diff options
Diffstat (limited to 'page.go')
| -rw-r--r-- | page.go | 38 |
1 files changed, 38 insertions, 0 deletions
@@ -3,6 +3,7 @@ package bolt import ( "fmt" "os" + "sort" "unsafe" ) @@ -132,3 +133,40 @@ type pgids []pgid func (s pgids) Len() int { return len(s) } func (s pgids) Swap(i, j int) { s[i], s[j] = s[j], s[i] } func (s pgids) Less(i, j int) bool { return s[i] < s[j] } + +// merge returns the sorted union of a and b. +func (a pgids) merge(b pgids) pgids { + // Return the opposite slice if one is nil. + if len(a) == 0 { + return b + } else if len(b) == 0 { + return a + } + + // Create a list to hold all elements from both lists. + merged := make(pgids, 0, len(a)+len(b)) + + // Assign lead to the slice with a lower starting value, follow to the higher value. + lead, follow := a, b + if b[0] < a[0] { + lead, follow = b, a + } + + // Continue while there are elements in the lead. + for len(lead) > 0 { + // Merge largest prefix of lead that is ahead of follow[0]. + n := sort.Search(len(lead), func(i int) bool { return lead[i] > follow[0] }) + merged = append(merged, lead[:n]...) + if n >= len(lead) { + break + } + + // Swap lead and follow. + lead, follow = follow, lead[n:] + } + + // Append what's left in follow. + merged = append(merged, follow...) + + return merged +} |