util/http: add trie matching func

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

util/http/trie.go

@@ -0,0 +1,201 @@
+package http
+
+import (
+	"regexp"
+	"strings"
+	"sync"
+)
+
+// Tree is a trie tree.
+type Trie struct {
+	rmu    sync.RWMutex
+	node   *node
+	rcache map[string]*regexp.Regexp
+}
+
+// node is a node of tree
+type node struct {
+	actions  map[string]interface{} // key is method, val is handler interface
+	children map[string]*node       // key is label of next nodes
+	label    string
+}
+
+const (
+	pathRoot          string = "/"
+	pathDelimiter     string = "/"
+	paramDelimiter    string = ":"
+	leftPtnDelimiter  string = "{"
+	rightPtnDelimiter string = "}"
+	ptnWildcard       string = "(.+)"
+)
+
+// NewTree creates a new trie tree.
+func NewTrie() *Trie {
+	return &Trie{
+		node: &node{
+			label:    pathRoot,
+			actions:  make(map[string]interface{}),
+			children: make(map[string]*node),
+		},
+		rcache: make(map[string]*regexp.Regexp),
+	}
+}
+
+// Insert inserts a route definition to tree.
+func (t *Trie) Insert(methods []string, path string, handler interface{}) {
+	curNode := t.node
+	if path == pathRoot {
+		curNode.label = path
+		for _, method := range methods {
+			curNode.actions[method] = handler
+		}
+		return
+	}
+	ep := splitPath(path)
+	for i, p := range ep {
+		nextNode, ok := curNode.children[p]
+		if ok {
+			curNode = nextNode
+		}
+		// Create a new node.
+		if !ok {
+			curNode.children[p] = &node{
+				label:    p,
+				actions:  make(map[string]interface{}),
+				children: make(map[string]*node),
+			}
+			curNode = curNode.children[p]
+		}
+		// last loop.
+		// If there is already registered data, overwrite it.
+		if i == len(ep)-1 {
+			curNode.label = p
+			for _, method := range methods {
+				curNode.actions[method] = handler
+			}
+			break
+		}
+	}
+}
+
+// Search searches a path from a tree.
+func (t *Trie) Search(method string, path string) (interface{}, map[string]string, bool) {
+	params := make(map[string]string)
+
+	curNode := t.node
+	for _, p := range splitPath(path) {
+		nextNode, ok := curNode.children[p]
+		if ok {
+			curNode = nextNode
+			continue
+		}
+		if len(curNode.children) == 0 {
+			if curNode.label != p {
+				// no matching path was found.
+				return nil, nil, false
+			}
+			break
+		}
+		isParamMatch := false
+		for c := range curNode.children {
+			if string([]rune(c)[0]) == leftPtnDelimiter {
+				ptn := getPattern(c)
+				t.rmu.RLock()
+				reg, ok := t.rcache[ptn]
+				t.rmu.RUnlock()
+				if !ok {
+					var err error
+					reg, err = regexp.Compile(ptn)
+					if err != nil {
+						return nil, nil, false
+					}
+					t.rmu.Lock()
+					t.rcache[ptn] = reg
+					t.rmu.Unlock()
+				}
+				if reg.Match([]byte(p)) {
+					pn := getParamName(c)
+					params[pn] = p
+					curNode = curNode.children[c]
+					isParamMatch = true
+					break
+				}
+				// no matching param was found.
+				return nil, nil, false
+			}
+		}
+		if !isParamMatch {
+			return nil, nil, false
+		}
+	}
+	if path == pathRoot {
+		if len(curNode.actions) == 0 {
+			return nil, nil, false
+		}
+	}
+
+	handler, ok := curNode.actions[method]
+	if !ok || handler == nil {
+		return nil, nil, false
+	}
+	return handler, params, true
+}
+
+// getPattern gets a pattern from a label
+// {id:[^\d+$]} -> ^\d+$
+// {id}         -> (.+)
+func getPattern(label string) string {
+	leftI := strings.Index(label, leftPtnDelimiter)
+	rightI := strings.Index(label, paramDelimiter)
+	// if label doesn't have any pattern, return wild card pattern as default.
+	if leftI == -1 || rightI == -1 {
+		return ptnWildcard
+	}
+	return label[rightI+1 : len(label)-1]
+}
+
+// getParamName gets a parameter from a label
+// {id:[^\d+$]} -> id
+// {id}         -> id
+func getParamName(label string) string {
+	leftI := strings.Index(label, leftPtnDelimiter)
+	rightI := func(l string) int {
+		r := []rune(l)
+
+		var n int
+
+	loop:
+		for i := 0; i < len(r); i++ {
+			n = i
+			switch string(r[i]) {
+			case paramDelimiter:
+				n = i
+				break loop
+			case rightPtnDelimiter:
+				n = i
+				break loop
+			}
+
+			if i == len(r)-1 {
+				n = i + 1
+				break loop
+			}
+		}
+
+		return n
+	}(label)
+
+	return label[leftI+1 : rightI]
+}
+
+// splitPath removes an empty value in slice.
+func splitPath(path string) []string {
+	s := strings.Split(path, pathDelimiter)
+	var r []string
+	for _, str := range s {
+		if str != "" {
+			r = append(r, str)
+		}
+	}
+	return r
+}

util/http/trie_test.go

@@ -0,0 +1,42 @@
+package http
+
+import (
+	"net/http"
+	"testing"
+)
+
+func TestTrieNoMatchMethod(t *testing.T) {
+	tr := NewTrie()
+	tr.Insert([]string{http.MethodPut}, "/v1/create/{id}", nil)
+
+	_, _, ok := tr.Search(http.MethodPost, "/v1/create")
+	if ok {
+		t.Fatalf("must be not found error")
+	}
+}
+
+type handler struct{}
+
+func TestTrieMatchRegexp(t *testing.T) {
+	tr := NewTrie()
+	tr.Insert([]string{http.MethodPut}, "/v1/create/{category}/{id:[0-9]+}", &handler{})
+
+	_, params, ok := tr.Search(http.MethodPut, "/v1/create/test_cat/12345")
+	if !ok {
+		t.Fatalf("route not found")
+	} else if len(params) != 2 {
+		t.Fatalf("param matching error %v", params)
+	} else if params["category"] != "test_cat" {
+		t.Fatalf("param matching error %v", params)
+	}
+}
+
+func TestTrieMatchRegexpFail(t *testing.T) {
+	tr := NewTrie()
+	tr.Insert([]string{http.MethodPut}, "/v1/create/{id:[a-z]+}", &handler{})
+
+	_, _, ok := tr.Search(http.MethodPut, "/v1/create/12345")
+	if ok {
+		t.Fatalf("route must not be not found")
+	}
+}