Separate string adapter from storage policy

src/ArduinoJson/Strings/Adapters/FlashString.hpp

@@ -0,0 +1,80 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright Benoit Blanchon 2014-2021
+// MIT License
+
+#pragma once
+
+#include <Arduino.h>
+
+#include <ArduinoJson/Polyfills/pgmspace.hpp>
+#include <ArduinoJson/Strings/IsString.hpp>
+
+namespace ARDUINOJSON_NAMESPACE {
+
+class FlashString {
+ public:
+  static const size_t typeSortKey = 1;
+
+  FlashString(const __FlashStringHelper* str, size_t sz)
+      : _str(reinterpret_cast<const char*>(str)), _size(sz) {}
+
+  bool isNull() const {
+    return !_str;
+  }
+
+  char operator[](size_t i) const {
+    ARDUINOJSON_ASSERT(_str != 0);
+    ARDUINOJSON_ASSERT(i <= _size);
+    return static_cast<char>(pgm_read_byte(_str + i));
+  }
+
+  size_t size() const {
+    return _size;
+  }
+
+  friend bool stringEquals(FlashString a, SizedRamString b) {
+    ARDUINOJSON_ASSERT(a.typeSortKey < b.typeSortKey);
+    ARDUINOJSON_ASSERT(!a.isNull());
+    ARDUINOJSON_ASSERT(!b.isNull());
+    if (a.size() != b.size())
+      return false;
+    return ::memcmp_P(b.data(), a._str, a._size) == 0;
+  }
+
+  friend int stringCompare(FlashString a, SizedRamString b) {
+    ARDUINOJSON_ASSERT(a.typeSortKey < b.typeSortKey);
+    ARDUINOJSON_ASSERT(!a.isNull());
+    ARDUINOJSON_ASSERT(!b.isNull());
+    size_t minsize = a.size() < b.size() ? a.size() : b.size();
+    int res = ::memcmp_P(b.data(), a._str, minsize);
+    if (res)
+      return -res;
+    if (a.size() < b.size())
+      return -1;
+    if (a.size() > b.size())
+      return 1;
+    return 0;
+  }
+
+  friend void stringGetChars(FlashString s, char* p, size_t n) {
+    ARDUINOJSON_ASSERT(s.size() <= n);
+    ::memcpy_P(p, s._str, n);
+  }
+
+ private:
+  const char* _str;
+  size_t _size;
+};
+
+inline FlashString adaptString(const __FlashStringHelper* s) {
+  return FlashString(s, s ? strlen_P(reinterpret_cast<const char*>(s)) : 0);
+}
+
+inline FlashString adaptString(const __FlashStringHelper* s, size_t n) {
+  return FlashString(s, n);
+}
+
+template <>
+struct IsString<const __FlashStringHelper*> : true_type {};
+
+}  // namespace ARDUINOJSON_NAMESPACE