Dependency Walkthroughs

Reading a pull request in the order git lists it (alphabetically) often means reading the UI before the model it renders. OrderFilesByDependency reorders a diff so each Go file comes after the changed files it depends on. mrman uses it for its file tree.

import (
  "github.com/bluekeyes/go-gitdiff/gitdiff"
  "github.com/infrashift/vizzini-pr-reviewer/pkg/reviewer"
)

files, _, err := gitdiff.Parse(patch)
if err != nil {
  return err
}
for _, f := range reviewer.OrderFilesByDependency(files) {
  fmt.Println(f.NewName)
}
// model/user.go
// service/users.go
// ui/profile.go

What counts as a dependency

File A depends on file B when…	Example
A imports B’s package	ui/profile.go imports example.com/app/service
A and B share a directory and A uses a type B declares	handler.go has a *Service field declared in service.go

Only the diff is read, so no checkout is needed. New files are parsed in full with go/parser. For modified files, the new side of each hunk is parsed if it forms a valid file. Otherwise it is scanned token by token, which still finds imports, type declarations and references in a fragment.

Ordering rules

• Each file is placed only after the files it depends on (Kahn’s topological sort).
• Ties go to the shallower path, then alphabetical order, so the result is identical for every input order.
• Go allows type cycles within a package. A cycle is broken the same way: the shallowest path comes first.
• Non-Go files (docs, CUE, SQL) follow the Go files in their original diff order.