bound_is_count")
             return "{} ({})".format(str(b["m_data"]["baton"]), ",".join(info))
 
-    def bounds_img(self):
-        """Return an image of the main_type bounds."""
-        b = self.val["flds_bnds"]["bounds"].dereference()
-        low = self.bound_img("low")
-        high = self.bound_img("high")
-
-        img = "flds_bnds.bounds = {%s, %s}" % (low, high)
-        if b["flag_bound_evaluated"]:
-            img += " [evaluated]"
-        return img
-
     def type_specific_img(self):
         """Return a string image of the main_type type_specific union.
         Only the relevant component of that union is printed (based on
@@ -216,54 +161,86 @@ class StructMainTypePrettyPrinter:
         type_specific_kind = str(self.val["type_specific_field"])
         type_specific = self.val["type_specific"]
         if type_specific_kind == "TYPE_SPECIFIC_NONE":
-            img = "type_specific_field = %s" % type_specific_kind
+            return "type_specific_field", type_specific_kind
         elif type_specific_kind == "TYPE_SPECIFIC_CPLUS_STUFF":
-            img = "cplus_stuff = %s" % type_specific["cplus_stuff"]
+            return "cplus_stuff", type_specific["cplus_stuff"]
         elif type_specific_kind == "TYPE_SPECIFIC_GNAT_STUFF":
-            img = (
-                "gnat_stuff = {descriptive_type = %s}"
-                % type_specific["gnat_stuff"]["descriptive_type"]
+            return (
+                "gnat_stuff.descriptive_type",
+                type_specific["gnat_stuff"]["descriptive_type"],
             )
         elif type_specific_kind == "TYPE_SPECIFIC_FLOATFORMAT":
-            img = "floatformat[0..1] = %s" % type_specific["floatformat"]
+            return "floatformat[0..1]", type_specific["floatformat"]
         elif type_specific_kind == "TYPE_SPECIFIC_FUNC":
-            img = (
-                "calling_convention = %d"
-                % type_specific["func_stuff"]["calling_convention"]
+            return (
+                "calling_convention",
+                type_specific["func_stuff"]["calling_convention"],
             )
             # tail_call_list is not printed.
         elif type_specific_kind == "TYPE_SPECIFIC_SELF_TYPE":
-            img = "self_type = %s" % type_specific["self_type"]
-        elif type_specific_kind == "TYPE_SPECIFIC_FIXED_POINT":
-            # The scaling factor is an opaque structure, so we cannot
-            # decode its value from Python (not without insider knowledge).
-            img = (
-                "scaling_factor: <opaque> (call __gmpz_dump with "
-                " _mp_num and _mp_den fields if needed)"
-            )
-        else:
-            img = (
-                "type_specific = ??? (unknown type_secific_kind: %s)"
-                % type_specific_kind
-            )
-        return img
+            return "self_type", type_specific["self_type"]
+        return (
+            "type_specific",
+            "??? (unknown type_secific_kind: %s)" % type_specific_kind,
+        )
 
-    def to_string(self):
-        """Return a pretty-printed image of our main_type."""
-        fields = []
-        fields.append("name = %s" % self.val["name"])
-        fields.append("code = %s" % self.val["code"])
-        fields.append("flags = [%s]" % self.flags_to_string())
-        fields.append("owner = %s" % self.owner_to_string())
-        fields.append("target_type = %s" % self.val["target_type"])
+    def children(self):
+        yield "name", self.val["name"].format_string(symbols=False, address=False)
+        yield "code", self.val["code"]
+        yield "flags", "[%s]" % self.flags_to_string()
+        if self.val["m_flag_objfile_owned"] != 0:
+            yield "owner.objfile", self.val["m_owner"]["objfile"]
+        else:
+            yield "owner.gdbarch", self.val["m_owner"]["gdbarch"]
+        yield "target_type", self.val["target_type"]
         if self.val["nfields"] > 0:
-            for fieldno in range(self.val["nfields"]):
-                fields.append(self.struct_field_img(fieldno))
+            fields = self.val["flds_bnds"]["fields"]
+            field_array_type = (
+                fields.type.target().array(self.val["nfields"] - 1).pointer()
+            )
+            yield "flds_bnds.fields", fields.cast(field_array_type).dereference()
         if self.val["code"] == gdb.TYPE_CODE_RANGE:
-            fields.append(self.bounds_img())
-        fields.append(self.type_specific_img())
+            b = self.val["flds_bnds"]["bounds"].dereference()
+            low = self.bound_img("low")
+            high = self.bound_img("high")
+
+            img = "{%s, %s}" % (low, high)
+            if b["flag_bound_evaluated"]:
+                img += " [evaluated]"
+            yield "flds_bnds.bounds", img
+        yield self.type_specific_img()
+
+
+class StructFieldPrettyPrinter:
+    """Pretty-print an objet of type field"""
+
+    def __init__(self, val):
+        self.val = val
+
+    def children(self):
+        if self.val["artificial"]:
+            yield "artificial", self.val["artificial"]
+        yield "name", self.val["name"].format_string(symbols=False, address=False)
+        yield "type", self.val["m_type"]
+        yield "loc_kind", self.val["loc_kind"]
+        yield "bitsize", self.val["bitsize"]
 
-        return "\n{" + ",\n ".join(fields) + "}"
+        loc_val = self.val["loc"]
+        loc_kind = str(self.val["loc_kind"])
+        if loc_kind == "FIELD_LOC_KIND_BITPOS":
+            yield "bitpos", loc_val["bitpos"]
+        elif loc_kind == "FIELD_LOC_KIND_ENUMVAL":
+            yield "enumval", loc_val["enumval"]
+        elif loc_kind == "FIELD_LOC_KIND_PHYSADDR":
+            yield "physaddr", loc_val["physaddr"]
+        elif loc_kind == "FIELD_LOC_KIND_PHYSNAME":
+            yield "physname", loc_val["physname"].format_string(
+                symbols=False, address=False
+            )
+        elif loc_kind == "FIELD_LOC_KIND_DWARF_BLOCK":
+            yield "dwarf_block", loc_val["dwarf_block"]
+        else:
+            yield "loc", "???"
 
 
 class CoreAddrPrettyPrinter:
@@ -284,6 +261,8 @@ def type_lookup_function(val):
         return StructTypePrettyPrinter(val)
     elif val.type.tag == "main_type":
         return StructMainTypePrettyPrinter(val)
+    elif val.type.tag == "field":
+        return StructFieldPrettyPrinter(val)
     elif val.type.name == "CORE_ADDR":
         return CoreAddrPrettyPrinter(val)
     return None
-- 
2.31.1