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// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package lex
import (
"text/scanner"
"cmd/internal/src"
)
// A Slice reads from a slice of Tokens.
type Slice struct {
tokens []Token
base *src.PosBase
line int
pos int
}
func NewSlice(base *src.PosBase, line int, tokens []Token) *Slice {
return &Slice{
tokens: tokens,
base: base,
line: line,
pos: -1, // Next will advance to zero.
}
}
func (s *Slice) Next() ScanToken {
s.pos++
if s.pos >= len(s.tokens) {
return scanner.EOF
}
return s.tokens[s.pos].ScanToken
}
func (s *Slice) Text() string {
return s.tokens[s.pos].text
}
func (s *Slice) File() string {
return s.base.Filename()
}
func (s *Slice) Base() *src.PosBase {
return s.base
}
func (s *Slice) SetBase(base *src.PosBase) {
// Cannot happen because we only have slices of already-scanned text,
// but be prepared.
s.base = base
}
func (s *Slice) Line() int {
return s.line
}
func (s *Slice) Col() int {
// TODO: Col is only called when defining a macro and all it cares about is increasing
// position to discover whether there is a blank before the parenthesis.
// We only get here if defining a macro inside a macro.
// This imperfect implementation means we cannot tell the difference between
// #define A #define B(x) x
// and
// #define A #define B (x) x
// The first definition of B has an argument, the second doesn't. Because we let
// text/scanner strip the blanks for us, this is extremely rare, hard to fix, and not worth it.
return s.pos
}
func (s *Slice) Close() {
}
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