| // Licensed to the Apache Software Foundation (ASF) under one or more |
| // contributor license agreements. See the NOTICE file distributed with |
| // this work for additional information regarding copyright ownership. |
| // The ASF licenses this file to You under the Apache License, Version 2.0 |
| // (the "License"); you may not use this file except in compliance with |
| // the License. You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package lexer |
| |
| type runeNode struct { |
| r rune |
| next *runeNode |
| } |
| |
| type runeStack struct { |
| start *runeNode |
| } |
| |
| func newRuneStack() runeStack { |
| return runeStack{} |
| } |
| |
| func (s *runeStack) push(r rune) { |
| node := &runeNode{r: r} |
| if s.start == nil { |
| s.start = node |
| } else { |
| node.next = s.start |
| s.start = node |
| } |
| } |
| |
| func (s *runeStack) pop() rune { |
| if s.start == nil { |
| return EOFRune |
| } else { |
| n := s.start |
| s.start = n.next |
| return n.r |
| } |
| } |
| |
| func (s *runeStack) clear() { |
| s.start = nil |
| } |