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parse.go
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454 lines (422 loc) · 9.36 KB
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package sf
import (
"encoding/base64"
"errors"
"strconv"
"strings"
)
var (
// ErrUnexpectedEOL reports an unexpected end-of-line.
ErrUnexpectedEOL = errors.New("sf: unexpected EOL")
// ErrUnrecognized reports an illegal character.
ErrUnrecognized = errors.New("sf: unrecognized char")
// ErrTooManyDigits reports a too big integer or fractional component.
ErrTooManyDigits = errors.New("sf: too many digits")
)
// Parse parses an structured-field dictionary multi-line header.
func ParseDict(header []string) (Dict, error) {
return ParseDictLine(joinMultiLines(header))
}
// ParseLine parses a structured-field dictionary single-line header.
func ParseDictLine(header string) (Dict, error) {
var (
dict Dict
pair *Pair
err error
input = []byte(header)
pos = 0
)
pos = skipSpaces(input, pos)
if pos >= len(input) {
return dict, nil
}
for {
pair, pos, err = parsePair(input, pos)
if err != nil {
return nil, err
}
dict = dict.Add(pair.Key, pair.Value)
pos = skipSpaces(input, pos)
if pos >= len(input) || input[pos] != ',' {
break
}
pos++
}
return dict, nil
}
// Parse parses an structured-field list multi-line header.
func ParseList(header []string) (List, error) {
return ParseListLine(joinMultiLines(header))
}
// ParseLine parses a structured-field list single-line header.
func ParseListLine(header string) (List, error) {
var (
list List
member Member
err error
input = []byte(header)
pos = 0
)
pos = skipSpaces(input, pos)
if pos >= len(input) {
return list, nil
}
for {
member, pos, err = parseMember(input, pos)
if err != nil {
return nil, err
}
list = append(list, member)
pos = skipSpaces(input, pos)
if pos >= len(input) || input[pos] != ',' {
break
}
pos++
}
return list, nil
}
// ParseLine parses a structured-field item single-line header.
func ParseItemLine(header string) (*Item, error) {
input := []byte(header)
it, pos, err := parseItem(input, 0)
if err != nil {
return nil, err
}
pos = skipSpaces(input, pos)
if pos < len(input) {
return nil, ErrUnrecognized
}
return it, nil
}
func joinMultiLines(header []string) string {
nonEmptyLines := make([]string, 0, len(header))
for _, h := range header {
if trimmed := strings.TrimSpace(h); trimmed != "" {
nonEmptyLines = append(nonEmptyLines, trimmed)
}
}
return strings.Join(nonEmptyLines, ", ")
}
func parsePair(input []byte, pos int) (*Pair, int, error) {
key, pos, err := parseKey(input, pos)
if err != nil {
return nil, pos, err
}
var (
value Member
p ParamList
)
if pos < len(input) && input[pos] == '=' {
value, pos, err = parseMember(input, pos+1)
if err != nil {
return nil, pos, err
}
} else {
p, pos, err = parseParams(input, pos)
if err != nil {
return nil, pos, err
}
value = &Item{Bool(true), p}
}
return &Pair{key, value}, pos, nil
}
func parseMember(input []byte, pos int) (Member, int, error) {
pos = skipSpaces(input, pos)
if pos >= len(input) {
return nil, pos, ErrUnexpectedEOL
}
if input[pos] == '(' {
return parseInnerList(input, pos)
}
return parseItem(input, pos)
}
func parseInnerList(input []byte, pos int) (*InnerList, int, error) {
if pos >= len(input) {
return nil, pos, ErrUnexpectedEOL
}
if input[pos] != '(' {
return nil, pos, ErrUnrecognized
}
pos++
var (
items []*Item
it *Item
err error
)
for {
pos = skipSpaces(input, pos)
if pos >= len(input) {
return nil, pos, ErrUnexpectedEOL
}
if input[pos] == ')' {
pos++
break
}
it, pos, err = parseItem(input, pos)
if err != nil {
return nil, pos, err
}
items = append(items, it)
}
p, pos, err := parseParams(input, pos)
if err != nil {
return nil, pos, err
}
return &InnerList{items, p}, pos, nil
}
func parseItem(input []byte, pos int) (*Item, int, error) {
b, pos, err := parseBareItem(input, pos)
if err != nil {
return nil, pos, err
}
p, pos, err := parseParams(input, pos)
if err != nil {
return nil, pos, err
}
return &Item{b, p}, pos, nil
}
func parseParams(input []byte, pos int) (ParamList, int, error) {
var (
params ParamList
key string
value BareItem
err error
)
for {
pos = skipSpaces(input, pos)
if pos >= len(input) || input[pos] != ';' {
break
}
key, pos, err = parseKey(input, pos+1)
if err != nil {
return nil, pos, err
}
value = Bool(true)
if pos < len(input) && input[pos] == '=' {
value, pos, err = parseBareItem(input, pos+1)
if err != nil {
return nil, pos, err
}
}
params = params.Add(key, value)
}
return params, pos, nil
}
func parseKey(input []byte, pos int) (string, int, error) {
pos = skipSpaces(input, pos)
if pos >= len(input) {
return "", pos, ErrUnexpectedEOL
}
if input[pos] != '*' && !isLower(input[pos]) {
return "", pos, ErrUnrecognized
}
var sb strings.Builder
for pos < len(input) && isKeyChar(input[pos]) {
sb.WriteByte(input[pos])
pos++
}
return sb.String(), pos, nil
}
var bareItemParsers = []struct {
Cond func(byte) bool
Parse func([]byte, int) (BareItem, int, error)
}{
{func(b byte) bool { return b == '-' || isDigit(b) }, parseNumber},
{func(b byte) bool { return b == '"' }, parseString},
{func(b byte) bool { return b == '*' || isAlpha(b) }, parseToken},
{func(b byte) bool { return b == ':' }, parseByteSeq},
{func(b byte) bool { return b == '?' }, parseBool},
}
func parseBareItem(input []byte, pos int) (BareItem, int, error) {
pos = skipSpaces(input, pos)
if pos >= len(input) {
return nil, pos, ErrUnexpectedEOL
}
for _, p := range bareItemParsers {
if p.Cond(input[pos]) {
return p.Parse(input, pos)
}
}
return nil, pos, ErrUnrecognized
}
func parseNumber(input []byte, pos int) (BareItem, int, error) {
if input[pos] != '-' && !isDigit(input[pos]) {
return nil, pos, ErrUnrecognized
}
sign := int64(1)
if input[pos] == '-' {
sign = -1
pos++
}
if pos == len(input) {
return nil, pos, ErrUnexpectedEOL
}
if !isDigit(input[pos]) {
return nil, pos, ErrUnrecognized
}
var sb strings.Builder
decimalPlaces := -1
for pos < len(input) {
if isDigit(input[pos]) {
if sb.Len() == 15 {
return nil, pos, ErrTooManyDigits
}
sb.WriteByte(input[pos])
if decimalPlaces >= 0 {
if decimalPlaces == 3 {
return nil, pos, ErrTooManyDigits
}
decimalPlaces++
}
} else if input[pos] == '.' {
if decimalPlaces != -1 {
break
}
decimalPlaces = 0
} else {
break
}
pos++
}
n, _ := strconv.ParseInt(sb.String(), 10, 64)
switch decimalPlaces {
case -1:
return Integer(sign * n), pos, nil
case 1:
return Decimal(sign * n * 100), pos, nil
case 2:
return Decimal(sign * n * 10), pos, nil
case 3:
return Decimal(sign * n), pos, nil
}
return nil, pos, ErrUnrecognized
}
func parseString(input []byte, pos int) (BareItem, int, error) {
if input[pos] != '"' {
return nil, pos, ErrUnrecognized
}
var sb strings.Builder
sb.WriteByte(input[pos])
pos++
for pos < len(input) && input[pos] != '"' {
if input[pos] == '\\' {
sb.WriteByte(input[pos])
pos++
if pos == len(input) {
return nil, pos, ErrUnexpectedEOL
}
if input[pos] != '"' && input[pos] != '\\' {
return nil, pos, ErrUnrecognized
}
}
if !isPrint(input[pos]) {
return nil, pos, ErrUnrecognized
}
sb.WriteByte(input[pos])
pos++
}
if pos == len(input) {
return nil, pos, ErrUnexpectedEOL
}
sb.WriteByte(input[pos])
s, _ := strconv.Unquote(sb.String())
return String(s), pos + 1, nil
}
func parseToken(input []byte, pos int) (BareItem, int, error) {
if input[pos] != '*' && !isAlpha(input[pos]) {
return nil, pos, ErrUnrecognized
}
var sb strings.Builder
for pos < len(input) && isTokenChar(input[pos]) {
sb.WriteByte(input[pos])
pos++
}
return Token(sb.String()), pos, nil
}
func parseByteSeq(input []byte, pos int) (BareItem, int, error) {
if input[pos] != ':' {
return nil, pos, ErrUnrecognized
}
var sb strings.Builder
pos++
for pos < len(input) && input[pos] != ':' {
if !isBase64Char(input[pos]) {
return nil, pos, ErrUnrecognized
}
sb.WriteByte(input[pos])
pos++
}
if pos == len(input) {
return nil, pos, ErrUnexpectedEOL
}
b, _ := base64.StdEncoding.DecodeString(sb.String())
return ByteSeq(b), pos + 1, nil
}
func parseBool(input []byte, pos int) (BareItem, int, error) {
if input[pos] != '?' {
return nil, pos, ErrUnrecognized
}
pos++
if pos == len(input) {
return nil, pos, ErrUnexpectedEOL
}
switch input[pos] {
case '0':
return Bool(false), pos + 1, nil
case '1':
return Bool(true), pos + 1, nil
}
return nil, pos, ErrUnrecognized
}
func skipSpaces(input []byte, pos int) int {
for pos < len(input) && input[pos] == ' ' {
pos++
}
return pos
}
func isPrint(b byte) bool {
return ' ' <= b && b <= '~'
}
func isDigit(b byte) bool {
return '0' <= b && b <= '9'
}
func isAlpha(b byte) bool {
return isLower(b) || isUpper(b)
}
func isUpper(b byte) bool {
return 'A' <= b && b <= 'Z'
}
func isLower(b byte) bool {
return 'a' <= b && b <= 'z'
}
func isKeyChar(b byte) bool {
if isLower(b) || isDigit(b) {
return true
}
switch b {
case '_', '-', '.', '*':
return true
}
return false
}
func isTokenChar(b byte) bool {
if isAlpha(b) || isDigit(b) {
return true
}
switch b {
case '!', '#', '$', '%', '&', '\'', '*', '+', '-',
'.', '^', '_', '`', '|', '~', ':', '/':
return true
}
return false
}
func isBase64Char(b byte) bool {
if isAlpha(b) || isDigit(b) {
return true
}
switch b {
case '+', '/', '=':
return true
}
return false
}