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-rw-r--r--vendor/golang.org/x/text/cases/context.go376
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diff --git a/vendor/golang.org/x/text/cases/context.go b/vendor/golang.org/x/text/cases/context.go
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+// Copyright 2014 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.
+
+package cases
+
+import "golang.org/x/text/transform"
+
+// A context is used for iterating over source bytes, fetching case info and
+// writing to a destination buffer.
+//
+// Casing operations may need more than one rune of context to decide how a rune
+// should be cased. Casing implementations should call checkpoint on context
+// whenever it is known to be safe to return the runes processed so far.
+//
+// It is recommended for implementations to not allow for more than 30 case
+// ignorables as lookahead (analogous to the limit in norm) and to use state if
+// unbounded lookahead is needed for cased runes.
+type context struct {
+ dst, src []byte
+ atEOF bool
+
+ pDst int // pDst points past the last written rune in dst.
+ pSrc int // pSrc points to the start of the currently scanned rune.
+
+ // checkpoints safe to return in Transform, where nDst <= pDst and nSrc <= pSrc.
+ nDst, nSrc int
+ err error
+
+ sz int // size of current rune
+ info info // case information of currently scanned rune
+
+ // State preserved across calls to Transform.
+ isMidWord bool // false if next cased letter needs to be title-cased.
+}
+
+func (c *context) Reset() {
+ c.isMidWord = false
+}
+
+// ret returns the return values for the Transform method. It checks whether
+// there were insufficient bytes in src to complete and introduces an error
+// accordingly, if necessary.
+func (c *context) ret() (nDst, nSrc int, err error) {
+ if c.err != nil || c.nSrc == len(c.src) {
+ return c.nDst, c.nSrc, c.err
+ }
+ // This point is only reached by mappers if there was no short destination
+ // buffer. This means that the source buffer was exhausted and that c.sz was
+ // set to 0 by next.
+ if c.atEOF && c.pSrc == len(c.src) {
+ return c.pDst, c.pSrc, nil
+ }
+ return c.nDst, c.nSrc, transform.ErrShortSrc
+}
+
+// retSpan returns the return values for the Span method. It checks whether
+// there were insufficient bytes in src to complete and introduces an error
+// accordingly, if necessary.
+func (c *context) retSpan() (n int, err error) {
+ _, nSrc, err := c.ret()
+ return nSrc, err
+}
+
+// checkpoint sets the return value buffer points for Transform to the current
+// positions.
+func (c *context) checkpoint() {
+ if c.err == nil {
+ c.nDst, c.nSrc = c.pDst, c.pSrc+c.sz
+ }
+}
+
+// unreadRune causes the last rune read by next to be reread on the next
+// invocation of next. Only one unreadRune may be called after a call to next.
+func (c *context) unreadRune() {
+ c.sz = 0
+}
+
+func (c *context) next() bool {
+ c.pSrc += c.sz
+ if c.pSrc == len(c.src) || c.err != nil {
+ c.info, c.sz = 0, 0
+ return false
+ }
+ v, sz := trie.lookup(c.src[c.pSrc:])
+ c.info, c.sz = info(v), sz
+ if c.sz == 0 {
+ if c.atEOF {
+ // A zero size means we have an incomplete rune. If we are atEOF,
+ // this means it is an illegal rune, which we will consume one
+ // byte at a time.
+ c.sz = 1
+ } else {
+ c.err = transform.ErrShortSrc
+ return false
+ }
+ }
+ return true
+}
+
+// writeBytes adds bytes to dst.
+func (c *context) writeBytes(b []byte) bool {
+ if len(c.dst)-c.pDst < len(b) {
+ c.err = transform.ErrShortDst
+ return false
+ }
+ // This loop is faster than using copy.
+ for _, ch := range b {
+ c.dst[c.pDst] = ch
+ c.pDst++
+ }
+ return true
+}
+
+// writeString writes the given string to dst.
+func (c *context) writeString(s string) bool {
+ if len(c.dst)-c.pDst < len(s) {
+ c.err = transform.ErrShortDst
+ return false
+ }
+ // This loop is faster than using copy.
+ for i := 0; i < len(s); i++ {
+ c.dst[c.pDst] = s[i]
+ c.pDst++
+ }
+ return true
+}
+
+// copy writes the current rune to dst.
+func (c *context) copy() bool {
+ return c.writeBytes(c.src[c.pSrc : c.pSrc+c.sz])
+}
+
+// copyXOR copies the current rune to dst and modifies it by applying the XOR
+// pattern of the case info. It is the responsibility of the caller to ensure
+// that this is a rune with a XOR pattern defined.
+func (c *context) copyXOR() bool {
+ if !c.copy() {
+ return false
+ }
+ if c.info&xorIndexBit == 0 {
+ // Fast path for 6-bit XOR pattern, which covers most cases.
+ c.dst[c.pDst-1] ^= byte(c.info >> xorShift)
+ } else {
+ // Interpret XOR bits as an index.
+ // TODO: test performance for unrolling this loop. Verify that we have
+ // at least two bytes and at most three.
+ idx := c.info >> xorShift
+ for p := c.pDst - 1; ; p-- {
+ c.dst[p] ^= xorData[idx]
+ idx--
+ if xorData[idx] == 0 {
+ break
+ }
+ }
+ }
+ return true
+}
+
+// hasPrefix returns true if src[pSrc:] starts with the given string.
+func (c *context) hasPrefix(s string) bool {
+ b := c.src[c.pSrc:]
+ if len(b) < len(s) {
+ return false
+ }
+ for i, c := range b[:len(s)] {
+ if c != s[i] {
+ return false
+ }
+ }
+ return true
+}
+
+// caseType returns an info with only the case bits, normalized to either
+// cLower, cUpper, cTitle or cUncased.
+func (c *context) caseType() info {
+ cm := c.info & 0x7
+ if cm < 4 {
+ return cm
+ }
+ if cm >= cXORCase {
+ // xor the last bit of the rune with the case type bits.
+ b := c.src[c.pSrc+c.sz-1]
+ return info(b&1) ^ cm&0x3
+ }
+ if cm == cIgnorableCased {
+ return cLower
+ }
+ return cUncased
+}
+
+// lower writes the lowercase version of the current rune to dst.
+func lower(c *context) bool {
+ ct := c.caseType()
+ if c.info&hasMappingMask == 0 || ct == cLower {
+ return c.copy()
+ }
+ if c.info&exceptionBit == 0 {
+ return c.copyXOR()
+ }
+ e := exceptions[c.info>>exceptionShift:]
+ offset := 2 + e[0]&lengthMask // size of header + fold string
+ if nLower := (e[1] >> lengthBits) & lengthMask; nLower != noChange {
+ return c.writeString(e[offset : offset+nLower])
+ }
+ return c.copy()
+}
+
+func isLower(c *context) bool {
+ ct := c.caseType()
+ if c.info&hasMappingMask == 0 || ct == cLower {
+ return true
+ }
+ if c.info&exceptionBit == 0 {
+ c.err = transform.ErrEndOfSpan
+ return false
+ }
+ e := exceptions[c.info>>exceptionShift:]
+ if nLower := (e[1] >> lengthBits) & lengthMask; nLower != noChange {
+ c.err = transform.ErrEndOfSpan
+ return false
+ }
+ return true
+}
+
+// upper writes the uppercase version of the current rune to dst.
+func upper(c *context) bool {
+ ct := c.caseType()
+ if c.info&hasMappingMask == 0 || ct == cUpper {
+ return c.copy()
+ }
+ if c.info&exceptionBit == 0 {
+ return c.copyXOR()
+ }
+ e := exceptions[c.info>>exceptionShift:]
+ offset := 2 + e[0]&lengthMask // size of header + fold string
+ // Get length of first special case mapping.
+ n := (e[1] >> lengthBits) & lengthMask
+ if ct == cTitle {
+ // The first special case mapping is for lower. Set n to the second.
+ if n == noChange {
+ n = 0
+ }
+ n, e = e[1]&lengthMask, e[n:]
+ }
+ if n != noChange {
+ return c.writeString(e[offset : offset+n])
+ }
+ return c.copy()
+}
+
+// isUpper writes the isUppercase version of the current rune to dst.
+func isUpper(c *context) bool {
+ ct := c.caseType()
+ if c.info&hasMappingMask == 0 || ct == cUpper {
+ return true
+ }
+ if c.info&exceptionBit == 0 {
+ c.err = transform.ErrEndOfSpan
+ return false
+ }
+ e := exceptions[c.info>>exceptionShift:]
+ // Get length of first special case mapping.
+ n := (e[1] >> lengthBits) & lengthMask
+ if ct == cTitle {
+ n = e[1] & lengthMask
+ }
+ if n != noChange {
+ c.err = transform.ErrEndOfSpan
+ return false
+ }
+ return true
+}
+
+// title writes the title case version of the current rune to dst.
+func title(c *context) bool {
+ ct := c.caseType()
+ if c.info&hasMappingMask == 0 || ct == cTitle {
+ return c.copy()
+ }
+ if c.info&exceptionBit == 0 {
+ if ct == cLower {
+ return c.copyXOR()
+ }
+ return c.copy()
+ }
+ // Get the exception data.
+ e := exceptions[c.info>>exceptionShift:]
+ offset := 2 + e[0]&lengthMask // size of header + fold string
+
+ nFirst := (e[1] >> lengthBits) & lengthMask
+ if nTitle := e[1] & lengthMask; nTitle != noChange {
+ if nFirst != noChange {
+ e = e[nFirst:]
+ }
+ return c.writeString(e[offset : offset+nTitle])
+ }
+ if ct == cLower && nFirst != noChange {
+ // Use the uppercase version instead.
+ return c.writeString(e[offset : offset+nFirst])
+ }
+ // Already in correct case.
+ return c.copy()
+}
+
+// isTitle reports whether the current rune is in title case.
+func isTitle(c *context) bool {
+ ct := c.caseType()
+ if c.info&hasMappingMask == 0 || ct == cTitle {
+ return true
+ }
+ if c.info&exceptionBit == 0 {
+ if ct == cLower {
+ c.err = transform.ErrEndOfSpan
+ return false
+ }
+ return true
+ }
+ // Get the exception data.
+ e := exceptions[c.info>>exceptionShift:]
+ if nTitle := e[1] & lengthMask; nTitle != noChange {
+ c.err = transform.ErrEndOfSpan
+ return false
+ }
+ nFirst := (e[1] >> lengthBits) & lengthMask
+ if ct == cLower && nFirst != noChange {
+ c.err = transform.ErrEndOfSpan
+ return false
+ }
+ return true
+}
+
+// foldFull writes the foldFull version of the current rune to dst.
+func foldFull(c *context) bool {
+ if c.info&hasMappingMask == 0 {
+ return c.copy()
+ }
+ ct := c.caseType()
+ if c.info&exceptionBit == 0 {
+ if ct != cLower || c.info&inverseFoldBit != 0 {
+ return c.copyXOR()
+ }
+ return c.copy()
+ }
+ e := exceptions[c.info>>exceptionShift:]
+ n := e[0] & lengthMask
+ if n == 0 {
+ if ct == cLower {
+ return c.copy()
+ }
+ n = (e[1] >> lengthBits) & lengthMask
+ }
+ return c.writeString(e[2 : 2+n])
+}
+
+// isFoldFull reports whether the current run is mapped to foldFull
+func isFoldFull(c *context) bool {
+ if c.info&hasMappingMask == 0 {
+ return true
+ }
+ ct := c.caseType()
+ if c.info&exceptionBit == 0 {
+ if ct != cLower || c.info&inverseFoldBit != 0 {
+ c.err = transform.ErrEndOfSpan
+ return false
+ }
+ return true
+ }
+ e := exceptions[c.info>>exceptionShift:]
+ n := e[0] & lengthMask
+ if n == 0 && ct == cLower {
+ return true
+ }
+ c.err = transform.ErrEndOfSpan
+ return false
+}