138 lines
3.2 KiB
C++
138 lines
3.2 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#pragma once
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#include <folly/Exception.h>
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#ifndef RN_EXPORT
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#ifdef _MSC_VER
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#define RN_EXPORT
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#else
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#define RN_EXPORT __attribute__((visibility("default")))
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#endif
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#endif
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namespace facebook {
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namespace react {
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// JSExecutor functions sometimes take large strings, on the order of
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// megabytes. Copying these can be expensive. Introducing a
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// move-only, non-CopyConstructible type will let the compiler ensure
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// that no copies occur. folly::MoveWrapper should be used when a
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// large string needs to be curried into a std::function<>, which must
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// by CopyConstructible.
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class JSBigString {
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public:
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JSBigString() = default;
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// Not copyable
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JSBigString(const JSBigString &) = delete;
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JSBigString &operator=(const JSBigString &) = delete;
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virtual ~JSBigString() {}
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virtual bool isAscii() const = 0;
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// This needs to be a \0 terminated string
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virtual const char *c_str() const = 0;
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// Length of the c_str without the NULL byte.
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virtual size_t size() const = 0;
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};
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// Concrete JSBigString implementation which holds a std::string
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// instance.
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class JSBigStdString : public JSBigString {
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public:
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JSBigStdString(std::string str, bool isAscii = false)
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: m_isAscii(isAscii), m_str(std::move(str)) {}
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bool isAscii() const override {
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return m_isAscii;
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}
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const char *c_str() const override {
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return m_str.c_str();
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}
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size_t size() const override {
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return m_str.size();
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}
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private:
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bool m_isAscii;
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std::string m_str;
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};
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// Concrete JSBigString implementation which holds a heap-allocated
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// buffer, and provides an accessor for writing to it. This can be
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// used to construct a JSBigString in place, such as by reading from a
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// file.
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class RN_EXPORT JSBigBufferString : public JSBigString {
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public:
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JSBigBufferString(size_t size) : m_data(new char[size + 1]), m_size(size) {
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// Guarantee nul-termination. The caller is responsible for
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// filling in the rest of m_data.
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m_data[m_size] = '\0';
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}
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~JSBigBufferString() {
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delete[] m_data;
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}
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bool isAscii() const override {
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return true;
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}
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const char *c_str() const override {
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return m_data;
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}
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size_t size() const override {
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return m_size;
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}
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char *data() {
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return m_data;
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}
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private:
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char *m_data;
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size_t m_size;
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};
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// JSBigString interface implemented by a file-backed mmap region.
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class RN_EXPORT JSBigFileString : public JSBigString {
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public:
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JSBigFileString(int fd, size_t size, off_t offset = 0);
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~JSBigFileString();
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bool isAscii() const override {
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return true;
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}
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const char *c_str() const override;
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size_t size() const override;
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int fd() const;
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static std::unique_ptr<const JSBigFileString> fromPath(
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const std::string &sourceURL);
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private:
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int m_fd; // The file descriptor being mmaped
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size_t m_size; // The size of the mmaped region
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mutable off_t m_pageOff; // The offset in the mmaped region to the data.
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off_t m_mapOff; // The offset in the file to the mmaped region.
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mutable const char *m_data; // Pointer to the mmaped region.
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};
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} // namespace react
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} // namespace facebook
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