Implement GCP Cloud Function

match/match.go

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