wweic commented on a change in pull request #4628: [Object] Add String container
URL: https://github.com/apache/incubator-tvm/pull/4628#discussion_r376696045
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File path: include/tvm/runtime/container.h
##########
@@ -274,7 +276,181 @@ class ADT : public ObjectRef {
TVM_DEFINE_OBJECT_REF_METHODS(ADT, ObjectRef, ADTObj);
};
+/*! \brief An object representing string. It's POD type. */
+class StringObj : public Object {
+ public:
+ /*! \brief The length of the string object. */
+ uint32_t size;
+
+ /*! \brief The pointer to string data. */
+ const char* data;
+
+ static constexpr const uint32_t _type_index = TypeIndex::kDynamic;
+ static constexpr const char* _type_key = "String";
+ TVM_DECLARE_FINAL_OBJECT_INFO(StringObj, Object);
+
+ private:
+ /*! \brief String object which is moved from std::string container. */
+ class FromStd;
+
+ friend class String;
+};
+
+/*! \brief reference to string objects. */
+class String : public ObjectRef {
+ public:
+ /*!
+ * \brief Construct a new String object
+ *
+ * \param other The moved/copied std::string object
+ *
+ * \note If user passes const reference, it will trigger copy. If it's
rvalue,
+ * it will be moved into other.
+ */
+ inline explicit String(std::string other);
+
+ /*!
+ * \brief Compare is equal to other std::string
+ *
+ * \param other The other string
+ */
+ bool operator==(const std::string& other) const {
+ return size() == other.size() &&
+ other.compare(0, other.size(), get()->data, size()) == 0;
+ }
+
+ /*!
+ * \brief Compare is not equal to other std::string
+ *
+ * \param other The other string
+ */
+ bool operator!=(const std::string& other) const { return !operator==(other);
}
+
+ /*!
+ * \brief Compare is equal to other char string
+ *
+ * \param other The other char string
+ */
+ inline bool operator==(const char* other) const;
+
+ /*!
+ * \brief Compare is not equal to other char string
+ *
+ * \param other The other char string
+ */
+ inline bool operator!=(const char* other) const;
+
+ /*!
+ * \brief Compares this to other for at most len chars
+ *
+ * \return zero if both char sequences compare equal. negative if this appear
+ * before other, positive otherwise.
+ */
+ int compare(const String& other, size_t len) const {
+ return compare(other.data(), len);
+ }
+
+ /*!
+ * \brief Compares this to other for at most len chars
+ *
+ * \return zero if both char sequences compare equal. negative if this appear
+ * before other, positive otherwise.
+ */
+ int compare(const std::string& other, size_t len) const {
+ return compare(other.data(), len);
+ }
+
+ /*!
+ * \brief Compares this to other for at most len chars
+ *
+ * \return zero if both char sequences compare equal. negative if this appear
+ * before other, positive otherwise.
+ */
+ int compare(const char* other, size_t len) const {
+ return std::strncmp(get()->data, other, len);
+ }
+
+ /*!
+ * \brief Returns a pointer to the char array in the string.
+ *
+ * \return const char*
+ */
+ inline const char* c_str() const { return get()->data; }
+
+ /*!
+ * \brief Return the length of the string
+ *
+ * \return size_t string length
+ */
+ inline size_t size() const {
+ const auto* ptr = get();
+ if (ptr == nullptr) {
+ return 0;
+ }
+ return ptr->size;
+ }
+
+ /*!
+ * \brief Return the length of the string
+ *
+ * \return size_t string length
+ */
+ inline size_t length() const { return size(); }
+
+ /*!
+ * \brief Return the data pointer
+ *
+ * \return const char* data pointer
+ */
+ inline const char* data() const { return get()->data; }
+
+ /*! \return the internal StringObj pointer */
+ const StringObj* get() const { return operator->(); }
+
+ /*!
+ * \brief Convert String to an std::sting object
+ *
+ * \return std::string
+ */
+ operator std::string() const { return std::string{get()->data, size()}; }
+
+ TVM_DEFINE_OBJECT_REF_METHODS(String, ObjectRef, StringObj);
+};
+
+/*! \brief An object representing string moved from std::string. */
+class StringObj::FromStd : public StringObj {
+ public:
+ /*! \brief Container that holds the memory. */
+ std::string data_container;
+};
+
+inline String::String(std::string other) {
+ auto ptr = make_object<StringObj::FromStd>();
+ ptr->data_container.swap(other);
+ ptr->size = ptr->data_container.size();
+ ptr->data = ptr->data_container.data();
+ data_ = std::move(ptr);
+}
+
+inline bool String::operator==(const char* other) const {
+ return !operator!=(other);
+}
+
+inline bool String::operator!=(const char* other) const {
+ return size() != std::strlen(other) || compare(other, size()) != 0;
+}
+
} // namespace runtime
} // namespace tvm
+namespace std {
+
+template <>
+struct hash<::tvm::runtime::String> {
+ std::size_t operator()(const ::tvm::runtime::String& str) const {
+ return std::hash<std::string>()((std::string)str);
Review comment:
How about we cache the hash value of `std::hash` in `String`?
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