// 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) } }