From f4715ec87f03cda417a33a5fba901229f6687ce2 Mon Sep 17 00:00:00 2001
From: King_DuckZ <king_duckz@gmx.com>
Date: Sun, 23 Jul 2017 14:02:44 +0100
Subject: [PATCH] Add a sample gdb pretty printer for Vec<std::array> types

---
 gdb/vectorwrapper.py | 72 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 gdb/vectorwrapper.py

diff --git a/gdb/vectorwrapper.py b/gdb/vectorwrapper.py
new file mode 100644
index 0000000..2197d90
--- /dev/null
+++ b/gdb/vectorwrapper.py
@@ -0,0 +1,72 @@
+ #
+ # Copyright 2015-2017 Michele "King_DuckZ" Santullo
+ #
+ # Licensed under the Apache License, Version 2.0 (the "License");
+ # you may not use this file except in compliance with the License.
+ # You may obtain a copy of the License at
+ #
+ #     http://www.apache.org/licenses/LICENSE-2.0
+ #
+ # Unless required by applicable law or agreed to in writing, software
+ # distributed under the License is distributed on an "AS IS" BASIS,
+ # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ # See the License for the specific language governing permissions and
+ # limitations under the License.
+
+import gdb.printing
+
+#NOTE:
+#This pretty-printer has been written for vectorwrapper + std::array.
+#You will have to customize it if your wrapped type is different.
+
+class VectorWrapperPrinter(object):
+    "Print values in a VectorWrapper"
+
+    class _iterator(object):
+        def __init__(self, start, size):
+            self.item = start
+            self.pos = 0
+            self.size = size
+
+        def __iter__(self):
+            return self
+
+        def __next__(self):
+            if self.pos == self.size:
+                raise StopIteration
+            elt = self.item.dereference()
+            self.item = self.item + 1
+            self.pos = self.pos + 1
+            return str(elt)
+
+    def __init__(self, val):
+        self.val = val
+        self.dimensions = int(val.type.template_argument(1))
+
+    def to_string(self):
+        #get the scalar[n] value
+        stdarray_elems = self.val['m_wrapped']['_M_elems']
+        #get the actual scalar type
+        elem_type = self.val['m_wrapped'].type.template_argument(0)
+        #cast scalar[n] to scalar*
+        ptr = stdarray_elems.address.cast(elem_type.pointer())
+        #iterate over the values in scalar* and str() them
+        retval = "vec" + str(self.dimensions) + "<" + \
+            ", ".join(
+                str(itm) for itm in self._iterator(ptr, self.dimensions)
+            ) + ">"
+        return retval
+
+    def display_hint(self):
+        return 'string'
+
+def build_pretty_printer():
+    pp = gdb.printing.RegexpCollectionPrettyPrinter(__name__)
+    #add your namespace before 'vwr' if you're using a custom one
+    pp.add_printer('vwr', '^vwr::Vec<.+$', VectorWrapperPrinter)
+    return pp
+
+gdb.printing.register_pretty_printer(
+    gdb.current_objfile(),
+    build_pretty_printer()
+)