# Manipulating Paths

Plywood provides the WindowsPath and PosixPath classes for manipulating filesystem paths. All member functions are static and accept StringView arguments:

PosixPath::join("path/to", "file");     // "path/to/file"
WindowsPath::split("path\\to\\file");   // {"path\\to", "file"}


Plywood also provides NativePath, a type alias for either WindowsPath or PosixPath depending on the target platform:

NativePath::join(PLY_WORKSPACE_FOLDER, "repos/plywood/docs");


You'll likely use NativePath most often, but there's nothing to stop you from using WindowsPath on POSIX or PosixPath on Windows.

The WindowsPath class recognizes both forward and backslash characters as path separators. Its join(), normalize() and makeRelative() functions normalize all path separators to backslashes.

The PosixPath class only treats forward slashes as path separators.

Neither of these classes interact with the filesystem in any way. These path manipulation functions operate purely on strings.

You can also manipulate paths indirectly using a PathFormat object, which can be obtained by calling format(). All WindowsPath and PosixPath member functions are static, and all PathFormat member functions are non-static.

## Normalized Paths

The join(), normalize() and makeRelative() member functions all return normalized paths. A normalized path is one in which redundant path separators are collapsed, references to the current directory "." are discarded unless it is the only component, and references to the parent directory ".." collapse the parent directory if there is one. A normalized WindowsPath contains no forward slashes and uses only backslashes as path separators. An empty string is normalized to ".". Normalized paths may or may not include a trailing path separator; see each function for further details.

## Unicode Support

UTF-8 is the preferred character encoding for paths, but for practical purposes, the only characters treated specially are / \ . : and ASCII letters. Therefore, these path functions work just as well with ISO 8859-1, Windows-1252 and pure ASCII strings.

The FileSystem functions, on the other hand, do expect UTF-8 strings.

#include <ply-runtime/filesystem/Path.h>

Also included from <ply-runtime/Base.h>.

## Member Functions

static const char& sepByte()

WindowsPath returns a backslash. PosixPath returns a forward slash.

static bool isSepByte(char c)

WindowsPath returns true if c is a forward or backslash. PosixPath returns true if c is a forward slash.

static bool endsWithSep(StringView path)

WindowsPath returns true if path ends with a forward or backslash. PosixPath returns true if path ends with a forward slash.

static bool hasDriveLetter(StringView path)

WindowsPath returns true if path begins with a drive letter prefix such as "C:". PosixPath always returns false.

static StringView getDriveLetter(StringView path)

If path begins with a drive letter such as "C:", WindowsPath returns the drive letter including the colon. PosixPath always returns an empty string.

static bool isAbsolute(StringView path)

WindowsPath returns true if path begins with a drive letter and path separator. PosixPath returns true if path begins with '/'.

WindowsPath::isAbsolute("C:\\");       // true
WindowsPath::isAbsolute("d:/my/path"); // true
WindowsPath::isAbsolute("C:file");     // false
WindowsPath::isAbsolute("\\my\\path"); // false
PosixPath::isAbsolute("/my/path");     // true


An empty string satisfies neither isAbsolute() nor isRelative(). For WindowsPath, a path that begin with a drive letter or path separator only (such as "C:file" and "\\my\\path") satisfies neither isAbsolute() nor isRelative().

You can make a path absolute using FileSystem::getAbsolutePath().

static bool isRelative(StringView path)

Returns true if path is non-empty and does not begin with a drive letter or path separator.

WindowsPath::isRelative("file");       // true
WindowsPath::isRelative("my\\path");   // true
WindowsPath::isRelative("C:file");     // false
WindowsPath::isRelative("\\my\\path"); // false
PosixPath::isRelative("my/path");      // true


An empty string satisfies neither isAbsolute() nor isRelative(). For WindowsPath, a path that begin with a drive letter or path separator only (such as "C:file" and "\\my\\path") satisfies neither isAbsolute() nor isRelative().

static Tuple<StringView, StringView> split(StringView path)

Splits path into a Tuple where second is the last path component and first is everything leading up to that. Similar to os.path.split() in Python. second will never contain a path separator; if path ends with a path separator, second will be empty. If there is no path separator in path, first will be empty. Trailing slashes are stripped from first unless it is the root. WindowsPath::split() does not convert forward slashes to backslashes.

PosixPath::split("path/to/file");       // {"path/to", "file"}
PosixPath::split("path/to/folder/");    // {"path/to/folder", ""}
PosixPath::split("/file_in_root");      // {"/", "file_in_root"}
PosixPath::split("file");               // {"", "file"}
WindowsPath::split("path\\to\\file");   // {"path\\to", "file"}
WindowsPath::split("path/to/file");     // {"path/to", "file"}

static Array<StringView> splitFull(StringView path)

Splits path into an array of items where each item contains a single path component. When WindowsPath is given an absolute path, it returns the drive letter and first path separator as the first component. When PosixPath is given an absolute path, it returns "/" as the first component. None of the other components contain a path separator. If path ends with a path separator, the last component is an empty string.

PosixPath::splitFull("path/to/file");       // {"path", "to", "file"}
PosixPath::splitFull("path/to/folder/");    // {"path", "to", "folder", ""}
PosixPath::splitFull("/file_in_root");      // {"/", "file_in_root"}
WindowsPath::splitFull("path\\to/file");    // {"path", "to", "file"}
WindowsPath::splitFull("C:\\file_in_root"); // {"C:\\", "file_in_root"}

static Tuple<StringView, StringView> splitExt(StringView path)

Splits path into a Tuple such that first + second == path, and second is empty or begins with a period and contains at most one period. Similar to os.path.splitext() in Python. Leading periods on the basename, as in ".gitignore", are ignored.

PosixPath::splitExt("file.txt");           // {"file", ".txt"}
PosixPath::splitExt("file");               // {"file"}
PosixPath::splitExt("file.tar.gz");        // {"file.tar", ".gz"}
PosixPath::splitExt("path/to/file.txt");   // {"path/to/file", ".txt"}
PosixPath::splitExt("folder.tmp/");        // {"folder.tmp/", ""}
PosixPath::splitExt("folder.tmp/file");    // {"folder.tmp/file", ""}
PosixPath::splitExt(".gitignore");         // {".gitignore", ""}
PosixPath::splitExt("path/to/.gitignore"); // {"path/to/.gitignore", ""}

static String join(components...)

Joins one or more path components together and normalizes the result. Note that this function is not the same as os.path.join() in Python. It's closer (but not identical) to os.path.normpath(os.path.join()) in Python.

The returned path has a trailing slash if and only if the last component has a trailing slash or is an empty string. If any argument is an absolute path, all previous arguments are thrown away except for any drive letter that was encountered. For WindowsPath, if any argument contains a drive letter, all previous arguments are thrown away.

PosixPath::join("path/to", "file");          // "path/to/file"
PosixPath::join("path/to", "folder/");       // "path/to/folder/"
PosixPath::join("path/to", "folder", "");    // "path/to/folder/"
PosixPath::join("path/to", "./file");        // "path/to/file"
PosixPath::join("path/to/file", "../other"); // "path/to/other"

static String normalize(components...)

Equivalent to join().

static bool isNormalized(StringView path)

Equivalent to path == normalize(path).

static String makeRelative(StringView ancestor, StringView descendant)

Returns a new path relative such that join(ancestor, relative) is equivalent to descendant. If ancestor is an absolute path, descendant must also be an absolute path, and if ancestor is a relative path, descendant must also be a relative path. The returned path is normalized. The returned path has a trailing slash if and only if descendant has a trailing slash.

PosixPath::makeRelative("/path/to", "/path/to/file");        // "file"
PosixPath::makeRelative("/path/to/", "/path/to/file");       // "file"
PosixPath::makeRelative("/path/to", "/path/to/a/b");         // "a/b"
PosixPath::makeRelative("/path/to/file", "/path/to/other");  // "../other"
PosixPath::makeRelative("/path/to/file", "/path/to/other/"); // "../other/"
PosixPath::makeRelative("path/to", "path/to");               // "."
PosixPath::makeRelative("path/to/", "path/to");              // "."
PosixPath::makeRelative("path/to", "path/to/");              // "./"

static PathFormat format()

Returns a PathFormat object that exposes the same functionality as WindowsPath or PosixPath, but using non-static member functions instead of static member functions. You can pass the PathFormat object to other functions to perform platform-specific path manipulation indirectly.

static HybridString from<SrcFormat>(StringView path)

Converts the path separators in path. PosixPath::from<WindowsPath>() converts all backslashes to forward slashes. WindowsPath::from<PosixPath>() and WindowsPath::from<WindowsPath>() convert all forward slashes to backslashes. Otherwise the returned string is identical.

// Returns "path\\to\\file":
WindowsPath::from<PosixPath>("path/to/file");

// Returns "C:/path/to/file":
PosixPath::from<WindowsPath>("C:\\path\\to\\file");

static HybridString from(const PathFormat& srcFormat, StringView path)

Same as the previous function, but the source format is determined by function argument instead of template argument.

// Returns "path\\to\\file":
WindowsPath::from(PosixPath::format(), "path/to/file");

// Returns "C:/path/to/file":
PosixPath::from(WindowsPath::format(), "C:\\path\\to\\file");