mirror of
https://github.com/VictoriaMetrics/VictoriaMetrics.git
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100 lines
2.2 KiB
Go
100 lines
2.2 KiB
Go
package quicktemplate
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import (
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"bytes"
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"fmt"
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"strings"
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)
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func hasSpecialChars(s string) bool {
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if strings.IndexByte(s, '"') >= 0 || strings.IndexByte(s, '\\') >= 0 || strings.IndexByte(s, '<') >= 0 || strings.IndexByte(s, '\'') >= 0 {
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return true
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}
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for i := 0; i < len(s); i++ {
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if s[i] < 0x20 {
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return true
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}
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}
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return false
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}
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// AppendJSONString appends json-encoded string s to dst and returns the result.
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//
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// If addQuotes is true, then the appended json string is wrapped into double quotes.
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func AppendJSONString(dst []byte, s string, addQuotes bool) []byte {
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if !hasSpecialChars(s) {
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// Fast path - nothing to escape.
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if !addQuotes {
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return append(dst, s...)
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}
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dst = append(dst, '"')
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dst = append(dst, s...)
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dst = append(dst, '"')
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return dst
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}
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// Slow path - there are chars to escape.
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if addQuotes {
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dst = append(dst, '"')
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}
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dst = jsonReplacer.AppendReplace(dst, s)
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if addQuotes {
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dst = append(dst, '"')
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}
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return dst
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}
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var jsonReplacer = newByteReplacer(func() ([]byte, []string) {
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oldChars := []byte("\n\r\t\b\f\"\\<'")
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newStrings := []string{`\n`, `\r`, `\t`, `\b`, `\f`, `\"`, `\\`, `\u003c`, `\u0027`}
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for i := 0; i < 0x20; i++ {
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c := byte(i)
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if n := bytes.IndexByte(oldChars, c); n >= 0 {
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continue
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}
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oldChars = append(oldChars, byte(i))
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newStrings = append(newStrings, fmt.Sprintf(`\u%04x`, i))
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}
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return oldChars, newStrings
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}())
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type byteReplacer struct {
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m [256]byte
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newStrings []string
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}
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func newByteReplacer(oldChars []byte, newStrings []string) *byteReplacer {
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if len(oldChars) != len(newStrings) {
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panic(fmt.Errorf("len(oldChars)=%d must be equal to len(newStrings)=%d", len(oldChars), len(newStrings)))
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}
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if len(oldChars) >= 255 {
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panic(fmt.Errorf("len(oldChars)=%d must be smaller than 255", len(oldChars)))
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}
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var m [256]byte
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for i := range m[:] {
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m[i] = 255
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}
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for i, c := range oldChars {
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m[c] = byte(i)
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}
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return &byteReplacer{
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m: m,
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newStrings: newStrings,
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}
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}
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func (br *byteReplacer) AppendReplace(dst []byte, s string) []byte {
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m := br.m
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newStrings := br.newStrings
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for i := 0; i < len(s); i++ {
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c := s[i]
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n := m[c]
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if n == 255 {
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dst = append(dst, c)
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} else {
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dst = append(dst, newStrings[n]...)
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}
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}
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return dst
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}
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