[libcxx-commits] [libcxx] [llvm] [libcxx][lldb] Add initial LLDB data-formatters (PR #187677)

[Dave Lee via libcxx-commits]

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@@ -0,0 +1,263 @@
+"""
+Python LLDB data formatter for libc++ std::vector
+
+1-to-1 translation from the LLDB builtin std::vector formatter.
+
+Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+See https://llvm.org/LICENSE.txt for license information.
+SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+"""
+
+import lldb
+
+
+def get_data_pointer(root):
+    """Get the data pointer from a vector, handling compressed pair layout."""
+    # Try new layout
+    cap_sp = root.GetChildMemberWithName("__cap_")
+    if cap_sp and cap_sp.IsValid():
+        return cap_sp
+
+    # Try old compressed pair layout
+    end_cap_sp = root.GetChildMemberWithName("__end_cap_")
+    if not end_cap_sp or not end_cap_sp.IsValid():
+        return None
+
+    # Get first value of compressed pair
+    value_sp = end_cap_sp.GetChildMemberWithName("__value_")
+    if value_sp and value_sp.IsValid():
+        return value_sp
+
+    first_sp = end_cap_sp.GetChildMemberWithName("__first_")
+    if first_sp and first_sp.IsValid():
+        return first_sp
+
+    return None
+
+
+class LibCxxStdVectorSyntheticFrontEnd:
+    """Synthetic children frontend for libc++ std::vector."""
+
+    def __init__(self, valobj, internal_dict):
+        self.valobj = valobj
+        self.m_start = None
+        self.m_finish = None
+        self.m_element_type = None
+        self.m_element_size = 0
+        self.update()
----------------
kastiglione wrote:

It's not a big deal, but in my synthetic formatters, I never include a `self.update()` call in `__init__` because `update` gets called on the synthetic anyway.

https://github.com/llvm/llvm-project/pull/187677