feat: implement extensible model

.gitignore

@@ -1 +1,3 @@
 golinter
+vendor
+

defaultrules/no-else-return-rule.go

@@ -0,0 +1,56 @@
+package defaultrules
+
+import (
+	"go/ast"
+	"go/token"
+
+	"github.com/mgechev/golinter/file"
+	"github.com/mgechev/golinter/rules"
+	"github.com/mgechev/golinter/visitors"
+)
+
+const ruleName = "no-else-return"
+
+// LintElseRule lints given else constructs.
+type LintElseRule struct {
+	rules.Rule
+}
+
+// Apply applies the rule to given file.
+func (r *LintElseRule) Apply(file *file.File, arguments rules.RuleArguments) []rules.Failure {
+	res := &lintElseVisitor{}
+	visitors.Setup(res, rules.RuleConfig{Name: ruleName, Arguments: arguments}, file)
+	res.Visit(file.GetAST())
+	return res.GetFailures()
+}
+
+type lintElseVisitor struct {
+	visitors.RuleVisitor
+}
+
+func (w *lintElseVisitor) VisitIfStmt(node *ast.IfStmt) {
+	if node.Else == nil {
+		return
+	}
+	if _, ok := node.Else.(*ast.BlockStmt); !ok {
+		// only care about elses without conditions
+		return
+	}
+	if len(node.Body.List) == 0 {
+		return
+	}
+	// shortDecl := false // does the if statement have a ":=" initialization statement?
+	if node.Init != nil {
+		if as, ok := node.Init.(*ast.AssignStmt); ok && as.Tok == token.DEFINE {
+			// shortDecl = true
+		}
+	}
+	lastStmt := node.Body.List[len(node.Body.List)-1]
+	if _, ok := lastStmt.(*ast.ReturnStmt); ok {
+		w.AddFailure(rules.Failure{
+			Failure:  "if block ends with a return statement, so drop this else and outdent its block",
+			Type:     rules.FailureTypeWarning,
+			Position: w.GetPosition(node.Else.Pos(), node.Else.End()),
+		})
+	}
+}

file/file.go

@@ -0,0 +1,39 @@
+package file
+
+import (
+	"go/ast"
+	"go/parser"
+	"go/token"
+)
+
+// File abstraction used for representing files.
+type File struct {
+	Name    string
+	files   *token.FileSet
+	Content []byte
+	ast     *ast.File
+}
+
+// New creates a new file
+func New(name string, content []byte, files *token.FileSet) (*File, error) {
+	f, err := parser.ParseFile(files, name, content, parser.ParseComments)
+	if err != nil {
+		return nil, err
+	}
+	return &File{
+		Name:    name,
+		Content: content,
+		files:   files,
+		ast:     f,
+	}, nil
+}
+
+// ToPosition returns line and column for given position.
+func (f *File) ToPosition(pos token.Pos) token.Position {
+	return f.files.Position(pos)
+}
+
+// GetAST returns the AST of the file
+func (f *File) GetAST() *ast.File {
+	return f.ast
+}

formatters/cli_formatter.go

@@ -0,0 +1,78 @@
+package formatters
+
+import (
+	"bytes"
+	"fmt"
+
+	"github.com/mgechev/golinter/rules"
+	"github.com/olekukonko/tablewriter"
+	"github.com/ttacon/chalk"
+)
+
+const (
+	errorEmoji   = ""
+	warningEmoji = ""
+)
+
+// CLIFormatter is an implementation of the Formatter interface
+// which formats the errors to JSON.
+type CLIFormatter struct {
+	Metadata FormatterMetadata
+}
+
+func formatFailure(failure rules.Failure) []string {
+	fString := chalk.Blue.Color(failure.Failure)
+	fTypeStr := string(failure.Type)
+	fType := chalk.Red.Color(fTypeStr)
+	lineColumn := failure.Position
+	pos := chalk.Dim.TextStyle(fmt.Sprintf("(%d, %d)", lineColumn.Start.Line, lineColumn.Start.Column))
+	if failure.Type == rules.FailureTypeWarning {
+		fType = chalk.Yellow.Color(fTypeStr)
+	}
+	return []string{failure.GetFilename(), pos, fType, fString}
+}
+
+// Format formats the failures gotten from the linter.
+func (f *CLIFormatter) Format(failures []rules.Failure) (string, error) {
+	var result [][]string
+	var totalErrors = 0
+	for _, f := range failures {
+		result = append(result, formatFailure(f))
+		if f.Type == rules.FailureTypeError {
+			totalErrors++
+		}
+	}
+	total := len(failures)
+	ps := "problems"
+	if total == 1 {
+		ps = "problem"
+	}
+
+	fileReport := make(map[string][][]string)
+
+	for _, row := range result {
+		if _, ok := fileReport[row[0]]; !ok {
+			fileReport[row[0]] = [][]string{}
+		}
+
+		fileReport[row[0]] = append(fileReport[row[0]], []string{row[1], row[2], row[3]})
+	}
+
+	output := ""
+	for filename, val := range fileReport {
+		buf := new(bytes.Buffer)
+		table := tablewriter.NewWriter(buf)
+		table.SetBorder(false)
+		table.SetColumnSeparator("")
+		table.SetRowSeparator("")
+		table.SetAutoWrapText(false)
+		table.AppendBulk(val)
+		table.Render()
+		output += chalk.Dim.TextStyle(chalk.Underline.TextStyle(filename) + "\n")
+		output += buf.String() + "\n"
+	}
+
+	suffix := fmt.Sprintf("\n ✖ %d %s (%d errors) (%d warnings)", total, ps, totalErrors, total-totalErrors)
+
+	return output + suffix, nil
+}

formatters/formatter.go

@@ -1,13 +1,15 @@
 package formatters
 
-import "github.com/mgechev/golinter/visitors"
+import "github.com/mgechev/golinter/rules"
 
+// FormatterMetadata configuration of a formatter
 type FormatterMetadata struct {
 	Name        string
 	Description string
 	Sample      string
 }
 
+// Formatter defines an interface for failure formatters
 type Formatter interface {
-	Format([]visitors.Failure) string
+	Format([]rules.Failure) string
 }

formatters/json_formatter.go

@@ -0,0 +1,22 @@
+package formatters
+
+import (
+	"encoding/json"
+
+	"github.com/mgechev/golinter/rules"
+)
+
+// JSONFormatter is an implementation of the Formatter interface
+// which formats the errors to JSON.
+type JSONFormatter struct {
+	Metadata FormatterMetadata
+}
+
+// Format formats the failures gotten from the linter.
+func (f *JSONFormatter) Format(failures []rules.Failure) (string, error) {
+	result, error := json.Marshal(failures)
+	if error != nil {
+		return "", error
+	}
+	return string(result), nil
+}

formatters/jsonformatter.go

@@ -1,22 +0,0 @@
-package formatters
-
-import "github.com/mgechev/golinter/visitors"
-import "encoding/json"
-
-type JSONFormatter struct {
-	Metadata FormatterMetadata
-}
-
-// {
-//   Name: "JSON Formatter",
-//   Description: "This formatter produces JSON from the errors",
-//   Sample: "[{ \"position\": 10, \"failure\": \"Forbidden semicolon\" }]"
-// }
-
-func (f *JSONFormatter) Format(failures []visitors.Failure) (string, error) {
-	result, error := json.Marshal(failures)
-	if error != nil {
-		return "", error
-	}
-	return string(result), nil
-}

glide.lock

@@ -0,0 +1,10 @@
+hash: e7fa4d774614236f030e76f8adab9e29c97c0cfc9782e0cffb9c9df47be0e60e
+updated: 2017-08-27T19:03:09.172223776-07:00
+imports:
+- name: github.com/mattn/go-runewidth
+  version: 9e777a8366cce605130a531d2cd6363d07ad7317
+- name: github.com/olekukonko/tablewriter
+  version: be5337e7b39e64e5f91445ce7e721888dbab7387
+- name: github.com/ttacon/chalk
+  version: 76b3c8b611dea8f83e49e9ce81fc2b189e0ef3d2
+testImports: []

glide.yaml

@@ -0,0 +1,7 @@
+package: github.com/mgechev/golinter
+import:
+- package: github.com/ttacon/chalk
+  version: ~0.1.0
+- package: github.com/olekukonko/tablewriter
+- package: github.com/mattn/go-runewidth
+  version: ~0.0.2

linter/linter.go

@@ -0,0 +1,45 @@
+package linter
+
+import (
+	"go/token"
+
+	"github.com/mgechev/golinter/file"
+	"github.com/mgechev/golinter/rules"
+)
+
+// ReadFile defines an abstraction for reading files.
+type ReadFile func(path string) (result []byte, err error)
+
+// Linter is used for lintign set of files.
+type Linter struct {
+	reader ReadFile
+}
+
+// New creates a new Linter
+func New(reader ReadFile) Linter {
+	return Linter{reader: reader}
+}
+
+// Lint lints a set of files with the specified rules.
+func (l *Linter) Lint(filenames []string, ruleSet []rules.Rule) ([]rules.Failure, error) {
+	var fileSet token.FileSet
+	var failures []rules.Failure
+	for _, filename := range filenames {
+		content, err := l.reader(filename)
+		if err != nil {
+			return nil, err
+		}
+		file, err := file.New(filename, content, &fileSet)
+
+		if err != nil {
+			return nil, err
+		}
+
+		for _, rule := range ruleSet {
+			currentFailures := rule.Apply(file, []string{})
+			failures = append(failures, currentFailures...)
+		}
+	}
+
+	return failures, nil
+}

main.go

@@ -2,52 +2,42 @@ package main
 
 import (
 	"fmt"
-	"go/ast"
-	"go/parser"
-	"go/token"
 
-	"github.com/mgechev/golinter/syntaxvisitor"
+	"github.com/mgechev/golinter/defaultrules"
+	"github.com/mgechev/golinter/formatters"
+	"github.com/mgechev/golinter/linter"
+	"github.com/mgechev/golinter/rules"
 )
 
-type CustomLinter struct {
-	syntaxvisitor.SyntaxVisitor
-}
-
-func (w *CustomLinter) VisitIdent(node *ast.Ident) {
-	fmt.Println("Child", node.Name)
-}
-
-// This example demonstrates how to inspect the AST of a Go program.
-func ExampleInspect() {
-	// src is the input for which we want to inspect the AST.
+func main() {
 	src := `
   package p
-  const c = 1.0
-  var X = f(3.14)*2 + c
+
+  func Test() {
+    if true {
+      return 42;
+    } else {
+      return 23;
+    }
+  }
   `
 
-	// Create the AST by parsing src.
-	fset := token.NewFileSet() // positions are relative to fset
-	f, err := parser.ParseFile(fset, "src.go", src, 0)
+	linter := linter.New(func(file string) ([]byte, error) {
+		return []byte(src), nil
+	})
+	var result []rules.Rule
+	result = append(result, &defaultrules.LintElseRule{})
+
+	failures, err := linter.Lint([]string{"foo.go", "bar.go", "baz.go"}, result)
 	if err != nil {
 		panic(err)
 	}
 
-	var visitor CustomLinter
-	visitor.SyntaxVisitor.Impl = &visitor
-	visitor.Visit(f)
+	var formatter formatters.CLIFormatter
+	output, err := formatter.Format(failures)
+	if err != nil {
+		panic(err)
+	}
 
-	// output:
-	// src.go:2:9:	p
-	// src.go:3:7:	c
-	// src.go:3:11:	1.0
-	// src.go:4:5:	X
-	// src.go:4:9:	f
-	// src.go:4:11:	3.14
-	// src.go:4:17:	2
-	// src.go:4:21:	c
-}
-
-func main() {
-	ExampleInspect()
+	fmt.Println(output)
 }

rules/rule.go

@@ -0,0 +1,49 @@
+package rules
+
+import (
+	"go/token"
+
+	"github.com/mgechev/golinter/file"
+)
+
+const (
+	// FailureTypeWarning declares failures of type warning
+	FailureTypeWarning = "warning"
+	// FailureTypeError declares failures of type error.
+	FailureTypeError = "error"
+)
+
+// FailureType is the type for the failure types.
+type FailureType string
+
+// Failure defines a struct for a linting failure.
+type Failure struct {
+	Failure  string
+	Type     FailureType
+	Position FailurePosition
+	file     *file.File
+}
+
+// GetFilename returns the filename.
+func (f *Failure) GetFilename() string {
+	return f.Position.Start.Filename
+}
+
+// FailurePosition returns the failure position
+type FailurePosition struct {
+	Start token.Position
+	End   token.Position
+}
+
+// RuleArguments is type used for the arguments of a rule.
+type RuleArguments []string
+
+type RuleConfig struct {
+	Name      string
+	Arguments RuleArguments
+}
+
+// Rule defines an abstract rule.
+type Rule interface {
+	Apply(file *file.File, args RuleArguments) []Failure
+}

visitors/rule_visitor.go

@@ -0,0 +1,37 @@
+package visitors
+
+import (
+	"go/token"
+
+	"github.com/mgechev/golinter/file"
+	"github.com/mgechev/golinter/rules"
+)
+
+// RuleVisitor defines a struct for a visitor.
+type RuleVisitor struct {
+	SyntaxVisitor
+	RuleName      string
+	RuleArguments rules.RuleArguments
+	failures      []rules.Failure
+	File          *file.File
+}
+
+// AddFailure adds a failure to the ist of failures.
+func (w *RuleVisitor) AddFailure(failure rules.Failure) {
+	w.failures = append(w.failures, failure)
+}
+
+// GetFailures returns the list of failures.
+func (w *RuleVisitor) GetFailures() []rules.Failure {
+	return w.failures
+}
+
+// GetPosition returns position by given start and end token.Pos.
+func (w *RuleVisitor) GetPosition(start token.Pos, end token.Pos) rules.FailurePosition {
+	s := w.File.ToPosition(start)
+	e := w.File.ToPosition(end)
+	return rules.FailurePosition{
+		Start: s,
+		End:   e,
+	}
+}

visitors/rulevisitor.go

@@ -1,35 +0,0 @@
-package visitors
-
-import (
-	"go/token"
-)
-
-type RuleArguments []string
-
-const DefaultLength = 1
-
-type Failure struct {
-	Failure  string
-	Position token.Pos
-}
-
-type RuleVisitor struct {
-	SyntaxVisitor
-	ruleName      string
-	ruleArguments RuleArguments
-	failures      []Failure
-}
-
-func New(ruleName string, ruleArguments RuleArguments) *RuleVisitor {
-	result := RuleVisitor{ruleName: ruleName, ruleArguments: ruleArguments}
-	result.failures = make([]Failure, DefaultLength)
-	return &result
-}
-
-func (w *RuleVisitor) AddFailure(failure Failure) {
-	w.failures = append(w.failures, failure)
-}
-
-func (w *RuleVisitor) GetFailures() []Failure {
-	return w.failures
-}

visitors/setup.go

@@ -0,0 +1,27 @@
+package visitors
+
+import (
+	"errors"
+	"reflect"
+
+	"github.com/mgechev/golinter/file"
+	"github.com/mgechev/golinter/rules"
+)
+
+// Setup sets the proper pointers of given visitor.
+func Setup(v interface{}, conf rules.RuleConfig, file *file.File) error {
+	val := reflect.ValueOf(v).Elem()
+	field := val.FieldByName("RuleVisitor")
+	if !field.IsValid() {
+		return errors.New("invalid rule visitor")
+	}
+	field.Set(reflect.ValueOf(RuleVisitor{RuleName: conf.Name, RuleArguments: conf.Arguments, File: file}))
+
+	field = val.FieldByName("Impl")
+	if !field.IsValid() {
+		return errors.New("invalid rule visitor")
+	}
+	field.Set(reflect.ValueOf(v))
+
+	return nil
+}

visitors/syntax_visitor.go

@@ -5,10 +5,13 @@ import (
 	"go/ast"
 )
 
+// SyntaxVisitor implements a visitor which knows how to handle the individual
+// Go lang syntax constructs.
 type SyntaxVisitor struct {
 	Impl Visitor
 }
 
+// Visit accepts an ast.Node and traverse its children.
 func (w *SyntaxVisitor) Visit(node ast.Node) {
 	if node == nil {
 		return
@@ -181,6 +184,7 @@ func (w *SyntaxVisitor) Visit(node ast.Node) {
 	}
 }
 
+// VisitUnaryExpr visits an unary expression.
 func (w *SyntaxVisitor) VisitUnaryExpr(node *ast.UnaryExpr) {
 	w.Impl.Visit(node.X)
 }