Add LLDB pretty printer module

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