From dec76dd3ed035b9aa1982ef6809c3a0e2df16204 Mon Sep 17 00:00:00 2001
From: Joe Jevnik <joe@quantopian.com>
Date: Tue, 21 May 2019 14:41:14 -0400
Subject: [PATCH] DEV: add pretty printer gdb file

---
 gdb/libpy-gdb.py | 50 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 gdb/libpy-gdb.py

diff --git a/gdb/libpy-gdb.py b/gdb/libpy-gdb.py
new file mode 100644
index 00000000..45f56844
--- /dev/null
+++ b/gdb/libpy-gdb.py
@@ -0,0 +1,50 @@
+import re
+
+import gdb
+import numpy as np
+
+
+def pretty_printer(cls):
+    gdb.pretty_printers.append(cls.maybe_construct)
+    return cls
+
+
+@pretty_printer
+class Datetime64:
+    _pattern = re.compile(
+        r'^py::datetime64<std::chrono::duration<long,'
+        r' std::ratio<(\d+), (\d+)> > >$'
+    )
+
+    _units = {
+        (1, 1000000000): 'ns',
+        (1, 1000000): 'ms',
+        (1, 1000): 'us',
+        (1, 1): 's',
+        (60, 1): 'm',
+        (60 * 60, 1): 'h',
+        (60 * 60 * 24, 1): 'D',
+    }
+
+    def __init__(self, val, count, unit):
+        self.val = val
+        self.count = count
+        self.unit = unit
+
+    @classmethod
+    def maybe_construct(cls, val):
+        underlying = gdb.types.get_basic_type(val.type)
+
+        match = cls._pattern.match(str(underlying))
+        if match is None:
+            return None
+
+        num = int(match[1])
+        den = int(match[2])
+        return cls(val, int(val['m_value']['__r']), cls._units[num, den])
+
+    def children(self):
+        yield 'm_value', str(np.datetime64(self.count, self.unit))
+
+    def to_string(self):
+        return f'py::datetime64<py::chrono::{self.unit}>'