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-rw-r--r--src/strconv/quote.go604
1 files changed, 604 insertions, 0 deletions
diff --git a/src/strconv/quote.go b/src/strconv/quote.go
new file mode 100644
index 0000000..1b5bddf
--- /dev/null
+++ b/src/strconv/quote.go
@@ -0,0 +1,604 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:generate go run makeisprint.go -output isprint.go
+
+package strconv
+
+import (
+ "unicode/utf8"
+)
+
+const (
+ lowerhex = "0123456789abcdef"
+ upperhex = "0123456789ABCDEF"
+)
+
+// contains reports whether the string contains the byte c.
+func contains(s string, c byte) bool {
+ return index(s, c) != -1
+}
+
+func quoteWith(s string, quote byte, ASCIIonly, graphicOnly bool) string {
+ return string(appendQuotedWith(make([]byte, 0, 3*len(s)/2), s, quote, ASCIIonly, graphicOnly))
+}
+
+func quoteRuneWith(r rune, quote byte, ASCIIonly, graphicOnly bool) string {
+ return string(appendQuotedRuneWith(nil, r, quote, ASCIIonly, graphicOnly))
+}
+
+func appendQuotedWith(buf []byte, s string, quote byte, ASCIIonly, graphicOnly bool) []byte {
+ // Often called with big strings, so preallocate. If there's quoting,
+ // this is conservative but still helps a lot.
+ if cap(buf)-len(buf) < len(s) {
+ nBuf := make([]byte, len(buf), len(buf)+1+len(s)+1)
+ copy(nBuf, buf)
+ buf = nBuf
+ }
+ buf = append(buf, quote)
+ for width := 0; len(s) > 0; s = s[width:] {
+ r := rune(s[0])
+ width = 1
+ if r >= utf8.RuneSelf {
+ r, width = utf8.DecodeRuneInString(s)
+ }
+ if width == 1 && r == utf8.RuneError {
+ buf = append(buf, `\x`...)
+ buf = append(buf, lowerhex[s[0]>>4])
+ buf = append(buf, lowerhex[s[0]&0xF])
+ continue
+ }
+ buf = appendEscapedRune(buf, r, quote, ASCIIonly, graphicOnly)
+ }
+ buf = append(buf, quote)
+ return buf
+}
+
+func appendQuotedRuneWith(buf []byte, r rune, quote byte, ASCIIonly, graphicOnly bool) []byte {
+ buf = append(buf, quote)
+ if !utf8.ValidRune(r) {
+ r = utf8.RuneError
+ }
+ buf = appendEscapedRune(buf, r, quote, ASCIIonly, graphicOnly)
+ buf = append(buf, quote)
+ return buf
+}
+
+func appendEscapedRune(buf []byte, r rune, quote byte, ASCIIonly, graphicOnly bool) []byte {
+ var runeTmp [utf8.UTFMax]byte
+ if r == rune(quote) || r == '\\' { // always backslashed
+ buf = append(buf, '\\')
+ buf = append(buf, byte(r))
+ return buf
+ }
+ if ASCIIonly {
+ if r < utf8.RuneSelf && IsPrint(r) {
+ buf = append(buf, byte(r))
+ return buf
+ }
+ } else if IsPrint(r) || graphicOnly && isInGraphicList(r) {
+ n := utf8.EncodeRune(runeTmp[:], r)
+ buf = append(buf, runeTmp[:n]...)
+ return buf
+ }
+ switch r {
+ case '\a':
+ buf = append(buf, `\a`...)
+ case '\b':
+ buf = append(buf, `\b`...)
+ case '\f':
+ buf = append(buf, `\f`...)
+ case '\n':
+ buf = append(buf, `\n`...)
+ case '\r':
+ buf = append(buf, `\r`...)
+ case '\t':
+ buf = append(buf, `\t`...)
+ case '\v':
+ buf = append(buf, `\v`...)
+ default:
+ switch {
+ case r < ' ' || r == 0x7f:
+ buf = append(buf, `\x`...)
+ buf = append(buf, lowerhex[byte(r)>>4])
+ buf = append(buf, lowerhex[byte(r)&0xF])
+ case !utf8.ValidRune(r):
+ r = 0xFFFD
+ fallthrough
+ case r < 0x10000:
+ buf = append(buf, `\u`...)
+ for s := 12; s >= 0; s -= 4 {
+ buf = append(buf, lowerhex[r>>uint(s)&0xF])
+ }
+ default:
+ buf = append(buf, `\U`...)
+ for s := 28; s >= 0; s -= 4 {
+ buf = append(buf, lowerhex[r>>uint(s)&0xF])
+ }
+ }
+ }
+ return buf
+}
+
+// Quote returns a double-quoted Go string literal representing s. The
+// returned string uses Go escape sequences (\t, \n, \xFF, \u0100) for
+// control characters and non-printable characters as defined by
+// IsPrint.
+func Quote(s string) string {
+ return quoteWith(s, '"', false, false)
+}
+
+// AppendQuote appends a double-quoted Go string literal representing s,
+// as generated by Quote, to dst and returns the extended buffer.
+func AppendQuote(dst []byte, s string) []byte {
+ return appendQuotedWith(dst, s, '"', false, false)
+}
+
+// QuoteToASCII returns a double-quoted Go string literal representing s.
+// The returned string uses Go escape sequences (\t, \n, \xFF, \u0100) for
+// non-ASCII characters and non-printable characters as defined by IsPrint.
+func QuoteToASCII(s string) string {
+ return quoteWith(s, '"', true, false)
+}
+
+// AppendQuoteToASCII appends a double-quoted Go string literal representing s,
+// as generated by QuoteToASCII, to dst and returns the extended buffer.
+func AppendQuoteToASCII(dst []byte, s string) []byte {
+ return appendQuotedWith(dst, s, '"', true, false)
+}
+
+// QuoteToGraphic returns a double-quoted Go string literal representing s.
+// The returned string leaves Unicode graphic characters, as defined by
+// IsGraphic, unchanged and uses Go escape sequences (\t, \n, \xFF, \u0100)
+// for non-graphic characters.
+func QuoteToGraphic(s string) string {
+ return quoteWith(s, '"', false, true)
+}
+
+// AppendQuoteToGraphic appends a double-quoted Go string literal representing s,
+// as generated by QuoteToGraphic, to dst and returns the extended buffer.
+func AppendQuoteToGraphic(dst []byte, s string) []byte {
+ return appendQuotedWith(dst, s, '"', false, true)
+}
+
+// QuoteRune returns a single-quoted Go character literal representing the
+// rune. The returned string uses Go escape sequences (\t, \n, \xFF, \u0100)
+// for control characters and non-printable characters as defined by IsPrint.
+// If r is not a valid Unicode code point, it is interpreted as the Unicode
+// replacement character U+FFFD.
+func QuoteRune(r rune) string {
+ return quoteRuneWith(r, '\'', false, false)
+}
+
+// AppendQuoteRune appends a single-quoted Go character literal representing the rune,
+// as generated by QuoteRune, to dst and returns the extended buffer.
+func AppendQuoteRune(dst []byte, r rune) []byte {
+ return appendQuotedRuneWith(dst, r, '\'', false, false)
+}
+
+// QuoteRuneToASCII returns a single-quoted Go character literal representing
+// the rune. The returned string uses Go escape sequences (\t, \n, \xFF,
+// \u0100) for non-ASCII characters and non-printable characters as defined
+// by IsPrint.
+// If r is not a valid Unicode code point, it is interpreted as the Unicode
+// replacement character U+FFFD.
+func QuoteRuneToASCII(r rune) string {
+ return quoteRuneWith(r, '\'', true, false)
+}
+
+// AppendQuoteRuneToASCII appends a single-quoted Go character literal representing the rune,
+// as generated by QuoteRuneToASCII, to dst and returns the extended buffer.
+func AppendQuoteRuneToASCII(dst []byte, r rune) []byte {
+ return appendQuotedRuneWith(dst, r, '\'', true, false)
+}
+
+// QuoteRuneToGraphic returns a single-quoted Go character literal representing
+// the rune. If the rune is not a Unicode graphic character,
+// as defined by IsGraphic, the returned string will use a Go escape sequence
+// (\t, \n, \xFF, \u0100).
+// If r is not a valid Unicode code point, it is interpreted as the Unicode
+// replacement character U+FFFD.
+func QuoteRuneToGraphic(r rune) string {
+ return quoteRuneWith(r, '\'', false, true)
+}
+
+// AppendQuoteRuneToGraphic appends a single-quoted Go character literal representing the rune,
+// as generated by QuoteRuneToGraphic, to dst and returns the extended buffer.
+func AppendQuoteRuneToGraphic(dst []byte, r rune) []byte {
+ return appendQuotedRuneWith(dst, r, '\'', false, true)
+}
+
+// CanBackquote reports whether the string s can be represented
+// unchanged as a single-line backquoted string without control
+// characters other than tab.
+func CanBackquote(s string) bool {
+ for len(s) > 0 {
+ r, wid := utf8.DecodeRuneInString(s)
+ s = s[wid:]
+ if wid > 1 {
+ if r == '\ufeff' {
+ return false // BOMs are invisible and should not be quoted.
+ }
+ continue // All other multibyte runes are correctly encoded and assumed printable.
+ }
+ if r == utf8.RuneError {
+ return false
+ }
+ if (r < ' ' && r != '\t') || r == '`' || r == '\u007F' {
+ return false
+ }
+ }
+ return true
+}
+
+func unhex(b byte) (v rune, ok bool) {
+ c := rune(b)
+ switch {
+ case '0' <= c && c <= '9':
+ return c - '0', true
+ case 'a' <= c && c <= 'f':
+ return c - 'a' + 10, true
+ case 'A' <= c && c <= 'F':
+ return c - 'A' + 10, true
+ }
+ return
+}
+
+// UnquoteChar decodes the first character or byte in the escaped string
+// or character literal represented by the string s.
+// It returns four values:
+//
+// 1. value, the decoded Unicode code point or byte value;
+// 2. multibyte, a boolean indicating whether the decoded character requires a multibyte UTF-8 representation;
+// 3. tail, the remainder of the string after the character; and
+// 4. an error that will be nil if the character is syntactically valid.
+//
+// The second argument, quote, specifies the type of literal being parsed
+// and therefore which escaped quote character is permitted.
+// If set to a single quote, it permits the sequence \' and disallows unescaped '.
+// If set to a double quote, it permits \" and disallows unescaped ".
+// If set to zero, it does not permit either escape and allows both quote characters to appear unescaped.
+func UnquoteChar(s string, quote byte) (value rune, multibyte bool, tail string, err error) {
+ // easy cases
+ if len(s) == 0 {
+ err = ErrSyntax
+ return
+ }
+ switch c := s[0]; {
+ case c == quote && (quote == '\'' || quote == '"'):
+ err = ErrSyntax
+ return
+ case c >= utf8.RuneSelf:
+ r, size := utf8.DecodeRuneInString(s)
+ return r, true, s[size:], nil
+ case c != '\\':
+ return rune(s[0]), false, s[1:], nil
+ }
+
+ // hard case: c is backslash
+ if len(s) <= 1 {
+ err = ErrSyntax
+ return
+ }
+ c := s[1]
+ s = s[2:]
+
+ switch c {
+ case 'a':
+ value = '\a'
+ case 'b':
+ value = '\b'
+ case 'f':
+ value = '\f'
+ case 'n':
+ value = '\n'
+ case 'r':
+ value = '\r'
+ case 't':
+ value = '\t'
+ case 'v':
+ value = '\v'
+ case 'x', 'u', 'U':
+ n := 0
+ switch c {
+ case 'x':
+ n = 2
+ case 'u':
+ n = 4
+ case 'U':
+ n = 8
+ }
+ var v rune
+ if len(s) < n {
+ err = ErrSyntax
+ return
+ }
+ for j := 0; j < n; j++ {
+ x, ok := unhex(s[j])
+ if !ok {
+ err = ErrSyntax
+ return
+ }
+ v = v<<4 | x
+ }
+ s = s[n:]
+ if c == 'x' {
+ // single-byte string, possibly not UTF-8
+ value = v
+ break
+ }
+ if !utf8.ValidRune(v) {
+ err = ErrSyntax
+ return
+ }
+ value = v
+ multibyte = true
+ case '0', '1', '2', '3', '4', '5', '6', '7':
+ v := rune(c) - '0'
+ if len(s) < 2 {
+ err = ErrSyntax
+ return
+ }
+ for j := 0; j < 2; j++ { // one digit already; two more
+ x := rune(s[j]) - '0'
+ if x < 0 || x > 7 {
+ err = ErrSyntax
+ return
+ }
+ v = (v << 3) | x
+ }
+ s = s[2:]
+ if v > 255 {
+ err = ErrSyntax
+ return
+ }
+ value = v
+ case '\\':
+ value = '\\'
+ case '\'', '"':
+ if c != quote {
+ err = ErrSyntax
+ return
+ }
+ value = rune(c)
+ default:
+ err = ErrSyntax
+ return
+ }
+ tail = s
+ return
+}
+
+// QuotedPrefix returns the quoted string (as understood by Unquote) at the prefix of s.
+// If s does not start with a valid quoted string, QuotedPrefix returns an error.
+func QuotedPrefix(s string) (string, error) {
+ out, _, err := unquote(s, false)
+ return out, err
+}
+
+// Unquote interprets s as a single-quoted, double-quoted,
+// or backquoted Go string literal, returning the string value
+// that s quotes. (If s is single-quoted, it would be a Go
+// character literal; Unquote returns the corresponding
+// one-character string.)
+func Unquote(s string) (string, error) {
+ out, rem, err := unquote(s, true)
+ if len(rem) > 0 {
+ return "", ErrSyntax
+ }
+ return out, err
+}
+
+// unquote parses a quoted string at the start of the input,
+// returning the parsed prefix, the remaining suffix, and any parse errors.
+// If unescape is true, the parsed prefix is unescaped,
+// otherwise the input prefix is provided verbatim.
+func unquote(in string, unescape bool) (out, rem string, err error) {
+ // Determine the quote form and optimistically find the terminating quote.
+ if len(in) < 2 {
+ return "", in, ErrSyntax
+ }
+ quote := in[0]
+ end := index(in[1:], quote)
+ if end < 0 {
+ return "", in, ErrSyntax
+ }
+ end += 2 // position after terminating quote; may be wrong if escape sequences are present
+
+ switch quote {
+ case '`':
+ switch {
+ case !unescape:
+ out = in[:end] // include quotes
+ case !contains(in[:end], '\r'):
+ out = in[len("`") : end-len("`")] // exclude quotes
+ default:
+ // Carriage return characters ('\r') inside raw string literals
+ // are discarded from the raw string value.
+ buf := make([]byte, 0, end-len("`")-len("\r")-len("`"))
+ for i := len("`"); i < end-len("`"); i++ {
+ if in[i] != '\r' {
+ buf = append(buf, in[i])
+ }
+ }
+ out = string(buf)
+ }
+ // NOTE: Prior implementations did not verify that raw strings consist
+ // of valid UTF-8 characters and we continue to not verify it as such.
+ // The Go specification does not explicitly require valid UTF-8,
+ // but only mention that it is implicitly valid for Go source code
+ // (which must be valid UTF-8).
+ return out, in[end:], nil
+ case '"', '\'':
+ // Handle quoted strings without any escape sequences.
+ if !contains(in[:end], '\\') && !contains(in[:end], '\n') {
+ var valid bool
+ switch quote {
+ case '"':
+ valid = utf8.ValidString(in[len(`"`) : end-len(`"`)])
+ case '\'':
+ r, n := utf8.DecodeRuneInString(in[len("'") : end-len("'")])
+ valid = len("'")+n+len("'") == end && (r != utf8.RuneError || n != 1)
+ }
+ if valid {
+ out = in[:end]
+ if unescape {
+ out = out[1 : end-1] // exclude quotes
+ }
+ return out, in[end:], nil
+ }
+ }
+
+ // Handle quoted strings with escape sequences.
+ var buf []byte
+ in0 := in
+ in = in[1:] // skip starting quote
+ if unescape {
+ buf = make([]byte, 0, 3*end/2) // try to avoid more allocations
+ }
+ for len(in) > 0 && in[0] != quote {
+ // Process the next character,
+ // rejecting any unescaped newline characters which are invalid.
+ r, multibyte, rem, err := UnquoteChar(in, quote)
+ if in[0] == '\n' || err != nil {
+ return "", in0, ErrSyntax
+ }
+ in = rem
+
+ // Append the character if unescaping the input.
+ if unescape {
+ if r < utf8.RuneSelf || !multibyte {
+ buf = append(buf, byte(r))
+ } else {
+ var arr [utf8.UTFMax]byte
+ n := utf8.EncodeRune(arr[:], r)
+ buf = append(buf, arr[:n]...)
+ }
+ }
+
+ // Single quoted strings must be a single character.
+ if quote == '\'' {
+ break
+ }
+ }
+
+ // Verify that the string ends with a terminating quote.
+ if !(len(in) > 0 && in[0] == quote) {
+ return "", in0, ErrSyntax
+ }
+ in = in[1:] // skip terminating quote
+
+ if unescape {
+ return string(buf), in, nil
+ }
+ return in0[:len(in0)-len(in)], in, nil
+ default:
+ return "", in, ErrSyntax
+ }
+}
+
+// bsearch16 returns the smallest i such that a[i] >= x.
+// If there is no such i, bsearch16 returns len(a).
+func bsearch16(a []uint16, x uint16) int {
+ i, j := 0, len(a)
+ for i < j {
+ h := i + (j-i)>>1
+ if a[h] < x {
+ i = h + 1
+ } else {
+ j = h
+ }
+ }
+ return i
+}
+
+// bsearch32 returns the smallest i such that a[i] >= x.
+// If there is no such i, bsearch32 returns len(a).
+func bsearch32(a []uint32, x uint32) int {
+ i, j := 0, len(a)
+ for i < j {
+ h := i + (j-i)>>1
+ if a[h] < x {
+ i = h + 1
+ } else {
+ j = h
+ }
+ }
+ return i
+}
+
+// TODO: IsPrint is a local implementation of unicode.IsPrint, verified by the tests
+// to give the same answer. It allows this package not to depend on unicode,
+// and therefore not pull in all the Unicode tables. If the linker were better
+// at tossing unused tables, we could get rid of this implementation.
+// That would be nice.
+
+// IsPrint reports whether the rune is defined as printable by Go, with
+// the same definition as unicode.IsPrint: letters, numbers, punctuation,
+// symbols and ASCII space.
+func IsPrint(r rune) bool {
+ // Fast check for Latin-1
+ if r <= 0xFF {
+ if 0x20 <= r && r <= 0x7E {
+ // All the ASCII is printable from space through DEL-1.
+ return true
+ }
+ if 0xA1 <= r && r <= 0xFF {
+ // Similarly for ¡ through ÿ...
+ return r != 0xAD // ...except for the bizarre soft hyphen.
+ }
+ return false
+ }
+
+ // Same algorithm, either on uint16 or uint32 value.
+ // First, find first i such that isPrint[i] >= x.
+ // This is the index of either the start or end of a pair that might span x.
+ // The start is even (isPrint[i&^1]) and the end is odd (isPrint[i|1]).
+ // If we find x in a range, make sure x is not in isNotPrint list.
+
+ if 0 <= r && r < 1<<16 {
+ rr, isPrint, isNotPrint := uint16(r), isPrint16, isNotPrint16
+ i := bsearch16(isPrint, rr)
+ if i >= len(isPrint) || rr < isPrint[i&^1] || isPrint[i|1] < rr {
+ return false
+ }
+ j := bsearch16(isNotPrint, rr)
+ return j >= len(isNotPrint) || isNotPrint[j] != rr
+ }
+
+ rr, isPrint, isNotPrint := uint32(r), isPrint32, isNotPrint32
+ i := bsearch32(isPrint, rr)
+ if i >= len(isPrint) || rr < isPrint[i&^1] || isPrint[i|1] < rr {
+ return false
+ }
+ if r >= 0x20000 {
+ return true
+ }
+ r -= 0x10000
+ j := bsearch16(isNotPrint, uint16(r))
+ return j >= len(isNotPrint) || isNotPrint[j] != uint16(r)
+}
+
+// IsGraphic reports whether the rune is defined as a Graphic by Unicode. Such
+// characters include letters, marks, numbers, punctuation, symbols, and
+// spaces, from categories L, M, N, P, S, and Zs.
+func IsGraphic(r rune) bool {
+ if IsPrint(r) {
+ return true
+ }
+ return isInGraphicList(r)
+}
+
+// isInGraphicList reports whether the rune is in the isGraphic list. This separation
+// from IsGraphic allows quoteWith to avoid two calls to IsPrint.
+// Should be called only if IsPrint fails.
+func isInGraphicList(r rune) bool {
+ // We know r must fit in 16 bits - see makeisprint.go.
+ if r > 0xFFFF {
+ return false
+ }
+ rr := uint16(r)
+ i := bsearch16(isGraphic, rr)
+ return i < len(isGraphic) && rr == isGraphic[i]
+}