Follow golangci-lint

11 files changed, 36 insertions, 103 deletions

diff --git a/cmd/vartan/show.go b/cmd/vartan/show.go
index 920ba66..04fc4e2 100644
--- a/cmd/vartan/show.go
+++ b/cmd/vartan/show.go
@@ -14,9 +14,6 @@ import (
 	"github.com/spf13/cobra"
 )
 
-var showFlags = struct {
-}{}
-
 func init() {
 	cmd := &cobra.Command{
 		Use:     "show",
@@ -150,7 +147,7 @@ func writeDescription(w io.Writer, desc *spec.Description) error {
 			}
 
 			if count == 1 {
-				return fmt.Sprintf("1 conflict was detected.")
+				return "1 conflict was detected."
 			} else if count > 1 {
 				return fmt.Sprintf("%v conflicts were detected.", count)
 			}
diff --git a/grammar/follow.go b/grammar/follow.go
index f835bba..67e5f70 100644
--- a/grammar/follow.go
+++ b/grammar/follow.go
@@ -87,20 +87,6 @@ func (flw *followSet) find(sym symbol) (*followEntry, error) {
 	return e, nil
 }
 
-type followComContext struct {
-	prods  *productionSet
-	first  *firstSet
-	follow *followSet
-}
-
-func newFollowComContext(prods *productionSet, first *firstSet) *followComContext {
-	return &followComContext{
-		prods:  prods,
-		first:  first,
-		follow: newFollow(prods),
-	}
-}
-
 func genFollowSet(prods *productionSet, first *firstSet) (*followSet, error) {
 	ntsyms := map[symbol]struct{}{}
 	for _, prod := range prods.getAllProductions() {
@@ -110,11 +96,11 @@ func genFollowSet(prods *productionSet, first *firstSet) (*followSet, error) {
 		ntsyms[prod.lhs] = struct{}{}
 	}
 
-	cc := newFollowComContext(prods, first)
+	follow := newFollow(prods)
 	for {
 		more := false
 		for ntsym := range ntsyms {
-			e, err := cc.follow.find(ntsym)
+			e, err := follow.find(ntsym)
 			if err != nil {
 				return nil, err
 			}
@@ -138,7 +124,7 @@ func genFollowSet(prods *productionSet, first *firstSet) (*followSet, error) {
 						more = true
 					}
 					if fst.empty {
-						flw, err := cc.follow.find(prod.lhs)
+						flw, err := follow.find(prod.lhs)
 						if err != nil {
 							return nil, err
 						}
@@ -155,43 +141,5 @@ func genFollowSet(prods *productionSet, first *firstSet) (*followSet, error) {
 		}
 	}
 
-	return cc.follow, nil
-}
-
-func genFollowEntry(cc *followComContext, acc *followEntry, ntsym symbol) (bool, error) {
-	changed := false
-
-	if ntsym.isStart() {
-		added := acc.addEOF()
-		if added {
-			changed = true
-		}
-	}
-	for _, prod := range cc.prods.getAllProductions() {
-		for i, sym := range prod.rhs {
-			if sym != ntsym {
-				continue
-			}
-			fst, err := cc.first.find(prod, i+1)
-			if err != nil {
-				return false, err
-			}
-			added := acc.merge(fst, nil)
-			if added {
-				changed = true
-			}
-			if fst.empty {
-				flw, err := cc.follow.find(prod.lhs)
-				if err != nil {
-					return false, err
-				}
-				added := acc.merge(nil, flw)
-				if added {
-					changed = true
-				}
-			}
-		}
-	}
-
-	return changed, nil
+	return follow, nil
 }
diff --git a/grammar/follow_test.go b/grammar/follow_test.go
index ba2d973..af3f064 100644
--- a/grammar/follow_test.go
+++ b/grammar/follow_test.go
@@ -158,6 +158,9 @@ func genActualFollow(t *testing.T, src string) (*followSet, *Grammar) {
 		t.Fatal(err)
 	}
 	flw, err := genFollowSet(gram.productionSet, fst)
+	if err != nil {
+		t.Fatal(err)
+	}
 	if flw == nil {
 		t.Fatal("genFollow returned nil without any error")
 	}
diff --git a/grammar/grammar.go b/grammar/grammar.go
index 2294219..7dbd0ed 100644
--- a/grammar/grammar.go
+++ b/grammar/grammar.go
@@ -116,7 +116,7 @@ func (b *GrammarBuilder) Build() (*Grammar, error) {
 			if len(md.Parameters) != 1 || md.Parameters[0].ID == "" {
 				b.errs = append(b.errs, &verr.SpecError{
 					Cause:  semErrMDInvalidParam,
-					Detail: fmt.Sprintf("'name' takes just one ID parameter"),
+					Detail: "'name' takes just one ID parameter",
 					Row:    md.Pos.Row,
 					Col:    md.Pos.Col,
 				})
@@ -480,7 +480,7 @@ func genLexEntry(prod *spec.ProductionNode) (*mlspec.LexEntry, bool, string, *ve
 			if len(dir.Parameters) == 0 {
 				return nil, false, "", &verr.SpecError{
 					Cause:  semErrDirInvalidParam,
-					Detail: fmt.Sprintf("'mode' directive needs an ID parameter"),
+					Detail: "'mode' directive needs an ID parameter",
 					Row:    dir.Pos.Row,
 					Col:    dir.Pos.Col,
 				}, nil
@@ -489,7 +489,7 @@ func genLexEntry(prod *spec.ProductionNode) (*mlspec.LexEntry, bool, string, *ve
 				if param.ID == "" {
 					return nil, false, "", &verr.SpecError{
 						Cause:  semErrDirInvalidParam,
-						Detail: fmt.Sprintf("'mode' directive needs an ID parameter"),
+						Detail: "'mode' directive needs an ID parameter",
 						Row:    param.Pos.Row,
 						Col:    param.Pos.Col,
 					}, nil
@@ -528,7 +528,7 @@ func genLexEntry(prod *spec.ProductionNode) (*mlspec.LexEntry, bool, string, *ve
 			if len(dir.Parameters) > 0 {
 				return nil, false, "", &verr.SpecError{
 					Cause:  semErrDirInvalidParam,
-					Detail: fmt.Sprintf("'skip' directive needs no parameter"),
+					Detail: "'skip' directive needs no parameter",
 					Row:    dir.Pos.Row,
 					Col:    dir.Pos.Col,
 				}, nil
@@ -538,7 +538,7 @@ func genLexEntry(prod *spec.ProductionNode) (*mlspec.LexEntry, bool, string, *ve
 			if len(dir.Parameters) != 1 || dir.Parameters[0].ID == "" {
 				return nil, false, "", &verr.SpecError{
 					Cause:  semErrDirInvalidParam,
-					Detail: fmt.Sprintf("'push' directive needs an ID parameter"),
+					Detail: "'push' directive needs an ID parameter",
 					Row:    dir.Pos.Row,
 					Col:    dir.Pos.Col,
 				}, nil
@@ -548,7 +548,7 @@ func genLexEntry(prod *spec.ProductionNode) (*mlspec.LexEntry, bool, string, *ve
 			if len(dir.Parameters) > 0 {
 				return nil, false, "", &verr.SpecError{
 					Cause:  semErrDirInvalidParam,
-					Detail: fmt.Sprintf("'pop' directive needs no parameter"),
+					Detail: "'pop' directive needs no parameter",
 					Row:    dir.Pos.Row,
 					Col:    dir.Pos.Col,
 				}, nil
@@ -558,7 +558,7 @@ func genLexEntry(prod *spec.ProductionNode) (*mlspec.LexEntry, bool, string, *ve
 			if len(dir.Parameters) != 1 || dir.Parameters[0].String == "" {
 				return nil, false, "", &verr.SpecError{
 					Cause:  semErrDirInvalidParam,
-					Detail: fmt.Sprintf("'alias' directive needs a string parameter"),
+					Detail: "'alias' directive needs a string parameter",
 					Row:    dir.Pos.Row,
 					Col:    dir.Pos.Col,
 				}, nil
@@ -762,7 +762,7 @@ func (b *GrammarBuilder) genProductionsAndActions(root *spec.RootNode, symTabAnd
 					if len(dir.Parameters) != 1 || dir.Parameters[0].Tree == nil {
 						b.errs = append(b.errs, &verr.SpecError{
 							Cause:  semErrDirInvalidParam,
-							Detail: fmt.Sprintf("'ast' directive needs a tree parameter"),
+							Detail: "'ast' directive needs a tree parameter",
 							Row:    dir.Pos.Row,
 							Col:    dir.Pos.Col,
 						})
@@ -829,7 +829,7 @@ func (b *GrammarBuilder) genProductionsAndActions(root *spec.RootNode, symTabAnd
 					if len(dir.Parameters) != 1 || dir.Parameters[0].ID == "" {
 						b.errs = append(b.errs, &verr.SpecError{
 							Cause:  semErrDirInvalidParam,
-							Detail: fmt.Sprintf("'prec' directive needs an ID parameter"),
+							Detail: "'prec' directive needs an ID parameter",
 							Row:    dir.Pos.Row,
 							Col:    dir.Pos.Col,
 						})
@@ -859,7 +859,7 @@ func (b *GrammarBuilder) genProductionsAndActions(root *spec.RootNode, symTabAnd
 					if len(dir.Parameters) > 0 {
 						b.errs = append(b.errs, &verr.SpecError{
 							Cause:  semErrDirInvalidParam,
-							Detail: fmt.Sprintf("'recover' directive needs no parameter"),
+							Detail: "'recover' directive needs no parameter",
 							Row:    dir.Pos.Row,
 							Col:    dir.Pos.Col,
 						})
@@ -1140,7 +1140,10 @@ func Compile(gram *Grammar, opts ...CompileOption) (*spec.CompiledGrammar, error
 				return nil, err
 			}
 
-			f.Write(d)
+			_, err = f.Write(d)
+			if err != nil {
+				return nil, fmt.Errorf("failed to write a description file: %w", err)
+			}
 		}
 
 		if len(b.conflicts) > 0 {
diff --git a/grammar/parsing_table.go b/grammar/parsing_table.go
index 28f6392..0b858fb 100644
--- a/grammar/parsing_table.go
+++ b/grammar/parsing_table.go
@@ -56,10 +56,6 @@ func newGoToEntry(state stateNum) goToEntry {
 	return goToEntry(state)
 }
 
-func (e goToEntry) isEmpty() bool {
-	return e == goToEntryEmpty
-}
-
 func (e goToEntry) describe() (GoToType, stateNum) {
 	if e == goToEntryEmpty {
 		return GoToTypeError, stateNumInitial
diff --git a/grammar/production.go b/grammar/production.go
index d4ea7a1..87b392f 100644
--- a/grammar/production.go
+++ b/grammar/production.go
@@ -58,10 +58,6 @@ func newProduction(lhs symbol, rhs []symbol) (*production, error) {
 	}, nil
 }
 
-func (p *production) equals(q *production) bool {
-	return q.id == p.id
-}
-
 func (p *production) isEmpty() bool {
 	return p.rhsLen == 0
 }
diff --git a/grammar/symbol.go b/grammar/symbol.go
index 3a7dfb6..ee58737 100644
--- a/grammar/symbol.go
+++ b/grammar/symbol.go
@@ -122,10 +122,7 @@ func (s symbol) isNonTerminal() bool {
 		return false
 	}
 	kind, _, _, _ := s.describe()
-	if kind == symbolKindNonTerminal {
-		return true
-	}
-	return false
+	return kind == symbolKindNonTerminal
 }
 
 func (s symbol) isTerminal() bool {
diff --git a/grammar/symbol_test.go b/grammar/symbol_test.go
index fda3ddf..0cf2a06 100644
--- a/grammar/symbol_test.go
+++ b/grammar/symbol_test.go
@@ -4,15 +4,15 @@ import "testing"
 
 func TestSymbol(t *testing.T) {
 	tab := newSymbolTable()
-	tab.registerStartSymbol("expr'")
-	tab.registerNonTerminalSymbol("expr")
-	tab.registerNonTerminalSymbol("term")
-	tab.registerNonTerminalSymbol("factor")
-	tab.registerTerminalSymbol("id")
-	tab.registerTerminalSymbol("add")
-	tab.registerTerminalSymbol("mul")
-	tab.registerTerminalSymbol("l_paren")
-	tab.registerTerminalSymbol("r_paren")
+	_, _ = tab.registerStartSymbol("expr'")
+	_, _ = tab.registerNonTerminalSymbol("expr")
+	_, _ = tab.registerNonTerminalSymbol("term")
+	_, _ = tab.registerNonTerminalSymbol("factor")
+	_, _ = tab.registerTerminalSymbol("id")
+	_, _ = tab.registerTerminalSymbol("add")
+	_, _ = tab.registerTerminalSymbol("mul")
+	_, _ = tab.registerTerminalSymbol("l_paren")
+	_, _ = tab.registerTerminalSymbol("r_paren")
 
 	nonTermTexts := []string{
 		"", // Nil
diff --git a/spec/lexer.go b/spec/lexer.go
index 80beba0..ba64925 100644
--- a/spec/lexer.go
+++ b/spec/lexer.go
@@ -205,7 +205,7 @@ func (l *lexer) lexAndSkipWSs() (*token, error) {
 				// The escape sequences in a pattern string are interpreted by the lexer, except for the \".
 				// We must interpret the \" before passing them to the lexer because they are delimiters for
 				// the pattern strings.
-				fmt.Fprintf(&b, strings.ReplaceAll(string(tok.Lexeme), `\"`, `"`))
+				fmt.Fprint(&b, strings.ReplaceAll(string(tok.Lexeme), `\"`, `"`))
 			case KindIDEscapeSymbol:
 				return nil, &verr.SpecError{
 					Cause: synErrIncompletedEscSeq,
@@ -240,13 +240,13 @@ func (l *lexer) lexAndSkipWSs() (*token, error) {
 			}
 			switch tok.KindID {
 			case KindIDCharSeq:
-				fmt.Fprintf(&b, string(tok.Lexeme))
+				fmt.Fprint(&b, string(tok.Lexeme))
 			case KindIDEscapedQuot:
 				// Remove '\' character.
-				fmt.Fprintf(&b, `'`)
+				fmt.Fprint(&b, `'`)
 			case KindIDEscapedBackSlash:
 				// Remove '\' character.
-				fmt.Fprintf(&b, `\`)
+				fmt.Fprint(&b, `\`)
 			case KindIDEscapeSymbol:
 				return nil, &verr.SpecError{
 					Cause: synErrIncompletedEscSeq,
diff --git a/spec/parser.go b/spec/parser.go
index 71ee50b..7f3d8f7 100644
--- a/spec/parser.go
+++ b/spec/parser.go
@@ -193,8 +193,6 @@ func (p *parser) parseMetaData() *DirectiveNode {
 
 		p.errs = append(p.errs, specErr)
 		p.skipOverTo(tokenKindNewline)
-
-		return
 	}()
 
 	p.consume(tokenKindNewline)
@@ -241,8 +239,6 @@ func (p *parser) parseFragment() *FragmentNode {
 
 		p.errs = append(p.errs, specErr)
 		p.skipOverTo(tokenKindSemicolon)
-
-		return
 	}()
 
 	p.consume(tokenKindNewline)
@@ -308,8 +304,6 @@ func (p *parser) parseProduction() *ProductionNode {
 
 		p.errs = append(p.errs, specErr)
 		p.skipOverTo(tokenKindSemicolon)
-
-		return
 	}()
 
 	p.consume(tokenKindNewline)
diff --git a/spec/syntax_error.go b/spec/syntax_error.go
index f82186a..a35a90c 100644
--- a/spec/syntax_error.go
+++ b/spec/syntax_error.go
@@ -19,7 +19,6 @@ var (
 	synErrAutoGenID         = newSyntaxError("you cannot define an identifier beginning with an underscore")
 	synErrUnclosedTerminal  = newSyntaxError("unclosed terminal")
 	synErrUnclosedString    = newSyntaxError("unclosed string")
-	synErrInvalidEscSeq     = newSyntaxError("invalid escape sequence")
 	synErrIncompletedEscSeq = newSyntaxError("incompleted escape sequence; unexpected EOF following a backslash")
 	synErrEmptyPattern      = newSyntaxError("a pattern must include at least one character")
 	synErrEmptyString       = newSyntaxError("a string must include at least one character")