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// Copyright 2021 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package parser
import (
antlr "github.com/antlr/antlr4/runtime/Go/antlr/v4"
"github.com/google/cel-go/common/runes"
)
type charStream struct {
buf runes.Buffer
pos int
src string
}
// Consume implements (antlr.CharStream).Consume.
func (c *charStream) Consume() {
if c.pos >= c.buf.Len() {
panic("cannot consume EOF")
}
c.pos++
}
// LA implements (antlr.CharStream).LA.
func (c *charStream) LA(offset int) int {
if offset == 0 {
return 0
}
if offset < 0 {
offset++
}
pos := c.pos + offset - 1
if pos < 0 || pos >= c.buf.Len() {
return antlr.TokenEOF
}
return int(c.buf.Get(pos))
}
// LT mimics (*antlr.InputStream).LT.
func (c *charStream) LT(offset int) int {
return c.LA(offset)
}
// Mark implements (antlr.CharStream).Mark.
func (c *charStream) Mark() int {
return -1
}
// Release implements (antlr.CharStream).Release.
func (c *charStream) Release(marker int) {}
// Index implements (antlr.CharStream).Index.
func (c *charStream) Index() int {
return c.pos
}
// Seek implements (antlr.CharStream).Seek.
func (c *charStream) Seek(index int) {
if index <= c.pos {
c.pos = index
return
}
if index < c.buf.Len() {
c.pos = index
} else {
c.pos = c.buf.Len()
}
}
// Size implements (antlr.CharStream).Size.
func (c *charStream) Size() int {
return c.buf.Len()
}
// GetSourceName implements (antlr.CharStream).GetSourceName.
func (c *charStream) GetSourceName() string {
return c.src
}
// GetText implements (antlr.CharStream).GetText.
func (c *charStream) GetText(start, stop int) string {
if stop >= c.buf.Len() {
stop = c.buf.Len() - 1
}
if start >= c.buf.Len() {
return ""
}
return c.buf.Slice(start, stop+1)
}
// GetTextFromTokens implements (antlr.CharStream).GetTextFromTokens.
func (c *charStream) GetTextFromTokens(start, stop antlr.Token) string {
if start != nil && stop != nil {
return c.GetText(start.GetTokenIndex(), stop.GetTokenIndex())
}
return ""
}
// GetTextFromInterval implements (antlr.CharStream).GetTextFromInterval.
func (c *charStream) GetTextFromInterval(i *antlr.Interval) string {
return c.GetText(i.Start, i.Stop)
}
// String mimics (*antlr.InputStream).String.
func (c *charStream) String() string {
return c.buf.Slice(0, c.buf.Len())
}
var _ antlr.CharStream = &charStream{}
func newCharStream(buf runes.Buffer, desc string) antlr.CharStream {
return &charStream{
buf: buf,
src: desc,
}
}
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