[now-go] Ignore folders in analyze.go (#503)(#504) (#506)

* [now-go] Ignore folders in `analyze.go` (#503)(#504)

This commit adds some changes to the way the AST for the source is
built.

The `analyze.go` program now ignores every `vendor`, `.git` and
`testdata` folder. This improves performance, since `vendor` and `.git`
are usually large folders (#504).

By ignoring `testdata`, we mimick the behaviour of `go build` and avoid
failing the parsing because of invalid Go code inside of `testdata` (#503)

* [now-go] Don't ignore `.git` in analyze (#506)

If the user wants to ignore `.git`, he should put it into `.nowignore`

packages/now-go/util/analyze.go

@@ -10,9 +10,22 @@ import (
 	"log"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strings"
 )
 
+var ignoredFoldersRegex []*regexp.Regexp
+
+func init() {
+	ignoredFolders := []string{"vendor", "testdata"}
+
+	// Build the regex that matches if a path contains the respective ignored folder
+	// The pattern will look like: (.*/)?vendor/.*, which matches every path that contains a vendor folder
+	for _, folder := range ignoredFolders {
+		ignoredFoldersRegex = append(ignoredFoldersRegex, regexp.MustCompile("(.*/)?"+folder+"/.*"))
+	}
+}
+
 type analyze struct {
 	PackageName string   `json:"packageName"`
 	FuncName    string   `json:"functionName"`
@@ -40,8 +53,9 @@ func visit(files *[]string) filepath.WalkFunc {
 		}
 
 		// we don't need Dirs, or test files
-		// we only want `.go` files
-		if info.IsDir() || itf || filepath.Ext(path) != ".go" {
+		// we only want `.go` files. Further, we ignore
+		// every file that is in one of the ignored folders.
+		if info.IsDir() || itf || filepath.Ext(path) != ".go" || isInIgnoredFolder(path) {
 			return nil
 		}
 
@@ -50,6 +64,19 @@ func visit(files *[]string) filepath.WalkFunc {
 	}
 }
 
+// isInIgnoredFolder checks if the given path is in one of the ignored folders.
+func isInIgnoredFolder(path string) bool {
+	// Make sure the regex works for Windows paths
+	path = filepath.ToSlash(path)
+
+	for _, pattern := range ignoredFoldersRegex {
+		if pattern.MatchString(path) {
+			return true
+		}
+	}
+	return false
+}
+
 // return unique file
 func unique(files []string) []string {
 	encountered := map[string]bool{}