func parseCustomTemplate()

in pkg/genlib/generator_with_custom_template.go [28:83]
45 lines of code
11 McCabe index (conditional complexity)

func parseCustomTemplate(template []byte) ([]string, map[string][]byte, []byte) {
	if len(template) == 0 {
		return nil, nil, nil
	}

	tokenizer := regexp.MustCompile(`([^{]*)({{\.[^}]+}})*`)
	allIndexes := tokenizer.FindAllSubmatchIndex(template, -1)

	orderedFields := make([]string, 0, len(allIndexes))
	templateFieldsMap := make(map[string][]byte, len(allIndexes))

	var fieldPrefixBuffer []byte
	var fieldPrefixPreviousN int
	var trimTrailingTemplateN int

	for i, loc := range allIndexes {
		var fieldName []byte
		var fieldPrefix []byte

		if loc[4] > -1 && loc[5] > -1 {
			fieldName = template[loc[4]+3 : loc[5]-2]
		}

		if loc[2] > -1 && loc[3] > -1 {
			fieldPrefix = template[loc[2]:loc[3]]
		}

		if len(fieldName) == 0 {
			if template[fieldPrefixPreviousN] == byte(123) {
				fieldPrefixBuffer = append(fieldPrefixBuffer, byte(123))
			} else {
				if i == len(allIndexes)-1 {
					fieldPrefixBuffer = template[trimTrailingTemplateN:]
				} else {
					fieldPrefixBuffer = append(fieldPrefixBuffer, fieldPrefix...)
					fieldPrefixBufferIdx := bytes.Index(template[trimTrailingTemplateN:], fieldPrefixBuffer)
					if fieldPrefixBufferIdx > 0 {
						trimTrailingTemplateN += fieldPrefixBufferIdx
					}

				}
			}
		} else {
			fieldPrefixBuffer = append(fieldPrefixBuffer, fieldPrefix...)
			trimTrailingTemplateN = loc[5]
			templateFieldsMap[string(fieldName)] = fieldPrefixBuffer
			orderedFields = append(orderedFields, string(fieldName))
			fieldPrefixBuffer = nil
		}

		fieldPrefixPreviousN = loc[2]
	}

	return orderedFields, templateFieldsMap, fieldPrefixBuffer

}