summaryrefslogtreecommitdiff
path: root/src/pkg/strings/replace.go
diff options
context:
space:
mode:
Diffstat (limited to 'src/pkg/strings/replace.go')
-rw-r--r--src/pkg/strings/replace.go518
1 files changed, 0 insertions, 518 deletions
diff --git a/src/pkg/strings/replace.go b/src/pkg/strings/replace.go
deleted file mode 100644
index 4752641be..000000000
--- a/src/pkg/strings/replace.go
+++ /dev/null
@@ -1,518 +0,0 @@
-// Copyright 2011 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 strings
-
-import "io"
-
-// Replacer replaces a list of strings with replacements.
-// It is safe for concurrent use by multiple goroutines.
-type Replacer struct {
- r replacer
-}
-
-// replacer is the interface that a replacement algorithm needs to implement.
-type replacer interface {
- Replace(s string) string
- WriteString(w io.Writer, s string) (n int, err error)
-}
-
-// NewReplacer returns a new Replacer from a list of old, new string pairs.
-// Replacements are performed in order, without overlapping matches.
-func NewReplacer(oldnew ...string) *Replacer {
- if len(oldnew)%2 == 1 {
- panic("strings.NewReplacer: odd argument count")
- }
-
- if len(oldnew) == 2 && len(oldnew[0]) > 1 {
- return &Replacer{r: makeSingleStringReplacer(oldnew[0], oldnew[1])}
- }
-
- allNewBytes := true
- for i := 0; i < len(oldnew); i += 2 {
- if len(oldnew[i]) != 1 {
- return &Replacer{r: makeGenericReplacer(oldnew)}
- }
- if len(oldnew[i+1]) != 1 {
- allNewBytes = false
- }
- }
-
- if allNewBytes {
- r := byteReplacer{}
- for i := range r {
- r[i] = byte(i)
- }
- // The first occurrence of old->new map takes precedence
- // over the others with the same old string.
- for i := len(oldnew) - 2; i >= 0; i -= 2 {
- o := oldnew[i][0]
- n := oldnew[i+1][0]
- r[o] = n
- }
- return &Replacer{r: &r}
- }
-
- r := byteStringReplacer{}
- // The first occurrence of old->new map takes precedence
- // over the others with the same old string.
- for i := len(oldnew) - 2; i >= 0; i -= 2 {
- o := oldnew[i][0]
- n := oldnew[i+1]
- r[o] = []byte(n)
- }
- return &Replacer{r: &r}
-}
-
-// Replace returns a copy of s with all replacements performed.
-func (r *Replacer) Replace(s string) string {
- return r.r.Replace(s)
-}
-
-// WriteString writes s to w with all replacements performed.
-func (r *Replacer) WriteString(w io.Writer, s string) (n int, err error) {
- return r.r.WriteString(w, s)
-}
-
-// trieNode is a node in a lookup trie for prioritized key/value pairs. Keys
-// and values may be empty. For example, the trie containing keys "ax", "ay",
-// "bcbc", "x" and "xy" could have eight nodes:
-//
-// n0 -
-// n1 a-
-// n2 .x+
-// n3 .y+
-// n4 b-
-// n5 .cbc+
-// n6 x+
-// n7 .y+
-//
-// n0 is the root node, and its children are n1, n4 and n6; n1's children are
-// n2 and n3; n4's child is n5; n6's child is n7. Nodes n0, n1 and n4 (marked
-// with a trailing "-") are partial keys, and nodes n2, n3, n5, n6 and n7
-// (marked with a trailing "+") are complete keys.
-type trieNode struct {
- // value is the value of the trie node's key/value pair. It is empty if
- // this node is not a complete key.
- value string
- // priority is the priority (higher is more important) of the trie node's
- // key/value pair; keys are not necessarily matched shortest- or longest-
- // first. Priority is positive if this node is a complete key, and zero
- // otherwise. In the example above, positive/zero priorities are marked
- // with a trailing "+" or "-".
- priority int
-
- // A trie node may have zero, one or more child nodes:
- // * if the remaining fields are zero, there are no children.
- // * if prefix and next are non-zero, there is one child in next.
- // * if table is non-zero, it defines all the children.
- //
- // Prefixes are preferred over tables when there is one child, but the
- // root node always uses a table for lookup efficiency.
-
- // prefix is the difference in keys between this trie node and the next.
- // In the example above, node n4 has prefix "cbc" and n4's next node is n5.
- // Node n5 has no children and so has zero prefix, next and table fields.
- prefix string
- next *trieNode
-
- // table is a lookup table indexed by the next byte in the key, after
- // remapping that byte through genericReplacer.mapping to create a dense
- // index. In the example above, the keys only use 'a', 'b', 'c', 'x' and
- // 'y', which remap to 0, 1, 2, 3 and 4. All other bytes remap to 5, and
- // genericReplacer.tableSize will be 5. Node n0's table will be
- // []*trieNode{ 0:n1, 1:n4, 3:n6 }, where the 0, 1 and 3 are the remapped
- // 'a', 'b' and 'x'.
- table []*trieNode
-}
-
-func (t *trieNode) add(key, val string, priority int, r *genericReplacer) {
- if key == "" {
- if t.priority == 0 {
- t.value = val
- t.priority = priority
- }
- return
- }
-
- if t.prefix != "" {
- // Need to split the prefix among multiple nodes.
- var n int // length of the longest common prefix
- for ; n < len(t.prefix) && n < len(key); n++ {
- if t.prefix[n] != key[n] {
- break
- }
- }
- if n == len(t.prefix) {
- t.next.add(key[n:], val, priority, r)
- } else if n == 0 {
- // First byte differs, start a new lookup table here. Looking up
- // what is currently t.prefix[0] will lead to prefixNode, and
- // looking up key[0] will lead to keyNode.
- var prefixNode *trieNode
- if len(t.prefix) == 1 {
- prefixNode = t.next
- } else {
- prefixNode = &trieNode{
- prefix: t.prefix[1:],
- next: t.next,
- }
- }
- keyNode := new(trieNode)
- t.table = make([]*trieNode, r.tableSize)
- t.table[r.mapping[t.prefix[0]]] = prefixNode
- t.table[r.mapping[key[0]]] = keyNode
- t.prefix = ""
- t.next = nil
- keyNode.add(key[1:], val, priority, r)
- } else {
- // Insert new node after the common section of the prefix.
- next := &trieNode{
- prefix: t.prefix[n:],
- next: t.next,
- }
- t.prefix = t.prefix[:n]
- t.next = next
- next.add(key[n:], val, priority, r)
- }
- } else if t.table != nil {
- // Insert into existing table.
- m := r.mapping[key[0]]
- if t.table[m] == nil {
- t.table[m] = new(trieNode)
- }
- t.table[m].add(key[1:], val, priority, r)
- } else {
- t.prefix = key
- t.next = new(trieNode)
- t.next.add("", val, priority, r)
- }
-}
-
-func (r *genericReplacer) lookup(s string, ignoreRoot bool) (val string, keylen int, found bool) {
- // Iterate down the trie to the end, and grab the value and keylen with
- // the highest priority.
- bestPriority := 0
- node := &r.root
- n := 0
- for node != nil {
- if node.priority > bestPriority && !(ignoreRoot && node == &r.root) {
- bestPriority = node.priority
- val = node.value
- keylen = n
- found = true
- }
-
- if s == "" {
- break
- }
- if node.table != nil {
- index := r.mapping[s[0]]
- if int(index) == r.tableSize {
- break
- }
- node = node.table[index]
- s = s[1:]
- n++
- } else if node.prefix != "" && HasPrefix(s, node.prefix) {
- n += len(node.prefix)
- s = s[len(node.prefix):]
- node = node.next
- } else {
- break
- }
- }
- return
-}
-
-// genericReplacer is the fully generic algorithm.
-// It's used as a fallback when nothing faster can be used.
-type genericReplacer struct {
- root trieNode
- // tableSize is the size of a trie node's lookup table. It is the number
- // of unique key bytes.
- tableSize int
- // mapping maps from key bytes to a dense index for trieNode.table.
- mapping [256]byte
-}
-
-func makeGenericReplacer(oldnew []string) *genericReplacer {
- r := new(genericReplacer)
- // Find each byte used, then assign them each an index.
- for i := 0; i < len(oldnew); i += 2 {
- key := oldnew[i]
- for j := 0; j < len(key); j++ {
- r.mapping[key[j]] = 1
- }
- }
-
- for _, b := range r.mapping {
- r.tableSize += int(b)
- }
-
- var index byte
- for i, b := range r.mapping {
- if b == 0 {
- r.mapping[i] = byte(r.tableSize)
- } else {
- r.mapping[i] = index
- index++
- }
- }
- // Ensure root node uses a lookup table (for performance).
- r.root.table = make([]*trieNode, r.tableSize)
-
- for i := 0; i < len(oldnew); i += 2 {
- r.root.add(oldnew[i], oldnew[i+1], len(oldnew)-i, r)
- }
- return r
-}
-
-type appendSliceWriter []byte
-
-// Write writes to the buffer to satisfy io.Writer.
-func (w *appendSliceWriter) Write(p []byte) (int, error) {
- *w = append(*w, p...)
- return len(p), nil
-}
-
-// WriteString writes to the buffer without string->[]byte->string allocations.
-func (w *appendSliceWriter) WriteString(s string) (int, error) {
- *w = append(*w, s...)
- return len(s), nil
-}
-
-type stringWriterIface interface {
- WriteString(string) (int, error)
-}
-
-type stringWriter struct {
- w io.Writer
-}
-
-func (w stringWriter) WriteString(s string) (int, error) {
- return w.w.Write([]byte(s))
-}
-
-func getStringWriter(w io.Writer) stringWriterIface {
- sw, ok := w.(stringWriterIface)
- if !ok {
- sw = stringWriter{w}
- }
- return sw
-}
-
-func (r *genericReplacer) Replace(s string) string {
- buf := make(appendSliceWriter, 0, len(s))
- r.WriteString(&buf, s)
- return string(buf)
-}
-
-func (r *genericReplacer) WriteString(w io.Writer, s string) (n int, err error) {
- sw := getStringWriter(w)
- var last, wn int
- var prevMatchEmpty bool
- for i := 0; i <= len(s); {
- // Fast path: s[i] is not a prefix of any pattern.
- if i != len(s) && r.root.priority == 0 {
- index := int(r.mapping[s[i]])
- if index == r.tableSize || r.root.table[index] == nil {
- i++
- continue
- }
- }
-
- // Ignore the empty match iff the previous loop found the empty match.
- val, keylen, match := r.lookup(s[i:], prevMatchEmpty)
- prevMatchEmpty = match && keylen == 0
- if match {
- wn, err = sw.WriteString(s[last:i])
- n += wn
- if err != nil {
- return
- }
- wn, err = sw.WriteString(val)
- n += wn
- if err != nil {
- return
- }
- i += keylen
- last = i
- continue
- }
- i++
- }
- if last != len(s) {
- wn, err = sw.WriteString(s[last:])
- n += wn
- }
- return
-}
-
-// singleStringReplacer is the implementation that's used when there is only
-// one string to replace (and that string has more than one byte).
-type singleStringReplacer struct {
- finder *stringFinder
- // value is the new string that replaces that pattern when it's found.
- value string
-}
-
-func makeSingleStringReplacer(pattern string, value string) *singleStringReplacer {
- return &singleStringReplacer{finder: makeStringFinder(pattern), value: value}
-}
-
-func (r *singleStringReplacer) Replace(s string) string {
- var buf []byte
- i, matched := 0, false
- for {
- match := r.finder.next(s[i:])
- if match == -1 {
- break
- }
- matched = true
- buf = append(buf, s[i:i+match]...)
- buf = append(buf, r.value...)
- i += match + len(r.finder.pattern)
- }
- if !matched {
- return s
- }
- buf = append(buf, s[i:]...)
- return string(buf)
-}
-
-func (r *singleStringReplacer) WriteString(w io.Writer, s string) (n int, err error) {
- sw := getStringWriter(w)
- var i, wn int
- for {
- match := r.finder.next(s[i:])
- if match == -1 {
- break
- }
- wn, err = sw.WriteString(s[i : i+match])
- n += wn
- if err != nil {
- return
- }
- wn, err = sw.WriteString(r.value)
- n += wn
- if err != nil {
- return
- }
- i += match + len(r.finder.pattern)
- }
- wn, err = sw.WriteString(s[i:])
- n += wn
- return
-}
-
-// byteReplacer is the implementation that's used when all the "old"
-// and "new" values are single ASCII bytes.
-// The array contains replacement bytes indexed by old byte.
-type byteReplacer [256]byte
-
-func (r *byteReplacer) Replace(s string) string {
- var buf []byte // lazily allocated
- for i := 0; i < len(s); i++ {
- b := s[i]
- if r[b] != b {
- if buf == nil {
- buf = []byte(s)
- }
- buf[i] = r[b]
- }
- }
- if buf == nil {
- return s
- }
- return string(buf)
-}
-
-func (r *byteReplacer) WriteString(w io.Writer, s string) (n int, err error) {
- // TODO(bradfitz): use io.WriteString with slices of s, avoiding allocation.
- bufsize := 32 << 10
- if len(s) < bufsize {
- bufsize = len(s)
- }
- buf := make([]byte, bufsize)
-
- for len(s) > 0 {
- ncopy := copy(buf, s[:])
- s = s[ncopy:]
- for i, b := range buf[:ncopy] {
- buf[i] = r[b]
- }
- wn, err := w.Write(buf[:ncopy])
- n += wn
- if err != nil {
- return n, err
- }
- }
- return n, nil
-}
-
-// byteStringReplacer is the implementation that's used when all the
-// "old" values are single ASCII bytes but the "new" values vary in size.
-// The array contains replacement byte slices indexed by old byte.
-// A nil []byte means that the old byte should not be replaced.
-type byteStringReplacer [256][]byte
-
-func (r *byteStringReplacer) Replace(s string) string {
- newSize := len(s)
- anyChanges := false
- for i := 0; i < len(s); i++ {
- b := s[i]
- if r[b] != nil {
- anyChanges = true
- // The -1 is because we are replacing 1 byte with len(r[b]) bytes.
- newSize += len(r[b]) - 1
- }
- }
- if !anyChanges {
- return s
- }
- buf := make([]byte, newSize)
- bi := buf
- for i := 0; i < len(s); i++ {
- b := s[i]
- if r[b] != nil {
- n := copy(bi, r[b])
- bi = bi[n:]
- } else {
- bi[0] = b
- bi = bi[1:]
- }
- }
- return string(buf)
-}
-
-func (r *byteStringReplacer) WriteString(w io.Writer, s string) (n int, err error) {
- sw := getStringWriter(w)
- last := 0
- for i := 0; i < len(s); i++ {
- b := s[i]
- if r[b] == nil {
- continue
- }
- if last != i {
- nw, err := sw.WriteString(s[last:i])
- n += nw
- if err != nil {
- return n, err
- }
- }
- last = i + 1
- nw, err := w.Write(r[b])
- n += nw
- if err != nil {
- return n, err
- }
- }
- if last != len(s) {
- var nw int
- nw, err = sw.WriteString(s[last:])
- n += nw
- }
- return
-}
View Lorry Controller Status