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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-16 19:23:18 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-16 19:23:18 +0000
commit43a123c1ae6613b3efeed291fa552ecd909d3acf (patch)
treefd92518b7024bc74031f78a1cf9e454b65e73665 /src/index/suffixarray/sais2.go
parentInitial commit. (diff)
downloadgolang-1.20-43a123c1ae6613b3efeed291fa552ecd909d3acf.tar.xz
golang-1.20-43a123c1ae6613b3efeed291fa552ecd909d3acf.zip
Adding upstream version 1.20.14.upstream/1.20.14upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/index/suffixarray/sais2.go')
-rw-r--r--src/index/suffixarray/sais2.go1741
1 files changed, 1741 insertions, 0 deletions
diff --git a/src/index/suffixarray/sais2.go b/src/index/suffixarray/sais2.go
new file mode 100644
index 0000000..32b8972
--- /dev/null
+++ b/src/index/suffixarray/sais2.go
@@ -0,0 +1,1741 @@
+// 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.
+
+// Code generated by go generate; DO NOT EDIT.
+
+package suffixarray
+
+func text_64(text []byte, sa []int64) {
+ if int(int64(len(text))) != len(text) || len(text) != len(sa) {
+ panic("suffixarray: misuse of text_64")
+ }
+ sais_8_64(text, 256, sa, make([]int64, 2*256))
+}
+
+func sais_8_64(text []byte, textMax int, sa, tmp []int64) {
+ if len(sa) != len(text) || len(tmp) < int(textMax) {
+ panic("suffixarray: misuse of sais_8_64")
+ }
+
+ // Trivial base cases. Sorting 0 or 1 things is easy.
+ if len(text) == 0 {
+ return
+ }
+ if len(text) == 1 {
+ sa[0] = 0
+ return
+ }
+
+ // Establish slices indexed by text character
+ // holding character frequency and bucket-sort offsets.
+ // If there's only enough tmp for one slice,
+ // we make it the bucket offsets and recompute
+ // the character frequency each time we need it.
+ var freq, bucket []int64
+ if len(tmp) >= 2*textMax {
+ freq, bucket = tmp[:textMax], tmp[textMax:2*textMax]
+ freq[0] = -1 // mark as uninitialized
+ } else {
+ freq, bucket = nil, tmp[:textMax]
+ }
+
+ // The SAIS algorithm.
+ // Each of these calls makes one scan through sa.
+ // See the individual functions for documentation
+ // about each's role in the algorithm.
+ numLMS := placeLMS_8_64(text, sa, freq, bucket)
+ if numLMS <= 1 {
+ // 0 or 1 items are already sorted. Do nothing.
+ } else {
+ induceSubL_8_64(text, sa, freq, bucket)
+ induceSubS_8_64(text, sa, freq, bucket)
+ length_8_64(text, sa, numLMS)
+ maxID := assignID_8_64(text, sa, numLMS)
+ if maxID < numLMS {
+ map_64(sa, numLMS)
+ recurse_64(sa, tmp, numLMS, maxID)
+ unmap_8_64(text, sa, numLMS)
+ } else {
+ // If maxID == numLMS, then each LMS-substring
+ // is unique, so the relative ordering of two LMS-suffixes
+ // is determined by just the leading LMS-substring.
+ // That is, the LMS-suffix sort order matches the
+ // (simpler) LMS-substring sort order.
+ // Copy the original LMS-substring order into the
+ // suffix array destination.
+ copy(sa, sa[len(sa)-numLMS:])
+ }
+ expand_8_64(text, freq, bucket, sa, numLMS)
+ }
+ induceL_8_64(text, sa, freq, bucket)
+ induceS_8_64(text, sa, freq, bucket)
+
+ // Mark for caller that we overwrote tmp.
+ tmp[0] = -1
+}
+
+func sais_32(text []int32, textMax int, sa, tmp []int32) {
+ if len(sa) != len(text) || len(tmp) < int(textMax) {
+ panic("suffixarray: misuse of sais_32")
+ }
+
+ // Trivial base cases. Sorting 0 or 1 things is easy.
+ if len(text) == 0 {
+ return
+ }
+ if len(text) == 1 {
+ sa[0] = 0
+ return
+ }
+
+ // Establish slices indexed by text character
+ // holding character frequency and bucket-sort offsets.
+ // If there's only enough tmp for one slice,
+ // we make it the bucket offsets and recompute
+ // the character frequency each time we need it.
+ var freq, bucket []int32
+ if len(tmp) >= 2*textMax {
+ freq, bucket = tmp[:textMax], tmp[textMax:2*textMax]
+ freq[0] = -1 // mark as uninitialized
+ } else {
+ freq, bucket = nil, tmp[:textMax]
+ }
+
+ // The SAIS algorithm.
+ // Each of these calls makes one scan through sa.
+ // See the individual functions for documentation
+ // about each's role in the algorithm.
+ numLMS := placeLMS_32(text, sa, freq, bucket)
+ if numLMS <= 1 {
+ // 0 or 1 items are already sorted. Do nothing.
+ } else {
+ induceSubL_32(text, sa, freq, bucket)
+ induceSubS_32(text, sa, freq, bucket)
+ length_32(text, sa, numLMS)
+ maxID := assignID_32(text, sa, numLMS)
+ if maxID < numLMS {
+ map_32(sa, numLMS)
+ recurse_32(sa, tmp, numLMS, maxID)
+ unmap_32(text, sa, numLMS)
+ } else {
+ // If maxID == numLMS, then each LMS-substring
+ // is unique, so the relative ordering of two LMS-suffixes
+ // is determined by just the leading LMS-substring.
+ // That is, the LMS-suffix sort order matches the
+ // (simpler) LMS-substring sort order.
+ // Copy the original LMS-substring order into the
+ // suffix array destination.
+ copy(sa, sa[len(sa)-numLMS:])
+ }
+ expand_32(text, freq, bucket, sa, numLMS)
+ }
+ induceL_32(text, sa, freq, bucket)
+ induceS_32(text, sa, freq, bucket)
+
+ // Mark for caller that we overwrote tmp.
+ tmp[0] = -1
+}
+
+func sais_64(text []int64, textMax int, sa, tmp []int64) {
+ if len(sa) != len(text) || len(tmp) < int(textMax) {
+ panic("suffixarray: misuse of sais_64")
+ }
+
+ // Trivial base cases. Sorting 0 or 1 things is easy.
+ if len(text) == 0 {
+ return
+ }
+ if len(text) == 1 {
+ sa[0] = 0
+ return
+ }
+
+ // Establish slices indexed by text character
+ // holding character frequency and bucket-sort offsets.
+ // If there's only enough tmp for one slice,
+ // we make it the bucket offsets and recompute
+ // the character frequency each time we need it.
+ var freq, bucket []int64
+ if len(tmp) >= 2*textMax {
+ freq, bucket = tmp[:textMax], tmp[textMax:2*textMax]
+ freq[0] = -1 // mark as uninitialized
+ } else {
+ freq, bucket = nil, tmp[:textMax]
+ }
+
+ // The SAIS algorithm.
+ // Each of these calls makes one scan through sa.
+ // See the individual functions for documentation
+ // about each's role in the algorithm.
+ numLMS := placeLMS_64(text, sa, freq, bucket)
+ if numLMS <= 1 {
+ // 0 or 1 items are already sorted. Do nothing.
+ } else {
+ induceSubL_64(text, sa, freq, bucket)
+ induceSubS_64(text, sa, freq, bucket)
+ length_64(text, sa, numLMS)
+ maxID := assignID_64(text, sa, numLMS)
+ if maxID < numLMS {
+ map_64(sa, numLMS)
+ recurse_64(sa, tmp, numLMS, maxID)
+ unmap_64(text, sa, numLMS)
+ } else {
+ // If maxID == numLMS, then each LMS-substring
+ // is unique, so the relative ordering of two LMS-suffixes
+ // is determined by just the leading LMS-substring.
+ // That is, the LMS-suffix sort order matches the
+ // (simpler) LMS-substring sort order.
+ // Copy the original LMS-substring order into the
+ // suffix array destination.
+ copy(sa, sa[len(sa)-numLMS:])
+ }
+ expand_64(text, freq, bucket, sa, numLMS)
+ }
+ induceL_64(text, sa, freq, bucket)
+ induceS_64(text, sa, freq, bucket)
+
+ // Mark for caller that we overwrote tmp.
+ tmp[0] = -1
+}
+
+func freq_8_64(text []byte, freq, bucket []int64) []int64 {
+ if freq != nil && freq[0] >= 0 {
+ return freq // already computed
+ }
+ if freq == nil {
+ freq = bucket
+ }
+
+ freq = freq[:256] // eliminate bounds check for freq[c] below
+ for i := range freq {
+ freq[i] = 0
+ }
+ for _, c := range text {
+ freq[c]++
+ }
+ return freq
+}
+
+func freq_32(text []int32, freq, bucket []int32) []int32 {
+ if freq != nil && freq[0] >= 0 {
+ return freq // already computed
+ }
+ if freq == nil {
+ freq = bucket
+ }
+
+ for i := range freq {
+ freq[i] = 0
+ }
+ for _, c := range text {
+ freq[c]++
+ }
+ return freq
+}
+
+func freq_64(text []int64, freq, bucket []int64) []int64 {
+ if freq != nil && freq[0] >= 0 {
+ return freq // already computed
+ }
+ if freq == nil {
+ freq = bucket
+ }
+
+ for i := range freq {
+ freq[i] = 0
+ }
+ for _, c := range text {
+ freq[c]++
+ }
+ return freq
+}
+
+func bucketMin_8_64(text []byte, freq, bucket []int64) {
+ freq = freq_8_64(text, freq, bucket)
+ freq = freq[:256] // establish len(freq) = 256, so 0 ≤ i < 256 below
+ bucket = bucket[:256] // eliminate bounds check for bucket[i] below
+ total := int64(0)
+ for i, n := range freq {
+ bucket[i] = total
+ total += n
+ }
+}
+
+func bucketMin_32(text []int32, freq, bucket []int32) {
+ freq = freq_32(text, freq, bucket)
+ total := int32(0)
+ for i, n := range freq {
+ bucket[i] = total
+ total += n
+ }
+}
+
+func bucketMin_64(text []int64, freq, bucket []int64) {
+ freq = freq_64(text, freq, bucket)
+ total := int64(0)
+ for i, n := range freq {
+ bucket[i] = total
+ total += n
+ }
+}
+
+func bucketMax_8_64(text []byte, freq, bucket []int64) {
+ freq = freq_8_64(text, freq, bucket)
+ freq = freq[:256] // establish len(freq) = 256, so 0 ≤ i < 256 below
+ bucket = bucket[:256] // eliminate bounds check for bucket[i] below
+ total := int64(0)
+ for i, n := range freq {
+ total += n
+ bucket[i] = total
+ }
+}
+
+func bucketMax_32(text []int32, freq, bucket []int32) {
+ freq = freq_32(text, freq, bucket)
+ total := int32(0)
+ for i, n := range freq {
+ total += n
+ bucket[i] = total
+ }
+}
+
+func bucketMax_64(text []int64, freq, bucket []int64) {
+ freq = freq_64(text, freq, bucket)
+ total := int64(0)
+ for i, n := range freq {
+ total += n
+ bucket[i] = total
+ }
+}
+
+func placeLMS_8_64(text []byte, sa, freq, bucket []int64) int {
+ bucketMax_8_64(text, freq, bucket)
+
+ numLMS := 0
+ lastB := int64(-1)
+ bucket = bucket[:256] // eliminate bounds check for bucket[c1] below
+
+ // The next stanza of code (until the blank line) loop backward
+ // over text, stopping to execute a code body at each position i
+ // such that text[i] is an L-character and text[i+1] is an S-character.
+ // That is, i+1 is the position of the start of an LMS-substring.
+ // These could be hoisted out into a function with a callback,
+ // but at a significant speed cost. Instead, we just write these
+ // seven lines a few times in this source file. The copies below
+ // refer back to the pattern established by this original as the
+ // "LMS-substring iterator".
+ //
+ // In every scan through the text, c0, c1 are successive characters of text.
+ // In this backward scan, c0 == text[i] and c1 == text[i+1].
+ // By scanning backward, we can keep track of whether the current
+ // position is type-S or type-L according to the usual definition:
+ //
+ // - position len(text) is type S with text[len(text)] == -1 (the sentinel)
+ // - position i is type S if text[i] < text[i+1], or if text[i] == text[i+1] && i+1 is type S.
+ // - position i is type L if text[i] > text[i+1], or if text[i] == text[i+1] && i+1 is type L.
+ //
+ // The backward scan lets us maintain the current type,
+ // update it when we see c0 != c1, and otherwise leave it alone.
+ // We want to identify all S positions with a preceding L.
+ // Position len(text) is one such position by definition, but we have
+ // nowhere to write it down, so we eliminate it by untruthfully
+ // setting isTypeS = false at the start of the loop.
+ c0, c1, isTypeS := byte(0), byte(0), false
+ for i := len(text) - 1; i >= 0; i-- {
+ c0, c1 = text[i], c0
+ if c0 < c1 {
+ isTypeS = true
+ } else if c0 > c1 && isTypeS {
+ isTypeS = false
+
+ // Bucket the index i+1 for the start of an LMS-substring.
+ b := bucket[c1] - 1
+ bucket[c1] = b
+ sa[b] = int64(i + 1)
+ lastB = b
+ numLMS++
+ }
+ }
+
+ // We recorded the LMS-substring starts but really want the ends.
+ // Luckily, with two differences, the start indexes and the end indexes are the same.
+ // The first difference is that the rightmost LMS-substring's end index is len(text),
+ // so the caller must pretend that sa[-1] == len(text), as noted above.
+ // The second difference is that the first leftmost LMS-substring start index
+ // does not end an earlier LMS-substring, so as an optimization we can omit
+ // that leftmost LMS-substring start index (the last one we wrote).
+ //
+ // Exception: if numLMS <= 1, the caller is not going to bother with
+ // the recursion at all and will treat the result as containing LMS-substring starts.
+ // In that case, we don't remove the final entry.
+ if numLMS > 1 {
+ sa[lastB] = 0
+ }
+ return numLMS
+}
+
+func placeLMS_32(text []int32, sa, freq, bucket []int32) int {
+ bucketMax_32(text, freq, bucket)
+
+ numLMS := 0
+ lastB := int32(-1)
+
+ // The next stanza of code (until the blank line) loop backward
+ // over text, stopping to execute a code body at each position i
+ // such that text[i] is an L-character and text[i+1] is an S-character.
+ // That is, i+1 is the position of the start of an LMS-substring.
+ // These could be hoisted out into a function with a callback,
+ // but at a significant speed cost. Instead, we just write these
+ // seven lines a few times in this source file. The copies below
+ // refer back to the pattern established by this original as the
+ // "LMS-substring iterator".
+ //
+ // In every scan through the text, c0, c1 are successive characters of text.
+ // In this backward scan, c0 == text[i] and c1 == text[i+1].
+ // By scanning backward, we can keep track of whether the current
+ // position is type-S or type-L according to the usual definition:
+ //
+ // - position len(text) is type S with text[len(text)] == -1 (the sentinel)
+ // - position i is type S if text[i] < text[i+1], or if text[i] == text[i+1] && i+1 is type S.
+ // - position i is type L if text[i] > text[i+1], or if text[i] == text[i+1] && i+1 is type L.
+ //
+ // The backward scan lets us maintain the current type,
+ // update it when we see c0 != c1, and otherwise leave it alone.
+ // We want to identify all S positions with a preceding L.
+ // Position len(text) is one such position by definition, but we have
+ // nowhere to write it down, so we eliminate it by untruthfully
+ // setting isTypeS = false at the start of the loop.
+ c0, c1, isTypeS := int32(0), int32(0), false
+ for i := len(text) - 1; i >= 0; i-- {
+ c0, c1 = text[i], c0
+ if c0 < c1 {
+ isTypeS = true
+ } else if c0 > c1 && isTypeS {
+ isTypeS = false
+
+ // Bucket the index i+1 for the start of an LMS-substring.
+ b := bucket[c1] - 1
+ bucket[c1] = b
+ sa[b] = int32(i + 1)
+ lastB = b
+ numLMS++
+ }
+ }
+
+ // We recorded the LMS-substring starts but really want the ends.
+ // Luckily, with two differences, the start indexes and the end indexes are the same.
+ // The first difference is that the rightmost LMS-substring's end index is len(text),
+ // so the caller must pretend that sa[-1] == len(text), as noted above.
+ // The second difference is that the first leftmost LMS-substring start index
+ // does not end an earlier LMS-substring, so as an optimization we can omit
+ // that leftmost LMS-substring start index (the last one we wrote).
+ //
+ // Exception: if numLMS <= 1, the caller is not going to bother with
+ // the recursion at all and will treat the result as containing LMS-substring starts.
+ // In that case, we don't remove the final entry.
+ if numLMS > 1 {
+ sa[lastB] = 0
+ }
+ return numLMS
+}
+
+func placeLMS_64(text []int64, sa, freq, bucket []int64) int {
+ bucketMax_64(text, freq, bucket)
+
+ numLMS := 0
+ lastB := int64(-1)
+
+ // The next stanza of code (until the blank line) loop backward
+ // over text, stopping to execute a code body at each position i
+ // such that text[i] is an L-character and text[i+1] is an S-character.
+ // That is, i+1 is the position of the start of an LMS-substring.
+ // These could be hoisted out into a function with a callback,
+ // but at a significant speed cost. Instead, we just write these
+ // seven lines a few times in this source file. The copies below
+ // refer back to the pattern established by this original as the
+ // "LMS-substring iterator".
+ //
+ // In every scan through the text, c0, c1 are successive characters of text.
+ // In this backward scan, c0 == text[i] and c1 == text[i+1].
+ // By scanning backward, we can keep track of whether the current
+ // position is type-S or type-L according to the usual definition:
+ //
+ // - position len(text) is type S with text[len(text)] == -1 (the sentinel)
+ // - position i is type S if text[i] < text[i+1], or if text[i] == text[i+1] && i+1 is type S.
+ // - position i is type L if text[i] > text[i+1], or if text[i] == text[i+1] && i+1 is type L.
+ //
+ // The backward scan lets us maintain the current type,
+ // update it when we see c0 != c1, and otherwise leave it alone.
+ // We want to identify all S positions with a preceding L.
+ // Position len(text) is one such position by definition, but we have
+ // nowhere to write it down, so we eliminate it by untruthfully
+ // setting isTypeS = false at the start of the loop.
+ c0, c1, isTypeS := int64(0), int64(0), false
+ for i := len(text) - 1; i >= 0; i-- {
+ c0, c1 = text[i], c0
+ if c0 < c1 {
+ isTypeS = true
+ } else if c0 > c1 && isTypeS {
+ isTypeS = false
+
+ // Bucket the index i+1 for the start of an LMS-substring.
+ b := bucket[c1] - 1
+ bucket[c1] = b
+ sa[b] = int64(i + 1)
+ lastB = b
+ numLMS++
+ }
+ }
+
+ // We recorded the LMS-substring starts but really want the ends.
+ // Luckily, with two differences, the start indexes and the end indexes are the same.
+ // The first difference is that the rightmost LMS-substring's end index is len(text),
+ // so the caller must pretend that sa[-1] == len(text), as noted above.
+ // The second difference is that the first leftmost LMS-substring start index
+ // does not end an earlier LMS-substring, so as an optimization we can omit
+ // that leftmost LMS-substring start index (the last one we wrote).
+ //
+ // Exception: if numLMS <= 1, the caller is not going to bother with
+ // the recursion at all and will treat the result as containing LMS-substring starts.
+ // In that case, we don't remove the final entry.
+ if numLMS > 1 {
+ sa[lastB] = 0
+ }
+ return numLMS
+}
+
+func induceSubL_8_64(text []byte, sa, freq, bucket []int64) {
+ // Initialize positions for left side of character buckets.
+ bucketMin_8_64(text, freq, bucket)
+ bucket = bucket[:256] // eliminate bounds check for bucket[cB] below
+
+ // As we scan the array left-to-right, each sa[i] = j > 0 is a correctly
+ // sorted suffix array entry (for text[j:]) for which we know that j-1 is type L.
+ // Because j-1 is type L, inserting it into sa now will sort it correctly.
+ // But we want to distinguish a j-1 with j-2 of type L from type S.
+ // We can process the former but want to leave the latter for the caller.
+ // We record the difference by negating j-1 if it is preceded by type S.
+ // Either way, the insertion (into the text[j-1] bucket) is guaranteed to
+ // happen at sa[i´] for some i´ > i, that is, in the portion of sa we have
+ // yet to scan. A single pass therefore sees indexes j, j-1, j-2, j-3,
+ // and so on, in sorted but not necessarily adjacent order, until it finds
+ // one preceded by an index of type S, at which point it must stop.
+ //
+ // As we scan through the array, we clear the worked entries (sa[i] > 0) to zero,
+ // and we flip sa[i] < 0 to -sa[i], so that the loop finishes with sa containing
+ // only the indexes of the leftmost L-type indexes for each LMS-substring.
+ //
+ // The suffix array sa therefore serves simultaneously as input, output,
+ // and a miraculously well-tailored work queue.
+
+ // placeLMS_8_64 left out the implicit entry sa[-1] == len(text),
+ // corresponding to the identified type-L index len(text)-1.
+ // Process it before the left-to-right scan of sa proper.
+ // See body in loop for commentary.
+ k := len(text) - 1
+ c0, c1 := text[k-1], text[k]
+ if c0 < c1 {
+ k = -k
+ }
+
+ // Cache recently used bucket index:
+ // we're processing suffixes in sorted order
+ // and accessing buckets indexed by the
+ // byte before the sorted order, which still
+ // has very good locality.
+ // Invariant: b is cached, possibly dirty copy of bucket[cB].
+ cB := c1
+ b := bucket[cB]
+ sa[b] = int64(k)
+ b++
+
+ for i := 0; i < len(sa); i++ {
+ j := int(sa[i])
+ if j == 0 {
+ // Skip empty entry.
+ continue
+ }
+ if j < 0 {
+ // Leave discovered type-S index for caller.
+ sa[i] = int64(-j)
+ continue
+ }
+ sa[i] = 0
+
+ // Index j was on work queue, meaning k := j-1 is L-type,
+ // so we can now place k correctly into sa.
+ // If k-1 is L-type, queue k for processing later in this loop.
+ // If k-1 is S-type (text[k-1] < text[k]), queue -k to save for the caller.
+ k := j - 1
+ c0, c1 := text[k-1], text[k]
+ if c0 < c1 {
+ k = -k
+ }
+
+ if cB != c1 {
+ bucket[cB] = b
+ cB = c1
+ b = bucket[cB]
+ }
+ sa[b] = int64(k)
+ b++
+ }
+}
+
+func induceSubL_32(text []int32, sa, freq, bucket []int32) {
+ // Initialize positions for left side of character buckets.
+ bucketMin_32(text, freq, bucket)
+
+ // As we scan the array left-to-right, each sa[i] = j > 0 is a correctly
+ // sorted suffix array entry (for text[j:]) for which we know that j-1 is type L.
+ // Because j-1 is type L, inserting it into sa now will sort it correctly.
+ // But we want to distinguish a j-1 with j-2 of type L from type S.
+ // We can process the former but want to leave the latter for the caller.
+ // We record the difference by negating j-1 if it is preceded by type S.
+ // Either way, the insertion (into the text[j-1] bucket) is guaranteed to
+ // happen at sa[i´] for some i´ > i, that is, in the portion of sa we have
+ // yet to scan. A single pass therefore sees indexes j, j-1, j-2, j-3,
+ // and so on, in sorted but not necessarily adjacent order, until it finds
+ // one preceded by an index of type S, at which point it must stop.
+ //
+ // As we scan through the array, we clear the worked entries (sa[i] > 0) to zero,
+ // and we flip sa[i] < 0 to -sa[i], so that the loop finishes with sa containing
+ // only the indexes of the leftmost L-type indexes for each LMS-substring.
+ //
+ // The suffix array sa therefore serves simultaneously as input, output,
+ // and a miraculously well-tailored work queue.
+
+ // placeLMS_32 left out the implicit entry sa[-1] == len(text),
+ // corresponding to the identified type-L index len(text)-1.
+ // Process it before the left-to-right scan of sa proper.
+ // See body in loop for commentary.
+ k := len(text) - 1
+ c0, c1 := text[k-1], text[k]
+ if c0 < c1 {
+ k = -k
+ }
+
+ // Cache recently used bucket index:
+ // we're processing suffixes in sorted order
+ // and accessing buckets indexed by the
+ // int32 before the sorted order, which still
+ // has very good locality.
+ // Invariant: b is cached, possibly dirty copy of bucket[cB].
+ cB := c1
+ b := bucket[cB]
+ sa[b] = int32(k)
+ b++
+
+ for i := 0; i < len(sa); i++ {
+ j := int(sa[i])
+ if j == 0 {
+ // Skip empty entry.
+ continue
+ }
+ if j < 0 {
+ // Leave discovered type-S index for caller.
+ sa[i] = int32(-j)
+ continue
+ }
+ sa[i] = 0
+
+ // Index j was on work queue, meaning k := j-1 is L-type,
+ // so we can now place k correctly into sa.
+ // If k-1 is L-type, queue k for processing later in this loop.
+ // If k-1 is S-type (text[k-1] < text[k]), queue -k to save for the caller.
+ k := j - 1
+ c0, c1 := text[k-1], text[k]
+ if c0 < c1 {
+ k = -k
+ }
+
+ if cB != c1 {
+ bucket[cB] = b
+ cB = c1
+ b = bucket[cB]
+ }
+ sa[b] = int32(k)
+ b++
+ }
+}
+
+func induceSubL_64(text []int64, sa, freq, bucket []int64) {
+ // Initialize positions for left side of character buckets.
+ bucketMin_64(text, freq, bucket)
+
+ // As we scan the array left-to-right, each sa[i] = j > 0 is a correctly
+ // sorted suffix array entry (for text[j:]) for which we know that j-1 is type L.
+ // Because j-1 is type L, inserting it into sa now will sort it correctly.
+ // But we want to distinguish a j-1 with j-2 of type L from type S.
+ // We can process the former but want to leave the latter for the caller.
+ // We record the difference by negating j-1 if it is preceded by type S.
+ // Either way, the insertion (into the text[j-1] bucket) is guaranteed to
+ // happen at sa[i´] for some i´ > i, that is, in the portion of sa we have
+ // yet to scan. A single pass therefore sees indexes j, j-1, j-2, j-3,
+ // and so on, in sorted but not necessarily adjacent order, until it finds
+ // one preceded by an index of type S, at which point it must stop.
+ //
+ // As we scan through the array, we clear the worked entries (sa[i] > 0) to zero,
+ // and we flip sa[i] < 0 to -sa[i], so that the loop finishes with sa containing
+ // only the indexes of the leftmost L-type indexes for each LMS-substring.
+ //
+ // The suffix array sa therefore serves simultaneously as input, output,
+ // and a miraculously well-tailored work queue.
+
+ // placeLMS_64 left out the implicit entry sa[-1] == len(text),
+ // corresponding to the identified type-L index len(text)-1.
+ // Process it before the left-to-right scan of sa proper.
+ // See body in loop for commentary.
+ k := len(text) - 1
+ c0, c1 := text[k-1], text[k]
+ if c0 < c1 {
+ k = -k
+ }
+
+ // Cache recently used bucket index:
+ // we're processing suffixes in sorted order
+ // and accessing buckets indexed by the
+ // int64 before the sorted order, which still
+ // has very good locality.
+ // Invariant: b is cached, possibly dirty copy of bucket[cB].
+ cB := c1
+ b := bucket[cB]
+ sa[b] = int64(k)
+ b++
+
+ for i := 0; i < len(sa); i++ {
+ j := int(sa[i])
+ if j == 0 {
+ // Skip empty entry.
+ continue
+ }
+ if j < 0 {
+ // Leave discovered type-S index for caller.
+ sa[i] = int64(-j)
+ continue
+ }
+ sa[i] = 0
+
+ // Index j was on work queue, meaning k := j-1 is L-type,
+ // so we can now place k correctly into sa.
+ // If k-1 is L-type, queue k for processing later in this loop.
+ // If k-1 is S-type (text[k-1] < text[k]), queue -k to save for the caller.
+ k := j - 1
+ c0, c1 := text[k-1], text[k]
+ if c0 < c1 {
+ k = -k
+ }
+
+ if cB != c1 {
+ bucket[cB] = b
+ cB = c1
+ b = bucket[cB]
+ }
+ sa[b] = int64(k)
+ b++
+ }
+}
+
+func induceSubS_8_64(text []byte, sa, freq, bucket []int64) {
+ // Initialize positions for right side of character buckets.
+ bucketMax_8_64(text, freq, bucket)
+ bucket = bucket[:256] // eliminate bounds check for bucket[cB] below
+
+ // Analogous to induceSubL_8_64 above,
+ // as we scan the array right-to-left, each sa[i] = j > 0 is a correctly
+ // sorted suffix array entry (for text[j:]) for which we know that j-1 is type S.
+ // Because j-1 is type S, inserting it into sa now will sort it correctly.
+ // But we want to distinguish a j-1 with j-2 of type S from type L.
+ // We can process the former but want to leave the latter for the caller.
+ // We record the difference by negating j-1 if it is preceded by type L.
+ // Either way, the insertion (into the text[j-1] bucket) is guaranteed to
+ // happen at sa[i´] for some i´ < i, that is, in the portion of sa we have
+ // yet to scan. A single pass therefore sees indexes j, j-1, j-2, j-3,
+ // and so on, in sorted but not necessarily adjacent order, until it finds
+ // one preceded by an index of type L, at which point it must stop.
+ // That index (preceded by one of type L) is an LMS-substring start.
+ //
+ // As we scan through the array, we clear the worked entries (sa[i] > 0) to zero,
+ // and we flip sa[i] < 0 to -sa[i] and compact into the top of sa,
+ // so that the loop finishes with the top of sa containing exactly
+ // the LMS-substring start indexes, sorted by LMS-substring.
+
+ // Cache recently used bucket index:
+ cB := byte(0)
+ b := bucket[cB]
+
+ top := len(sa)
+ for i := len(sa) - 1; i >= 0; i-- {
+ j := int(sa[i])
+ if j == 0 {
+ // Skip empty entry.
+ continue
+ }
+ sa[i] = 0
+ if j < 0 {
+ // Leave discovered LMS-substring start index for caller.
+ top--
+ sa[top] = int64(-j)
+ continue
+ }
+
+ // Index j was on work queue, meaning k := j-1 is S-type,
+ // so we can now place k correctly into sa.
+ // If k-1 is S-type, queue k for processing later in this loop.
+ // If k-1 is L-type (text[k-1] > text[k]), queue -k to save for the caller.
+ k := j - 1
+ c1 := text[k]
+ c0 := text[k-1]
+ if c0 > c1 {
+ k = -k
+ }
+
+ if cB != c1 {
+ bucket[cB] = b
+ cB = c1
+ b = bucket[cB]
+ }
+ b--
+ sa[b] = int64(k)
+ }
+}
+
+func induceSubS_32(text []int32, sa, freq, bucket []int32) {
+ // Initialize positions for right side of character buckets.
+ bucketMax_32(text, freq, bucket)
+
+ // Analogous to induceSubL_32 above,
+ // as we scan the array right-to-left, each sa[i] = j > 0 is a correctly
+ // sorted suffix array entry (for text[j:]) for which we know that j-1 is type S.
+ // Because j-1 is type S, inserting it into sa now will sort it correctly.
+ // But we want to distinguish a j-1 with j-2 of type S from type L.
+ // We can process the former but want to leave the latter for the caller.
+ // We record the difference by negating j-1 if it is preceded by type L.
+ // Either way, the insertion (into the text[j-1] bucket) is guaranteed to
+ // happen at sa[i´] for some i´ < i, that is, in the portion of sa we have
+ // yet to scan. A single pass therefore sees indexes j, j-1, j-2, j-3,
+ // and so on, in sorted but not necessarily adjacent order, until it finds
+ // one preceded by an index of type L, at which point it must stop.
+ // That index (preceded by one of type L) is an LMS-substring start.
+ //
+ // As we scan through the array, we clear the worked entries (sa[i] > 0) to zero,
+ // and we flip sa[i] < 0 to -sa[i] and compact into the top of sa,
+ // so that the loop finishes with the top of sa containing exactly
+ // the LMS-substring start indexes, sorted by LMS-substring.
+
+ // Cache recently used bucket index:
+ cB := int32(0)
+ b := bucket[cB]
+
+ top := len(sa)
+ for i := len(sa) - 1; i >= 0; i-- {
+ j := int(sa[i])
+ if j == 0 {
+ // Skip empty entry.
+ continue
+ }
+ sa[i] = 0
+ if j < 0 {
+ // Leave discovered LMS-substring start index for caller.
+ top--
+ sa[top] = int32(-j)
+ continue
+ }
+
+ // Index j was on work queue, meaning k := j-1 is S-type,
+ // so we can now place k correctly into sa.
+ // If k-1 is S-type, queue k for processing later in this loop.
+ // If k-1 is L-type (text[k-1] > text[k]), queue -k to save for the caller.
+ k := j - 1
+ c1 := text[k]
+ c0 := text[k-1]
+ if c0 > c1 {
+ k = -k
+ }
+
+ if cB != c1 {
+ bucket[cB] = b
+ cB = c1
+ b = bucket[cB]
+ }
+ b--
+ sa[b] = int32(k)
+ }
+}
+
+func induceSubS_64(text []int64, sa, freq, bucket []int64) {
+ // Initialize positions for right side of character buckets.
+ bucketMax_64(text, freq, bucket)
+
+ // Analogous to induceSubL_64 above,
+ // as we scan the array right-to-left, each sa[i] = j > 0 is a correctly
+ // sorted suffix array entry (for text[j:]) for which we know that j-1 is type S.
+ // Because j-1 is type S, inserting it into sa now will sort it correctly.
+ // But we want to distinguish a j-1 with j-2 of type S from type L.
+ // We can process the former but want to leave the latter for the caller.
+ // We record the difference by negating j-1 if it is preceded by type L.
+ // Either way, the insertion (into the text[j-1] bucket) is guaranteed to
+ // happen at sa[i´] for some i´ < i, that is, in the portion of sa we have
+ // yet to scan. A single pass therefore sees indexes j, j-1, j-2, j-3,
+ // and so on, in sorted but not necessarily adjacent order, until it finds
+ // one preceded by an index of type L, at which point it must stop.
+ // That index (preceded by one of type L) is an LMS-substring start.
+ //
+ // As we scan through the array, we clear the worked entries (sa[i] > 0) to zero,
+ // and we flip sa[i] < 0 to -sa[i] and compact into the top of sa,
+ // so that the loop finishes with the top of sa containing exactly
+ // the LMS-substring start indexes, sorted by LMS-substring.
+
+ // Cache recently used bucket index:
+ cB := int64(0)
+ b := bucket[cB]
+
+ top := len(sa)
+ for i := len(sa) - 1; i >= 0; i-- {
+ j := int(sa[i])
+ if j == 0 {
+ // Skip empty entry.
+ continue
+ }
+ sa[i] = 0
+ if j < 0 {
+ // Leave discovered LMS-substring start index for caller.
+ top--
+ sa[top] = int64(-j)
+ continue
+ }
+
+ // Index j was on work queue, meaning k := j-1 is S-type,
+ // so we can now place k correctly into sa.
+ // If k-1 is S-type, queue k for processing later in this loop.
+ // If k-1 is L-type (text[k-1] > text[k]), queue -k to save for the caller.
+ k := j - 1
+ c1 := text[k]
+ c0 := text[k-1]
+ if c0 > c1 {
+ k = -k
+ }
+
+ if cB != c1 {
+ bucket[cB] = b
+ cB = c1
+ b = bucket[cB]
+ }
+ b--
+ sa[b] = int64(k)
+ }
+}
+
+func length_8_64(text []byte, sa []int64, numLMS int) {
+ end := 0 // index of current LMS-substring end (0 indicates final LMS-substring)
+
+ // The encoding of N text bytes into a “length” word
+ // adds 1 to each byte, packs them into the bottom
+ // N*8 bits of a word, and then bitwise inverts the result.
+ // That is, the text sequence A B C (hex 41 42 43)
+ // encodes as ^uint64(0x42_43_44).
+ // LMS-substrings can never start or end with 0xFF.
+ // Adding 1 ensures the encoded byte sequence never
+ // starts or ends with 0x00, so that present bytes can be
+ // distinguished from zero-padding in the top bits,
+ // so the length need not be separately encoded.
+ // Inverting the bytes increases the chance that a
+ // 4-byte encoding will still be ≥ len(text).
+ // In particular, if the first byte is ASCII (<= 0x7E, so +1 <= 0x7F)
+ // then the high bit of the inversion will be set,
+ // making it clearly not a valid length (it would be a negative one).
+ //
+ // cx holds the pre-inverted encoding (the packed incremented bytes).
+ cx := uint64(0) // byte-only
+
+ // This stanza (until the blank line) is the "LMS-substring iterator",
+ // described in placeLMS_8_64 above, with one line added to maintain cx.
+ c0, c1, isTypeS := byte(0), byte(0), false
+ for i := len(text) - 1; i >= 0; i-- {
+ c0, c1 = text[i], c0
+ cx = cx<<8 | uint64(c1+1) // byte-only
+ if c0 < c1 {
+ isTypeS = true
+ } else if c0 > c1 && isTypeS {
+ isTypeS = false
+
+ // Index j = i+1 is the start of an LMS-substring.
+ // Compute length or encoded text to store in sa[j/2].
+ j := i + 1
+ var code int64
+ if end == 0 {
+ code = 0
+ } else {
+ code = int64(end - j)
+ if code <= 64/8 && ^cx >= uint64(len(text)) { // byte-only
+ code = int64(^cx) // byte-only
+ } // byte-only
+ }
+ sa[j>>1] = code
+ end = j + 1
+ cx = uint64(c1 + 1) // byte-only
+ }
+ }
+}
+
+func length_32(text []int32, sa []int32, numLMS int) {
+ end := 0 // index of current LMS-substring end (0 indicates final LMS-substring)
+
+ // The encoding of N text int32s into a “length” word
+ // adds 1 to each int32, packs them into the bottom
+ // N*8 bits of a word, and then bitwise inverts the result.
+ // That is, the text sequence A B C (hex 41 42 43)
+ // encodes as ^uint32(0x42_43_44).
+ // LMS-substrings can never start or end with 0xFF.
+ // Adding 1 ensures the encoded int32 sequence never
+ // starts or ends with 0x00, so that present int32s can be
+ // distinguished from zero-padding in the top bits,
+ // so the length need not be separately encoded.
+ // Inverting the int32s increases the chance that a
+ // 4-int32 encoding will still be ≥ len(text).
+ // In particular, if the first int32 is ASCII (<= 0x7E, so +1 <= 0x7F)
+ // then the high bit of the inversion will be set,
+ // making it clearly not a valid length (it would be a negative one).
+ //
+ // cx holds the pre-inverted encoding (the packed incremented int32s).
+
+ // This stanza (until the blank line) is the "LMS-substring iterator",
+ // described in placeLMS_32 above, with one line added to maintain cx.
+ c0, c1, isTypeS := int32(0), int32(0), false
+ for i := len(text) - 1; i >= 0; i-- {
+ c0, c1 = text[i], c0
+ if c0 < c1 {
+ isTypeS = true
+ } else if c0 > c1 && isTypeS {
+ isTypeS = false
+
+ // Index j = i+1 is the start of an LMS-substring.
+ // Compute length or encoded text to store in sa[j/2].
+ j := i + 1
+ var code int32
+ if end == 0 {
+ code = 0
+ } else {
+ code = int32(end - j)
+ }
+ sa[j>>1] = code
+ end = j + 1
+ }
+ }
+}
+
+func length_64(text []int64, sa []int64, numLMS int) {
+ end := 0 // index of current LMS-substring end (0 indicates final LMS-substring)
+
+ // The encoding of N text int64s into a “length” word
+ // adds 1 to each int64, packs them into the bottom
+ // N*8 bits of a word, and then bitwise inverts the result.
+ // That is, the text sequence A B C (hex 41 42 43)
+ // encodes as ^uint64(0x42_43_44).
+ // LMS-substrings can never start or end with 0xFF.
+ // Adding 1 ensures the encoded int64 sequence never
+ // starts or ends with 0x00, so that present int64s can be
+ // distinguished from zero-padding in the top bits,
+ // so the length need not be separately encoded.
+ // Inverting the int64s increases the chance that a
+ // 4-int64 encoding will still be ≥ len(text).
+ // In particular, if the first int64 is ASCII (<= 0x7E, so +1 <= 0x7F)
+ // then the high bit of the inversion will be set,
+ // making it clearly not a valid length (it would be a negative one).
+ //
+ // cx holds the pre-inverted encoding (the packed incremented int64s).
+
+ // This stanza (until the blank line) is the "LMS-substring iterator",
+ // described in placeLMS_64 above, with one line added to maintain cx.
+ c0, c1, isTypeS := int64(0), int64(0), false
+ for i := len(text) - 1; i >= 0; i-- {
+ c0, c1 = text[i], c0
+ if c0 < c1 {
+ isTypeS = true
+ } else if c0 > c1 && isTypeS {
+ isTypeS = false
+
+ // Index j = i+1 is the start of an LMS-substring.
+ // Compute length or encoded text to store in sa[j/2].
+ j := i + 1
+ var code int64
+ if end == 0 {
+ code = 0
+ } else {
+ code = int64(end - j)
+ }
+ sa[j>>1] = code
+ end = j + 1
+ }
+ }
+}
+
+func assignID_8_64(text []byte, sa []int64, numLMS int) int {
+ id := 0
+ lastLen := int64(-1) // impossible
+ lastPos := int64(0)
+ for _, j := range sa[len(sa)-numLMS:] {
+ // Is the LMS-substring at index j new, or is it the same as the last one we saw?
+ n := sa[j/2]
+ if n != lastLen {
+ goto New
+ }
+ if uint64(n) >= uint64(len(text)) {
+ // “Length” is really encoded full text, and they match.
+ goto Same
+ }
+ {
+ // Compare actual texts.
+ n := int(n)
+ this := text[j:][:n]
+ last := text[lastPos:][:n]
+ for i := 0; i < n; i++ {
+ if this[i] != last[i] {
+ goto New
+ }
+ }
+ goto Same
+ }
+ New:
+ id++
+ lastPos = j
+ lastLen = n
+ Same:
+ sa[j/2] = int64(id)
+ }
+ return id
+}
+
+func assignID_32(text []int32, sa []int32, numLMS int) int {
+ id := 0
+ lastLen := int32(-1) // impossible
+ lastPos := int32(0)
+ for _, j := range sa[len(sa)-numLMS:] {
+ // Is the LMS-substring at index j new, or is it the same as the last one we saw?
+ n := sa[j/2]
+ if n != lastLen {
+ goto New
+ }
+ if uint32(n) >= uint32(len(text)) {
+ // “Length” is really encoded full text, and they match.
+ goto Same
+ }
+ {
+ // Compare actual texts.
+ n := int(n)
+ this := text[j:][:n]
+ last := text[lastPos:][:n]
+ for i := 0; i < n; i++ {
+ if this[i] != last[i] {
+ goto New
+ }
+ }
+ goto Same
+ }
+ New:
+ id++
+ lastPos = j
+ lastLen = n
+ Same:
+ sa[j/2] = int32(id)
+ }
+ return id
+}
+
+func assignID_64(text []int64, sa []int64, numLMS int) int {
+ id := 0
+ lastLen := int64(-1) // impossible
+ lastPos := int64(0)
+ for _, j := range sa[len(sa)-numLMS:] {
+ // Is the LMS-substring at index j new, or is it the same as the last one we saw?
+ n := sa[j/2]
+ if n != lastLen {
+ goto New
+ }
+ if uint64(n) >= uint64(len(text)) {
+ // “Length” is really encoded full text, and they match.
+ goto Same
+ }
+ {
+ // Compare actual texts.
+ n := int(n)
+ this := text[j:][:n]
+ last := text[lastPos:][:n]
+ for i := 0; i < n; i++ {
+ if this[i] != last[i] {
+ goto New
+ }
+ }
+ goto Same
+ }
+ New:
+ id++
+ lastPos = j
+ lastLen = n
+ Same:
+ sa[j/2] = int64(id)
+ }
+ return id
+}
+
+func map_64(sa []int64, numLMS int) {
+ w := len(sa)
+ for i := len(sa) / 2; i >= 0; i-- {
+ j := sa[i]
+ if j > 0 {
+ w--
+ sa[w] = j - 1
+ }
+ }
+}
+
+func recurse_64(sa, oldTmp []int64, numLMS, maxID int) {
+ dst, saTmp, text := sa[:numLMS], sa[numLMS:len(sa)-numLMS], sa[len(sa)-numLMS:]
+
+ // Set up temporary space for recursive call.
+ // We must pass sais_64 a tmp buffer with at least maxID entries.
+ //
+ // The subproblem is guaranteed to have length at most len(sa)/2,
+ // so that sa can hold both the subproblem and its suffix array.
+ // Nearly all the time, however, the subproblem has length < len(sa)/3,
+ // in which case there is a subproblem-sized middle of sa that
+ // we can reuse for temporary space (saTmp).
+ // When recurse_64 is called from sais_8_64, oldTmp is length 512
+ // (from text_64), and saTmp will typically be much larger, so we'll use saTmp.
+ // When deeper recursions come back to recurse_64, now oldTmp is
+ // the saTmp from the top-most recursion, it is typically larger than
+ // the current saTmp (because the current sa gets smaller and smaller
+ // as the recursion gets deeper), and we keep reusing that top-most
+ // large saTmp instead of the offered smaller ones.
+ //
+ // Why is the subproblem length so often just under len(sa)/3?
+ // See Nong, Zhang, and Chen, section 3.6 for a plausible explanation.
+ // In brief, the len(sa)/2 case would correspond to an SLSLSLSLSLSL pattern
+ // in the input, perfect alternation of larger and smaller input bytes.
+ // Real text doesn't do that. If each L-type index is randomly followed
+ // by either an L-type or S-type index, then half the substrings will
+ // be of the form SLS, but the other half will be longer. Of that half,
+ // half (a quarter overall) will be SLLS; an eighth will be SLLLS, and so on.
+ // Not counting the final S in each (which overlaps the first S in the next),
+ // This works out to an average length 2×½ + 3×¼ + 4×⅛ + ... = 3.
+ // The space we need is further reduced by the fact that many of the
+ // short patterns like SLS will often be the same character sequences
+ // repeated throughout the text, reducing maxID relative to numLMS.
+ //
+ // For short inputs, the averages may not run in our favor, but then we
+ // can often fall back to using the length-512 tmp available in the
+ // top-most call. (Also a short allocation would not be a big deal.)
+ //
+ // For pathological inputs, we fall back to allocating a new tmp of length
+ // max(maxID, numLMS/2). This level of the recursion needs maxID,
+ // and all deeper levels of the recursion will need no more than numLMS/2,
+ // so this one allocation is guaranteed to suffice for the entire stack
+ // of recursive calls.
+ tmp := oldTmp
+ if len(tmp) < len(saTmp) {
+ tmp = saTmp
+ }
+ if len(tmp) < numLMS {
+ // TestSAIS/forcealloc reaches this code.
+ n := maxID
+ if n < numLMS/2 {
+ n = numLMS / 2
+ }
+ tmp = make([]int64, n)
+ }
+
+ // sais_64 requires that the caller arrange to clear dst,
+ // because in general the caller may know dst is
+ // freshly-allocated and already cleared. But this one is not.
+ for i := range dst {
+ dst[i] = 0
+ }
+ sais_64(text, maxID, dst, tmp)
+}
+
+func unmap_8_64(text []byte, sa []int64, numLMS int) {
+ unmap := sa[len(sa)-numLMS:]
+ j := len(unmap)
+
+ // "LMS-substring iterator" (see placeLMS_8_64 above).
+ c0, c1, isTypeS := byte(0), byte(0), false
+ for i := len(text) - 1; i >= 0; i-- {
+ c0, c1 = text[i], c0
+ if c0 < c1 {
+ isTypeS = true
+ } else if c0 > c1 && isTypeS {
+ isTypeS = false
+
+ // Populate inverse map.
+ j--
+ unmap[j] = int64(i + 1)
+ }
+ }
+
+ // Apply inverse map to subproblem suffix array.
+ sa = sa[:numLMS]
+ for i := 0; i < len(sa); i++ {
+ sa[i] = unmap[sa[i]]
+ }
+}
+
+func unmap_32(text []int32, sa []int32, numLMS int) {
+ unmap := sa[len(sa)-numLMS:]
+ j := len(unmap)
+
+ // "LMS-substring iterator" (see placeLMS_32 above).
+ c0, c1, isTypeS := int32(0), int32(0), false
+ for i := len(text) - 1; i >= 0; i-- {
+ c0, c1 = text[i], c0
+ if c0 < c1 {
+ isTypeS = true
+ } else if c0 > c1 && isTypeS {
+ isTypeS = false
+
+ // Populate inverse map.
+ j--
+ unmap[j] = int32(i + 1)
+ }
+ }
+
+ // Apply inverse map to subproblem suffix array.
+ sa = sa[:numLMS]
+ for i := 0; i < len(sa); i++ {
+ sa[i] = unmap[sa[i]]
+ }
+}
+
+func unmap_64(text []int64, sa []int64, numLMS int) {
+ unmap := sa[len(sa)-numLMS:]
+ j := len(unmap)
+
+ // "LMS-substring iterator" (see placeLMS_64 above).
+ c0, c1, isTypeS := int64(0), int64(0), false
+ for i := len(text) - 1; i >= 0; i-- {
+ c0, c1 = text[i], c0
+ if c0 < c1 {
+ isTypeS = true
+ } else if c0 > c1 && isTypeS {
+ isTypeS = false
+
+ // Populate inverse map.
+ j--
+ unmap[j] = int64(i + 1)
+ }
+ }
+
+ // Apply inverse map to subproblem suffix array.
+ sa = sa[:numLMS]
+ for i := 0; i < len(sa); i++ {
+ sa[i] = unmap[sa[i]]
+ }
+}
+
+func expand_8_64(text []byte, freq, bucket, sa []int64, numLMS int) {
+ bucketMax_8_64(text, freq, bucket)
+ bucket = bucket[:256] // eliminate bound check for bucket[c] below
+
+ // Loop backward through sa, always tracking
+ // the next index to populate from sa[:numLMS].
+ // When we get to one, populate it.
+ // Zero the rest of the slots; they have dead values in them.
+ x := numLMS - 1
+ saX := sa[x]
+ c := text[saX]
+ b := bucket[c] - 1
+ bucket[c] = b
+
+ for i := len(sa) - 1; i >= 0; i-- {
+ if i != int(b) {
+ sa[i] = 0
+ continue
+ }
+ sa[i] = saX
+
+ // Load next entry to put down (if any).
+ if x > 0 {
+ x--
+ saX = sa[x] // TODO bounds check
+ c = text[saX]
+ b = bucket[c] - 1
+ bucket[c] = b
+ }
+ }
+}
+
+func expand_32(text []int32, freq, bucket, sa []int32, numLMS int) {
+ bucketMax_32(text, freq, bucket)
+
+ // Loop backward through sa, always tracking
+ // the next index to populate from sa[:numLMS].
+ // When we get to one, populate it.
+ // Zero the rest of the slots; they have dead values in them.
+ x := numLMS - 1
+ saX := sa[x]
+ c := text[saX]
+ b := bucket[c] - 1
+ bucket[c] = b
+
+ for i := len(sa) - 1; i >= 0; i-- {
+ if i != int(b) {
+ sa[i] = 0
+ continue
+ }
+ sa[i] = saX
+
+ // Load next entry to put down (if any).
+ if x > 0 {
+ x--
+ saX = sa[x] // TODO bounds check
+ c = text[saX]
+ b = bucket[c] - 1
+ bucket[c] = b
+ }
+ }
+}
+
+func expand_64(text []int64, freq, bucket, sa []int64, numLMS int) {
+ bucketMax_64(text, freq, bucket)
+
+ // Loop backward through sa, always tracking
+ // the next index to populate from sa[:numLMS].
+ // When we get to one, populate it.
+ // Zero the rest of the slots; they have dead values in them.
+ x := numLMS - 1
+ saX := sa[x]
+ c := text[saX]
+ b := bucket[c] - 1
+ bucket[c] = b
+
+ for i := len(sa) - 1; i >= 0; i-- {
+ if i != int(b) {
+ sa[i] = 0
+ continue
+ }
+ sa[i] = saX
+
+ // Load next entry to put down (if any).
+ if x > 0 {
+ x--
+ saX = sa[x] // TODO bounds check
+ c = text[saX]
+ b = bucket[c] - 1
+ bucket[c] = b
+ }
+ }
+}
+
+func induceL_8_64(text []byte, sa, freq, bucket []int64) {
+ // Initialize positions for left side of character buckets.
+ bucketMin_8_64(text, freq, bucket)
+ bucket = bucket[:256] // eliminate bounds check for bucket[cB] below
+
+ // This scan is similar to the one in induceSubL_8_64 above.
+ // That one arranges to clear all but the leftmost L-type indexes.
+ // This scan leaves all the L-type indexes and the original S-type
+ // indexes, but it negates the positive leftmost L-type indexes
+ // (the ones that induceS_8_64 needs to process).
+
+ // expand_8_64 left out the implicit entry sa[-1] == len(text),
+ // corresponding to the identified type-L index len(text)-1.
+ // Process it before the left-to-right scan of sa proper.
+ // See body in loop for commentary.
+ k := len(text) - 1
+ c0, c1 := text[k-1], text[k]
+ if c0 < c1 {
+ k = -k
+ }
+
+ // Cache recently used bucket index.
+ cB := c1
+ b := bucket[cB]
+ sa[b] = int64(k)
+ b++
+
+ for i := 0; i < len(sa); i++ {
+ j := int(sa[i])
+ if j <= 0 {
+ // Skip empty or negated entry (including negated zero).
+ continue
+ }
+
+ // Index j was on work queue, meaning k := j-1 is L-type,
+ // so we can now place k correctly into sa.
+ // If k-1 is L-type, queue k for processing later in this loop.
+ // If k-1 is S-type (text[k-1] < text[k]), queue -k to save for the caller.
+ // If k is zero, k-1 doesn't exist, so we only need to leave it
+ // for the caller. The caller can't tell the difference between
+ // an empty slot and a non-empty zero, but there's no need
+ // to distinguish them anyway: the final suffix array will end up
+ // with one zero somewhere, and that will be a real zero.
+ k := j - 1
+ c1 := text[k]
+ if k > 0 {
+ if c0 := text[k-1]; c0 < c1 {
+ k = -k
+ }
+ }
+
+ if cB != c1 {
+ bucket[cB] = b
+ cB = c1
+ b = bucket[cB]
+ }
+ sa[b] = int64(k)
+ b++
+ }
+}
+
+func induceL_32(text []int32, sa, freq, bucket []int32) {
+ // Initialize positions for left side of character buckets.
+ bucketMin_32(text, freq, bucket)
+
+ // This scan is similar to the one in induceSubL_32 above.
+ // That one arranges to clear all but the leftmost L-type indexes.
+ // This scan leaves all the L-type indexes and the original S-type
+ // indexes, but it negates the positive leftmost L-type indexes
+ // (the ones that induceS_32 needs to process).
+
+ // expand_32 left out the implicit entry sa[-1] == len(text),
+ // corresponding to the identified type-L index len(text)-1.
+ // Process it before the left-to-right scan of sa proper.
+ // See body in loop for commentary.
+ k := len(text) - 1
+ c0, c1 := text[k-1], text[k]
+ if c0 < c1 {
+ k = -k
+ }
+
+ // Cache recently used bucket index.
+ cB := c1
+ b := bucket[cB]
+ sa[b] = int32(k)
+ b++
+
+ for i := 0; i < len(sa); i++ {
+ j := int(sa[i])
+ if j <= 0 {
+ // Skip empty or negated entry (including negated zero).
+ continue
+ }
+
+ // Index j was on work queue, meaning k := j-1 is L-type,
+ // so we can now place k correctly into sa.
+ // If k-1 is L-type, queue k for processing later in this loop.
+ // If k-1 is S-type (text[k-1] < text[k]), queue -k to save for the caller.
+ // If k is zero, k-1 doesn't exist, so we only need to leave it
+ // for the caller. The caller can't tell the difference between
+ // an empty slot and a non-empty zero, but there's no need
+ // to distinguish them anyway: the final suffix array will end up
+ // with one zero somewhere, and that will be a real zero.
+ k := j - 1
+ c1 := text[k]
+ if k > 0 {
+ if c0 := text[k-1]; c0 < c1 {
+ k = -k
+ }
+ }
+
+ if cB != c1 {
+ bucket[cB] = b
+ cB = c1
+ b = bucket[cB]
+ }
+ sa[b] = int32(k)
+ b++
+ }
+}
+
+func induceL_64(text []int64, sa, freq, bucket []int64) {
+ // Initialize positions for left side of character buckets.
+ bucketMin_64(text, freq, bucket)
+
+ // This scan is similar to the one in induceSubL_64 above.
+ // That one arranges to clear all but the leftmost L-type indexes.
+ // This scan leaves all the L-type indexes and the original S-type
+ // indexes, but it negates the positive leftmost L-type indexes
+ // (the ones that induceS_64 needs to process).
+
+ // expand_64 left out the implicit entry sa[-1] == len(text),
+ // corresponding to the identified type-L index len(text)-1.
+ // Process it before the left-to-right scan of sa proper.
+ // See body in loop for commentary.
+ k := len(text) - 1
+ c0, c1 := text[k-1], text[k]
+ if c0 < c1 {
+ k = -k
+ }
+
+ // Cache recently used bucket index.
+ cB := c1
+ b := bucket[cB]
+ sa[b] = int64(k)
+ b++
+
+ for i := 0; i < len(sa); i++ {
+ j := int(sa[i])
+ if j <= 0 {
+ // Skip empty or negated entry (including negated zero).
+ continue
+ }
+
+ // Index j was on work queue, meaning k := j-1 is L-type,
+ // so we can now place k correctly into sa.
+ // If k-1 is L-type, queue k for processing later in this loop.
+ // If k-1 is S-type (text[k-1] < text[k]), queue -k to save for the caller.
+ // If k is zero, k-1 doesn't exist, so we only need to leave it
+ // for the caller. The caller can't tell the difference between
+ // an empty slot and a non-empty zero, but there's no need
+ // to distinguish them anyway: the final suffix array will end up
+ // with one zero somewhere, and that will be a real zero.
+ k := j - 1
+ c1 := text[k]
+ if k > 0 {
+ if c0 := text[k-1]; c0 < c1 {
+ k = -k
+ }
+ }
+
+ if cB != c1 {
+ bucket[cB] = b
+ cB = c1
+ b = bucket[cB]
+ }
+ sa[b] = int64(k)
+ b++
+ }
+}
+
+func induceS_8_64(text []byte, sa, freq, bucket []int64) {
+ // Initialize positions for right side of character buckets.
+ bucketMax_8_64(text, freq, bucket)
+ bucket = bucket[:256] // eliminate bounds check for bucket[cB] below
+
+ cB := byte(0)
+ b := bucket[cB]
+
+ for i := len(sa) - 1; i >= 0; i-- {
+ j := int(sa[i])
+ if j >= 0 {
+ // Skip non-flagged entry.
+ // (This loop can't see an empty entry; 0 means the real zero index.)
+ continue
+ }
+
+ // Negative j is a work queue entry; rewrite to positive j for final suffix array.
+ j = -j
+ sa[i] = int64(j)
+
+ // Index j was on work queue (encoded as -j but now decoded),
+ // meaning k := j-1 is L-type,
+ // so we can now place k correctly into sa.
+ // If k-1 is S-type, queue -k for processing later in this loop.
+ // If k-1 is L-type (text[k-1] > text[k]), queue k to save for the caller.
+ // If k is zero, k-1 doesn't exist, so we only need to leave it
+ // for the caller.
+ k := j - 1
+ c1 := text[k]
+ if k > 0 {
+ if c0 := text[k-1]; c0 <= c1 {
+ k = -k
+ }
+ }
+
+ if cB != c1 {
+ bucket[cB] = b
+ cB = c1
+ b = bucket[cB]
+ }
+ b--
+ sa[b] = int64(k)
+ }
+}
+
+func induceS_32(text []int32, sa, freq, bucket []int32) {
+ // Initialize positions for right side of character buckets.
+ bucketMax_32(text, freq, bucket)
+
+ cB := int32(0)
+ b := bucket[cB]
+
+ for i := len(sa) - 1; i >= 0; i-- {
+ j := int(sa[i])
+ if j >= 0 {
+ // Skip non-flagged entry.
+ // (This loop can't see an empty entry; 0 means the real zero index.)
+ continue
+ }
+
+ // Negative j is a work queue entry; rewrite to positive j for final suffix array.
+ j = -j
+ sa[i] = int32(j)
+
+ // Index j was on work queue (encoded as -j but now decoded),
+ // meaning k := j-1 is L-type,
+ // so we can now place k correctly into sa.
+ // If k-1 is S-type, queue -k for processing later in this loop.
+ // If k-1 is L-type (text[k-1] > text[k]), queue k to save for the caller.
+ // If k is zero, k-1 doesn't exist, so we only need to leave it
+ // for the caller.
+ k := j - 1
+ c1 := text[k]
+ if k > 0 {
+ if c0 := text[k-1]; c0 <= c1 {
+ k = -k
+ }
+ }
+
+ if cB != c1 {
+ bucket[cB] = b
+ cB = c1
+ b = bucket[cB]
+ }
+ b--
+ sa[b] = int32(k)
+ }
+}
+
+func induceS_64(text []int64, sa, freq, bucket []int64) {
+ // Initialize positions for right side of character buckets.
+ bucketMax_64(text, freq, bucket)
+
+ cB := int64(0)
+ b := bucket[cB]
+
+ for i := len(sa) - 1; i >= 0; i-- {
+ j := int(sa[i])
+ if j >= 0 {
+ // Skip non-flagged entry.
+ // (This loop can't see an empty entry; 0 means the real zero index.)
+ continue
+ }
+
+ // Negative j is a work queue entry; rewrite to positive j for final suffix array.
+ j = -j
+ sa[i] = int64(j)
+
+ // Index j was on work queue (encoded as -j but now decoded),
+ // meaning k := j-1 is L-type,
+ // so we can now place k correctly into sa.
+ // If k-1 is S-type, queue -k for processing later in this loop.
+ // If k-1 is L-type (text[k-1] > text[k]), queue k to save for the caller.
+ // If k is zero, k-1 doesn't exist, so we only need to leave it
+ // for the caller.
+ k := j - 1
+ c1 := text[k]
+ if k > 0 {
+ if c0 := text[k-1]; c0 <= c1 {
+ k = -k
+ }
+ }
+
+ if cB != c1 {
+ bucket[cB] = b
+ cB = c1
+ b = bucket[cB]
+ }
+ b--
+ sa[b] = int64(k)
+ }
+}