acceptsLanguageOfferExtended() — fiber Function Reference

Architecture documentation for the acceptsLanguageOfferExtended() function in helpers.go from the fiber codebase.

Function go FiberCore Routing

Entity Profile

FiberCore→ Routing→ acceptsLanguageOfferExtended() — fiber Function Reference

Dependency Diagram

graph TD
  caf94e5f_a094_efb5_d604_9ddb963923db["acceptsLanguageOfferExtended()"]
  bec0e401_e4cd_f765_6df3_a79059073e50["helpers.go"]
  caf94e5f_a094_efb5_d604_9ddb963923db -->|defined in| bec0e401_e4cd_f765_6df3_a79059073e50
  style caf94e5f_a094_efb5_d604_9ddb963923db fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

helpers.go lines 268–318

func acceptsLanguageOfferExtended(spec, offer string, _ headerParams) bool {
	if spec == "*" {
		return true
	}
	if spec == "" || offer == "" {
		return false
	}

	// Use stack-allocated arrays to avoid heap allocations for typical language tags
	var rsBuf, tsBuf [8]string
	rs := rsBuf[:0]
	ts := tsBuf[:0]

	// Parse spec subtags without allocation for typical cases
	for s := range strings.SplitSeq(spec, "-") {
		rs = append(rs, s)
	}
	// Parse offer subtags without allocation for typical cases
	for s := range strings.SplitSeq(offer, "-") {
		ts = append(ts, s)
	}

	// Step 2: first subtag must match (or be '*')
	if rs[0] != "*" && !utils.EqualFold(rs[0], ts[0]) {
		return false
	}

	i, j := 1, 1 // i = range index, j = tag index
	for i < len(rs) {
		if rs[i] == "*" { // 3.A: '*' matches zero or more subtags
			i++
			continue
		}
		if j >= len(ts) { // 3.B: ran out of tag subtags
			return false
		}
		if utils.EqualFold(rs[i], ts[j]) { // 3.C: exact subtag match
			i++
			j++
			continue
		}
		// 3.D: singleton barrier (one letter or digit, incl. 'x')
		if len(ts[j]) == 1 {
			return false
		}
		// 3.E: slide forward in the tag and try again
		j++
	}
	// 4: matched all range subtags
	return true
}