From 4cc5fa4c9c324c18908a7786358c7f6cac8a7f82 Mon Sep 17 00:00:00 2001
From: jacqueline <me@jacqueline.id.au>
Date: Tue, 31 Oct 2023 09:01:34 +1100
Subject: Store the current collator in the database

---
 src/locale/include/collation.hpp | 32 +++++++++++++++++++++++++++++---
 1 file changed, 29 insertions(+), 3 deletions(-)

(limited to 'src/locale/include')

diff --git a/src/locale/include/collation.hpp b/src/locale/include/collation.hpp
index e8b6fa17..b666860d 100644
--- a/src/locale/include/collation.hpp
+++ b/src/locale/include/collation.hpp
@@ -8,6 +8,7 @@
 
 #include <cstddef>
 #include <memory>
+#include <optional>
 #include <string>
 
 #include "esp_partition.h"
@@ -17,31 +18,56 @@
 
 namespace locale {
 
+/*
+ * Interface for sorting database entries.
+ * For performance, our database exclusively orders entries via byte
+ * comparisons of each key. Our collators therefore work by transforming keys
+ * such that a byte-order comparison results in a natural ordering.
+ */
 class ICollator {
  public:
   virtual ~ICollator() {}
 
+  /*
+   * Returns an identify that uniquely describes this collator. Does not need
+   * to be human readable.
+   */
+  virtual auto Describe() -> std::optional<std::string> = 0;
   virtual auto Transform(const std::string&) -> std::string = 0;
 };
 
+/* Creates and returns the best available collator. */
+auto CreateCollator() -> std::unique_ptr<ICollator>;
+
+/*
+ * Collator that doesn't do anything. Used only when there is no available
+ * locale data.
+ */
 class NoopCollator : public ICollator {
  public:
+  auto Describe() -> std::optional<std::string> override { return {}; }
   auto Transform(const std::string& in) -> std::string override { return in; }
 };
 
-auto CreateCollator() -> std::unique_ptr<ICollator>;
-
+/*
+ * Collator that uses glibc's `strxfrm` to transform keys. Relies on an
+ * LC_COLLATE file (+ 8 byte name header) flashed on a partition in internal
+ * flash.
+ */
 class GLibCollator : public ICollator {
  public:
   static auto create() -> GLibCollator*;
   ~GLibCollator();
 
+  auto Describe() -> std::optional<std::string> override { return name_; }
   auto Transform(const std::string& in) -> std::string override;
 
  private:
-  GLibCollator(const esp_partition_mmap_handle_t,
+  GLibCollator(const std::string& name,
+               const esp_partition_mmap_handle_t,
                std::unique_ptr<locale_data_t>);
 
+  const std::string name_;
   const esp_partition_mmap_handle_t handle_;
   std::unique_ptr<locale_data_t> locale_data_;
 };
-- 
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