Lesson 26 · Picking one - Build a Fuzzy Finder

Picking one

The whole point of a finder is to pick something. Today you add accept - the operation that returns the currently selected candidate, the value a user commits to by pressing Enter.

The goal

Return the selected candidate, and signal cleanly when there is nothing to accept.

Start here - the target

TO DO

Scenario: Accepting the selection

Givena Finder whose results are ["src/app.go", "src/main.go", "go.mod"]

Whenaccept is called with the selection at index 1, then with the selection at index 0, then on a Finder with no results

Thenat index 1 it returns "src/main.go", at index 0 it returns "src/app.go", and with no results it signals "nothing selected" (an ok flag of false), never indexing off the end

Background

Accept is the finder’s output. Every earlier operation exists to get the right candidate under the cursor; accept is where that candidate leaves the finder and becomes the answer - the path you cd into, the file you open, the branch you check out. It reads the selected result and returns its candidate.

The edge that matters is an empty result list: with nothing matching, there is nothing to accept, so accept must say so rather than index into an empty slice and crash. Returning a value plus an ok flag is the same “missing is its own answer” shape the matcher used back in lesson two - a clean signal the caller can branch on. With movement and accept in place, the finder model is functionally complete; what remains is drawing it and feeding it keystrokes.

Make it work

// Return the selected candidate plus an ok flag, mirroring the
// found-or-not pattern from matching.
func (f *Finder) Accept() (string, bool) {
  if len(f.Results) == 0 { return "", false }
  return f.Results[f.Selection].Candidate, true
}

CheckpointDONE

The finder can return the candidate the user chose. Commit and stop here.