// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package lex
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import (
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"text/scanner"
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"cmd/internal/src"
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)
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// A Stack is a stack of TokenReaders. As the top TokenReader hits EOF,
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// it resumes reading the next one down.
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type Stack struct {
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tr []TokenReader
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}
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// Push adds tr to the top (end) of the input stack. (Popping happens automatically.)
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func (s *Stack) Push(tr TokenReader) {
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s.tr = append(s.tr, tr)
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}
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func (s *Stack) Next() ScanToken {
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tos := s.tr[len(s.tr)-1]
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tok := tos.Next()
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for tok == scanner.EOF && len(s.tr) > 1 {
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tos.Close()
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// Pop the topmost item from the stack and resume with the next one down.
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s.tr = s.tr[:len(s.tr)-1]
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tok = s.Next()
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}
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return tok
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}
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func (s *Stack) Text() string {
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return s.tr[len(s.tr)-1].Text()
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}
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func (s *Stack) File() string {
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return s.Base().Filename()
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}
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func (s *Stack) Base() *src.PosBase {
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return s.tr[len(s.tr)-1].Base()
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}
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func (s *Stack) SetBase(base *src.PosBase) {
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s.tr[len(s.tr)-1].SetBase(base)
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}
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func (s *Stack) Line() int {
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return s.tr[len(s.tr)-1].Line()
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}
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func (s *Stack) Col() int {
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return s.tr[len(s.tr)-1].Col()
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}
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func (s *Stack) Close() { // Unused.
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}
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