1 files changed, 75 insertions, 0 deletions
diff --git a/cli/internal/turbopath/anchored_system_path.go b/cli/internal/turbopath/anchored_system_path.go
new file mode 100644
index 0000000..0957ead
--- /dev/null
+++ b/cli/internal/turbopath/anchored_system_path.go
@@ -0,0 +1,75 @@
+package turbopath
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// AnchoredSystemPath is a path stemming from a specified root using system separators.
+type AnchoredSystemPath string
+
+// ToString returns a string represenation of this Path.
+// Used for interfacing with APIs that require a string.
+func (p AnchoredSystemPath) ToString() string {
+	return string(p)
+}
+
+// ToStringDuringMigration returns the string representation of this path, and is for
+// use in situations where we expect a future path migration to remove the need for the
+// string representation
+func (p AnchoredSystemPath) ToStringDuringMigration() string {
+	return string(p)
+}
+
+// ToSystemPath returns itself.
+func (p AnchoredSystemPath) ToSystemPath() AnchoredSystemPath {
+	return p
+}
+
+// ToUnixPath converts a AnchoredSystemPath to a AnchoredUnixPath.
+func (p AnchoredSystemPath) ToUnixPath() AnchoredUnixPath {
+	return AnchoredUnixPath(filepath.ToSlash(p.ToString()))
+}
+
+// RelativeTo calculates the relative path between two AnchoredSystemPath`s.
+func (p AnchoredSystemPath) RelativeTo(basePath AnchoredSystemPath) (AnchoredSystemPath, error) {
+	processed, err := filepath.Rel(basePath.ToString(), p.ToString())
+	return AnchoredSystemPath(processed), err
+}
+
+// RestoreAnchor prefixes the AnchoredSystemPath with its anchor to return an AbsoluteSystemPath.
+func (p AnchoredSystemPath) RestoreAnchor(anchor AbsoluteSystemPath) AbsoluteSystemPath {
+	return AbsoluteSystemPath(filepath.Join(anchor.ToString(), p.ToString()))
+}
+
+// Dir returns filepath.Dir for the path.
+func (p AnchoredSystemPath) Dir() AnchoredSystemPath {
+	return AnchoredSystemPath(filepath.Dir(p.ToString()))
+}
+
+// Join appends relative path segments to this AnchoredSystemPath.
+func (p AnchoredSystemPath) Join(additional ...RelativeSystemPath) AnchoredSystemPath {
+	cast := RelativeSystemPathArray(additional)
+	return AnchoredSystemPath(filepath.Join(p.ToString(), filepath.Join(cast.ToStringArray()...)))
+}
+
+// HasPrefix is strings.HasPrefix for paths, ensuring that it matches on separator boundaries.
+// This does NOT perform Clean in advance.
+func (p AnchoredSystemPath) HasPrefix(prefix AnchoredSystemPath) bool {
+	prefixLen := len(prefix)
+	pathLen := len(p)
+
+	if prefixLen > pathLen {
+		// Can't be a prefix if longer.
+		return false
+	} else if prefixLen == pathLen {
+		// Can be a prefix if they're equal, but otherwise no.
+		return p == prefix
+	}
+
+	// otherPath is definitely shorter than p.
+	// We need to confirm that p[len(otherPath)] is a system separator.
+
+	return strings.HasPrefix(p.ToString(), prefix.ToString()) && os.IsPathSeparator(p[prefixLen])
+}