ceph-csi/vendor/github.com/antlr4-go/antlr/v4/input_stream.go

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// Copyright (c) 2012-2022 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
import (
"bufio"
"io"
)
type InputStream struct {
name string
index int
data []rune
size int
}
// NewIoStream creates a new input stream from the given io.Reader reader.
// Note that the reader is read completely into memory and so it must actually
// have a stopping point - you cannot pass in a reader on an open-ended source such
// as a socket for instance.
func NewIoStream(reader io.Reader) *InputStream {
rReader := bufio.NewReader(reader)
is := &InputStream{
name: "<empty>",
index: 0,
}
// Pre-build the buffer and read runes reasonably efficiently given that
// we don't exactly know how big the input is.
//
is.data = make([]rune, 0, 512)
for {
r, _, err := rReader.ReadRune()
if err != nil {
break
}
is.data = append(is.data, r)
}
is.size = len(is.data) // number of runes
return is
}
// NewInputStream creates a new input stream from the given string
func NewInputStream(data string) *InputStream {
is := &InputStream{
name: "<empty>",
index: 0,
data: []rune(data), // This is actually the most efficient way
}
is.size = len(is.data) // number of runes, but we could also use len(data), which is efficient too
return is
}
func (is *InputStream) reset() {
is.index = 0
}
// Consume moves the input pointer to the next character in the input stream
func (is *InputStream) Consume() {
if is.index >= is.size {
// assert is.LA(1) == TokenEOF
panic("cannot consume EOF")
}
is.index++
}
// LA returns the character at the given offset from the start of the input stream
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])
}
// LT returns the character at the given offset from the start of the input stream
func (is *InputStream) LT(offset int) int {
return is.LA(offset)
}
// Index returns the current offset in to the input stream
func (is *InputStream) Index() int {
return is.index
}
// Size returns the total number of characters in the input stream
func (is *InputStream) Size() int {
return is.size
}
// Mark does nothing here as we have entire buffer
func (is *InputStream) Mark() int {
return -1
}
// Release does nothing here as we have entire buffer
func (is *InputStream) Release(_ int) {
}
// Seek the input point to the provided index offset
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)
}
// GetText returns the text from the input stream from the start to the stop index
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])
}
// GetTextFromTokens returns the text from the input stream from the first character of the start token to the last
// character of the stop token
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 ""
}
// String returns the entire input stream as a string
func (is *InputStream) String() string {
return string(is.data)
}