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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"
"os"
)
// This is an InputStream that is loaded from a file all at once
// when you construct the object.
type FileStream struct {
InputStream
filename string
}
//goland:noinspection GoUnusedExportedFunction
func NewFileStream(fileName string) (*FileStream, error) {
f, err := os.Open(fileName)
if err != nil {
return nil, err
}
defer func(f *os.File) {
errF := f.Close()
if errF != nil {
}
}(f)
reader := bufio.NewReader(f)
fInfo, err := f.Stat()
if err != nil {
return nil, err
}
fs := &FileStream{
InputStream: InputStream{
index: 0,
name: fileName,
},
filename: fileName,
}
// Pre-build the buffer and read runes efficiently
//
fs.data = make([]rune, 0, fInfo.Size())
for {
r, _, err := reader.ReadRune()
if err != nil {
break
}
fs.data = append(fs.data, r)
}
fs.size = len(fs.data) // Size in runes
// All done.
//
return fs, nil
}
func (f *FileStream) GetSourceName() string {
return f.filename
}
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