From 312a998873bf86e9371377317ad82aa0e624f1b3 Mon Sep 17 00:00:00 2001 From: Niels Lohmann Date: Sat, 23 Jan 2021 13:26:44 +0100 Subject: [PATCH] :children_crossing: add GDB pretty printer --- README.md | 1 + third_party/gdb_pretty_printer/README.md | 77 +++++++++++++++++++ .../gdb_pretty_printer/nlohmann-json.py | 28 +++++++ 3 files changed, 106 insertions(+) create mode 100644 third_party/gdb_pretty_printer/README.md create mode 100644 third_party/gdb_pretty_printer/nlohmann-json.py diff --git a/README.md b/README.md index 19d8f722c..eb56d6c6f 100644 --- a/README.md +++ b/README.md @@ -1528,6 +1528,7 @@ I deeply appreciate the help of the following people. - [KonanM](https://github.com/KonanM) proposed an implementation for the `NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE`/`NLOHMANN_DEFINE_TYPE_INTRUSIVE` macros. - [Guillaume Racicot](https://github.com/gracicot) implemented `string_view` support and allowed C++20 support. - [Alex Reinking](https://github.com/alexreinking) improved CMake support for `FetchContent`. +- [Hannes Domani](https://github.com/ssbssa) provided a GDB pretty printer. Thanks a lot for helping out! Please [let me know](mailto:mail@nlohmann.me) if I forgot someone. diff --git a/third_party/gdb_pretty_printer/README.md b/third_party/gdb_pretty_printer/README.md new file mode 100644 index 000000000..f5f61927b --- /dev/null +++ b/third_party/gdb_pretty_printer/README.md @@ -0,0 +1,77 @@ +# GDB Pretty Printer + +File [nlohmann-json.py](nlohmann-json.py) contains a pretty printer for GDB for JSON values of this library. It was originally published as [Gist](https://gist.github.com/ssbssa/60da5339c6e6036b2afce17de06050ea#file-nlohmann-json-py) by [Hannes Domani](https://github.com/ssbssa). + +## How to use + +- Add line + + ``` + source /path/to/nlohmann-json.py + ``` + + to `~/.gdbinit`. Note you must replace `/path/to` with whatever path you stored file `nlohmann-json.py`. +- In GDB, debug as usual. When you want to pretty-print a JSON value `var`, type + + ``` + p -pretty on -array on -- var + ``` + + The result should look like + + ``` + $1 = std::map with 5 elements = { + ["Baptiste"] = std::map with 1 element = { + ["first"] = "second" + }, + ["Emmanuel"] = std::vector of length 3, capacity 3 = { + 3, + "25", + 0.5 + }, + ["Jean"] = 0.7, + ["Zorg"] = std::map with 8 elements = { + ["array"] = std::vector of length 3, capacity 3 = { + 1, + 0, + 2 + }, + ["awesome_str"] = "bleh", + ["bool"] = true, + ["flex"] = 0.2, + ["float"] = 5.22, + ["int"] = 5, + ["nested"] = std::map with 1 element = { + ["bar"] = "barz" + }, + ["trap "] = "you fell" + }, + ["empty"] = nlohmann::detail::value_t::null + } + ``` + +Tested with GDB 9.2. See [#1952](https://github.com/nlohmann/json/issues/1952) for more information. Please post questions there. + +## Copyright + +MIT License + +Copyright (C) 2020 [Hannes Domani](https://github.com/ssbssa) + +Permission is hereby granted, free of charge, to any person obtaining a copy +of this software and associated documentation files (the "Software"), to deal +in the Software without restriction, including without limitation the rights +to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the Software is +furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in all +copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +SOFTWARE. diff --git a/third_party/gdb_pretty_printer/nlohmann-json.py b/third_party/gdb_pretty_printer/nlohmann-json.py new file mode 100644 index 000000000..5bac45f61 --- /dev/null +++ b/third_party/gdb_pretty_printer/nlohmann-json.py @@ -0,0 +1,28 @@ +import gdb +import re + +class JsonValuePrinter: + "Print a json-value" + + def __init__(self, val): + self.val = val + + def to_string(self): + if self.val.type.strip_typedefs().code == gdb.TYPE_CODE_FLT: + return ("%.6f" % float(self.val)).rstrip("0") + return self.val + +def json_lookup_function(val): + if re.search("^nlohmann::basic_json<.*>$", val.type.strip_typedefs().name): + t = str(val['m_type']) + if t.startswith("nlohmann::detail::value_t::"): + try: + union_val = val['m_value'][t[27:]] + if union_val.type.code == gdb.TYPE_CODE_PTR: + return gdb.default_visualizer(union_val.dereference()) + else: + return JsonValuePrinter(union_val) + except: + return JsonValuePrinter(val['m_type']) + +gdb.pretty_printers.append(json_lookup_function)