heuristics regexp engine configurable #3, adapt IsVendor optimization & tests

Regex collation optimization for IsVendor now fails gracefully.
Tests that are affected by non-RE2 syntax are explicitly marked.

internal/code-generator/assets/vendor.go.tmpl

@@ -2,15 +2,21 @@ package data
 
 import "github.com/go-enry/go-enry/v2/regex"
 
+{{define "mustCompile" -}}
+	{{ if isRE2 .  -}}
+		regex.MustCompile({{ . | stringVal }})
+	{{- else -}}
+		regex.MustCompileRuby({{ . | stringVal }})
+	{{- end -}}
+{{end}}
+
 var VendorMatchers = []regex.EnryRegexp{
 	{{range $re := . -}}
-	{{ if isRE2 $re  -}}
-		regex.MustCompile({{ $re | stringVal }}),
-	{{- else -}}
-		regex.MustCompileRuby({{ $re | stringVal }}),
-	{{ end }}
+		{{ template "mustCompile" $re }},
 	{{end -}}
 }
 
 // FastVendorMatcher is equivalent to matching any of the VendorMatchers.
-var FastVendorMatcher = regex.MustCompile(`{{ optimize . }}`)
+{{with $singleRE := collateAllRegexps . -}}
+var FastVendorMatcher = {{template "mustCompile" $singleRE}}
+{{end}}

internal/code-generator/generator/vendor.go

@@ -41,34 +41,14 @@ func Vendor(fileToParse, samplesDir, outPath, tmplPath, tmplName, commit string)
 }
 
 func executeVendorTemplate(out io.Writer, regexps []string, tmplPath, tmplName, commit string) error {
-	funcs := template.FuncMap{"optimize": collateAllMatchers}
+	funcs := template.FuncMap{"collateAllRegexps": collateAllRegexps}
 	return executeTemplate(out, tmplName, tmplPath, commit, funcs, regexps)
 }
 
-func collateAllMatchers(regexps []string) string {
-	// We now collate all regexps from VendorMatchers to a single large regexp
+// collateAllRegexps all regexps to a single large regexp.
+func collateAllRegexps(regexps []string) string {
 	// which is at least twice as fast to test than simply iterating & matching.
 	//
-	// ---
-	//
-	// We could test each matcher from VendorMatchers in turn i.e.
-	//
-	//  	func IsVendor(filename string) bool {
-	// 			for _, matcher := range data.VendorMatchers {
-	// 				if matcher.MatchString(filename) {
-	//					return true
-	//				}
-	//			}
-	//			return false
-	//		}
-	//
-	// Or naïvely concatentate all these regexps using groups i.e.
-	//
-	//		`(regexp1)|(regexp2)|(regexp3)|...`
-	//
-	// However, both of these are relatively slow and don't take advantage
-	// of the inherent structure within our regexps.
-	//
 	// Imperical observation: by looking at the regexps, we only have 3 types.
 	//  1. Those that start with `^`
 	//  2. Those that start with `(^|/)`
@@ -88,12 +68,9 @@ func collateAllMatchers(regexps []string) string {
 
 	sort.Strings(regexps)
 
+	// Check prefix, group expressions
 	var caretPrefixed, caretOrSlashPrefixed, theRest []string
-	// Check prefix, add to the respective group slices
 	for _, re := range regexps {
-		if !isRE2(re) {
-			continue
-		}
 		if strings.HasPrefix(re, caret) {
 			caretPrefixed = append(caretPrefixed, re[len(caret):])
 		} else if strings.HasPrefix(re, caretOrSlash) {
@@ -102,6 +79,7 @@ func collateAllMatchers(regexps []string) string {
 			theRest = append(theRest, re)
 		}
 	}
+
 	var sb strings.Builder
 	appendGroupWithCommonPrefix(&sb, "^", caretPrefixed)
 	sb.WriteString("|")

utils.go

@@ -63,7 +63,21 @@ func IsDotFile(path string) bool {
 
 // IsVendor returns whether or not path is a vendor path.
 func IsVendor(path string) bool {
-	return data.FastVendorMatcher.MatchString(path)
+	// fast path: single collatated regex, if the engine supports its syntax
+	if data.FastVendorMatcher != nil {
+		return data.FastVendorMatcher.MatchString(path)
+	}
+
+	// slow path: skip individual rules with unsupported syntax
+	for _, matcher := range data.VendorMatchers {
+		if matcher == nil {
+			continue
+		}
+		if matcher.MatchString(path) {
+			return true
+		}
+	}
+	return false
 }
 
 // IsTest returns whether or not path is a test path.

utils_test.go

@@ -7,57 +7,62 @@ import (
 	"path/filepath"
 	"testing"
 
+	"github.com/go-enry/go-enry/v2/regex"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
-//TODO(bzz): port all from test/test_file_blob.rb test_vendored()
-//https://github.com/github/linguist/blob/86adc140d3e8903980565a2984f5532edf4ae875/test/test_file_blob.rb#L270-L583
+// TODO(bzz): port all from test/test_file_blob.rb test_vendored()
+// https://github.com/github/linguist/blob/86adc140d3e8903980565a2984f5532edf4ae875/test/test_file_blob.rb#L270-L583
 var vendorTests = []struct {
-	path     string
-	expected bool
+	skipOnRE2 bool // some rules are (present in code but) missing at runtime on RE2
+	path      string
+	expected  bool
 }{
-	{"cache/", true},
-	{"something_cache/", false},
-	{"random/cache/", true},
-	{"cache", false},
-	{"dependencies/", true},
-	{"Dependencies/", true},
-	{"dependency/", false},
-	{"dist/", true},
-	{"dist", false},
-	{"random/dist/", true},
-	{"random/dist", false},
-	{"deps/", true},
-	{"foodeps/", false},
-	{"configure", true},
-	{"a/configure", true},
-	{"config.guess", true},
-	{"config.guess/", false},
-	{".vscode/", true},
-	{"doc/_build/", true},
-	{"a/docs/_build/", true},
-	{"a/dasdocs/_build-vsdoc.js", true},
-	{"a/dasdocs/_build-vsdoc.j", false},
-	{"foo/bar", false},
-	{".sublime-project", true},
-	{"foo/vendor/foo", true},
-	{"leaflet.draw-src.js", true},
-	{"foo/bar/MochiKit.js", true},
-	{"foo/bar/dojo.js", true},
-	{"foo/env/whatever", true},
-	{"some/python/venv/", false},
-	{"foo/.imageset/bar", true},
-	{"Vagrantfile", true},
-	{"src/bootstrap-custom.js", true},
-	// {"/css/bootstrap.rtl.css", true}, // from linguist v7.23
+	{path: "cache/", expected: true},
+	{false, "something_cache/", false},
+	{false, "random/cache/", true},
+	{false, "cache", false},
+	{false, "dependencies/", true},
+	{false, "Dependencies/", true},
+	{false, "dependency/", false},
+	{false, "dist/", true},
+	{false, "dist", false},
+	{false, "random/dist/", true},
+	{false, "random/dist", false},
+	{false, "deps/", true},
+	{false, "foodeps/", false},
+	{false, "configure", true},
+	{false, "a/configure", true},
+	{false, "config.guess", true},
+	{false, "config.guess/", false},
+	{false, ".vscode/", true},
+	{false, "doc/_build/", true},
+	{false, "a/docs/_build/", true},
+	{false, "a/dasdocs/_build-vsdoc.js", true},
+	{false, "a/dasdocs/_build-vsdoc.j", false},
+	{false, "foo/bar", false},
+	{false, ".sublime-project", true},
+	{false, "foo/vendor/foo", true},
+	{false, "leaflet.draw-src.js", true},
+	{false, "foo/bar/MochiKit.js", true},
+	{false, "foo/bar/dojo.js", true},
+	{false, "foo/env/whatever", true},
+	{false, "some/python/venv/", false},
+	{false, "foo/.imageset/bar", true},
+	{false, "Vagrantfile", true},
+	{true, "src/bootstrap-custom.js", true},
+	// {true, "/css/bootstrap.rtl.css", true}, // from linguist v7.23
 }
 
 func TestIsVendor(t *testing.T) {
-	for _, tt := range vendorTests {
-		t.Run(tt.path, func(t *testing.T) {
-			if got := IsVendor(tt.path); got != tt.expected {
-				t.Errorf("IsVendor(%q) = %v, expected %v", tt.path, got, tt.expected)
+	for _, test := range vendorTests {
+		t.Run(test.path, func(t *testing.T) {
+			if got := IsVendor(test.path); got != test.expected {
+				if regex.Name == regex.RE2 && test.skipOnRE2 {
+					return // skip
+				}
+				t.Errorf("IsVendor(%q) = %v, expected %v (usuing %s)", test.path, got, test.expected, regex.Name)
 			}
 		})
 	}