⬆️ Update dependencies
This commit is contained in:
-1
@@ -1 +0,0 @@
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language: go
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+15
-199
@@ -1,202 +1,18 @@
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Copyright (c) 2020 Josh Baker
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+45
@@ -0,0 +1,45 @@
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# B-tree Path Hints
|
||||
|
||||
I use a thing I call path hints in my B-tree [C](https://github.com/tidwall/btree.c) and [Go](https://github.com/tidwall/btree) implementations. It's a search optimization.
|
||||
|
||||
## The B-tree
|
||||
|
||||
A standard [B-tree](https://en.wikipedia.org/wiki/B-tree) is an ordered tree-based data structure that stores its items in nodes. The B-tree has a single root node, which may have children nodes, and those children nodes may also have children nodes.
|
||||
|
||||
<img width="322" alt="image" src="https://user-images.githubusercontent.com/1156077/127664015-14ca38bb-1a3b-4d2f-80ff-27be0bd3d886.png">
|
||||
|
||||
Searching for items in a B-tree is fast. [O(log N)](https://en.wikipedia.org/wiki/Big_O_notation) to be exact.
|
||||
This is because the [binary search algorithm](https://en.wikipedia.org/wiki/Binary_search_algorithm) is used.
|
||||
|
||||
A binary search works by first comparing the item at the middle-most index of the root node with the target item.
|
||||
If the middle item is greater than the target item, then it divides the node in two and does the binary search on the left part of the node. If the middle is less, it searches the right part. And so on. If the target item is found, then the search stop. If the item is not found, then the search is passed to the child node at the appropriate index. This traversal terminates when item is found or there are no more child nodes.
|
||||
|
||||
<img width="600" alt="image" src="https://user-images.githubusercontent.com/1156077/127664822-6ab4f8f6-8ab5-477e-8e17-f52346f02819.png">
|
||||
|
||||
## The Path
|
||||
|
||||
Each index is a component of the path to the item (or where the item should be stored, if it does not exist in the tree).
|
||||
|
||||
Take the first example image. The item 9 is at path “1/0”. The item 16 is at path “1”. The item 21 is at path “2/1”. The item 5 is at path “0/2”.
|
||||
|
||||
## The Path Hint
|
||||
|
||||
A Path Hint is a predefined path that is provided to B-tree operations. It’s just a hint that says, “Hey B-tree, instead of starting your binary search with the middle index, start with what I provide you. My path may be wrong, and if so please provide me with the correct path so I get it right the next time.”
|
||||
|
||||
I’ve found using path hints can lead to a little performance increase of 150% - 300%. This is because in real-world cases the items that I’m working with are usually nearby each other in the tree.
|
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|
||||
Take for example inserting a group of timeseries points. They may often be received as chucks of near-contiguous items.
|
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Or, I'm sequentially inserting an ordered group of rows somewhere in the middle of a table.
|
||||
Or, I have a Redis-style key/value store, where the keys look have the common structure “user:98512:name”, “user:98512:email”, and I want to update a bunch of values for specified user.
|
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Using a path hint may help to avoid the unnecessary binary searching in each of these examples.
|
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|
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While I may see a 3x boost in when the path hint is right on, I'll only see around 5% decrease when the path hint is totally wrong.
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||||
|
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## Using a Path Hint
|
||||
|
||||
All of the functions that take in a path hint argument mutate the path hint argument.
|
||||
|
||||
For single-threaded programs, it’s possible to use one shared path hint per B-tree for the life of the program.
|
||||
For multi-threaded programs, I find it best to use one path hint per B-tree , per thread.
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For server-client programs, one path hint per B-tree, per client should suffice.
|
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+394
-50
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BTree implementation for Go
|
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===========================
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# btree
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|
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|
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[](https://godoc.org/github.com/tidwall/btree)
|
||||
|
||||
This package provides an in-memory B-Tree implementation for Go, useful as
|
||||
an ordered, mutable data structure.
|
||||
An efficient [B-tree](https://en.wikipedia.org/wiki/B-tree) implementation in Go.
|
||||
|
||||
This is a fork of the wonderful [google/btree](https://github.com/google/btree) package. It's has all the same great features and adds a few more.
|
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## Features
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|
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- Descend* functions for iterating backwards.
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- Iteration performance boost.
|
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- User defined context.
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||||
- Support for [Generics](#generics) (Go 1.18+).
|
||||
- `Map` and `Set` types for ordered key-value maps and sets,
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- Fast bulk loading for pre-ordered data using the `Load()` method.
|
||||
- `Copy()` method with copy-on-write support.
|
||||
- Thread-safe operations.
|
||||
- [Path hinting](PATH_HINT.md) optimization for operations with nearby keys.
|
||||
|
||||
User defined context
|
||||
--------------------
|
||||
This is a great new feature that allows for entering the same item into multiple B-trees, and each B-tree have a different ordering formula.
|
||||
## Using
|
||||
|
||||
For example:
|
||||
To start using this package, install Go and run:
|
||||
|
||||
```sh
|
||||
$ go get github.com/tidwall/btree
|
||||
```
|
||||
|
||||
## B-tree types
|
||||
|
||||
This package includes the following types of B-trees:
|
||||
|
||||
- [`btree.Map`](#btreemap):
|
||||
A fast B-tree for storing ordered key value pairs.
|
||||
Go 1.18+
|
||||
- [`btree.Set`](#btreeset):
|
||||
Like `Map`, but only for storing keys.
|
||||
Go 1.18+
|
||||
- [`btree.BTreeG`](#btreegeneric):
|
||||
A feature-rich B-tree for storing data using a custom comparator.
|
||||
Go 1.18+
|
||||
- [`btree.BTree`](#btreebtree):
|
||||
Like `BTreeG` but uses the `interface{}` type for data. Backwards compatible.
|
||||
Go 1.16+
|
||||
|
||||
### btree.Map
|
||||
|
||||
```go
|
||||
// Basic
|
||||
Set(key, value) // insert or replace an item
|
||||
Get(key, value) // get an existing item
|
||||
Delete(key) // delete an item
|
||||
Len() // return the number of items in the map
|
||||
|
||||
// Iteration
|
||||
Scan(iter) // scan items in ascending order
|
||||
Reverse(iter) // scan items in descending order
|
||||
Ascend(key, iter) // scan items in ascending order that are >= to key
|
||||
Descend(key, iter) // scan items in descending order that are <= to key.
|
||||
Iter() // returns a read-only iterator for for-loops.
|
||||
|
||||
// Array-like operations
|
||||
GetAt(index) // returns the item at index
|
||||
DeleteAt(index) // deletes the item at index
|
||||
|
||||
// Bulk-loading
|
||||
Load(key, value) // load presorted items into tree
|
||||
```
|
||||
|
||||
#### Example
|
||||
|
||||
```go
|
||||
package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"github.com/tidwall/btree"
|
||||
)
|
||||
|
||||
func main() {
|
||||
// create a map
|
||||
var users btree.Map[string, string]
|
||||
|
||||
// add some users
|
||||
users.Set("user:4", "Andrea")
|
||||
users.Set("user:6", "Andy")
|
||||
users.Set("user:2", "Andy")
|
||||
users.Set("user:1", "Jane")
|
||||
users.Set("user:5", "Janet")
|
||||
users.Set("user:3", "Steve")
|
||||
|
||||
// Iterate over the maps and print each user
|
||||
users.Scan(func(key, value string) bool {
|
||||
fmt.Printf("%s %s\n", key, value)
|
||||
return true
|
||||
})
|
||||
fmt.Printf("\n")
|
||||
|
||||
// Delete a couple
|
||||
users.Delete("user:5")
|
||||
users.Delete("user:1")
|
||||
|
||||
// print the map again
|
||||
users.Scan(func(key, value string) bool {
|
||||
fmt.Printf("%s %s\n", key, value)
|
||||
return true
|
||||
})
|
||||
fmt.Printf("\n")
|
||||
|
||||
// Output:
|
||||
// user:1 Jane
|
||||
// user:2 Andy
|
||||
// user:3 Steve
|
||||
// user:4 Andrea
|
||||
// user:5 Janet
|
||||
// user:6 Andy
|
||||
//
|
||||
// user:2 Andy
|
||||
// user:3 Steve
|
||||
// user:4 Andrea
|
||||
// user:6 Andy
|
||||
}
|
||||
```
|
||||
|
||||
### btree.Set
|
||||
|
||||
```go
|
||||
// Basic
|
||||
Insert(key) // insert an item
|
||||
Contains(key) // test if item exists
|
||||
Delete(key) // delete an item
|
||||
Len() // return the number of items in the set
|
||||
|
||||
// Iteration
|
||||
Scan(iter) // scan items in ascending order
|
||||
Reverse(iter) // scan items in descending order
|
||||
Ascend(key, iter) // scan items in ascending order that are >= to key
|
||||
Descend(key, iter) // scan items in descending order that are <= to key.
|
||||
Iter() // returns a read-only iterator for for-loops.
|
||||
|
||||
// Array-like operations
|
||||
GetAt(index) // returns the item at index
|
||||
DeleteAt(index) // deletes the item at index
|
||||
|
||||
// Bulk-loading
|
||||
Load(key) // load presorted item into tree
|
||||
```
|
||||
|
||||
#### Example
|
||||
|
||||
```go
|
||||
package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"github.com/tidwall/btree"
|
||||
)
|
||||
|
||||
func main() {
|
||||
// create a set
|
||||
var names btree.Set[string]
|
||||
|
||||
// add some names
|
||||
names.Insert("Jane")
|
||||
names.Insert("Andrea")
|
||||
names.Insert("Steve")
|
||||
names.Insert("Andy")
|
||||
names.Insert("Janet")
|
||||
names.Insert("Andy")
|
||||
|
||||
// Iterate over the maps and print each user
|
||||
names.Scan(func(key string) bool {
|
||||
fmt.Printf("%s\n", key)
|
||||
return true
|
||||
})
|
||||
fmt.Printf("\n")
|
||||
|
||||
// Delete a couple
|
||||
names.Delete("Steve")
|
||||
names.Delete("Andy")
|
||||
|
||||
// print the map again
|
||||
names.Scan(func(key string) bool {
|
||||
fmt.Printf("%s\n", key)
|
||||
return true
|
||||
})
|
||||
fmt.Printf("\n")
|
||||
|
||||
// Output:
|
||||
// Andrea
|
||||
// Andy
|
||||
// Jane
|
||||
// Janet
|
||||
// Steve
|
||||
//
|
||||
// Andrea
|
||||
// Jane
|
||||
// Janet
|
||||
}
|
||||
```
|
||||
|
||||
### btree.BTreeG
|
||||
|
||||
```go
|
||||
// Basic
|
||||
Set(item) // insert or replace an item
|
||||
Get(item) // get an existing item
|
||||
Delete(item) // delete an item
|
||||
Len() // return the number of items in the btree
|
||||
|
||||
// Iteration
|
||||
Scan(iter) // scan items in ascending order
|
||||
Reverse(iter) // scan items in descending order
|
||||
Ascend(key, iter) // scan items in ascending order that are >= to key
|
||||
Descend(key, iter) // scan items in descending order that are <= to key.
|
||||
Iter() // returns a read-only iterator for for-loops.
|
||||
|
||||
// Array-like operations
|
||||
GetAt(index) // returns the item at index
|
||||
DeleteAt(index) // deletes the item at index
|
||||
|
||||
// Bulk-loading
|
||||
Load(item) // load presorted items into tree
|
||||
|
||||
// Path hinting
|
||||
SetHint(item, *hint) // insert or replace an existing item
|
||||
GetHint(item, *hint) // get an existing item
|
||||
DeleteHint(item, *hint) // delete an item
|
||||
|
||||
// Copy-on-write
|
||||
Copy() // copy the btree
|
||||
```
|
||||
|
||||
#### Example
|
||||
|
||||
```go
|
||||
package main
|
||||
@@ -32,30 +241,154 @@ type Item struct {
|
||||
Key, Val string
|
||||
}
|
||||
|
||||
func (i1 *Item) Less(item btree.Item, ctx interface{}) bool {
|
||||
i2 := item.(*Item)
|
||||
switch tag := ctx.(type) {
|
||||
case string:
|
||||
if tag == "vals" {
|
||||
if i1.Val < i2.Val {
|
||||
return true
|
||||
} else if i1.Val > i2.Val {
|
||||
return false
|
||||
}
|
||||
// Both vals are equal so we should fall though
|
||||
// and let the key comparison take over.
|
||||
}
|
||||
// byKeys is a comparison function that compares item keys and returns true
|
||||
// when a is less than b.
|
||||
func byKeys(a, b Item) bool {
|
||||
return a.Key < b.Key
|
||||
}
|
||||
|
||||
// byVals is a comparison function that compares item values and returns true
|
||||
// when a is less than b.
|
||||
func byVals(a, b Item) bool {
|
||||
if a.Val < b.Val {
|
||||
return true
|
||||
}
|
||||
return i1.Key < i2.Key
|
||||
if a.Val > b.Val {
|
||||
return false
|
||||
}
|
||||
// Both vals are equal so we should fall though
|
||||
// and let the key comparison take over.
|
||||
return byKeys(a, b)
|
||||
}
|
||||
|
||||
func main() {
|
||||
|
||||
// Create a tree for keys and a tree for values.
|
||||
// The "keys" tree will be sorted on the Keys field.
|
||||
// The "values" tree will be sorted on the Values field.
|
||||
keys := btree.New(16, "keys")
|
||||
vals := btree.New(16, "vals")
|
||||
keys := btree.NewBTreeG[Item](byKeys)
|
||||
vals := btree.NewBTreeG[Item](byVals)
|
||||
|
||||
// Create some items.
|
||||
users := []Item{
|
||||
Item{Key: "user:1", Val: "Jane"},
|
||||
Item{Key: "user:2", Val: "Andy"},
|
||||
Item{Key: "user:3", Val: "Steve"},
|
||||
Item{Key: "user:4", Val: "Andrea"},
|
||||
Item{Key: "user:5", Val: "Janet"},
|
||||
Item{Key: "user:6", Val: "Andy"},
|
||||
}
|
||||
|
||||
// Insert each user into both trees
|
||||
for _, user := range users {
|
||||
keys.Set(user)
|
||||
vals.Set(user)
|
||||
}
|
||||
|
||||
// Iterate over each user in the key tree
|
||||
keys.Scan(func(item Item) bool {
|
||||
fmt.Printf("%s %s\n", item.Key, item.Val)
|
||||
return true
|
||||
})
|
||||
fmt.Printf("\n")
|
||||
|
||||
// Iterate over each user in the val tree
|
||||
vals.Scan(func(item Item) bool {
|
||||
fmt.Printf("%s %s\n", item.Key, item.Val)
|
||||
return true
|
||||
})
|
||||
|
||||
// Output:
|
||||
// user:1 Jane
|
||||
// user:2 Andy
|
||||
// user:3 Steve
|
||||
// user:4 Andrea
|
||||
// user:5 Janet
|
||||
// user:6 Andy
|
||||
//
|
||||
// user:4 Andrea
|
||||
// user:2 Andy
|
||||
// user:6 Andy
|
||||
// user:1 Jane
|
||||
// user:5 Janet
|
||||
// user:3 Steve
|
||||
}
|
||||
```
|
||||
|
||||
### btree.BTree
|
||||
|
||||
```go
|
||||
// Basic
|
||||
Set(item) // insert or replace an item
|
||||
Get(item) // get an existing item
|
||||
Delete(item) // delete an item
|
||||
Len() // return the number of items in the btree
|
||||
|
||||
// Iteration
|
||||
Scan(iter) // scan items in ascending order
|
||||
Reverse(iter) // scan items in descending order
|
||||
Ascend(key, iter) // scan items in ascending order that are >= to key
|
||||
Descend(key, iter) // scan items in descending order that are <= to key.
|
||||
Iter() // returns a read-only iterator for for-loops.
|
||||
|
||||
// Array-like operations
|
||||
GetAt(index) // returns the item at index
|
||||
DeleteAt(index) // deletes the item at index
|
||||
|
||||
// Bulk-loading
|
||||
Load(item) // load presorted items into tree
|
||||
|
||||
// Path hinting
|
||||
SetHint(item, *hint) // insert or replace an existing item
|
||||
GetHint(item, *hint) // get an existing item
|
||||
DeleteHint(item, *hint) // delete an item
|
||||
|
||||
// Copy-on-write
|
||||
Copy() // copy the btree
|
||||
```
|
||||
|
||||
#### Example
|
||||
|
||||
```go
|
||||
package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
|
||||
"github.com/tidwall/btree"
|
||||
)
|
||||
|
||||
type Item struct {
|
||||
Key, Val string
|
||||
}
|
||||
|
||||
// byKeys is a comparison function that compares item keys and returns true
|
||||
// when a is less than b.
|
||||
func byKeys(a, b interface{}) bool {
|
||||
i1, i2 := a.(*Item), b.(*Item)
|
||||
return i1.Key < i2.Key
|
||||
}
|
||||
|
||||
// byVals is a comparison function that compares item values and returns true
|
||||
// when a is less than b.
|
||||
func byVals(a, b interface{}) bool {
|
||||
i1, i2 := a.(*Item), b.(*Item)
|
||||
if i1.Val < i2.Val {
|
||||
return true
|
||||
}
|
||||
if i1.Val > i2.Val {
|
||||
return false
|
||||
}
|
||||
// Both vals are equal so we should fall though
|
||||
// and let the key comparison take over.
|
||||
return byKeys(a, b)
|
||||
}
|
||||
|
||||
func main() {
|
||||
// Create a tree for keys and a tree for values.
|
||||
// The "keys" tree will be sorted on the Keys field.
|
||||
// The "values" tree will be sorted on the Values field.
|
||||
keys := btree.New(byKeys)
|
||||
vals := btree.New(byVals)
|
||||
|
||||
// Create some items.
|
||||
users := []*Item{
|
||||
@@ -69,12 +402,12 @@ func main() {
|
||||
|
||||
// Insert each user into both trees
|
||||
for _, user := range users {
|
||||
keys.ReplaceOrInsert(user)
|
||||
vals.ReplaceOrInsert(user)
|
||||
keys.Set(user)
|
||||
vals.Set(user)
|
||||
}
|
||||
|
||||
// Iterate over each user in the key tree
|
||||
keys.Ascend(func(item btree.Item) bool {
|
||||
keys.Ascend(nil, func(item interface{}) bool {
|
||||
kvi := item.(*Item)
|
||||
fmt.Printf("%s %s\n", kvi.Key, kvi.Val)
|
||||
return true
|
||||
@@ -82,26 +415,37 @@ func main() {
|
||||
|
||||
fmt.Printf("\n")
|
||||
// Iterate over each user in the val tree
|
||||
vals.Ascend(func(item btree.Item) bool {
|
||||
vals.Ascend(nil, func(item interface{}) bool {
|
||||
kvi := item.(*Item)
|
||||
fmt.Printf("%s %s\n", kvi.Key, kvi.Val)
|
||||
return true
|
||||
})
|
||||
|
||||
// Output:
|
||||
// user:1 Jane
|
||||
// user:2 Andy
|
||||
// user:3 Steve
|
||||
// user:4 Andrea
|
||||
// user:5 Janet
|
||||
// user:6 Andy
|
||||
//
|
||||
// user:4 Andrea
|
||||
// user:2 Andy
|
||||
// user:6 Andy
|
||||
// user:1 Jane
|
||||
// user:5 Janet
|
||||
// user:3 Steve
|
||||
}
|
||||
|
||||
// Should see the results
|
||||
/*
|
||||
user:1 Jane
|
||||
user:2 Andy
|
||||
user:3 Steve
|
||||
user:4 Andrea
|
||||
user:5 Janet
|
||||
user:6 Andy
|
||||
|
||||
user:4 Andrea
|
||||
user:2 Andy
|
||||
user:6 Andy
|
||||
user:1 Jane
|
||||
user:3 Steve
|
||||
*/
|
||||
```
|
||||
|
||||
## Performance
|
||||
|
||||
See [tidwall/btree-benchmark](https://github.com/tidwall/btree-benchmark) for benchmark numbers.
|
||||
|
||||
## Contact
|
||||
|
||||
Josh Baker [@tidwall](http://twitter.com/tidwall)
|
||||
|
||||
## License
|
||||
|
||||
Source code is available under the MIT [License](/LICENSE).
|
||||
|
||||
+221
-926
File diff suppressed because it is too large
Load Diff
+1303
File diff suppressed because it is too large
Load Diff
+1056
File diff suppressed because it is too large
Load Diff
+168
@@ -0,0 +1,168 @@
|
||||
package btree
|
||||
|
||||
type Set[K ordered] struct {
|
||||
base Map[K, struct{}]
|
||||
}
|
||||
|
||||
// Copy
|
||||
func (tr *Set[K]) Copy() *Set[K] {
|
||||
tr2 := new(Set[K])
|
||||
tr2.base = *tr.base.Copy()
|
||||
return tr2
|
||||
}
|
||||
|
||||
// Insert an item
|
||||
func (tr *Set[K]) Insert(key K) {
|
||||
tr.base.Set(key, struct{}{})
|
||||
}
|
||||
|
||||
func (tr *Set[K]) Scan(iter func(key K) bool) {
|
||||
tr.base.Scan(func(key K, value struct{}) bool {
|
||||
return iter(key)
|
||||
})
|
||||
}
|
||||
|
||||
// Get a value for key
|
||||
func (tr *Set[K]) Contains(key K) bool {
|
||||
_, ok := tr.base.Get(key)
|
||||
return ok
|
||||
}
|
||||
|
||||
// Len returns the number of items in the tree
|
||||
func (tr *Set[K]) Len() int {
|
||||
return tr.base.Len()
|
||||
}
|
||||
|
||||
// Delete an item
|
||||
func (tr *Set[K]) Delete(key K) {
|
||||
tr.base.Delete(key)
|
||||
}
|
||||
|
||||
// Ascend the tree within the range [pivot, last]
|
||||
// Pass nil for pivot to scan all item in ascending order
|
||||
// Return false to stop iterating
|
||||
func (tr *Set[K]) Ascend(pivot K, iter func(key K) bool) {
|
||||
tr.base.Ascend(pivot, func(key K, value struct{}) bool {
|
||||
return iter(key)
|
||||
})
|
||||
}
|
||||
|
||||
func (tr *Set[K]) Reverse(iter func(key K) bool) {
|
||||
tr.base.Reverse(func(key K, value struct{}) bool {
|
||||
return iter(key)
|
||||
})
|
||||
}
|
||||
|
||||
// Descend the tree within the range [pivot, first]
|
||||
// Pass nil for pivot to scan all item in descending order
|
||||
// Return false to stop iterating
|
||||
func (tr *Set[K]) Descend(pivot K, iter func(key K) bool) {
|
||||
tr.base.Descend(pivot, func(key K, value struct{}) bool {
|
||||
return iter(key)
|
||||
})
|
||||
}
|
||||
|
||||
// Load is for bulk loading pre-sorted items
|
||||
func (tr *Set[K]) Load(key K) {
|
||||
tr.base.Load(key, struct{}{})
|
||||
}
|
||||
|
||||
// Min returns the minimum item in tree.
|
||||
// Returns nil if the treex has no items.
|
||||
func (tr *Set[K]) Min() (K, bool) {
|
||||
key, _, ok := tr.base.Min()
|
||||
return key, ok
|
||||
}
|
||||
|
||||
// Max returns the maximum item in tree.
|
||||
// Returns nil if the tree has no items.
|
||||
func (tr *Set[K]) Max() (K, bool) {
|
||||
key, _, ok := tr.base.Max()
|
||||
return key, ok
|
||||
}
|
||||
|
||||
// PopMin removes the minimum item in tree and returns it.
|
||||
// Returns nil if the tree has no items.
|
||||
func (tr *Set[K]) PopMin() (K, bool) {
|
||||
key, _, ok := tr.base.PopMin()
|
||||
return key, ok
|
||||
}
|
||||
|
||||
// PopMax removes the maximum item in tree and returns it.
|
||||
// Returns nil if the tree has no items.
|
||||
func (tr *Set[K]) PopMax() (K, bool) {
|
||||
key, _, ok := tr.base.PopMax()
|
||||
return key, ok
|
||||
}
|
||||
|
||||
// GetAt returns the value at index.
|
||||
// Return nil if the tree is empty or the index is out of bounds.
|
||||
func (tr *Set[K]) GetAt(index int) (K, bool) {
|
||||
key, _, ok := tr.base.GetAt(index)
|
||||
return key, ok
|
||||
}
|
||||
|
||||
// DeleteAt deletes the item at index.
|
||||
// Return nil if the tree is empty or the index is out of bounds.
|
||||
func (tr *Set[K]) DeleteAt(index int) (K, bool) {
|
||||
key, _, ok := tr.base.DeleteAt(index)
|
||||
return key, ok
|
||||
}
|
||||
|
||||
// Height returns the height of the tree.
|
||||
// Returns zero if tree has no items.
|
||||
func (tr *Set[K]) Height() int {
|
||||
return tr.base.Height()
|
||||
}
|
||||
|
||||
// SetIter represents an iterator for btree.Set
|
||||
type SetIter[K ordered] struct {
|
||||
base MapIter[K, struct{}]
|
||||
}
|
||||
|
||||
// Iter returns a read-only iterator.
|
||||
func (tr *Set[K]) Iter() SetIter[K] {
|
||||
return SetIter[K]{tr.base.Iter()}
|
||||
}
|
||||
|
||||
// Seek to item greater-or-equal-to key.
|
||||
// Returns false if there was no item found.
|
||||
func (iter *SetIter[K]) Seek(key K) bool {
|
||||
return iter.base.Seek(key)
|
||||
}
|
||||
|
||||
// First moves iterator to first item in tree.
|
||||
// Returns false if the tree is empty.
|
||||
func (iter *SetIter[K]) First() bool {
|
||||
return iter.base.First()
|
||||
}
|
||||
|
||||
// Last moves iterator to last item in tree.
|
||||
// Returns false if the tree is empty.
|
||||
func (iter *SetIter[K]) Last() bool {
|
||||
return iter.base.Last()
|
||||
}
|
||||
|
||||
// Next moves iterator to the next item in iterator.
|
||||
// Returns false if the tree is empty or the iterator is at the end of
|
||||
// the tree.
|
||||
func (iter *SetIter[K]) Next() bool {
|
||||
return iter.base.Next()
|
||||
}
|
||||
|
||||
// Prev moves iterator to the previous item in iterator.
|
||||
// Returns false if the tree is empty or the iterator is at the beginning of
|
||||
// the tree.
|
||||
func (iter *SetIter[K]) Prev() bool {
|
||||
return iter.base.Prev()
|
||||
}
|
||||
|
||||
// Key returns the current iterator item key.
|
||||
func (iter *SetIter[K]) Key() K {
|
||||
return iter.base.Key()
|
||||
}
|
||||
|
||||
// Keys returns all the keys in order.
|
||||
func (tr *Set[K]) Keys() []K {
|
||||
return tr.base.Keys()
|
||||
}
|
||||
Reference in New Issue
Block a user