Initial commit

README.md

@@ -1 +1,15 @@
-# interfacebloat
+# interfacebloat
+
+A linter that checks length of interface.
+
+## Install
+
+```
+go install github.com/sashamelentyev/interfacebloat
+```
+
+## Examples
+
+```bash
+interfacebloat ./...
+```

go.mod

@@ -0,0 +1,13 @@
+module github.com/sashamelentyev/interfacebloat
+
+go 1.18
+
+require (
+	github.com/sashamelentyev/usestdlibvars v1.7.0
+	golang.org/x/tools v0.1.12
+)
+
+require (
+	golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4 // indirect
+	golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f // indirect
+)

go.sum

@@ -0,0 +1,8 @@
+github.com/sashamelentyev/usestdlibvars v1.7.0 h1:jjDzfl4RjcUWer1EwhNyipT+f+LL0HmcuGF0jDhb7sM=
+github.com/sashamelentyev/usestdlibvars v1.7.0/go.mod h1:BFt7b5mSVHaaa26ZupiNRV2ODViQBxZZVhtAxAJRrjs=
+golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4 h1:6zppjxzCulZykYSLyVDYbneBfbaBIQPYMevg0bEwv2s=
+golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
+golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f h1:v4INt8xihDGvnrfjMDVXGxw9wrfxYyCjk0KbXjhR55s=
+golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/tools v0.1.12 h1:VveCTK38A2rkS8ZqFY25HIDFscX5X9OoEhJd3quQmXU=
+golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=

main.go

@@ -0,0 +1,11 @@
+package main
+
+import (
+	"golang.org/x/tools/go/analysis/singlechecker"
+
+	"github.com/sashamelentyev/usestdlibvars/pkg/analyzer"
+)
+
+func main() {
+	singlechecker.Main(analyzer.New())
+}

pkg/analyzer/analyzer.go

@@ -0,0 +1,65 @@
+package analyzer
+
+import (
+	"flag"
+	"go/ast"
+	"go/token"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+const InterfaceLenFlag = "interface-len"
+
+const defaultInterfaceLen = 10
+
+// New returns new interfacebloat analyzer.
+func New() *analysis.Analyzer {
+	return &analysis.Analyzer{
+		Name:     "interfacebloat",
+		Doc:      "A linter that checks length of interface.",
+		Run:      run,
+		Flags:    flags(),
+		Requires: []*analysis.Analyzer{inspect.Analyzer},
+	}
+}
+
+func flags() flag.FlagSet {
+	flags := flag.NewFlagSet("", flag.ExitOnError)
+	flags.Int(InterfaceLenFlag, 10, "length of interface")
+	return *flags
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	insp := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	filter := []ast.Node{
+		(*ast.InterfaceType)(nil),
+	}
+
+	insp.Preorder(filter, func(node ast.Node) {
+		i, ok := node.(*ast.InterfaceType)
+		if !ok {
+			return
+		}
+		interfaceLen := interfaceLen(pass, InterfaceLenFlag)
+		if len(i.Methods.List) > interfaceLen {
+			report(pass, node.Pos(), interfaceLen)
+		}
+	})
+
+	return nil, nil
+}
+
+func interfaceLen(pass *analysis.Pass, name string) (interfaceLen int) {
+	interfaceLen, ok := pass.Analyzer.Flags.Lookup(name).Value.(flag.Getter).Get().(int)
+	if !ok {
+		interfaceLen = defaultInterfaceLen
+	}
+	return
+}
+
+func report(pass *analysis.Pass, pos token.Pos, interfaceLen int) {
+	pass.Reportf(pos, `length of interface greater than %d`, interfaceLen)
+}

pkg/analyzer/analyzer_test.go

@@ -0,0 +1,17 @@
+package analyzer
+
+import (
+	"testing"
+
+	"golang.org/x/tools/go/analysis/analysistest"
+)
+
+func TestUseStdlibVars(t *testing.T) {
+	pkgs := []string{
+		"a",
+	}
+
+	analyzer := New()
+
+	analysistest.Run(t, analysistest.TestData(), analyzer, pkgs...)
+}

pkg/analyzer/testdata/src/a/a.go

@@ -0,0 +1,47 @@
+package a
+
+type _ interface { // want "length of interface greater than 10"
+	a()
+	b()
+	c()
+	d()
+	f()
+	g()
+	h()
+	i()
+	j()
+	k()
+	l()
+}
+
+func _() {
+	var _ interface { // want "length of interface greater than 10"
+		a()
+		b()
+		c()
+		d()
+		f()
+		g()
+		h()
+		i()
+		j()
+		k()
+		l()
+	}
+}
+
+func __() interface { // want "length of interface greater than 10"
+	a()
+	b()
+	c()
+	d()
+	f()
+	g()
+	h()
+	i()
+	j()
+	k()
+	l()
+} {
+	return nil
+}