fix(radix): fallback to parent wildcard when static child has no handler

[AruneshDwivedi]

Fixes #72

Problem

When a path exactly matches a static child node that has no direct handler and no wildcard, but its parent has a wildcard route, the lookup incorrectly returned nil (with TSR=true) instead of falling back to the parent's wildcard handler.

This caused routes like /{path:*} and /test/{path:*} to fail to match /test, since the test prefix matched the static child test which had only an auto-generated trailing-slash child (no handler of its own).

Root Cause

In radix/node.go getFromChild, when path == child.path for a static child, the switch checked child.tsr first and immediately returned nil, true without considering that the parent might have a wildcard handler that should take precedence.

Fix

After checking child.handler and child.wildcard, check if the parent node has a wildcard and return it. Only fall back to tsr or continue to other children if no parent wildcard exists.

Testing

Added regression test covering the reported scenario. All existing tests continue to pass.

[erikdubbelboer]

Should this copy path instead of ""? With the routes from the test, /test now reaches the parent handler, but ctx.UserValue("path") is empty instead of "test".

This fails when added to radix/wildcard_fallback_test.go:

func TestParentWildcardValue(t *testing.T) {
	tree := New()
	handler := func(*fasthttp.RequestCtx) {}
	tree.Add("/{path:*}", handler)
	tree.Add("/test/{path:*}", handler)

	ctx := new(fasthttp.RequestCtx)
	h, tsr := tree.Get("/test", ctx)
	if h == nil || tsr {
		t.Fatalf("expected parent handler, got handler=%v tsr=%v", h != nil, tsr)
	}
	if got := ctx.UserValue("path"); got != "test" {
		t.Fatalf("path = %q, want %q", got, "test")
	}
}

[erikdubbelboer]

Adding an unrelated /team route makes /test return tsr=true again. It splits the shared te prefix, so the wildcard is now on an ancestor instead of the immediate parent. Can we let the lookup fall back to that wildcard before returning the redirect?

This fails when added to radix/wildcard_fallback_test.go:

func TestParentWildcardWithSharedPrefix(t *testing.T) {
	tree := New()
	tree.Add("/{path:*}", func(ctx *fasthttp.RequestCtx) { ctx.WriteString("parent") })
	tree.Add("/test/{path:*}", func(ctx *fasthttp.RequestCtx) { ctx.WriteString("child") })
	tree.Add("/team", func(*fasthttp.RequestCtx) {})

	ctx := new(fasthttp.RequestCtx)
	h, tsr := tree.Get("/test", ctx)
	if h == nil || tsr {
		t.Fatalf("expected parent handler, got handler=%v tsr=%v", h != nil, tsr)
	}
	h(ctx)
	if got := string(ctx.Response.Body()); got != "parent" {
		t.Fatalf("body = %q, want %q", got, "parent")
	}
}

[AruneshDwivedi]

Hey -- I've addressed both of your points: (1) is now copied via so UserValue("path") returns the correct value instead of empty string, (2) when a shared prefix like splits the parent node, we search up the ancestor chain for a wildcard before falling back to TSR. Added comprehensive tests covering all edge cases.

[AruneshDwivedi]

Addressed both issues: (1) path value now correctly set via gstrings.Copy(path) so ctx.UserValue("path") returns the right value, (2) added ancestor wildcard search for shared-prefix case where /team splits the parent node.

[erikdubbelboer]

@AruneshDwivedi the PR now just deletes radix/node.go? 🤷‍♂️