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Remove Path.roc for now
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interface Path
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exposes [Path, PathComponent, WindowsRoot, toComponents, walkComponents, fromStr, fromBytes]
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imports []
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## You can canonicalize a [Path] using [Path.canonicalize].
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##
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## Comparing canonical paths is often more reliable than comparing raw ones.
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## For example, `Path.fromStr "foo/bar/../baz" == Path.fromStr "foo/baz"` will return `False`,
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## because those are different paths even though their canonical equivalents would be equal.
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##
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## Also note that canonicalization reads from the file system (in order to resolve symbolic
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## links, and to convert relative paths into absolute ones). This means that it is not only
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## a [Task] (which can fail), but also that running [canonicalize] on the same [Path] twice
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## may give different answers. An example of a way this could happen is if a symbolic link
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## in the path changed on disk to point somewhere else in between the two [canonicalize] calls.
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##
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## Similarly, remember that canonical paths are not guaranteed to refer to a valid file. They
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## might have referred to one when they were canonicalized, but that file may have moved or
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## been deleted since the canonical path was created. So you might [canonicalize] a [Path],
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## and then immediately use that [Path] to read a file from disk, and still get back an error
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## because something relevant changed on the filesystem between the two operations.
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##
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## Also note that different filesystems have different rules for syntactically valid paths.
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## Suppose you're on a machine with two disks, one formatted as ext4 and another as FAT32.
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## It's possible to list the contents of a directory on the ext4 disk, and get a [CanPath] which
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## is valid on that disk, but invalid on the other disk. One way this could happen is if the
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## directory on the ext4 disk has a filename containing a `:` in it. `:` is allowed in ext4
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## paths but is considered invalid in FAT32 paths.
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Path := [
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# We store these separately for two reasons:
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# 1. If I'm calling an OS API, passing a path I got from the OS is definitely safe.
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# However, passing a Path I got from a RocStr might be unsafe; it may contain \0
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# characters, which would result in the operation happening on a totally different
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# path. As such, we need to check for \0s and fail without calling the OS API if we
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# find one in the path.
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# 2. If I'm converting the Path to a Str, doing that conversion on a Path that was
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# created from a RocStr needs no further processing. However, if it came from the OS,
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# then we need to know what charset to assume it had, in order to decode it properly.
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# These come from the OS (e.g. when reading a directory, calling `canonicalize`,
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# or reading an environment variable - which, incidentally, are nul-terminated),
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# so we know they are both nul-terminated and do not contain interior nuls.
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# As such, they can be passed directly to OS APIs.
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#
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# Note that the nul terminator byte is right after the end of the length (into the
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# unused capacity), so this can both be compared directly to other `List U8`s that
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# aren't nul-terminated, while also being able to be passed directly to OS APIs.
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FromOperatingSystem : List U8,
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# These come from userspace (e.g. Path.fromBytes), so they need to be checked for interior
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# nuls and then nul-terminated before the host can pass them to OS APIs.
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ArbitraryBytes : List U8,
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# This was created as a RocStr, so it might have interior nul bytes but it's definitely UTF-8.
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# That means we can `toStr` it trivially, but have to validate before sending it to OS
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# APIs that expect a nul-terminated `char*`.
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#
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# Note that both UNIX and Windows APIs will accept UTF-8, because on Windows the host calls
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# `_setmbcp(_MB_CP_UTF8);` to set the process's Code Page to UTF-8 before doing anything else.
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# See https://docs.microsoft.com/en-us/windows/apps/design/globalizing/use-utf8-code-page#-a-vs--w-apis
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# and https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/setmbcp?view=msvc-170
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# for more details on the UTF-8 Code Page in Windows.
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FromStr : Str,
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]
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## ## Creating and transforming
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## Note that the path may not be valid depending on the filesystem where it is used.
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## For example, paths containing `:` are valid on ext4 and NTFS filesystems, but not
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## on FAT ones. So if you have multiple disks on the same machine, but they have
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## different filesystems, then this path could be valid on one but invalid on another!
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##
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## It's safest to assume paths are invalid (even syntactically) until given to an operation
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## which uses them to open a file. If that operation succeeds, then the path was valid
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## (at the time). Otherwise, error handling can happen for that operation rather than validating
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## up front for a false sense of security (given symlinks, parts of a path being renamed, etc.).
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fromStr : Str -> Path
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fromStr = \str -> @Path (FromStr str)
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## Not all filesystems use Unicode paths. This function can be used to create a path which
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## is not valid Unicode (like a Roc [Str] is), but which is valid for a particular filesystem.
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##
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## Note that if the list contains any `0` bytes, sending this path to any file operations
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## (e.g. [File.read] or [WriteStream.openPath]) will fail.
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fromBytes : List U8 -> Path
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fromBytes = \bytes -> @Path (ArbitraryBytes bytes)
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## Note that canonicalization reads from the file system (in order to resolve symbolic
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## links, and to convert relative paths into absolute ones). This means that it is not only
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## a [Task] (which can fail), but also that running [canonicalize] on the same [Path] twice
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## may give different answers. An example of a way this could happen is if a symbolic link
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## in the path changed on disk to point somewhere else in between the two [canonicalize] calls.
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##
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## Returns an effect type of `[Metadata, Cwd]` because it can resolve symbolic links
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## and can access the current working directory by turning a relative path into an
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## absolute one (which can prepend the absolute path of the current working directory to
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## the relative path).
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canonicalize : Path -> Task Path (CanonicalizeErr *) [Metadata, Read [Env]]*
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## Unfortunately, operating system paths do not include information about which charset
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## they were originally encoded with. It's most common (but not guaranteed) that they will
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## have been encoded with the same charset as the operating system's curent locale (which
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## typically does not change after it is set during installation of the OS), so
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## this should convert a [Path] to a valid string as long as the path was created
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## with the given [Charset]. (Use [Env.charset] to get the current system charset.)
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##
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## For a conversion to [Str] that is lossy but does not return a [Result], see
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## [displayUtf8].
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toInner : Path -> [Str Str, Bytes (List U8)]
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## Assumes a path is encoded as [UTF-8](https://en.wikipedia.org/wiki/UTF-8),
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## and converts it to a string using [Str.displayUtf8].
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##
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## This conversion is lossy because the path may contain invalid UTF-8 bytes. If that happens,
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## any invalid bytes will be replaced with the [Unicode replacement character](https://unicode.org/glossary/#replacement_character)
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## instead of returning an error. As such, it's rarely a good idea to use the [Str] returned
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## by this function for any purpose other than displaying it to a user.
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##
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## When you don't know for sure what a path's encoding is, UTF-8 is a popular guess because
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## it's the default on UNIX and also is the encoding used in Roc strings. This platform also
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## automatically runs applications under the [UTF-8 code page](https://docs.microsoft.com/en-us/windows/apps/design/globalizing/use-utf8-code-page)
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## on Windows.
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##
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## Converting paths to strings can be an unreliable operation, because operating systems
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## don't record the paths' encodings. This means it's possible for the path to have been
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## encoded with a different character set than UTF-8 even if UTF-8 is the system default,
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## which means when [displayUtf8] converts them to a string, the string may include gibberish.
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## [Here is an example.](https://unix.stackexchange.com/questions/667652/can-a-file-path-be-invalid-utf-8/667863#667863)
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##
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## If you happen to know the [Charset] that was used to encode the path, you can use
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## [toStrUsingCharset] instead of [displayUtf8].
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displayUtf8 : Path -> Str
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displayUtf8 = \@Path path ->
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when path is
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FromStr str -> str
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NoInteriorNul bytes | ArbitraryBytes bytes ->
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Str.displayUtf8 bytes
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isEq : Path, Path -> Bool
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isEq = @Path p1, @Path p2 ->
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when p1 is
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NoInteriorNul bytes1 | ArbitraryBytes bytes1 ->
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when p2 is
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NoInteriorNul bytes2 | ArbitraryBytes bytes2 -> bytes1 == bytes2
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# We can't know the encoding that was originally used in the path, so we convert
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# the string to bytes and see if those bytes are equal to the path's bytes.
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#
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# This may sound unreliable, but it's how all paths are compared; since the OS
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# doesn't record which encoding was used to encode the path name, the only
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# reasonable# definition for path equality is byte-for-byte equality.
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FromStr str2 -> Str.isEqUtf8 str2 bytes1
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FromStr str1 ->
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when p2 is
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NoInteriorNul bytes2 | ArbitraryBytes bytes2 -> Str.isEqUtf8 str1 bytes2
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FromStr str2 -> str1 == str2
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compare : Path, Path -> [Lt, Eq, Gt]
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compare = @Path p1, @Path p2 ->
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when p1 is
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NoInteriorNul bytes1 | ArbitraryBytes bytes1 ->
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when p2 is
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NoInteriorNul bytes2 | ArbitraryBytes bytes2 -> Ord.compare bytes1 bytes2
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FromStr str2 -> Str.compareUtf8 str2 bytes1
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FromStr str1 ->
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when p2 is
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NoInteriorNul bytes2 | ArbitraryBytes bytes2 -> Ord.compare str1 bytes2
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FromStr str2 -> str1 == str2
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## ## Path Components
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PathComponent : [
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ParentDir, # e.g. ".." on UNIX or Windows
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CurrentDir, # e.g. "." on UNIX
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Named Str, # e.g. "stuff" on UNIX
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DirSep Str, # e.g. "/" on UNIX, "\" or "/" on Windows. Or, sometimes, "¥" on Windows - see
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# https://docs.microsoft.com/en-us/windows/win32/intl/character-sets-used-in-file-names
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#
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# This is included as an option so if you're transforming part of a path,
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# you can write back whatever separator was originally used.
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]
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## Note that a root of Slash (`/`) has different meanings on UNIX and on Windows.
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## * On UNIX, `/` at the beginning of the path refers to the filesystem root, and means the path is absolute.
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## * On Windows, `/` at the beginning of the path refers to the current disk drive, and means the path is relative.
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PathRoot : [
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WindowsSpecificRoot WindowsRoot, # e.g. "C:" on Windows
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Slash,
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None,
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]
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WindowsRoot : [
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# TODO see https://doc.rust-lang.org/std/path/enum.Prefix.html
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]
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## Returns the root of the path.
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root : Path -> PathRoot
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components : Path -> (PathRoot, List PathComponent)
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## Walk over the path's [components].
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walk :
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Path,
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# None means it's a relative path
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(PathRoot -> state),
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(state, PathComponent -> state)
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-> state
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## Returns the path without its last [`component`](#components).
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##
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## If the path was empty or contained only a [root](#PathRoot), returns the original path.
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dropLast : Path -> Path
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# TODO see https://doc.rust-lang.org/std/path/struct.Path.html#method.join for
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# the definition of the term "adjoin" - should we use that term?
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append : Path, Path -> Path
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append = \@Path prefix, @Path suffix ->
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@Path when prefix is
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NoInteriorNul prefixBytes ->
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when suffix is
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NoInteriorNul suffixBytes
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List.append prefixBytes suffixBytes
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# Neither prefix nor suffix had interior nuls, so the answer won't either.
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|> NoInteriorNul
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ArbitraryBytes suffixBytes ->
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List.append prefixBytes suffixBytes
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|> ArbitraryBytes
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FromStr suffixStr ->
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# Append suffixStr by writing it to the end of prefixBytes
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Str.writeUtf8 suffixStr prefixBytes (List.len prefixBytes)
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|> ArbitraryBytes
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ArbitraryBytes prefixBytes ->
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when suffix is
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ArbitraryBytes suffixBytes | NoInteriorNul suffixBytes ->
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List.append prefixBytes suffixBytes
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|> ArbitraryBytes
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FromStr suffixStr ->
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# Append suffixStr by writing it to the end of prefixBytes
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Str.writeUtf8 suffixStr prefixBytes (List.len prefixBytes)
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|> ArbitraryBytes
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FromStr prefixStr ->
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when suffix is
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ArbitraryBytes suffixBytes | NoInteriorNul suffixBytes ->
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List.append (Str.toUtf8 prefixStr) suffixBytes
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|> ArbitraryBytes
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FromStr suffixStr ->
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Str.append prefixStr suffixStr
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|> FromStr
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appendStr : Path, Str -> Path
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appendStr = \@Path prefix, suffixStr ->
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@Path when prefix is
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NoInteriorNul prefixBytes | ArbitraryBytes prefixBytes ->
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# Append suffixStr by writing it to the end of prefixBytes
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Str.writeUtf8 suffixStr prefixBytes (List.len prefixBytes)
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|> ArbitraryBytes
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FromStr prefixStr ->
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Str.append prefixStr suffixStr
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|> FromStr
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## Returns `True` if the first path begins with the second.
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startsWith : Path, Path -> Bool
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startsWith = \@Path path, @Path prefix ->
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when path is
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NoInteriorNul pathBytes | ArbitraryBytes pathBytes ->
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when prefix is
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NoInteriorNul prefixBytes | ArbitraryBytes prefixBytes ->
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List.startsWith pathBytes prefixBytes
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FromStr prefixStr ->
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strLen = Str.byteCount str
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if strLen == List.len pathBytes then
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# Grab the first N bytes of the list, where N = byte length of string.
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bytesPrefix = List.takeAt pathBytes 0 strLen
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# Compare the two for equality.
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Str.isEqUtf8 prefixStr bytesPrefix
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else
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False
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FromStr pathStr ->
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when prefix is
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NoInteriorNul prefixBytes | ArbitraryBytes prefixBytes ->
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Str.startsWithUtf8 pathStr prefixBytes
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FromStr prefixStr ->
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Str.startsWith pathStr prefixStr
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## Returns `True` if the first path ends with the second.
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endsWith : Path, Path -> Bool
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endsWith = \@Path path, @Path prefix ->
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when path is
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NoInteriorNul pathBytes | ArbitraryBytes pathBytes ->
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when suffix is
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NoInteriorNul suffixBytes | ArbitraryBytes suffixBytes ->
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List.endsWith pathBytes suffixBytes
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FromStr suffixStr ->
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strLen = Str.byteCount suffixStr
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if strLen == List.len pathBytes then
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# Grab the last N bytes of the list, where N = byte length of string.
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bytesSuffix = List.takeAt pathBytes (strLen - 1) strLen
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# Compare the two for equality.
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Str.startsWithUtf8 suffixStr bytesSuffix
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else
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False
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FromStr pathStr ->
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when suffix is
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NoInteriorNul suffixBytes | ArbitraryBytes suffixBytes ->
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Str.endsWithUtf8 pathStr suffixBytes
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FromStr suffixStr ->
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Str.endsWith pathStr suffixStr
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# TODO https://doc.rust-lang.org/std/path/struct.Path.html#method.strip_prefix
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# TODO idea: what if it's File.openRead and File.openWrite? And then e.g. File.metadata,
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# File.isDir, etc.
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## If the last component of this path has no `.`, appends `.` followed by the given string.
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## Otherwise, replaces everything after the last `.` with the given string.
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##
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## Examples:
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##
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## Path.fromStr "foo/bar/baz" |> Path.withExtension "txt" # foo/bar/baz.txt
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## Path.fromStr "foo/bar/baz." |> Path.withExtension "txt" # foo/bar/baz.txt
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## Path.fromStr "foo/bar/baz.xz" |> Path.withExtension "txt" # foo/bar/baz.txt
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withExtension : Path, Str -> Path
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withExtension = \@Path path, extension ->
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when path is
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NoInteriorNul bytes | ArbitraryBytes bytes ->
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beforeDot =
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when List.splitLast '.' is
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Ok (before, _) -> before
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Err NotFound -> list
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beforeDot
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|> List.reserve (1 + List.len bytes)
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|> List.append '.'
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|> List.concat bytes
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FromStr str ->
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beforeDot =
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when Str.splitLast str "." is
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Ok (before, _) -> before
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Err NotFound -> str
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beforeDot
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|> Str.reserve (1 + Str.byteCount str)
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|> Str.append "."
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|> Str.concat str
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# NOTE: no withExtensionBytes because it's too narrow. If you really need to get some
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# non-Unicode in there, do it with
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# Returns `True` if the path is absolute.
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#
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# A path is only absolute if it begins with an absolute root
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# (see [PathRoot] for examples of roots) _and_ it contains neither `..` nor `.` path
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# components.
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#
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# Note that an absolute path may contain unresolved symlinks, so even an absolute path
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# may change when passed to [canonicalize].
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#
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# This returns a [Task] because the answer varies by operating system; on UNIX,
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# `/blah` is an absolute path, but on Windows, `/blah` is a relative path. The
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# task returns the appropriate answer for the operating system on which it's run.
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# isAbsolute
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