Update xpath dependency (#507)

vendor/github.com/antchfx/htmlquery/.travis.yml

@@ -1,9 +1,9 @@
 language: go
 
 go:
-  - 1.6
-  - 1.7
-  - 1.8
+  - 1.9.x
+  - 1.12.x
+  - 1.13.x
 
 install:
   - go get golang.org/x/net/html/charset

vendor/github.com/antchfx/htmlquery/README.md

@@ -10,7 +10,7 @@ Overview
 
 `htmlquery` is an XPath query package for HTML, lets you extract data or evaluate from HTML documents by an XPath expression.
 
-`htmlquery` build-in the query object caching feature based on [LRU](https://godoc.org/github.com/golang/groupcache/lru), this feature will caching the recently used XPATH query string. enable caching can avoid re-compile XPath expression each query. 
+`htmlquery` built-in the query object caching feature based on [LRU](https://godoc.org/github.com/golang/groupcache/lru), this feature will caching the recently used XPATH query string. Enable query caching can avoid re-compile XPath expression each query. 
 
 Installation
 ====
@@ -101,7 +101,17 @@ Yes, you can. We offer the `QuerySelector` and `QuerySelectorAll` methods, It wi
 
 Cache a query expression object(or reused) will avoid re-compile XPath query expression, improve your query performance.
 
-#### Disable caching feature
+#### XPath query object cache performance
+
+```
+goos: windows
+goarch: amd64
+pkg: github.com/antchfx/htmlquery
+BenchmarkSelectorCache-4                20000000                55.2 ns/op
+BenchmarkDisableSelectorCache-4           500000              3162 ns/op
+```
+
+#### How to disable caching?
 
 ```
 htmlquery.DisableSelectorCache = true

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

@@ -3,9 +3,8 @@ package htmlquery
 import (
 	"sync"
 
-	"github.com/golang/groupcache/lru"
-
 	"github.com/antchfx/xpath"
+	"github.com/golang/groupcache/lru"
 )
 
 // DisableSelectorCache will disable caching for the query selector if value is true.
@@ -16,8 +15,9 @@ var DisableSelectorCache = false
 var SelectorCacheMaxEntries = 50
 
 var (
-	cacheOnce sync.Once
-	cache     *lru.Cache
+	cacheOnce  sync.Once
+	cache      *lru.Cache
+	cacheMutex sync.Mutex
 )
 
 func getQuery(expr string) (*xpath.Expr, error) {
@@ -25,8 +25,10 @@ func getQuery(expr string) (*xpath.Expr, error) {
 		return xpath.Compile(expr)
 	}
 	cacheOnce.Do(func() {
-		cache = lru.New(50)
+		cache = lru.New(SelectorCacheMaxEntries)
 	})
+	cacheMutex.Lock()
+	defer cacheMutex.Unlock()
 	if v, ok := cache.Get(expr); ok {
 		return v.(*xpath.Expr), nil
 	}

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

@@ -0,0 +1,9 @@
+module github.com/antchfx/htmlquery
+
+go 1.14
+
+require (
+	github.com/antchfx/xpath v1.1.6
+	github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e
+	golang.org/x/net v0.0.0-20200421231249-e086a090c8fd
+)

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

@@ -0,0 +1,11 @@
+github.com/antchfx/xpath v1.1.6 h1:6sVh6hB5T6phw1pFpHRQ+C4bd8sNI+O58flqtg7h0R0=
+github.com/antchfx/xpath v1.1.6/go.mod h1:Yee4kTMuNiPYJ7nSNorELQMr1J33uOpXDMByNYhvtNk=
+github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e h1:1r7pUrabqp18hOBcwBwiTsbnFeTZHV9eER/QT5JVZxY=
+github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/net v0.0.0-20200421231249-e086a090c8fd h1:QPwSajcTUrFriMF1nJ3XzgoqakqQEsnZf9LdXdi2nkI=
+golang.org/x/net v0.0.0-20200421231249-e086a090c8fd/go.mod h1:qpuaurCH72eLCgpAm/N6yyVIVM9cpaDIP3A8BGJEC5A=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=