golang sais2 代码
文件路径：/src/index/suffixarray/sais2.go
/ 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)
}
}