--- /dev/null
+// Copyright 2019 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 fuzzy
+
+import (
+ "unicode"
+)
+
+// RuneRole specifies the role of a rune in the context of an input.
+type RuneRole byte
+
+const (
+ // RNone specifies a rune without any role in the input (i.e., whitespace/non-ASCII).
+ RNone RuneRole = iota
+ // RSep specifies a rune with the role of segment separator.
+ RSep
+ // RTail specifies a rune which is a lower-case tail in a word in the input.
+ RTail
+ // RUCTail specifies a rune which is an upper-case tail in a word in the input.
+ RUCTail
+ // RHead specifies a rune which is the first character in a word in the input.
+ RHead
+)
+
+// RuneRoles detects the roles of each byte rune in an input string and stores it in the output
+// slice. The rune role depends on the input type. Stops when it parsed all the runes in the string
+// or when it filled the output. If output is nil, then it gets created.
+func RuneRoles(str string, reuse []RuneRole) []RuneRole {
+ var output []RuneRole
+ if cap(reuse) < len(str) {
+ output = make([]RuneRole, 0, len(str))
+ } else {
+ output = reuse[:0]
+ }
+
+ prev, prev2 := rtNone, rtNone
+ for i := 0; i < len(str); i++ {
+ r := rune(str[i])
+
+ role := RNone
+
+ curr := rtLower
+ if str[i] <= unicode.MaxASCII {
+ curr = runeType(rt[str[i]] - '0')
+ }
+
+ if curr == rtLower {
+ if prev == rtNone || prev == rtPunct {
+ role = RHead
+ } else {
+ role = RTail
+ }
+ } else if curr == rtUpper {
+ role = RHead
+
+ if prev == rtUpper {
+ // This and previous characters are both upper case.
+
+ if i+1 == len(str) {
+ // This is last character, previous was also uppercase -> this is UCTail
+ // i.e., (current char is C): aBC / BC / ABC
+ role = RUCTail
+ }
+ }
+ } else if curr == rtPunct {
+ switch r {
+ case '.', ':':
+ role = RSep
+ }
+ }
+ if curr != rtLower {
+ if i > 1 && output[i-1] == RHead && prev2 == rtUpper && (output[i-2] == RHead || output[i-2] == RUCTail) {
+ // The previous two characters were uppercase. The current one is not a lower case, so the
+ // previous one can't be a HEAD. Make it a UCTail.
+ // i.e., (last char is current char - B must be a UCTail): ABC / ZABC / AB.
+ output[i-1] = RUCTail
+ }
+ }
+
+ output = append(output, role)
+ prev2 = prev
+ prev = curr
+ }
+ return output
+}
+
+type runeType byte
+
+const (
+ rtNone runeType = iota
+ rtPunct
+ rtLower
+ rtUpper
+)
+
+const rt = "00000000000000000000000000000000000000000000001122222222221000000333333333333333333333333330000002222222222222222222222222200000"
+
+// LastSegment returns the substring representing the last segment from the input, where each
+// byte has an associated RuneRole in the roles slice. This makes sense only for inputs of Symbol
+// or Filename type.
+func LastSegment(input string, roles []RuneRole) string {
+ // Exclude ending separators.
+ end := len(input) - 1
+ for end >= 0 && roles[end] == RSep {
+ end--
+ }
+ if end < 0 {
+ return ""
+ }
+
+ start := end - 1
+ for start >= 0 && roles[start] != RSep {
+ start--
+ }
+
+ return input[start+1 : end+1]
+}
+
+// ToLower transforms the input string to lower case, which is stored in the output byte slice.
+// The lower casing considers only ASCII values - non ASCII values are left unmodified.
+// Stops when parsed all input or when it filled the output slice. If output is nil, then it gets
+// created.
+func ToLower(input string, reuse []byte) []byte {
+ output := reuse
+ if cap(reuse) < len(input) {
+ output = make([]byte, len(input))
+ }
+
+ for i := 0; i < len(input); i++ {
+ r := rune(input[i])
+ if r <= unicode.MaxASCII {
+ if 'A' <= r && r <= 'Z' {
+ r += 'a' - 'A'
+ }
+ }
+ output[i] = byte(r)
+ }
+ return output[:len(input)]
+}
+
+// WordConsumer defines a consumer for a word delimited by the [start,end) byte offsets in an input
+// (start is inclusive, end is exclusive).
+type WordConsumer func(start, end int)
+
+// Words find word delimiters in an input based on its bytes' mappings to rune roles. The offset
+// delimiters for each word are fed to the provided consumer function.
+func Words(roles []RuneRole, consume WordConsumer) {
+ var wordStart int
+ for i, r := range roles {
+ switch r {
+ case RUCTail, RTail:
+ case RHead, RNone, RSep:
+ if i != wordStart {
+ consume(wordStart, i)
+ }
+ wordStart = i
+ if r != RHead {
+ // Skip this character.
+ wordStart = i + 1
+ }
+ }
+ }
+ if wordStart != len(roles) {
+ consume(wordStart, len(roles))
+ }
+}
projects / dotfiles / .git / blobdiff