Method FormatValue

cmp/report_reflect.go:114–312

FormatValue prints the reflect.Value, taking extra care to avoid descending into pointers already in ptrs. As pointers are visited, ptrs is also updated.

(v reflect.Value, parentKind reflect.Kind, ptrs *pointerReferences)

// FormatValue prints the reflect.Value, taking extra care to avoid descending
// into pointers already in ptrs. As pointers are visited, ptrs is also updated.
func (opts formatOptions) FormatValue(v reflect.Value, parentKind reflect.Kind, ptrs *pointerReferences) (out textNode) {
	if !v.IsValid() {
		return nil
	}
	t := v.Type()

	// Check slice element for cycles.
	if parentKind == reflect.Slice {
		ptrRef, visited := ptrs.Push(v.Addr())
		if visited {
			return makeLeafReference(ptrRef, false)
		}
		defer ptrs.Pop()
		defer func() { out = wrapTrunkReference(ptrRef, false, out) }()
	}

	// Check whether there is an Error or String method to call.
	if !opts.AvoidStringer && v.CanInterface() {
		// Avoid calling Error or String methods on nil receivers since many
		// implementations crash when doing so.
		if (t.Kind() != reflect.Ptr && t.Kind() != reflect.Interface) || !v.IsNil() {
			var prefix, strVal string
			func() {
				// Swallow and ignore any panics from String or Error.
				defer func() { recover() }()
				switch v := v.Interface().(type) {
				case error:
					strVal = v.Error()
					prefix = "e"
				case fmt.Stringer:
					strVal = v.String()
					prefix = "s"
				}
			}()
			if prefix != "" {
				return opts.formatString(prefix, strVal)
			}
		}
	}

	// Check whether to explicitly wrap the result with the type.
	var skipType bool
	defer func() {
		if !skipType {
			out = opts.FormatType(t, out)
		}
	}()

	switch t.Kind() {
	case reflect.Bool:
		return textLine(fmt.Sprint(v.Bool()))
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		return textLine(fmt.Sprint(v.Int()))
	case reflect.Uint, reflect.Uint16, reflect.Uint32, reflect.Uint64:
		return textLine(fmt.Sprint(v.Uint()))
	case reflect.Uint8:
		if parentKind == reflect.Slice || parentKind == reflect.Array {
			return textLine(formatHex(v.Uint()))