github.com/vanus-labs/vanus/lib@v0.0.0-20231221070800-1334a7b9605e/bytes/parse.go (about)

     1  // Copyright 2023 Linkall Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package bytes
    16  
    17  import (
    18  	// standard libraries.
    19  	"errors"
    20  	"io"
    21  )
    22  
    23  var errUnexpectedChar = errors.New("unexpected character")
    24  
    25  func ExpectChar(r io.ByteReader, c byte) error {
    26  	b, err := r.ReadByte()
    27  	if err != nil || b != c {
    28  		return errUnexpectedChar
    29  	}
    30  	return nil
    31  }
    32  
    33  func ConsumeUntil(r io.ByteReader, w io.ByteWriter, stop func(byte) bool) (int, byte, error) {
    34  	for count := 0; ; count++ {
    35  		c, err := r.ReadByte()
    36  		if err != nil {
    37  			return count, 0, err
    38  		}
    39  		if stop(c) {
    40  			return count, c, nil
    41  		}
    42  		if err = w.WriteByte(c); err != nil {
    43  			return count, c, err
    44  		}
    45  	}
    46  }
    47  
    48  func Skip(r io.ByteReader, expect func(byte) bool) (int, byte, error) {
    49  	for count := 0; ; count++ {
    50  		c, err := r.ReadByte()
    51  		if err != nil {
    52  			return count, 0, err
    53  		}
    54  		if !expect(c) {
    55  			return count, c, nil
    56  		}
    57  	}
    58  }
    59  
    60  func IgnoreCount(_ int, c byte, err error) (byte, error) {
    61  	return c, err
    62  }
    63  
    64  func AcceptEOF(count int, c byte, err error) (int, bool, byte, error) {
    65  	switch {
    66  	case err == nil:
    67  		return count, false, c, nil
    68  	case err == io.EOF: //nolint:errorlint // io.EOF is not an error
    69  		return count, true, 0, nil
    70  	default:
    71  		return 0, false, 0, err
    72  	}
    73  }
    74  
    75  func Unread(r io.ByteScanner, eof bool, err error) error {
    76  	if err == nil && !eof {
    77  		err = r.UnreadByte()
    78  	}
    79  	return err
    80  }