github.com/vanus-labs/vanus/lib@v0.0.0-20231221070800-1334a7b9605e/json/parse/number.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 parse
    16  
    17  import (
    18  	// standard libraries.
    19  	"errors"
    20  	"io"
    21  
    22  	// this project.
    23  	"github.com/vanus-labs/vanus/lib/bytes"
    24  )
    25  
    26  var errInvalidInteger = errors.New("invalid integer")
    27  
    28  func IsDigit(c byte) bool {
    29  	return c >= '0' && c <= '9'
    30  }
    31  
    32  func ConsumeDigits(r io.ByteReader, w io.ByteWriter) (int, byte, error) {
    33  	return bytes.ConsumeUntil(r, w, func(c byte) bool {
    34  		return !IsDigit(c)
    35  	})
    36  }
    37  
    38  func ExpectIntegerExt(c byte, s io.ByteScanner) (int, error) {
    39  	if c == '0' {
    40  		return 0, nil
    41  	}
    42  
    43  	var err error
    44  	sign := 1
    45  	if c == '-' {
    46  		sign = -1
    47  		c, err = s.ReadByte()
    48  		if err != nil {
    49  			return 0, errInvalidInteger
    50  		}
    51  	}
    52  
    53  	if c < '1' || c > '9' {
    54  		return 0, errInvalidInteger
    55  	}
    56  	num := int(c - '0')
    57  
    58  	for {
    59  		c, err = s.ReadByte()
    60  		if err != nil {
    61  			if err == io.EOF { //nolint:errorlint // io.EOF is not an error.
    62  				return sign * num, nil
    63  			}
    64  			return 0, err
    65  		}
    66  
    67  		if !IsDigit(c) {
    68  			return sign * num, s.UnreadByte()
    69  		}
    70  
    71  		// TODO(james.yin): check overflow
    72  
    73  		num = num*10 + int(c-'0') //nolint:gomnd // 10 is base
    74  	}
    75  }