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-rw-r--r--lib/diskio/kmp.go147
1 files changed, 0 insertions, 147 deletions
diff --git a/lib/diskio/kmp.go b/lib/diskio/kmp.go
deleted file mode 100644
index 6949aa4..0000000
--- a/lib/diskio/kmp.go
+++ /dev/null
@@ -1,147 +0,0 @@
-// Copyright (C) 2022-2023 Luke Shumaker <lukeshu@lukeshu.com>
-//
-// SPDX-License-Identifier: GPL-2.0-or-later
-
-package diskio
-
-import (
- "errors"
- "io"
-)
-
-var ErrWildcard = errors.New("wildcard")
-
-func kmpEq2[K ~int64, V comparable](aS Sequence[K, V], aI K, bS Sequence[K, V], bI K) bool {
- aV, aErr := aS.Get(aI)
- bV, bErr := bS.Get(bI)
- if aErr != nil {
- //nolint:errorlint // The == is just a fast-path; we still fall back to errors.Is.
- if aErr == ErrWildcard || errors.Is(aErr, ErrWildcard) {
- aV = bV
- aErr = nil
- } else {
- panic(aErr)
- }
- }
- if bErr != nil {
- //nolint:errorlint // The == is just a fast-path; we still fall back to errors.Is.
- if bErr == ErrWildcard || errors.Is(bErr, ErrWildcard) {
- bV = aV
- bErr = nil
- } else {
- panic(bErr)
- }
- }
- if aErr != nil || bErr != nil {
- return false
- }
- return aV == bV
-}
-
-func kmpEq1[K ~int64, V comparable](aV V, bS Sequence[K, V], bI K) bool {
- bV, bErr := bS.Get(bI)
- if bErr != nil {
- //nolint:errorlint // The == is just a fast-path; we still fall back to errors.Is.
- if bErr == ErrWildcard || errors.Is(bErr, ErrWildcard) {
- return true
- }
- panic(bErr)
- }
- return aV == bV
-}
-
-// buildKMPTable takes the string 'substr', and returns a table such
-// that 'table[matchLen-1]' is the largest value 'val' for which 'val < matchLen' and
-// 'substr[:val] == substr[matchLen-val:matchLen]'.
-func buildKMPTable[K ~int64, V comparable](substr Sequence[K, V]) ([]K, error) {
- var substrLen K
- for {
- //nolint:errorlint // The == is just a fast-path; we still fall back to errors.Is.
- if _, err := substr.Get(substrLen); err != nil && !(err == ErrWildcard || errors.Is(err, ErrWildcard)) {
- if errors.Is(err, io.EOF) {
- break
- }
- return nil, err
- }
- substrLen++
- }
-
- table := make([]K, substrLen)
- for j := K(0); j < substrLen; j++ {
- if j == 0 {
- // First entry must always be 0 (in order to
- // satisfy 'val < matchLen').
- continue
- }
- val := table[j-1]
- // not a match; go back
- for val > 0 && !kmpEq2(substr, j, substr, val) {
- val = table[val-1]
- }
- // is a match; go forward
- if kmpEq2(substr, val, substr, j) {
- val++
- }
- table[j] = val
- }
- return table, nil
-}
-
-// IndexAll returns the starting-position of all possibly-overlapping
-// occurrences of 'substr' in the 'str' sequence.
-//
-// Will hop around in 'substr', but will only get the natural sequence
-// [0...) in order from 'str'. When hopping around in 'substr' it
-// assumes that once it has gotten a given index without error, it can
-// continue to do so without error; errors appearing later will cause
-// panics.
-//
-// Will panic if the length of 'substr' is 0.
-//
-// The 'substr' may include wildcard characters by returning
-// ErrWildcard for a position.
-//
-// Uses the Knuth-Morris-Pratt algorithm.
-func IndexAll[K ~int64, V comparable](str, substr Sequence[K, V]) ([]K, error) {
- table, err := buildKMPTable(substr)
- if err != nil {
- return nil, err
- }
- substrLen := K(len(table))
- if substrLen == 0 {
- panic(errors.New("diskio.IndexAll: empty substring"))
- }
-
- var matches []K
- var curMatchBeg K
- var curMatchLen K
-
- for pos := K(0); ; pos++ {
- chr, err := str.Get(pos)
- if err != nil {
- if errors.Is(err, io.EOF) {
- err = nil
- }
- return matches, err
- }
-
- // Consider 'chr'
- for curMatchLen > 0 && !kmpEq1(chr, substr, curMatchLen) { // shorten the match
- overlap := table[curMatchLen-1]
- curMatchBeg += curMatchLen - overlap
- curMatchLen = overlap
- }
- if kmpEq1(chr, substr, curMatchLen) { // lengthen the match
- if curMatchLen == 0 {
- curMatchBeg = pos
- }
- curMatchLen++
- if curMatchLen == substrLen {
- matches = append(matches, curMatchBeg)
- overlap := table[curMatchLen-1]
- curMatchBeg += curMatchLen - overlap
- curMatchLen = overlap
- }
- }
- }
-}