487 lines
15 KiB
Go
487 lines
15 KiB
Go
package parse
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import (
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"bytes"
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"fmt"
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"strconv"
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"unicode"
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)
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// Copy returns a copy of the given byte slice.
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func Copy(src []byte) (dst []byte) {
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dst = make([]byte, len(src))
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copy(dst, src)
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return
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}
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// ToLower converts all characters in the byte slice from A-Z to a-z.
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func ToLower(src []byte) []byte {
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for i, c := range src {
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if c >= 'A' && c <= 'Z' {
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src[i] = c + ('a' - 'A')
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}
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}
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return src
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}
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// EqualFold returns true when s matches case-insensitively the targetLower (which must be lowercase).
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func EqualFold(s, targetLower []byte) bool {
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if len(s) != len(targetLower) {
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return false
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}
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for i, c := range targetLower {
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d := s[i]
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if d != c && (d < 'A' || d > 'Z' || d+('a'-'A') != c) {
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return false
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}
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}
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return true
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}
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// Printable returns a printable string for given rune
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func Printable(r rune) string {
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if unicode.IsGraphic(r) {
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return fmt.Sprintf("%c", r)
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} else if r < 128 {
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return fmt.Sprintf("0x%02X", r)
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}
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return fmt.Sprintf("%U", r)
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}
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var whitespaceTable = [256]bool{
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// ASCII
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false, false, false, false, false, false, false, false,
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false, true, true, false, true, true, false, false, // tab, new line, form feed, carriage return
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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true, false, false, false, false, false, false, false, // space
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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// non-ASCII
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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}
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// IsWhitespace returns true for space, \n, \r, \t, \f.
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func IsWhitespace(c byte) bool {
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return whitespaceTable[c]
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}
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var newlineTable = [256]bool{
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// ASCII
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false, false, false, false, false, false, false, false,
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false, false, true, false, false, true, false, false, // new line, carriage return
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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// non-ASCII
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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}
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// IsNewline returns true for \n, \r.
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func IsNewline(c byte) bool {
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return newlineTable[c]
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}
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// IsAllWhitespace returns true when the entire byte slice consists of space, \n, \r, \t, \f.
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func IsAllWhitespace(b []byte) bool {
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for _, c := range b {
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if !IsWhitespace(c) {
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return false
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}
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}
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return true
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}
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// TrimWhitespace removes any leading and trailing whitespace characters.
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func TrimWhitespace(b []byte) []byte {
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n := len(b)
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start := n
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for i := 0; i < n; i++ {
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if !IsWhitespace(b[i]) {
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start = i
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break
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}
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}
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end := n
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for i := n - 1; i >= start; i-- {
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if !IsWhitespace(b[i]) {
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end = i + 1
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break
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}
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}
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return b[start:end]
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}
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// ReplaceMultipleWhitespace replaces character series of space, \n, \t, \f, \r into a single space or newline (when the serie contained a \n or \r).
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func ReplaceMultipleWhitespace(b []byte) []byte {
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j, k := 0, 0 // j is write position, k is start of next text section
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for i := 0; i < len(b); i++ {
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if IsWhitespace(b[i]) {
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start := i
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newline := IsNewline(b[i])
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i++
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for ; i < len(b) && IsWhitespace(b[i]); i++ {
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if IsNewline(b[i]) {
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newline = true
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}
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}
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if newline {
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b[start] = '\n'
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} else {
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b[start] = ' '
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}
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if 1 < i-start { // more than one whitespace
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if j == 0 {
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j = start + 1
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} else {
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j += copy(b[j:], b[k:start+1])
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}
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k = i
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}
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}
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}
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if j == 0 {
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return b
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} else if j == 1 { // only if starts with whitespace
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b[k-1] = b[0]
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return b[k-1:]
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} else if k < len(b) {
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j += copy(b[j:], b[k:])
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}
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return b[:j]
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}
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// replaceEntities will replace in b at index i, assuming that b[i] == '&' and that i+3<len(b). The returned int will be the last character of the entity, so that the next iteration can safely do i++ to continue and not miss any entitites.
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func replaceEntities(b []byte, i int, entitiesMap map[string][]byte, revEntitiesMap map[byte][]byte) ([]byte, int) {
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const MaxEntityLength = 31 // longest HTML entity: CounterClockwiseContourIntegral
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var r []byte
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j := i + 1
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if b[j] == '#' {
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j++
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if b[j] == 'x' {
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j++
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c := 0
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for ; j < len(b) && (b[j] >= '0' && b[j] <= '9' || b[j] >= 'a' && b[j] <= 'f' || b[j] >= 'A' && b[j] <= 'F'); j++ {
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if b[j] <= '9' {
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c = c<<4 + int(b[j]-'0')
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} else if b[j] <= 'F' {
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c = c<<4 + int(b[j]-'A') + 10
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} else if b[j] <= 'f' {
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c = c<<4 + int(b[j]-'a') + 10
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}
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}
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if j <= i+3 || 10000 <= c {
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return b, j - 1
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}
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if c < 128 {
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r = []byte{byte(c)}
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} else {
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r = append(r, '&', '#')
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r = strconv.AppendInt(r, int64(c), 10)
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r = append(r, ';')
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}
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} else {
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c := 0
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for ; j < len(b) && c < 128 && b[j] >= '0' && b[j] <= '9'; j++ {
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c = c*10 + int(b[j]-'0')
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}
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if j <= i+2 || 128 <= c {
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return b, j - 1
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}
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r = []byte{byte(c)}
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}
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} else {
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for ; j < len(b) && j-i-1 <= MaxEntityLength && b[j] != ';'; j++ {
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}
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if j <= i+1 || len(b) <= j {
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return b, j - 1
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}
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var ok bool
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r, ok = entitiesMap[string(b[i+1:j])]
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if !ok {
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return b, j
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}
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}
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// j is at semicolon
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n := j + 1 - i
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if j < len(b) && b[j] == ';' && 2 < n {
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if len(r) == 1 {
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if q, ok := revEntitiesMap[r[0]]; ok {
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if len(q) == len(b[i:j+1]) && bytes.Equal(q, b[i:j+1]) {
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return b, j
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}
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r = q
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} else if r[0] == '&' {
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// check if for example & is followed by something that could potentially be an entity
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k := j + 1
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if k < len(b) && b[k] == '#' {
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k++
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}
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for ; k < len(b) && k-j <= MaxEntityLength && (b[k] >= '0' && b[k] <= '9' || b[k] >= 'a' && b[k] <= 'z' || b[k] >= 'A' && b[k] <= 'Z'); k++ {
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}
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if k < len(b) && b[k] == ';' {
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return b, k
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}
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}
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}
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copy(b[i:], r)
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copy(b[i+len(r):], b[j+1:])
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b = b[:len(b)-n+len(r)]
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return b, i + len(r) - 1
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}
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return b, i
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}
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// ReplaceEntities replaces all occurrences of entites (such as ") to their respective unencoded bytes.
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func ReplaceEntities(b []byte, entitiesMap map[string][]byte, revEntitiesMap map[byte][]byte) []byte {
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for i := 0; i < len(b); i++ {
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if b[i] == '&' && i+3 < len(b) {
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b, i = replaceEntities(b, i, entitiesMap, revEntitiesMap)
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}
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}
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return b
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}
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// ReplaceMultipleWhitespaceAndEntities is a combination of ReplaceMultipleWhitespace and ReplaceEntities. It is faster than executing both sequentially.
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func ReplaceMultipleWhitespaceAndEntities(b []byte, entitiesMap map[string][]byte, revEntitiesMap map[byte][]byte) []byte {
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j, k := 0, 0 // j is write position, k is start of next text section
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for i := 0; i < len(b); i++ {
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if IsWhitespace(b[i]) {
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start := i
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newline := IsNewline(b[i])
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i++
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for ; i < len(b) && IsWhitespace(b[i]); i++ {
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if IsNewline(b[i]) {
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newline = true
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}
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}
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if newline {
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b[start] = '\n'
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} else {
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b[start] = ' '
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}
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if 1 < i-start { // more than one whitespace
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if j == 0 {
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j = start + 1
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} else {
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j += copy(b[j:], b[k:start+1])
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}
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k = i
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}
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}
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if i+3 < len(b) && b[i] == '&' {
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b, i = replaceEntities(b, i, entitiesMap, revEntitiesMap)
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}
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}
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if j == 0 {
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return b
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} else if j == 1 { // only if starts with whitespace
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b[k-1] = b[0]
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return b[k-1:]
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} else if k < len(b) {
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j += copy(b[j:], b[k:])
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}
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return b[:j]
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}
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// URLEncodingTable is a charmap for which characters need escaping in the URL encoding scheme
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var URLEncodingTable = [256]bool{
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// ASCII
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, false, true, true, true, true, true, false, // space, ", #, $, %, &
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false, false, false, true, true, false, false, true, // +, comma, /
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false, false, false, false, false, false, false, false,
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false, false, true, true, true, true, true, true, // :, ;, <, =, >, ?
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true, false, false, false, false, false, false, false, // @
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, true, true, true, true, false, // [, \, ], ^
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true, false, false, false, false, false, false, false, // `
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, true, true, true, false, true, // {, |, }, DEL
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// non-ASCII
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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}
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// DataURIEncodingTable is a charmap for which characters need escaping in the Data URI encoding scheme
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// Escape only non-printable characters, unicode and %, #, &.
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// IE11 additionally requires encoding of \, [, ], ", <, >, `, {, }, |, ^ which is not required by Chrome, Firefox, Opera, Edge, Safari, Yandex
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// To pass the HTML validator, restricted URL characters must be escaped: non-printable characters, space, <, >, #, %, "
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var DataURIEncodingTable = [256]bool{
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// ASCII
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, false, true, true, false, true, true, false, // space, ", #, %, &
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, true, false, true, false, // <, >
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, true, true, true, true, false, // [, \, ], ^
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true, false, false, false, false, false, false, false, // `
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, true, true, true, false, true, // {, |, }, DEL
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// non-ASCII
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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true, true, true, true, true, true, true, true,
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}
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// EncodeURL encodes bytes using the URL encoding scheme
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func EncodeURL(b []byte, table [256]bool) []byte {
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for i := 0; i < len(b); i++ {
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c := b[i]
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if table[c] {
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b = append(b, 0, 0)
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copy(b[i+3:], b[i+1:])
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b[i+0] = '%'
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b[i+1] = "0123456789ABCDEF"[c>>4]
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|
b[i+2] = "0123456789ABCDEF"[c&15]
|
|
}
|
|
}
|
|
return b
|
|
}
|
|
|
|
// DecodeURL decodes an URL encoded using the URL encoding scheme
|
|
func DecodeURL(b []byte) []byte {
|
|
for i := 0; i < len(b); i++ {
|
|
if b[i] == '%' && i+2 < len(b) {
|
|
j := i + 1
|
|
c := 0
|
|
for ; j < i+3 && (b[j] >= '0' && b[j] <= '9' || b[j] >= 'a' && b[j] <= 'f' || b[j] >= 'A' && b[j] <= 'F'); j++ {
|
|
if b[j] <= '9' {
|
|
c = c<<4 + int(b[j]-'0')
|
|
} else if b[j] <= 'F' {
|
|
c = c<<4 + int(b[j]-'A') + 10
|
|
} else if b[j] <= 'f' {
|
|
c = c<<4 + int(b[j]-'a') + 10
|
|
}
|
|
}
|
|
if j == i+3 && c < 128 {
|
|
b[i] = byte(c)
|
|
b = append(b[:i+1], b[i+3:]...)
|
|
}
|
|
} else if b[i] == '+' {
|
|
b[i] = ' '
|
|
}
|
|
}
|
|
return b
|
|
}
|