FreeCAD WebAssembly development snapshot

contrib/debugger/qt_pretty_printers_gdb.py

@@ -0,0 +1,124 @@
+# pylint: disable=line-too-long
+"""
+ QT Pretty Printer for GDB
+
+ Currently supports displaying the following QT types in the debugger
+     * QString
+
+
+ Can be used from GDB via:
+
+ (gdb) python
+ >import sys
+ >sys.path.insert(0, '{Your FreeCAD source dir}/contrib/debugger')
+ >from qt_pretty_printers_gdb import register_qt_printers
+ >register_qt_printers()
+ >end
+ QT pretty-printer script loaded.
+ QT pretty-printer registered.
+ (gdb) run
+ *breakpoint*
+ (gdb) p testString
+ $1 = This is a QString in the debugger!
+ (gdb)
+
+
+
+ Can be used in VSCode via launch.json
+
+ {
+     "version": "0.2.0",
+     "configurations": [
+         {
+             "name": "(gdb) Launch",
+             "type": "cppdbg",
+             "request": "launch",
+             "program": "${workspaceFolder}/build/bin/FreeCAD",
+             "args": [],
+             "stopAtEntry": true,
+             "cwd": "${workspaceFolder}/build",
+             "environment": [],
+             "externalConsole": false,
+             "MIMode": "gdb",
+             "setupCommands": [
+                 {
+                     "description": "Load QT pretty-printers for GDB",
+                     "text": "python import sys; sys.path.append('${workspaceFolder}/contrib/debugger'); from qt_pretty_printers_gdb import register_qt_printers; register_qt_printers()",
+                     "ignoreFailures": false
+                 },
+                 {
+                     "description": "Enable pretty-printing for gdb",
+                     "text": "-enable-pretty-printing",
+                     "ignoreFailures": true
+                 },
+                 {
+                     "description": "Set Disassembly Flavor to Intel",
+                     "text": "-gdb-set disassembly-flavor intel",
+                     "ignoreFailures": true
+                 }
+             ],
+             "miDebuggerPath": "/usr/bin/gdb"
+         }
+     ]
+ }
+
+
+ Note: There may be variances between different operating systems and/or build configurations
+       in how QString data is stored internally.  This was tested on debian12/amd64. @BootsSiR
+"""
+# pylint: enable=line-too-long
+
+import gdb
+
+class QStringPrinter:
+    """Pretty-printer class for QString objects in GDB."""
+    def __init__(self, val):
+        self.val = val
+
+    def to_string(self):
+        """Pretty-printer function for QString objects in LLDB."""
+        try:
+            d = self.val["d"]
+            if d == 0:
+                return 'null'
+
+            offset = int(d["offset"])
+            data_ptr = d.cast(gdb.lookup_type("char").pointer()) + offset
+            char16_t_ptr = data_ptr.cast(gdb.lookup_type("char16_t").pointer())
+
+            string_data = []
+            i = 0
+            while char16_t_ptr[i] != 0:
+                string_data.append(chr(char16_t_ptr[i]))
+                i += 1
+
+            return "".join(string_data)
+        except gdb.error as e:
+            if "Cannot access memory at address" in str(e):
+                return "<uninitialized>"
+            return f"<error: {str(e)}>"
+        except Exception as e: # pylint: disable=broad-except
+            return f"<unexpected error: {str(e)}>"
+
+
+def lookup_function(val):
+    """Maps a type to the appropriate pretty printer"""
+    try:
+        qstring_type = gdb.lookup_type("QString")
+        if val.type.strip_typedefs() == qstring_type:
+            return QStringPrinter(val)
+        return None
+    except gdb.error:
+        return None
+
+
+def register_qt_printers(objfile=None):
+    """Register the QString pretty-printer with GDB."""
+    if objfile is None:
+        objfile = gdb.current_objfile()
+
+    # Check if the printer is already registered
+    if not any(printer == lookup_function for printer in gdb.pretty_printers): # pylint: disable=comparison-with-callable
+        print("QT pretty-printer script loaded.")
+        gdb.pretty_printers.append(lookup_function)
+        print("QT pretty-printer registered.")