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// Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
// Use of this file is governed by the BSD 3-clause license that
// can be found in the LICENSE.txt file in the project root.
package antlr
type InputStream struct {
name string
index int
data []rune
size int
}
func NewInputStream(data string) *InputStream {
is := new(InputStream)
is.name = "<empty>"
is.index = 0
is.data = []rune(data)
is.size = len(is.data) // number of runes
return is
}
func (is *InputStream) reset() {
is.index = 0
}
func (is *InputStream) Consume() {
if is.index >= is.size {
// assert is.LA(1) == TokenEOF
panic("cannot consume EOF")
}
is.index++
}
func (is *InputStream) LA(offset int) int {
if offset == 0 {
return 0 // nil
}
if offset < 0 {
offset++ // e.g., translate LA(-1) to use offset=0
}
pos := is.index + offset - 1
if pos < 0 || pos >= is.size { // invalid
return TokenEOF
}
return int(is.data[pos])
}
func (is *InputStream) LT(offset int) int {
return is.LA(offset)
}
func (is *InputStream) Index() int {
return is.index
}
func (is *InputStream) Size() int {
return is.size
}
// mark/release do nothing we have entire buffer
func (is *InputStream) Mark() int {
return -1
}
func (is *InputStream) Release(marker int) {
}
func (is *InputStream) Seek(index int) {
if index <= is.index {
is.index = index // just jump don't update stream state (line,...)
return
}
// seek forward
is.index = intMin(index, is.size)
}
func (is *InputStream) GetText(start int, stop int) string {
if stop >= is.size {
stop = is.size - 1
}
if start >= is.size {
return ""
}
return string(is.data[start : stop+1])
}
func (is *InputStream) GetTextFromTokens(start, stop Token) string {
if start != nil && stop != nil {
return is.GetTextFromInterval(NewInterval(start.GetTokenIndex(), stop.GetTokenIndex()))
}
return ""
}
func (is *InputStream) GetTextFromInterval(i *Interval) string {
return is.GetText(i.Start, i.Stop)
}
func (*InputStream) GetSourceName() string {
return "Obtained from string"
}
func (is *InputStream) String() string {
return string(is.data)
}
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