Source file src/cmd/asm/internal/lex/stack.go

     1	// Copyright 2015 The Go Authors. All rights reserved.
     2	// Use of this source code is governed by a BSD-style
     3	// license that can be found in the LICENSE file.
     4	
     5	package lex
     6	
     7	import (
     8		"text/scanner"
     9	
    10		"cmd/internal/src"
    11	)
    12	
    13	// A Stack is a stack of TokenReaders. As the top TokenReader hits EOF,
    14	// it resumes reading the next one down.
    15	type Stack struct {
    16		tr []TokenReader
    17	}
    18	
    19	// Push adds tr to the top (end) of the input stack. (Popping happens automatically.)
    20	func (s *Stack) Push(tr TokenReader) {
    21		s.tr = append(s.tr, tr)
    22	}
    23	
    24	func (s *Stack) Next() ScanToken {
    25		tos := s.tr[len(s.tr)-1]
    26		tok := tos.Next()
    27		for tok == scanner.EOF && len(s.tr) > 1 {
    28			tos.Close()
    29			// Pop the topmost item from the stack and resume with the next one down.
    30			s.tr = s.tr[:len(s.tr)-1]
    31			tok = s.Next()
    32		}
    33		return tok
    34	}
    35	
    36	func (s *Stack) Text() string {
    37		return s.tr[len(s.tr)-1].Text()
    38	}
    39	
    40	func (s *Stack) File() string {
    41		return s.Base().Filename()
    42	}
    43	
    44	func (s *Stack) Base() *src.PosBase {
    45		return s.tr[len(s.tr)-1].Base()
    46	}
    47	
    48	func (s *Stack) SetBase(base *src.PosBase) {
    49		s.tr[len(s.tr)-1].SetBase(base)
    50	}
    51	
    52	func (s *Stack) Line() int {
    53		return s.tr[len(s.tr)-1].Line()
    54	}
    55	
    56	func (s *Stack) Col() int {
    57		return s.tr[len(s.tr)-1].Col()
    58	}
    59	
    60	func (s *Stack) Close() { // Unused.
    61	}
    62	

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