Function buildRouteURL

router.go:104–161

buildRouteURL generates a URL from route segments and parameters. This shared helper is used by both Route.URL() and DefaultRes.getLocationFromRoute() to ensure consistent URL generation behavior across APIs. Parameter resolution uses a deterministic three-step lookup: 1. Exact key match on segment

(route *Route, params Map)

//  2. Case-insensitive fallback picking the lexicographically-smallest matching key (when !caseSensitive)
//  3. Greedy parameter fallback for wildcard (*) and plus (+) parameters
func buildRouteURL(route *Route, params Map) (string, error) {
	if len(route.routeParser.segs) == 0 {
		return route.Path, nil
	}

	buf := bytebufferpool.Get()
	defer bytebufferpool.Put(buf)

	for _, segment := range route.routeParser.segs {
		if !segment.IsParam {
			_, err := buf.WriteString(segment.Const)
			if err != nil {
				return "", fmt.Errorf("failed to write string: %w", err)
			}
			continue
		}

		var (
			val   any
			found bool
		)

		// Prefer an exact parameter name match
		if val, found = params[segment.ParamName]; !found && !route.caseSensitive {
			// Fall back to a case-insensitive match using a deterministic winner
			var matchedKey string
			foundMatch := false
			for key := range params {
				if utils.EqualFold(key, segment.ParamName) && (!foundMatch || key < matchedKey) {
					matchedKey = key
					foundMatch = true
				}
			}
			if foundMatch {
				val = params[matchedKey]
				found = true
			}
		}

		// For greedy parameters, fall back to generic greedy keys
		if !found && segment.IsGreedy {
			for _, greedyKey := range preferredGreedyParameters(segment.ParamName) {
				if val, found = params[greedyKey]; found {
					break
				}
			}
		}

		if found {
			_, err := buf.WriteString(utils.ToString(val))
			if err != nil {
				return "", fmt.Errorf("failed to write string: %w", err)
			}
		}
	}

	return buf.String(), nil
}