wip string cache

src/string.cc

@@ -0,0 +1,77 @@
+#include "buffer.h"
+
+#include <cstring>
+#include <cstdint>
+#include <memory>
+#include <unordered_map>
+#include <unordered_set>
+#include <string>
+#include <vector>
+
+struct CXString {}; // TODO
+
+struct StringView {
+  StringView(const char* str, size_t len);
+
+  const char* const str;
+  size_t len;
+};
+
+struct StringDb {
+  StringView GetString(const std::string& str);
+  StringView GetString(const char* str);
+  StringView GetString(CXString cx_string);
+
+  struct StringStorage {
+    ~StringStorage();
+
+    static StringStorage CreateUnowned(const char* data, size_t len);
+    void Copy();
+
+    const char* data;
+    size_t len;
+    bool owns_data;
+  };
+
+  std::unordered_set<StringStorage> data_;
+};
+
+StringDb::StringStorage::~StringStorage() {
+  if (owns_data) {
+    free((void*)data);
+    data = nullptr;
+    owns_data = false;
+  }
+}
+
+StringDb::StringStorage StringDb::StringStorage::CreateUnowned(const char* data,
+                                                               size_t len) {
+  StringStorage result;
+  result.data = data;
+  result.len = len;
+  result.owns_data = false;
+  return result;
+}
+
+void StringDb::StringStorage::Copy() {
+  // Copy
+  char* new_data = (char*)malloc(len + 1);
+  strncpy(new_data, data, len + 1);
+  // Assign
+  data = new_data;
+  owns_data = true;
+}
+
+StringView::StringView(const char* str, size_t len) : str(str), len(len) {}
+
+StringView StringDb::GetString(const std::string& str) {
+  StringStorage lookup = StringStorage::CreateUnowned(str.c_str(), str.length());
+
+  auto it = data_.insert(str);
+  if (it.second)
+    it.first->Copy();
+
+  return StringView(it.first->c_str(), it.first->length());
+}
+
+