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https://github.com/carbon-language/carbon-lang.git
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Jon Meow
8a2ef22c2a
There's currently a bug with empty files, in that it initializes SourceBuffer with an invalid StringRef that results in a crash. That got me looking at the std::optional TODO, but the issue is that there are really three states: - Buffered - mmapped (not buffered) - Moved out of (no longer initialized) Technically an optional could work if we initialize the buffer on move out, indicating the mmap is gone. But the mode setup felt better to me. And then this also adds the size check. Which is really how I started looking at this.
78 lines
2.5 KiB
C++
78 lines
2.5 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#ifndef TOOLCHAIN_SOURCE_SOURCEBUFFER_H_
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#define TOOLCHAIN_SOURCE_SOURCEBUFFER_H_
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#include <string>
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#include <utility>
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#include "llvm/ADT/StringRef.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/Support/Error.h"
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namespace Carbon {
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// A buffer of Carbon source code.
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//
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// This class holds a buffer of Carbon source code as text and makes it
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// available for use in the rest of the Carbon compiler. It owns the memory for
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// the underlying source code text and ensures it lives as long as the buffer
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// objects.
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//
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// Every buffer of source code text is notionally loaded from a Carbon source
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// file, even if provided directly when constructing the buffer. The name that
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// should be used for that Carbon source file is also retained and made
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// available.
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//
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// Because the underlying memory for the source code text may have been read
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// from a file, and we may want to use facilities like `mmap` to simply map that
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// file into memory, the buffer itself is not copyable to avoid needing to
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// define copy semantics for a mapped file. We can relax this restriction with
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// some implementation complexity in the future if needed.
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class SourceBuffer {
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public:
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static auto CreateFromText(llvm::Twine text,
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llvm::StringRef filename = "/text")
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-> llvm::Expected<SourceBuffer>;
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static auto CreateFromFile(llvm::StringRef filename)
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-> llvm::Expected<SourceBuffer>;
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// Use one of the factory functions above to create a source buffer.
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SourceBuffer() = delete;
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// Cannot copy as there may be non-trivial owned file data; see the class
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// comment for details.
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SourceBuffer(const SourceBuffer& arg) = delete;
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SourceBuffer(SourceBuffer&& arg) noexcept;
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~SourceBuffer();
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[[nodiscard]] auto Filename() const -> llvm::StringRef { return filename_; }
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[[nodiscard]] auto Text() const -> llvm::StringRef { return text_; }
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private:
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enum class ContentMode {
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Uninitialized,
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MMapped,
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Owned,
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};
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// Constructor for mmapped content.
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SourceBuffer(std::string filename, llvm::StringRef text);
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// Constructor for owned content.
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SourceBuffer(std::string filename, std::string text);
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ContentMode content_mode_;
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std::string filename_;
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std::string text_storage_;
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llvm::StringRef text_;
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};
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} // namespace Carbon
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#endif // TOOLCHAIN_SOURCE_SOURCEBUFFER_H_
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