88 lines
1.4 KiB
Go
88 lines
1.4 KiB
Go
package match
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import (
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"bufio"
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"io"
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"github.com/ray1729/puzzle-solver/util"
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)
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type DB interface {
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FindMatches(s string) []string
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Add(s string)
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}
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type PrefixTreeImpl struct {
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Root *Node
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}
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func New() PrefixTreeImpl {
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return PrefixTreeImpl{Root: &Node{}}
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}
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func (db PrefixTreeImpl) Add(s string) {
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xs := util.LowerCaseAlpha(s)
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db.Root.add(xs, s)
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}
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type Node struct {
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Value byte
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Children []*Node
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Results []string
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}
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func (n *Node) add(xs []byte, s string) {
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if len(xs) == 0 {
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n.Results = append(n.Results, s)
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return
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}
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x := xs[0]
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var child *Node
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for _, c := range n.Children {
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if c.Value == x {
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child = c
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break
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}
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}
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if child == nil {
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child = &Node{Value: x}
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n.Children = append(n.Children, child)
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}
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child.add(xs[1:], s)
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}
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func Load(r io.Reader) (DB, error) {
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db := New()
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sc := bufio.NewScanner(r)
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for sc.Scan() {
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db.Add(sc.Text())
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}
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if err := sc.Err(); err != nil {
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return nil, err
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}
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return db, nil
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}
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func (db PrefixTreeImpl) FindMatches(s string) []string {
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return db.Root.find(util.LowerCaseAlphaOrDot(s))
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}
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func (n *Node) find(xs []byte) []string {
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if len(xs) == 0 {
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return n.Results
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}
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x := xs[0]
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if x == '.' {
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var result []string
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for _, c := range n.Children {
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result = append(result, c.find(xs[1:])...)
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}
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return result
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}
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for _, c := range n.Children {
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if c.Value == x {
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return c.find(xs[1:])
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}
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}
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return nil
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}
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