Function ScanDelimited

query/expr/scanner.go:470–516

(r io.RuneScanner, start, end rune, escapes map[rune]rune, escapesPassThru bool)

const eof = rune(0)

func ScanDelimited(r io.RuneScanner, start, end rune, escapes map[rune]rune, escapesPassThru bool) ([]byte, error) {
	// Scan start delimiter.
	if ch, _, err := r.ReadRune(); err != nil {
		return nil, err
	} else if ch != start {
		return nil, fmt.Errorf("expected %s; found %s", string(start), string(ch))
	}

	var buf bytes.Buffer
	for {
		ch0, _, err := r.ReadRune()
		if ch0 == end {
			return buf.Bytes(), nil
		} else if err != nil {
			return buf.Bytes(), err
		} else if ch0 == '\n' {
			return nil, errors.New("delimited text contains new line")
		} else if ch0 == '\\' {
			// If the next character is an escape then write the escaped char.
			// If it's not a valid escape then return an error.
			ch1, _, err := r.ReadRune()
			if err != nil {
				return nil, err
			}

			c, ok := escapes[ch1]
			if !ok {
				if escapesPassThru {
					// Unread ch1 (char after the \)
					_ = r.UnreadRune()
					// Write ch0 (\) to the output buffer.
					_, _ = buf.WriteRune(ch0)
					continue
				} else {
					buf.Reset()
					_, _ = buf.WriteRune(ch0)
					_, _ = buf.WriteRune(ch1)
					return buf.Bytes(), errBadEscape
				}
			}

			_, _ = buf.WriteRune(c)
		} else {
			_, _ = buf.WriteRune(ch0)
		}
	}
}

// ScanString reads a quoted string from a rune reader.
func ScanString(r io.RuneScanner) (string, error) {