case c.Is(ChecksumSHA1):
		return sha1.New()
	case c.Is(ChecksumSHA256):
		return sha256.New()
	}
	return nil
}

// Trailing return whether the checksum is trailing.
func (c ChecksumType) Trailing() bool {
	return c.Is(ChecksumTrailing)
}

// NewChecksumFromData returns a new checksum from specified algorithm and base64 encoded value.

		"substring('abcd' , 2 , 2)",

		"substring('abcd' , 22 )",
		"trim('  aab  ')",
		"trim(leading from '  aab  ')",
		"trim(trailing from '  aab  ')",
		"trim(both from '  aab  ')",

		"trim(both '12' from '  aab  ')",
		"trim(leading '12' from '  aab  ')",
		"trim(trailing '12' from '  aab  ')",
		"count(23)",
	}
	for i, tc := range validCases {
		err := p.ParseString(tc, &fex)
		if err != nil {

			length = endIdx - startIdx
		}

		endIdx = startIdx + length
	}

	return string(rs[startIdx:endIdx]), nil
}

const (
	trimLeading  = "LEADING"
	trimTrailing = "TRAILING"
	trimBoth     = "BOTH"
)

func evalSQLTrim(where *string, trimChars, text string) (result string, err error) {
	cutSet := " "
	if trimChars != "" {
		cutSet = trimChars
	}

	cs, err := GetContentChecksum(req.Header)
	if err != nil {
		return ErrInvalidChecksum
	}
	if cs == nil {
		return nil
	}
	r.contentHash = *cs
	if cs.Type.Trailing() {
		r.trailer = req.Trailer
	}
	return r.AddNonTrailingChecksum(cs, ignoreValue)
}

// AddChecksumNoTrailer will add checksum checks as specified in

			extractedSignedHeaders.Set(header, strconv.FormatInt(r.ContentLength, 10))
		default:
			return nil, ErrUnsignedHeaders
		}
	}
	return extractedSignedHeaders, ErrNone
}

// Trim leading and trailing spaces and replace sequential spaces with one space, following Trimall()
// in http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html
func signV4TrimAll(input string) string {

	// The extended form disables evaluation of . and .. path
	// elements and disables the interpretation of / as equivalent
	// to \. The conversion here rewrites / to \ and elides
	// . elements as well as trailing or duplicate separators. For
	// simplicity it avoids the conversion entirely for relative
	// paths or paths containing .. elements. For now,
	// \\server\share paths are not converted to

}

var etagRegex = regexp.MustCompile("\"*?([^\"]*?)\"*?$")

// canonicalizeETag returns ETag with leading and trailing double-quotes removed,
// if any present
func canonicalizeETag(etag string) string {
	return etagRegex.ReplaceAllString(etag, "$1")
}

// Init - populates the input values, initializes CondCheck

		}
		buf.WriteString(s3Select.Output.CSVArgs.RecordDelimiter)

		return nil
	case jsonFormat:
		err := record.WriteJSON(buf)
		if err != nil {
			return err
		}
		// Trim trailing newline from non-simd output
		if buf.Bytes()[buf.Len()-1] == '\n' {
			buf.Truncate(buf.Len() - 1)
		}
		buf.WriteString(s3Select.Output.JSONArgs.RecordDelimiter)

		return nil
	}

}

// pathsJoinPrefix - like pathJoin retains trailing SlashSeparator
// for all elements, prepends them with 'prefix' respectively.
func pathsJoinPrefix(prefix string, elem ...string) (paths []string) {
	paths = make([]string, len(elem))
	for i, e := range elem {
		paths[i] = pathJoin(prefix, e)
	}
	return paths
}

// pathJoin - like path.Join() but retains trailing SlashSeparator of the last element

		if cr.debug {
			fmt.Printf("prefix, want prefix %q, got %q", "x-amz-trailer-signature:", string(sig))
		}
		return errMalformedEncoding
	}

	// TODO: It seems like we may have to be prepared to rewrite and sort trailing headers:
	// https://docs.aws.amazon.com/IAM/latest/UserGuide/create-signed-request.html

	// Any value must end with a newline.
	// Not all clients send that.
	trailerRaw := valueBuffer.Bytes()