gotosocial/vendor/github.com/tdewolff/parse/v2/common.go

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// Package parse contains a collection of parsers for various formats in its subpackages.
package parse
import (
"bytes"
"encoding/base64"
"errors"
)
var (
dataSchemeBytes = []byte("data:")
base64Bytes = []byte("base64")
textMimeBytes = []byte("text/plain")
)
// ErrBadDataURI is returned by DataURI when the byte slice does not start with 'data:' or is too short.
var ErrBadDataURI = errors.New("not a data URI")
// Number returns the number of bytes that parse as a number of the regex format (+|-)?([0-9]+(\.[0-9]+)?|\.[0-9]+)((e|E)(+|-)?[0-9]+)?.
func Number(b []byte) int {
if len(b) == 0 {
return 0
}
i := 0
if b[i] == '+' || b[i] == '-' {
i++
if i >= len(b) {
return 0
}
}
firstDigit := (b[i] >= '0' && b[i] <= '9')
if firstDigit {
i++
for i < len(b) && b[i] >= '0' && b[i] <= '9' {
i++
}
}
if i < len(b) && b[i] == '.' {
i++
if i < len(b) && b[i] >= '0' && b[i] <= '9' {
i++
for i < len(b) && b[i] >= '0' && b[i] <= '9' {
i++
}
} else if firstDigit {
// . could belong to the next token
i--
return i
} else {
return 0
}
} else if !firstDigit {
return 0
}
iOld := i
if i < len(b) && (b[i] == 'e' || b[i] == 'E') {
i++
if i < len(b) && (b[i] == '+' || b[i] == '-') {
i++
}
if i >= len(b) || b[i] < '0' || b[i] > '9' {
// e could belong to next token
return iOld
}
for i < len(b) && b[i] >= '0' && b[i] <= '9' {
i++
}
}
return i
}
// Dimension parses a byte-slice and returns the length of the number and its unit.
func Dimension(b []byte) (int, int) {
num := Number(b)
if num == 0 || num == len(b) {
return num, 0
} else if b[num] == '%' {
return num, 1
} else if b[num] >= 'a' && b[num] <= 'z' || b[num] >= 'A' && b[num] <= 'Z' {
i := num + 1
for i < len(b) && (b[i] >= 'a' && b[i] <= 'z' || b[i] >= 'A' && b[i] <= 'Z') {
i++
}
return num, i - num
}
return num, 0
}
// Mediatype parses a given mediatype and splits the mimetype from the parameters.
// It works similar to mime.ParseMediaType but is faster.
func Mediatype(b []byte) ([]byte, map[string]string) {
i := 0
for i < len(b) && b[i] == ' ' {
i++
}
b = b[i:]
n := len(b)
mimetype := b
var params map[string]string
for i := 3; i < n; i++ { // mimetype is at least three characters long
if b[i] == ';' || b[i] == ' ' {
mimetype = b[:i]
if b[i] == ' ' {
i++ // space
for i < n && b[i] == ' ' {
i++
}
if n <= i || b[i] != ';' {
break
}
}
params = map[string]string{}
s := string(b)
PARAM:
i++ // semicolon
for i < n && s[i] == ' ' {
i++
}
start := i
for i < n && s[i] != '=' && s[i] != ';' && s[i] != ' ' {
i++
}
key := s[start:i]
for i < n && s[i] == ' ' {
i++
}
if i < n && s[i] == '=' {
i++
for i < n && s[i] == ' ' {
i++
}
start = i
for i < n && s[i] != ';' && s[i] != ' ' {
i++
}
} else {
start = i
}
params[key] = s[start:i]
for i < n && s[i] == ' ' {
i++
}
if i < n && s[i] == ';' {
goto PARAM
}
break
}
}
return mimetype, params
}
// DataURI parses the given data URI and returns the mediatype, data and ok.
func DataURI(dataURI []byte) ([]byte, []byte, error) {
if len(dataURI) > 5 && bytes.Equal(dataURI[:5], dataSchemeBytes) {
dataURI = dataURI[5:]
inBase64 := false
var mediatype []byte
i := 0
for j := 0; j < len(dataURI); j++ {
c := dataURI[j]
if c == '=' || c == ';' || c == ',' {
if c != '=' && bytes.Equal(TrimWhitespace(dataURI[i:j]), base64Bytes) {
if len(mediatype) > 0 {
mediatype = mediatype[:len(mediatype)-1]
}
inBase64 = true
i = j
} else if c != ',' {
mediatype = append(append(mediatype, TrimWhitespace(dataURI[i:j])...), c)
i = j + 1
} else {
mediatype = append(mediatype, TrimWhitespace(dataURI[i:j])...)
}
if c == ',' {
if len(mediatype) == 0 || mediatype[0] == ';' {
mediatype = textMimeBytes
}
data := dataURI[j+1:]
if inBase64 {
decoded := make([]byte, base64.StdEncoding.DecodedLen(len(data)))
n, err := base64.StdEncoding.Decode(decoded, data)
if err != nil {
return nil, nil, err
}
data = decoded[:n]
} else {
data = DecodeURL(data)
}
return mediatype, data, nil
}
}
}
}
return nil, nil, ErrBadDataURI
}
// QuoteEntity parses the given byte slice and returns the quote that got matched (' or ") and its entity length.
// TODO: deprecated
func QuoteEntity(b []byte) (quote byte, n int) {
if len(b) < 5 || b[0] != '&' {
return 0, 0
}
if b[1] == '#' {
if b[2] == 'x' {
i := 3
for i < len(b) && b[i] == '0' {
i++
}
if i+2 < len(b) && b[i] == '2' && b[i+2] == ';' {
if b[i+1] == '2' {
return '"', i + 3 // &#x22;
} else if b[i+1] == '7' {
return '\'', i + 3 // &#x27;
}
}
} else {
i := 2
for i < len(b) && b[i] == '0' {
i++
}
if i+2 < len(b) && b[i] == '3' && b[i+2] == ';' {
if b[i+1] == '4' {
return '"', i + 3 // &#34;
} else if b[i+1] == '9' {
return '\'', i + 3 // &#39;
}
}
}
} else if len(b) >= 6 && b[5] == ';' {
if bytes.Equal(b[1:5], []byte{'q', 'u', 'o', 't'}) {
return '"', 6 // &quot;
} else if bytes.Equal(b[1:5], []byte{'a', 'p', 'o', 's'}) {
return '\'', 6 // &apos;
}
}
return 0, 0
}