106 lines
2.4 KiB
Go
106 lines
2.4 KiB
Go
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package pmap
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type InplaceMap interface {
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Map
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SetInplace(Key, Value) InplaceMap
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}
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func (p pmap) SetInplace(k Key, v Value) InplaceMap {
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root, added := inplace_insert(p.root, k, v, p.hash)
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p.root = root
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if added {
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p.len++
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}
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return p
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}
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func inplace_insert(n interface{}, key Key, val Value, hashFn HashFunc) (newNode interface{}, added bool) {
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if n == nil {
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return leaf{key, val}, true
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}
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hash := hashFn(key)
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var insert func(n interface{}, shift uint32) interface{}
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insert = func(n interface{}, shift uint32) interface{} {
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// insert returns a new node (if the node should be replaced)
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// or nil (if the node is unchanged or modified in place)
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//fmt.Printf("insert %v %x %#v\n", shift, hash, n)
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switch n := n.(type) {
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case leaf:
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if n.k == key {
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// replace existing entry
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added = false
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return leaf{key, val}
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} else if h := hashFn(n.k); h == hash {
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// collision
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added = true
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return &collision{hash, []leaf{{key, val}, n}}
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} else {
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if h>>shift == hash>>shift {
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panic("pmap: infinite loop in insert")
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}
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// not a collision, so we must still have some hash bits left
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// split the trie
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x := newnode(n, h, shift)
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if x0 := insert(x, shift); x0 != nil {
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return x0
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}
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return x
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}
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case *node:
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c := n.getNode(shift, hash, key)
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if c == nil {
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// new node
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c = leaf{key, val}
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added = true
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m := bitmask(hash >> shift)
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n.bitmap |= m
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i := n.index(m)
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n.child = append(n.child, nil) // allocate space
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copy(n.child[i+1:], n.child[i:]) // shift array up
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n.child[i] = c // mutate node
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} else {
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c = insert(c, shift+nodeShift)
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if c == nil {
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return nil
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}
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m := bitmask(hash >> shift)
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i := n.index(m)
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n.child[i] = c // mutate node
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}
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n.check()
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return nil
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case *collision:
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if n.hash != hash {
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// not a collision, so we must still have some hash bits left
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// split the trie
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x := newnode(n, n.hash, shift)
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if x0 := insert(x, shift); x0 != nil {
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return x0
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}
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return x
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}
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for i := range n.leaf {
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if key == n.leaf[i].k {
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// replace existing entry
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n.leaf[i] = leaf{key, val} // mutate
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added = false
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return nil
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}
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}
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// new collision
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added = true
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n.leaf = append(n.leaf, leaf{key, val}) // mutate
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return nil
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default:
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panic("pmap: unhandled case in insert")
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}
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}
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newNode = insert(n, 0)
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if newNode == nil {
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newNode = n
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}
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return
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}
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