1 files changed, 143 insertions, 0 deletions
diff --git a/tools/nogo/matchers.go b/tools/nogo/matchers.go
new file mode 100644
index 000000000..57a250501
--- /dev/null
+++ b/tools/nogo/matchers.go
@@ -0,0 +1,143 @@
+// Copyright 2019 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package nogo
+
+import (
+	"go/token"
+	"path/filepath"
+	"regexp"
+	"strings"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+type matcher interface {
+	ShouldReport(d analysis.Diagnostic, fs *token.FileSet) bool
+}
+
+// pathRegexps filters explicit paths.
+type pathRegexps struct {
+	expr []*regexp.Regexp
+
+	// include, if true, indicates that paths matching any regexp in expr
+	// match.
+	//
+	// If false, paths matching no regexps in expr match.
+	include bool
+}
+
+// buildRegexps builds a list of regular expressions.
+//
+// This will panic on error.
+func buildRegexps(prefix string, args ...string) []*regexp.Regexp {
+	result := make([]*regexp.Regexp, 0, len(args))
+	for _, arg := range args {
+		result = append(result, regexp.MustCompile(filepath.Join(prefix, arg)))
+	}
+	return result
+}
+
+// ShouldReport implements matcher.ShouldReport.
+func (p *pathRegexps) ShouldReport(d analysis.Diagnostic, fs *token.FileSet) bool {
+	fullPos := fs.Position(d.Pos).String()
+	for _, path := range p.expr {
+		if path.MatchString(fullPos) {
+			return p.include
+		}
+	}
+	return !p.include
+}
+
+// internalExcluded excludes specific internal paths.
+func internalExcluded(paths ...string) *pathRegexps {
+	return &pathRegexps{
+		expr:    buildRegexps(internalPrefix, paths...),
+		include: false,
+	}
+}
+
+// excludedExcluded excludes specific external paths.
+func externalExcluded(paths ...string) *pathRegexps {
+	return &pathRegexps{
+		expr:    buildRegexps(externalPrefix, paths...),
+		include: false,
+	}
+}
+
+// internalMatches returns a path matcher for internal packages.
+func internalMatches() *pathRegexps {
+	return &pathRegexps{
+		expr:    buildRegexps(internalPrefix, ".*"),
+		include: true,
+	}
+}
+
+// resultExcluded excludes explicit message contents.
+type resultExcluded []string
+
+// ShouldReport implements matcher.ShouldReport.
+func (r resultExcluded) ShouldReport(d analysis.Diagnostic, _ *token.FileSet) bool {
+	for _, str := range r {
+		if strings.Contains(d.Message, str) {
+			return false
+		}
+	}
+	return true // Not excluded.
+}
+
+// andMatcher is a composite matcher.
+type andMatcher struct {
+	first  matcher
+	second matcher
+}
+
+// ShouldReport implements matcher.ShouldReport.
+func (a *andMatcher) ShouldReport(d analysis.Diagnostic, fs *token.FileSet) bool {
+	return a.first.ShouldReport(d, fs) && a.second.ShouldReport(d, fs)
+}
+
+// and is a syntactic convension for andMatcher.
+func and(first matcher, second matcher) *andMatcher {
+	return &andMatcher{
+		first:  first,
+		second: second,
+	}
+}
+
+// anyMatcher matches everything.
+type anyMatcher struct{}
+
+// ShouldReport implements matcher.ShouldReport.
+func (anyMatcher) ShouldReport(analysis.Diagnostic, *token.FileSet) bool {
+	return true
+}
+
+// alwaysMatches returns an anyMatcher instance.
+func alwaysMatches() anyMatcher {
+	return anyMatcher{}
+}
+
+// neverMatcher will never match.
+type neverMatcher struct{}
+
+// ShouldReport implements matcher.ShouldReport.
+func (neverMatcher) ShouldReport(analysis.Diagnostic, *token.FileSet) bool {
+	return false
+}
+
+// disableMatches returns a neverMatcher instance.
+func disableMatches() neverMatcher {
+	return neverMatcher{}
+}