Resolve entered command routes to canonical paths

internal/alias/resolver.go

@@ -132,3 +132,39 @@ func (resolver *Resolver) Resolve(path commandpath.Path) commandpath.Path {
 		current = next
 	}
 }
+
+// ResolveWithProvenance resolves a command path and carries the input token
+// indexes that contributed to each output component. Rewritten target
+// components inherit the origins of the matched source prefix.
+func (resolver *Resolver) ResolveWithProvenance(path commandpath.Path) (commandpath.Path, [][]int) {
+	current := path.Clone()
+	origins := make([][]int, len(path))
+	for index := range path {
+		origins[index] = []int{index}
+	}
+	for {
+		next, mapping, matched := resolver.ResolveOnce(current)
+		if !matched {
+			return current, origins
+		}
+
+		matchedOrigins := make([]int, 0)
+		seen := make(map[int]struct{})
+		for _, componentOrigins := range origins[:len(mapping.Source)] {
+			for _, origin := range componentOrigins {
+				if _, exists := seen[origin]; exists {
+					continue
+				}
+				seen[origin] = struct{}{}
+				matchedOrigins = append(matchedOrigins, origin)
+			}
+		}
+		nextOrigins := make([][]int, 0, len(mapping.Target)+len(origins)-len(mapping.Source))
+		for range mapping.Target {
+			nextOrigins = append(nextOrigins, append([]int(nil), matchedOrigins...))
+		}
+		nextOrigins = append(nextOrigins, origins[len(mapping.Source):]...)
+		current = next
+		origins = nextOrigins
+	}
+}