Add linting, fix linting issues

.travis.yml

@@ -1,8 +1,13 @@
 language: go
 
-install: go get golang.org/x/tools/imports/...
+install:
+    - go get golang.org/x/tools/imports/...
+    - wget -qO- https://github.com/golangci/golangci-lint/releases/download/v1.3.7/golangci-lint-1.3.7-linux-amd64.tar.gz | tar xvz --strip 1 golangci-lint-1.3.7-linux-amd64/golangci-lint
 
-script: go test -v ./...
+script:
+    - GOVERSION=$(go version | awk '{ print $3 }')
+    - test $GOVERSION = "devel" || ./golangci-lint run -v ./...
+    - go test -v ./...
 
 go:
     - 1.7.x

ast/ast.go

@@ -501,18 +501,18 @@ outer:
 		consumeN := 0
 		switch rn {
 		case '\\':
-			rn, _, _ := r.ReadRune()
+			rn, _, _ := r.ReadRune() // nolint: gas
 			switch rn {
 			case ']':
 				chars = append(chars, rn)
 				continue
 
 			case 'p':
-				rn, _, _ := r.ReadRune()
+				rn, _, _ := r.ReadRune() // nolint: gas
 				if rn == '{' {
 					buf.Reset()
 					for {
-						rn, _, _ := r.ReadRune()
+						rn, _, _ := r.ReadRune() // nolint: gas
 						if rn == '}' {
 							break
 						}
@@ -537,7 +537,7 @@ outer:
 			buf.Reset()
 			buf.WriteRune(rn)
 			for i := 0; i < consumeN; i++ {
-				rn, _, _ := r.ReadRune()
+				rn, _, _ := r.ReadRune() // nolint: gas
 				buf.WriteRune(rn)
 			}
 			rn, _, _, _ = strconv.UnquoteChar("\\"+buf.String(), 0)

ast/ast_optimize.go

@@ -68,7 +68,7 @@ func set(m map[string]map[string]struct{}, src, dst string) {
 // optimize is a Visitor, which is used with the Walk function
 // The purpose of this function is to perform the actual optimizations.
 // See Optimize for a detailed list of the performed optimizations.
-func (r *grammarOptimizer) optimize(expr0 Expression) Visitor {
+func (r *grammarOptimizer) optimize(expr0 Expression) Visitor { // nolint: gocyclo
 	switch expr := expr0.(type) {
 	case *ActionExpr:
 		expr.Expr = r.optimizeRule(expr.Expr)

bootstrap/cmd/pegscan/main.go

@@ -13,7 +13,7 @@ import (
 
 func main() {
 	if len(os.Args) > 2 {
-		fmt.Fprintln(os.Stderr, "USAGE: pegscan FILE")
+		fmt.Fprintln(os.Stderr, "USAGE: pegscan FILE") // nolint: gas
 		os.Exit(1)
 	}
 

builder/static_code.go

@@ -317,11 +317,11 @@ type expr struct {
 	expr interface{}
 }
 
-type andExpr expr //{{ if .Nolint }} nolint: structcheck {{else}} ==template== {{ end }}
-type notExpr expr //{{ if .Nolint }} nolint: structcheck {{else}} ==template== {{ end }}
-type zeroOrOneExpr expr //{{ if .Nolint }} nolint: structcheck {{else}} ==template== {{ end }}
+type andExpr expr        //{{ if .Nolint }} nolint: structcheck {{else}} ==template== {{ end }}
+type notExpr expr        //{{ if .Nolint }} nolint: structcheck {{else}} ==template== {{ end }}
+type zeroOrOneExpr expr  //{{ if .Nolint }} nolint: structcheck {{else}} ==template== {{ end }}
 type zeroOrMoreExpr expr //{{ if .Nolint }} nolint: structcheck {{else}} ==template== {{ end }}
-type oneOrMoreExpr expr //{{ if .Nolint }} nolint: structcheck {{else}} ==template== {{ end }}
+type oneOrMoreExpr expr  //{{ if .Nolint }} nolint: structcheck {{else}} ==template== {{ end }}
 
 //{{ if .Nolint }} nolint: structcheck {{else}} ==template== {{ end }}
 type ruleRefExpr struct {
@@ -475,7 +475,6 @@ func (p *parser) setOptions(opts []Option) {
 	}
 }
 
-
 //{{ if .Nolint }} nolint: structcheck,deadcode {{else}} ==template== {{ end }}
 type resultTuple struct {
 	v   interface{}

misc/cmd/unicode-classes/main.go

@@ -36,19 +36,3 @@ func main() {
 	}
 	fmt.Println("}")
 }
-
-// lenSorter was used to generate Unicode classes directly in the PEG
-// grammar (where longer classes had to come first).
-type lenSorter []string
-
-func (l lenSorter) Len() int      { return len(l) }
-func (l lenSorter) Swap(i, j int) { l[i], l[j] = l[j], l[i] }
-func (l lenSorter) Less(i, j int) bool {
-	li, lj := len(l[i]), len(l[j])
-	if lj < li {
-		return true
-	} else if li < lj {
-		return false
-	}
-	return l[j] < l[i]
-}