diff --git a/src/pkg/ebnf/ebnf.go b/src/pkg/ebnf/ebnf.go index 898a4817353..8333f583093 100644 --- a/src/pkg/ebnf/ebnf.go +++ b/src/pkg/ebnf/ebnf.go @@ -23,7 +23,6 @@ package ebnf import ( - "container/vector" "go/scanner" "go/token" "os" @@ -123,7 +122,7 @@ func isLexical(name string) bool { type verifier struct { scanner.ErrorVector - worklist vector.Vector + worklist []*Production reached Grammar // set of productions reached from (and including) the root production grammar Grammar } @@ -132,7 +131,7 @@ type verifier struct { func (v *verifier) push(prod *Production) { name := prod.Name.String if _, found := v.reached[name]; !found { - v.worklist.Push(prod) + v.worklist = append(v.worklist, prod) v.reached[name] = prod } } @@ -205,14 +204,19 @@ func (v *verifier) verify(grammar Grammar, start string) { // initialize verifier v.ErrorVector.Reset() - v.worklist.Resize(0, 0) + v.worklist = v.worklist[0:0] v.reached = make(Grammar) v.grammar = grammar // work through the worklist v.push(root) - for v.worklist.Len() > 0 { - prod := v.worklist.Pop().(*Production) + for { + n := len(v.worklist) - 1 + if n < 0 { + break + } + prod := v.worklist[n] + v.worklist = v.worklist[0:n] v.verifyExpr(prod.Expr, isLexical(prod.Name.String)) } diff --git a/src/pkg/ebnf/parser.go b/src/pkg/ebnf/parser.go index 64958787940..32edbacafeb 100644 --- a/src/pkg/ebnf/parser.go +++ b/src/pkg/ebnf/parser.go @@ -5,7 +5,6 @@ package ebnf import ( - "container/vector" "go/scanner" "go/token" "os" @@ -116,36 +115,30 @@ func (p *parser) parseTerm() (x Expression) { func (p *parser) parseSequence() Expression { - var list vector.Vector + var list Sequence for x := p.parseTerm(); x != nil; x = p.parseTerm() { - list.Push(x) + list = append(list, x) } // no need for a sequence if list.Len() < 2 - switch list.Len() { + switch len(list) { case 0: return nil case 1: - return list.At(0).(Expression) + return list[0] } - // convert list into a sequence - seq := make(Sequence, list.Len()) - for i := 0; i < list.Len(); i++ { - seq[i] = list.At(i).(Expression) - } - return seq + return list } func (p *parser) parseExpression() Expression { - var list vector.Vector + var list Alternative for { - x := p.parseSequence() - if x != nil { - list.Push(x) + if x := p.parseSequence(); x != nil { + list = append(list, x) } if p.tok != token.OR { break @@ -154,19 +147,14 @@ func (p *parser) parseExpression() Expression { } // no need for an Alternative node if list.Len() < 2 - switch list.Len() { + switch len(list) { case 0: return nil case 1: - return list.At(0).(Expression) + return list[0] } - // convert list into an Alternative node - alt := make(Alternative, list.Len()) - for i := 0; i < list.Len(); i++ { - alt[i] = list.At(i).(Expression) - } - return alt + return list }