Method ParseString

hrp/parser.go:172–276

ParseString parse string with variables

(raw string, variablesMapping map[string]interface{})

// ParseString parse string with variables
func (p *Parser) ParseString(raw string, variablesMapping map[string]interface{}) (interface{}, error) {
	matchStartPosition := 0
	parsedString := ""
	remainedString := raw

	for matchStartPosition < len(raw) {
		// locate $ char position
		startPosition := strings.Index(remainedString, "$")
		if startPosition == -1 { // no $ found
			// append remained string
			parsedString += remainedString
			break
		}

		// found $, check if variable or function
		matchStartPosition += startPosition
		parsedString += remainedString[0:startPosition]
		remainedString = remainedString[startPosition:]

		// Notice: notation priority
		// $$ > ${func($a, $b)} > $var

		// search $$, use $$ to escape $ notation
		if strings.HasPrefix(remainedString, "$$") { // found $$
			matchStartPosition += 2
			parsedString += "$"
			remainedString = remainedString[2:]
			continue
		}

		// search function like ${func($a, $b)}
		funcMatched := regexCompileFunction.FindStringSubmatch(remainedString)
		if len(funcMatched) == 3 {
			funcName := funcMatched[1]
			argsStr := funcMatched[2]
			arguments, err := parseFunctionArguments(argsStr)
			if err != nil {
				return raw, errors.Wrap(code.ParseFunctionError, err.Error())
			}
			parsedArgs, err := p.Parse(arguments, variablesMapping)
			if err != nil {
				return raw, err
			}

			result, err := p.callFunc(funcName, parsedArgs.([]interface{})...)
			if err != nil {
				log.Error().Str("funcName", funcName).Interface("arguments", arguments).
					Err(err).Msg("call function failed")
				return raw, errors.Wrap(code.CallFunctionError, err.Error())
			}
			log.Info().Str("funcName", funcName).Interface("arguments", arguments).
				Interface("output", result).Msg("call function success")

			if funcMatched[0] == raw {
				// raw_string is a function, e.g. "${add_one(3)}", return its eval value directly
				return result, nil
			}