Source file src/pkg/cmd/asm/internal/lex/slice.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 Slice reads from a slice of Tokens.
    14	type Slice struct {
    15		tokens []Token
    16		base   *src.PosBase
    17		line   int
    18		pos    int
    19	}
    20	
    21	func NewSlice(base *src.PosBase, line int, tokens []Token) *Slice {
    22		return &Slice{
    23			tokens: tokens,
    24			base:   base,
    25			line:   line,
    26			pos:    -1, // Next will advance to zero.
    27		}
    28	}
    29	
    30	func (s *Slice) Next() ScanToken {
    31		s.pos++
    32		if s.pos >= len(s.tokens) {
    33			return scanner.EOF
    34		}
    35		return s.tokens[s.pos].ScanToken
    36	}
    37	
    38	func (s *Slice) Text() string {
    39		return s.tokens[s.pos].text
    40	}
    41	
    42	func (s *Slice) File() string {
    43		return s.base.Filename()
    44	}
    45	
    46	func (s *Slice) Base() *src.PosBase {
    47		return s.base
    48	}
    49	
    50	func (s *Slice) SetBase(base *src.PosBase) {
    51		// Cannot happen because we only have slices of already-scanned text,
    52		// but be prepared.
    53		s.base = base
    54	}
    55	
    56	func (s *Slice) Line() int {
    57		return s.line
    58	}
    59	
    60	func (s *Slice) Col() int {
    61		// TODO: Col is only called when defining a macro and all it cares about is increasing
    62		// position to discover whether there is a blank before the parenthesis.
    63		// We only get here if defining a macro inside a macro.
    64		// This imperfect implementation means we cannot tell the difference between
    65		//	#define A #define B(x) x
    66		// and
    67		//	#define A #define B (x) x
    68		// The first has definition of B has an argument, the second doesn't. Because we let
    69		// text/scanner strip the blanks for us, this is extremely rare, hard to fix, and not worth it.
    70		return s.pos
    71	}
    72	
    73	func (s *Slice) Close() {
    74	}
    75	

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