wip

tagengine/node.go

@@ -0,0 +1,79 @@
+package tagengine
+
+import (
+	"fmt"
+	"strings"
+)
+
+type node struct {
+	Token    string
+	Matches  []*Rule // If a list of tokens reaches this node, it matches these.
+	Children map[string]*node
+}
+
+func (n *node) AddRule(r *Rule) {
+	n.addRule(r, 0)
+}
+
+func (n *node) addRule(r *Rule, idx int) {
+	if len(r.Includes) == idx {
+		n.Matches = append(n.Matches, r)
+		return
+	}
+
+	token := r.Includes[idx]
+
+	child, ok := n.Children[token]
+	if !ok {
+		child = &node{
+			Token:    token,
+			Children: map[string]*node{},
+		}
+		n.Children[token] = child
+	}
+
+	child.addRule(r, idx+1)
+}
+
+// Note that tokens must be sorted. This is the case for tokens created from
+// the tokenize function.
+func (n *node) Match(tokens []string) (rules []*Rule) {
+	return n.match(tokens, rules)
+}
+
+func (n *node) match(tokens []string, rules []*Rule) []*Rule {
+	// Check for a match.
+	if n.Matches != nil {
+		rules = append(rules, n.Matches...)
+	}
+
+	if len(tokens) == 0 {
+		return rules
+	}
+
+	// Attempt to match children.
+	for i := 0; i < len(tokens); i++ {
+		token := tokens[i]
+		if child, ok := n.Children[token]; ok {
+			rules = child.match(tokens[i+1:], rules)
+		}
+	}
+
+	return rules
+}
+
+func (n *node) Dump() {
+	n.dump(0)
+}
+
+func (n *node) dump(depth int) {
+	indent := strings.Repeat(" ", 2*depth)
+	tag := ""
+	for _, m := range n.Matches {
+		tag += " " + m.Tag
+	}
+	fmt.Printf("%s%s%s\n", indent, n.Token, tag)
+	for _, child := range n.Children {
+		child.dump(depth + 1)
+	}
+}