Update libkv dependency

vendor/golang.org/x/text/cases/context.go

@@ -4,9 +4,7 @@
 
 package cases
 
-import (
-	"golang.org/x/text/transform"
-)
+import "golang.org/x/text/transform"
 
 // A context is used for iterating over source bytes, fetching case info and
 // writing to a destination buffer.
@@ -56,6 +54,14 @@ func (c *context) ret() (nDst, nSrc int, err error) {
 	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() {
@@ -200,6 +206,23 @@ func lower(c *context) bool {
 	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()
@@ -226,6 +249,29 @@ func upper(c *context) bool {
 	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()
@@ -257,6 +303,33 @@ func title(c *context) bool {
 	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 {
@@ -279,3 +352,25 @@ func foldFull(c *context) bool {
 	}
 	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
+}