整理初版

third_party/asmjit/core/zonestring.h

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+// This file is part of AsmJit project <https://asmjit.com>
+//
+// See asmjit.h or LICENSE.md for license and copyright information
+// SPDX-License-Identifier: Zlib
+
+#ifndef ASMJIT_CORE_ZONESTRING_H_INCLUDED
+#define ASMJIT_CORE_ZONESTRING_H_INCLUDED
+
+#include "../core/globals.h"
+#include "../core/zone.h"
+
+ASMJIT_BEGIN_NAMESPACE
+
+//! \addtogroup asmjit_zone
+//! \{
+
+//! A helper class used by \ref ZoneString implementation.
+struct ZoneStringBase {
+  union {
+    struct {
+      uint32_t _size;
+      char _embedded[sizeof(void*) * 2 - 4];
+    };
+    struct {
+      void* _dummy;
+      char* _external;
+    };
+  };
+
+  inline void reset() noexcept {
+    _dummy = nullptr;
+    _external = nullptr;
+  }
+
+  Error setData(Zone* zone, uint32_t maxEmbeddedSize, const char* str, size_t size) noexcept {
+    if (size == SIZE_MAX)
+      size = strlen(str);
+
+    if (size <= maxEmbeddedSize) {
+      memcpy(_embedded, str, size);
+      _embedded[size] = '\0';
+    }
+    else {
+      char* external = static_cast<char*>(zone->dup(str, size, true));
+      if (ASMJIT_UNLIKELY(!external))
+        return DebugUtils::errored(kErrorOutOfMemory);
+      _external = external;
+    }
+
+    _size = uint32_t(size);
+    return kErrorOk;
+  }
+};
+
+//! A string template that can be zone allocated.
+//!
+//! Helps with creating strings that can be either statically allocated if they are small, or externally allocated
+//! in case their size exceeds the limit. The `N` represents the size of the whole `ZoneString` structure, based on
+//! that size the maximum size of the internal buffer is determined.
+template<size_t N>
+class ZoneString {
+public:
+  //! \name Constants
+  //! \{
+
+  enum : uint32_t {
+    kWholeSize = (N > sizeof(ZoneStringBase)) ? uint32_t(N) : uint32_t(sizeof(ZoneStringBase)),
+    kMaxEmbeddedSize = kWholeSize - 5
+  };
+
+  //! \}
+
+  //! \name Members
+  //! \{
+
+  union {
+    ZoneStringBase _base;
+    char _wholeData[kWholeSize];
+  };
+
+  //! \}
+
+  //! \name Construction & Destruction
+  //! \{
+
+  inline ZoneString() noexcept { reset(); }
+  inline void reset() noexcept { _base.reset(); }
+
+  //! \}
+
+  //! \name Accessors
+  //! \{
+
+  //! Tests whether the string is empty.
+  inline bool empty() const noexcept { return _base._size == 0; }
+
+  //! Returns the string data.
+  inline const char* data() const noexcept { return _base._size <= kMaxEmbeddedSize ? _base._embedded : _base._external; }
+  //! Returns the string size.
+  inline uint32_t size() const noexcept { return _base._size; }
+
+  //! Tests whether the string is embedded (e.g. no dynamically allocated).
+  inline bool isEmbedded() const noexcept { return _base._size <= kMaxEmbeddedSize; }
+
+  //! Copies a new `data` of the given `size` to the string.
+  //!
+  //! If the `size` exceeds the internal buffer the given `zone` will be used to duplicate the data, otherwise
+  //! the internal buffer will be used as a storage.
+  inline Error setData(Zone* zone, const char* data, size_t size) noexcept {
+    return _base.setData(zone, kMaxEmbeddedSize, data, size);
+  }
+
+  //! \}
+};
+
+//! \}
+
+ASMJIT_END_NAMESPACE
+
+#endif // ASMJIT_CORE_ZONESTRING_H_INCLUDED