Initial Commit of Matrix Handler

vendor/github.com/rs/zerolog/internal/json/string.go

@@ -0,0 +1,121 @@
+package json
+
+import "unicode/utf8"
+
+const hex = "0123456789abcdef"
+
+var noEscapeTable = [256]bool{}
+
+func init() {
+	for i := 0; i <= 0x7e; i++ {
+		noEscapeTable[i] = i >= 0x20 && i != '\\' && i != '"'
+	}
+}
+
+// AppendStrings encodes the input strings to json and
+// appends the encoded string list to the input byte slice.
+func (e Encoder) AppendStrings(dst []byte, vals []string) []byte {
+	if len(vals) == 0 {
+		return append(dst, '[', ']')
+	}
+	dst = append(dst, '[')
+	dst = e.AppendString(dst, vals[0])
+	if len(vals) > 1 {
+		for _, val := range vals[1:] {
+			dst = e.AppendString(append(dst, ','), val)
+		}
+	}
+	dst = append(dst, ']')
+	return dst
+}
+
+// AppendString encodes the input string to json and appends
+// the encoded string to the input byte slice.
+//
+// The operation loops though each byte in the string looking
+// for characters that need json or utf8 encoding. If the string
+// does not need encoding, then the string is appended in it's
+// entirety to the byte slice.
+// If we encounter a byte that does need encoding, switch up
+// the operation and perform a byte-by-byte read-encode-append.
+func (Encoder) AppendString(dst []byte, s string) []byte {
+	// Start with a double quote.
+	dst = append(dst, '"')
+	// Loop through each character in the string.
+	for i := 0; i < len(s); i++ {
+		// Check if the character needs encoding. Control characters, slashes,
+		// and the double quote need json encoding. Bytes above the ascii
+		// boundary needs utf8 encoding.
+		if !noEscapeTable[s[i]] {
+			// We encountered a character that needs to be encoded. Switch
+			// to complex version of the algorithm.
+			dst = appendStringComplex(dst, s, i)
+			return append(dst, '"')
+		}
+	}
+	// The string has no need for encoding an therefore is directly
+	// appended to the byte slice.
+	dst = append(dst, s...)
+	// End with a double quote
+	return append(dst, '"')
+}
+
+// appendStringComplex is used by appendString to take over an in
+// progress JSON string encoding that encountered a character that needs
+// to be encoded.
+func appendStringComplex(dst []byte, s string, i int) []byte {
+	start := 0
+	for i < len(s) {
+		b := s[i]
+		if b >= utf8.RuneSelf {
+			r, size := utf8.DecodeRuneInString(s[i:])
+			if r == utf8.RuneError && size == 1 {
+				// In case of error, first append previous simple characters to
+				// the byte slice if any and append a remplacement character code
+				// in place of the invalid sequence.
+				if start < i {
+					dst = append(dst, s[start:i]...)
+				}
+				dst = append(dst, `\ufffd`...)
+				i += size
+				start = i
+				continue
+			}
+			i += size
+			continue
+		}
+		if noEscapeTable[b] {
+			i++
+			continue
+		}
+		// We encountered a character that needs to be encoded.
+		// Let's append the previous simple characters to the byte slice
+		// and switch our operation to read and encode the remainder
+		// characters byte-by-byte.
+		if start < i {
+			dst = append(dst, s[start:i]...)
+		}
+		switch b {
+		case '"', '\\':
+			dst = append(dst, '\\', b)
+		case '\b':
+			dst = append(dst, '\\', 'b')
+		case '\f':
+			dst = append(dst, '\\', 'f')
+		case '\n':
+			dst = append(dst, '\\', 'n')
+		case '\r':
+			dst = append(dst, '\\', 'r')
+		case '\t':
+			dst = append(dst, '\\', 't')
+		default:
+			dst = append(dst, '\\', 'u', '0', '0', hex[b>>4], hex[b&0xF])
+		}
+		i++
+		start = i
+	}
+	if start < len(s) {
+		dst = append(dst, s[start:]...)
+	}
+	return dst
+}