6365bbfa81
More invariants are enforced in the type, and less state needs to be stored in the main sink itself. The method here is roughly that known as "session types". Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
94 lines
2.3 KiB
C++
94 lines
2.3 KiB
C++
#include "source-accessor.hh"
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#include "fs-sink.hh"
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#include "variant-wrapper.hh"
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namespace nix {
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/**
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* An source accessor for an in-memory file system.
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*/
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struct MemorySourceAccessor : virtual SourceAccessor
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{
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/**
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* In addition to being part of the implementation of
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* `MemorySourceAccessor`, this has a side benefit of nicely
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* defining what a "file system object" is in Nix.
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*/
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struct File {
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struct Regular {
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bool executable = false;
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std::string contents;
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GENERATE_CMP(Regular, me->executable, me->contents);
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};
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struct Directory {
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using Name = std::string;
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std::map<Name, File, std::less<>> contents;
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GENERATE_CMP(Directory, me->contents);
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};
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struct Symlink {
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std::string target;
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GENERATE_CMP(Symlink, me->target);
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};
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using Raw = std::variant<Regular, Directory, Symlink>;
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Raw raw;
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MAKE_WRAPPER_CONSTRUCTOR(File);
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GENERATE_CMP(File, me->raw);
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Stat lstat() const;
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};
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File root { File::Directory {} };
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GENERATE_CMP(MemorySourceAccessor, me->root);
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std::string readFile(const CanonPath & path) override;
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bool pathExists(const CanonPath & path) override;
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std::optional<Stat> maybeLstat(const CanonPath & path) override;
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DirEntries readDirectory(const CanonPath & path) override;
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std::string readLink(const CanonPath & path) override;
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/**
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* @param create If present, create this file and any parent directories
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* that are needed.
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*
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* Return null if
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*
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* - `create = false`: File does not exist.
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*
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* - `create = true`: some parent file was not a dir, so couldn't
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* look/create inside.
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*/
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File * open(const CanonPath & path, std::optional<File> create);
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CanonPath addFile(CanonPath path, std::string && contents);
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};
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/**
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* Write to a `MemorySourceAccessor` at the given path
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*/
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struct MemorySink : FileSystemObjectSink
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{
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MemorySourceAccessor & dst;
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MemorySink(MemorySourceAccessor & dst) : dst(dst) { }
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void createDirectory(const Path & path) override;
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void createRegularFile(
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const Path & path,
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std::function<void(CreateRegularFileSink &)>) override;
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void createSymlink(const Path & path, const std::string & target) override;
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};
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}
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