75 lines
2.2 KiB
Go
75 lines
2.2 KiB
Go
package zerolog
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import "unicode/utf8"
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const hex = "0123456789abcdef"
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// appendJSONString encodes the input string to json and appends
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// the encoded string to the input byte slice.
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//
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// The operation loops though each byte in the string looking
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// for characters that need json or utf8 encoding. If the string
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// does not need encoding, then the string is appended in it's
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// entirety to the byte slice.
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// If we encounter a byte that does need encoding, switch up
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// the operation and perform a byte-by-byte read-encode-append.
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func appendJSONString(dst []byte, s string) []byte {
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// Start with a double quote.
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dst = append(dst, '"')
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// Loop through each character in the string.
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for i := 0; i < len(s); i++ {
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// Check if the character needs encoding. Control characters, slashes,
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// and the double quote need json encoding. Bytes above the ascii
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// boundary needs utf8 encoding.
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if s[i] < ' ' || s[i] == '\\' || s[i] == '"' || s[i] > 126 {
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// We encountered a character that needs to be encoded. Let's
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// append the previous simple characters to the byte slice
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// and switch our operation to read and encode the remainder
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// characters byte-by-byte.
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dst = append(dst, s[:i]...)
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for i < len(s) {
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if b := s[i]; b < utf8.RuneSelf {
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switch b {
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case '"', '\\':
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dst = append(dst, '\\', b)
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case '\b':
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dst = append(dst, '\\', 'b')
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case '\f':
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dst = append(dst, '\\', 'f')
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case '\n':
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dst = append(dst, '\\', 'n')
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case '\r':
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dst = append(dst, '\\', 'r')
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case '\t':
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dst = append(dst, '\\', 't')
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default:
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if b >= 0x20 {
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dst = append(dst, b)
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} else {
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dst = append(dst, '\\', 'u', '0', '0',
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hex[b>>4], hex[b&0xF])
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}
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}
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i++
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continue
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}
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r, size := utf8.DecodeRuneInString(s[i:])
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if r == utf8.RuneError && size == 1 {
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dst = append(dst, `\ufffd`...)
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i++
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continue
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}
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dst = append(dst, s[i:i+size]...)
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i += size
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}
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// End with a double quote
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return append(dst, '"')
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}
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}
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// The string has no need for encoding an therefore is directly
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// appended to the byte slice.
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dst = append(dst, s...)
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// End with a double quote
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return append(dst, '"')
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}
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