[mapping] Use custom allocator (#9972)

esphome/components/mapping/__init__.py

@@ -10,7 +10,8 @@ from esphome.loader import get_component
 CODEOWNERS = ["@clydebarrow"]
 MULTI_CONF = True
 
-map_ = cg.std_ns.class_("map")
+mapping_ns = cg.esphome_ns.namespace("mapping")
+mapping_class = mapping_ns.class_("Mapping")
 
 CONF_ENTRIES = "entries"
 CONF_CLASS = "class"
@@ -29,7 +30,11 @@ class IndexType:
 
 INDEX_TYPES = {
     "int": IndexType(cv.int_, cg.int_, int),
-    "string": IndexType(cv.string, cg.std_string, str),
+    "string": IndexType(
+        cv.string,
+        cg.std_string,
+        str,
+    ),
 }
 
 
@@ -47,7 +52,7 @@ def to_schema(value):
 
 BASE_SCHEMA = cv.Schema(
     {
-        cv.Required(CONF_ID): cv.declare_id(map_),
+        cv.Required(CONF_ID): cv.declare_id(mapping_class),
         cv.Required(CONF_FROM): cv.one_of(*INDEX_TYPES, lower=True),
         cv.Required(CONF_TO): cv.string,
     },
@@ -123,12 +128,15 @@ async def to_code(config):
         if list(entries.values())[0].op != ".":
             value_type = value_type.operator("ptr")
     varid = config[CONF_ID]
-    varid.type = map_.template(index_type, value_type)
+    varid.type = mapping_class.template(
+        index_type,
+        value_type,
+    )
     var = MockObj(varid, ".")
     decl = VariableDeclarationExpression(varid.type, "", varid)
     add_global(decl)
     CORE.register_variable(varid, var)
 
     for key, value in entries.items():
-        cg.add(var.insert((key, value)))
+        cg.add(var.set(key, value))
     return var

esphome/components/mapping/mapping.h

@@ -0,0 +1,69 @@
+#pragma once
+
+#include "esphome/core/helpers.h"
+#include "esphome/core/log.h"
+#include <map>
+#include <string>
+
+namespace esphome::mapping {
+
+using alloc_string_t = std::basic_string<char, std::char_traits<char>, RAMAllocator<char>>;
+
+/**
+ *
+ * Mapping class with custom allocator.
+ * Additionally, when std::string is used as key or value, it will be replaced with a custom string type
+ * that uses RAMAllocator.
+ * @tparam K The type of the key in the mapping.
+ * @tparam V The type of the value in the mapping. Should be a basic type or pointer.
+ */
+
+static const char *const TAG = "mapping";
+
+template<typename K, typename V> class Mapping {
+ public:
+  // Constructor
+  Mapping() = default;
+
+  using key_t = const std::conditional_t<std::is_same_v<K, std::string>,
+                                         alloc_string_t,  // if K is std::string, custom string type
+                                         K>;
+  using value_t = std::conditional_t<std::is_same_v<V, std::string>,
+                                     alloc_string_t,  // if V is std::string, custom string type
+                                     V>;
+
+  void set(const K &key, const V &value) { this->map_[key_t{key}] = value; }
+
+  V get(const K &key) const {
+    auto it = this->map_.find(key_t{key});
+    if (it != this->map_.end()) {
+      return V{it->second};
+    }
+    if constexpr (std::is_pointer_v<K>) {
+      esph_log_e(TAG, "Key '%p' not found in mapping", key);
+    } else if constexpr (std::is_same_v<K, std::string>) {
+      esph_log_e(TAG, "Key '%s' not found in mapping", key.c_str());
+    } else {
+      esph_log_e(TAG, "Key '%s' not found in mapping", to_string(key).c_str());
+    }
+    return {};
+  }
+
+  // index map overload
+  V operator[](K key) { return this->get(key); }
+
+  // convenience function for strings to get a C-style string
+  template<typename T = V, std::enable_if_t<std::is_same_v<T, std::string>, int> = 0>
+  const char *operator[](K key) const {
+    auto it = this->map_.find(key_t{key});
+    if (it != this->map_.end()) {
+      return it->second.c_str();  // safe since value remains in map
+    }
+    return "";
+  }
+
+ protected:
+  std::map<key_t, value_t, std::less<key_t>, RAMAllocator<std::pair<key_t, value_t>>> map_;
+};
+
+}  // namespace esphome::mapping