Xpath scraping from URL (#285)

* Add xpath performer and scene scraping

* Add studio scraping

* Refactor code

* Fix compile error

* Don't overwrite performer URL during a scrape

vendor/github.com/antchfx/htmlquery/cache.go

@@ -0,0 +1,40 @@
+package htmlquery
+
+import (
+	"sync"
+
+	"github.com/golang/groupcache/lru"
+
+	"github.com/antchfx/xpath"
+)
+
+// DisableSelectorCache will disable caching for the query selector if value is true.
+var DisableSelectorCache = false
+
+// SelectorCacheMaxEntries allows how many selector object can be caching. Default is 50.
+// Will disable caching if SelectorCacheMaxEntries <= 0.
+var SelectorCacheMaxEntries = 50
+
+var (
+	cacheOnce sync.Once
+	cache     *lru.Cache
+)
+
+func getQuery(expr string) (*xpath.Expr, error) {
+	if DisableSelectorCache || SelectorCacheMaxEntries <= 0 {
+		return xpath.Compile(expr)
+	}
+	cacheOnce.Do(func() {
+		cache = lru.New(50)
+	})
+	if v, ok := cache.Get(expr); ok {
+		return v.(*xpath.Expr), nil
+	}
+	v, err := xpath.Compile(expr)
+	if err != nil {
+		return nil, err
+	}
+	cache.Add(expr, v)
+	return v, nil
+
+}