Merge pull request #282 from cppalliance/pretty_printer

Add LLDB pretty printer module

Author: mborland

doc/int128.adoc

@@ -20,6 +20,8 @@ Matt Borland
 
 include::int128/overview.adoc[]
 
+include::int128/printer.adoc[]
+
 include::int128/api_reference.adoc[]
 
 include::int128/file_structure.adoc[]

doc/int128/printer.adoc

@@ -0,0 +1,21 @@
+////
+Copyright 2025 Matt Borland
+Distributed under the Boost Software License, Version 1.0.
+https://www.boost.org/LICENSE_1_0.txt
+////
+
+[#pretty_printer]
+= Pretty Printers
+:idprefix: pretty_printers_
+
+The library contains a pretty printer for LLDB in the `extra/` folder.
+To use this, add the following line to your `~/.lldbinit` file:
+
+[source]
+----
+command script import /path/to/int128/extra/int128_printer.py
+----
+
+If this is successful, you should see the following message in your debugger upon startup:
+
+"int128_t and uint128_t pretty printers loaded successfully"

extra/int128_printer.py

@@ -0,0 +1,115 @@
+# int128_printer.py
+#
+# Struct definitions:
+# struct uint128_t { std::uint64_t low; std::uint64_t high; };
+# struct int128_t { std::uint64_t low; std::int64_t high; };
+#
+# On big endian machines the word order is reversed
+
+import lldb
+
+def uint128_summary(valobj, internal_dict):
+ """
+ Custom summary for uint128_t type (unsigned).
+ Displays as decimal (base 10).
+ """
+ try:
+ val = valobj.GetNonSyntheticValue()
+ high = val.GetChildMemberWithName("high").GetValueAsUnsigned()
+ low = val.GetChildMemberWithName("low").GetValueAsUnsigned()
+
+ value = (high << 64) | low
+ return str(value)
+ except Exception as e:
+ return f"<invalid uint128_t: {e}>"
+
+def int128_summary(valobj, internal_dict):
+ """
+ Custom summary for int128_t type (signed).
+ Displays as decimal (base 10).
+ """
+ try:
+ val = valobj.GetNonSyntheticValue()
+ # high is std::int64_t, so use GetValueAsSigned()
+ high = val.GetChildMemberWithName("high").GetValueAsSigned()
+ # low is std::uint64_t, so use GetValueAsUnsigned()
+ low = val.GetChildMemberWithName("low").GetValueAsUnsigned()
+
+ value = (high << 64) + low
+ return str(value)
+ except Exception as e:
+ return f"<invalid int128_t: {e}>"
+
+def __lldb_init_module(debugger, internal_dict):
+ uint128_pattern = r"^(const )?(boost::int128::uint128_t|(\w+::)*uint128_t)( &| \*)?$"
+ int128_pattern = r"^(const )?(boost::int128::int128_t|(\w+::)*int128_t)( &| \*)?$"
+
+ debugger.HandleCommand(
+ f'type summary add -x "{uint128_pattern}" -e -F int128_printer.uint128_summary'
+ )
+ debugger.HandleCommand(
+ f'type synthetic add -x "{uint128_pattern}" -l int128_printer.Uint128SyntheticProvider'
+ )
+
+ debugger.HandleCommand(
+ f'type summary add -x "{int128_pattern}" -e -F int128_printer.int128_summary'
+ )
+ debugger.HandleCommand(
+ f'type synthetic add -x "{int128_pattern}" -l int128_printer.Int128SyntheticProvider'
+ )
+
+ print("int128_t and uint128_t pretty printers loaded successfully")
+
+class Uint128SyntheticProvider:
+ def __init__(self, valobj, internal_dict):
+ self.valobj = valobj
+
+ def num_children(self):
+ return 2
+
+ def get_child_index(self, name):
+ if name == "low":
+ return 0
+ elif name == "high":
+ return 1
+ return -1
+
+ def get_child_at_index(self, index):
+ if index == 0:
+ return self.valobj.GetChildMemberWithName("low")
+ elif index == 1:
+ return self.valobj.GetChildMemberWithName("high")
+ return None
+
+ def update(self):
+ pass
+
+ def has_children(self):
+ return True
+
+class Int128SyntheticProvider:
+ def __init__(self, valobj, internal_dict):
+ self.valobj = valobj
+
+ def num_children(self):
+ return 2
+
+ def get_child_index(self, name):
+ if name == "low":
+ return 0
+ elif name == "high":
+ return 1
+ return -1
+
+ def get_child_at_index(self, index):
+ if index == 0:
+ return self.valobj.GetChildMemberWithName("low")
+ elif index == 1:
+ return self.valobj.GetChildMemberWithName("high")
+ return None
+
+ def update(self):
+ pass
+
+ def has_children(self):
+ return True