[api] Eliminate heap allocations when populating repeated fields from containers (#9948)

script/api_protobuf/api_protobuf.py

@@ -1170,6 +1170,10 @@ class FixedArrayRepeatedType(TypeInfo):
 class RepeatedTypeInfo(TypeInfo):
     def __init__(self, field: descriptor.FieldDescriptorProto) -> None:
         super().__init__(field)
+        # Check if this is a pointer field by looking for container_pointer option
+        self._container_type = get_field_opt(field, pb.container_pointer, "")
+        self._use_pointer = bool(self._container_type)
+
         # For repeated fields, we need to get the base type info
         # but we can't call create_field_type_info as it would cause recursion
         # So we extract just the type creation logic
@@ -1185,6 +1189,14 @@ class RepeatedTypeInfo(TypeInfo):
 
     @property
     def cpp_type(self) -> str:
+        if self._use_pointer and self._container_type:
+            # For pointer fields, use the specified container type
+            # If the container type already includes the element type (e.g., std::set<climate::ClimateMode>)
+            # use it as-is, otherwise append the element type
+            if "<" in self._container_type and ">" in self._container_type:
+                return f"const {self._container_type}*"
+            else:
+                return f"const {self._container_type}<{self._ti.cpp_type}>*"
         return f"std::vector<{self._ti.cpp_type}>"
 
     @property
@@ -1205,6 +1217,9 @@ class RepeatedTypeInfo(TypeInfo):
 
     @property
     def decode_varint_content(self) -> str:
+        # Pointer fields don't support decoding
+        if self._use_pointer:
+            return None
         content = self._ti.decode_varint
         if content is None:
             return None
@@ -1214,6 +1229,9 @@ class RepeatedTypeInfo(TypeInfo):
 
     @property
     def decode_length_content(self) -> str:
+        # Pointer fields don't support decoding
+        if self._use_pointer:
+            return None
         content = self._ti.decode_length
         if content is None and isinstance(self._ti, MessageType):
             # Special handling for non-template message decoding
@@ -1226,6 +1244,9 @@ class RepeatedTypeInfo(TypeInfo):
 
     @property
     def decode_32bit_content(self) -> str:
+        # Pointer fields don't support decoding
+        if self._use_pointer:
+            return None
         content = self._ti.decode_32bit
         if content is None:
             return None
@@ -1235,6 +1256,9 @@ class RepeatedTypeInfo(TypeInfo):
 
     @property
     def decode_64bit_content(self) -> str:
+        # Pointer fields don't support decoding
+        if self._use_pointer:
+            return None
         content = self._ti.decode_64bit
         if content is None:
             return None
@@ -1249,16 +1273,31 @@ class RepeatedTypeInfo(TypeInfo):
 
     @property
     def encode_content(self) -> str:
-        o = f"for (auto {'' if self._ti_is_bool else '&'}it : this->{self.field_name}) {{\n"
-        if isinstance(self._ti, EnumType):
-            o += f"  buffer.{self._ti.encode_func}({self.number}, static_cast<uint32_t>(it), true);\n"
+        if self._use_pointer:
+            # For pointer fields, just dereference (pointer should never be null in our use case)
+            o = f"for (const auto &it : *this->{self.field_name}) {{\n"
+            if isinstance(self._ti, EnumType):
+                o += f"  buffer.{self._ti.encode_func}({self.number}, static_cast<uint32_t>(it), true);\n"
+            else:
+                o += f"  buffer.{self._ti.encode_func}({self.number}, it, true);\n"
+            o += "}"
+            return o
         else:
-            o += f"  buffer.{self._ti.encode_func}({self.number}, it, true);\n"
-        o += "}"
-        return o
+            o = f"for (auto {'' if self._ti_is_bool else '&'}it : this->{self.field_name}) {{\n"
+            if isinstance(self._ti, EnumType):
+                o += f"  buffer.{self._ti.encode_func}({self.number}, static_cast<uint32_t>(it), true);\n"
+            else:
+                o += f"  buffer.{self._ti.encode_func}({self.number}, it, true);\n"
+            o += "}"
+            return o
 
     @property
     def dump_content(self) -> str:
+        if self._use_pointer:
+            # For pointer fields, dereference and use the existing helper
+            return _generate_array_dump_content(
+                self._ti, f"*this->{self.field_name}", self.name, is_bool=False
+            )
         return _generate_array_dump_content(
             self._ti, f"this->{self.field_name}", self.name, is_bool=self._ti_is_bool
         )
@@ -1269,30 +1308,34 @@ class RepeatedTypeInfo(TypeInfo):
     def get_size_calculation(self, name: str, force: bool = False) -> str:
         # For repeated fields, we always need to pass force=True to the underlying type's calculation
         # This is because the encode method always sets force=true for repeated fields
+
+        # Handle message types separately as they use a dedicated helper
         if isinstance(self._ti, MessageType):
-            # For repeated messages, use the dedicated helper that handles iteration internally
             field_id_size = self._ti.calculate_field_id_size()
-            o = f"size.add_repeated_message({field_id_size}, {name});"
-            return o
+            container = f"*{name}" if self._use_pointer else name
+            return f"size.add_repeated_message({field_id_size}, {container});"
 
-        # For other repeated types, use the underlying type's size calculation with force=True
-        o = f"if (!{name}.empty()) {{\n"
+        # For non-message types, generate size calculation with iteration
+        container_ref = f"*{name}" if self._use_pointer else name
+        empty_check = f"{name}->empty()" if self._use_pointer else f"{name}.empty()"
 
-        # Check if this is a fixed-size type by seeing if it has a fixed byte count
+        o = f"if (!{empty_check}) {{\n"
+
+        # Check if this is a fixed-size type
         num_bytes = self._ti.get_fixed_size_bytes()
         if num_bytes is not None:
-            # Fixed types have constant size per element, so we can multiply
+            # Fixed types have constant size per element
             field_id_size = self._ti.calculate_field_id_size()
-            # Pre-calculate the total bytes per element
             bytes_per_element = field_id_size + num_bytes
-            o += (
-                f"  size.add_precalculated_size({name}.size() * {bytes_per_element});\n"
-            )
+            size_expr = f"{name}->size()" if self._use_pointer else f"{name}.size()"
+            o += f"  size.add_precalculated_size({size_expr} * {bytes_per_element});\n"
         else:
             # Other types need the actual value
-            o += f"  for (const auto {'' if self._ti_is_bool else '&'}it : {name}) {{\n"
+            auto_ref = "" if self._ti_is_bool else "&"
+            o += f"  for (const auto {auto_ref}it : {container_ref}) {{\n"
             o += f"    {self._ti.get_size_calculation('it', True)}\n"
             o += "  }\n"
+
         o += "}"
         return o
 
@@ -2080,6 +2123,7 @@ def main() -> None:
     d = descriptor.FileDescriptorSet.FromString(proto_content)
 
     file = d.file[0]
+
     content = FILE_HEADER
     content += """\
 #pragma once
@@ -2088,7 +2132,10 @@ def main() -> None:
 #include "esphome/core/string_ref.h"
 
 #include "proto.h"
+#include "api_pb2_includes.h"
+"""
 
+    content += """
 namespace esphome::api {
 
 """