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-rw-r--r--vendor/golang.org/x/net/html/atom/atom.go78
1 files changed, 78 insertions, 0 deletions
diff --git a/vendor/golang.org/x/net/html/atom/atom.go b/vendor/golang.org/x/net/html/atom/atom.go
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+// Copyright 2012 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 atom provides integer codes (also known as atoms) for a fixed set of
+// frequently occurring HTML strings: tag names and attribute keys such as "p"
+// and "id".
+//
+// Sharing an atom's name between all elements with the same tag can result in
+// fewer string allocations when tokenizing and parsing HTML. Integer
+// comparisons are also generally faster than string comparisons.
+//
+// The value of an atom's particular code is not guaranteed to stay the same
+// between versions of this package. Neither is any ordering guaranteed:
+// whether atom.H1 < atom.H2 may also change. The codes are not guaranteed to
+// be dense. The only guarantees are that e.g. looking up "div" will yield
+// atom.Div, calling atom.Div.String will return "div", and atom.Div != 0.
+package atom // import "golang.org/x/net/html/atom"
+
+// Atom is an integer code for a string. The zero value maps to "".
+type Atom uint32
+
+// String returns the atom's name.
+func (a Atom) String() string {
+ start := uint32(a >> 8)
+ n := uint32(a & 0xff)
+ if start+n > uint32(len(atomText)) {
+ return ""
+ }
+ return atomText[start : start+n]
+}
+
+func (a Atom) string() string {
+ return atomText[a>>8 : a>>8+a&0xff]
+}
+
+// fnv computes the FNV hash with an arbitrary starting value h.
+func fnv(h uint32, s []byte) uint32 {
+ for i := range s {
+ h ^= uint32(s[i])
+ h *= 16777619
+ }
+ return h
+}
+
+func match(s string, t []byte) bool {
+ for i, c := range t {
+ if s[i] != c {
+ return false
+ }
+ }
+ return true
+}
+
+// Lookup returns the atom whose name is s. It returns zero if there is no
+// such atom. The lookup is case sensitive.
+func Lookup(s []byte) Atom {
+ if len(s) == 0 || len(s) > maxAtomLen {
+ return 0
+ }
+ h := fnv(hash0, s)
+ if a := table[h&uint32(len(table)-1)]; int(a&0xff) == len(s) && match(a.string(), s) {
+ return a
+ }
+ if a := table[(h>>16)&uint32(len(table)-1)]; int(a&0xff) == len(s) && match(a.string(), s) {
+ return a
+ }
+ return 0
+}
+
+// String returns a string whose contents are equal to s. In that sense, it is
+// equivalent to string(s) but may be more efficient.
+func String(s []byte) string {
+ if a := Lookup(s); a != 0 {
+ return a.String()
+ }
+ return string(s)
+}