Ruby和amp；Python之间的正则表达式差异

我刚刚开始学习《代码2023的到来》，并试图用它来学习一些新的编程语言.我已经(有些)熟悉了Python，而且实际上我今天刚刚安装了Ruby.

第1天，第2部分，我使用正则表达式来搜索数字及其拼写版本.Python中的正则表达式(生成正确的结果): (?=(0|1|2|3|4|5|6|7|8|9|zero|one|two|three|four|five|six|seven|eight|nine))个

当我在Ruby中使用这个正则表达式时，我得到的结果为零.有趣的是，当我使用这个正则表达式时，我在python和ruby中得到了完全相同的结果，但这是不正确的答案: r"0|1|2|3|4|5|6|7|8|9|zero|one|two|three|four|five|six|seven|eight|nine"个

因此，我认为答案与积极的前瞻性断言有关，但我不知道为什么，以及它的做法有什么不同.

下面是这两个文件.

Python:

import re

input = open("../resources/input.txt","r")
lines = input.readlines()

targets = [
    '0','1','2','3','4','5','6','7','8','9',
    'zero','one','two','three','four','five','six','seven','eight','nine'
]
values = {
    '0': 0,
    '1': 1,
    '2': 2,
    '3': 3,
    '4': 4,
    '5': 5,
    '6': 6,
    '7': 7,
    '8': 8,
    '9': 9,
    'zero': 0,
    'one': 1,
    'two': 2,
    'three': 3,
    'four': 4,
    'five': 5,
    'six': 6,
    'seven': 7,
    'eight': 8,
    'nine': 9
}

sum = 0

for line in lines:
    numbers = re.findall(r"(?=("+'|'.join(targets)+r"))", line)

    firstDigitValue = values[numbers[0]] * 10
    lastDigitValue = values[numbers[-1]]

    sum += (firstDigitValue+lastDigitValue)



print(sum)

露比:

# Init vars
sum = 0

reg = /\d|zero|one|two|three|four|five|six|seven|eight|nine/
reg2 = /(?=(0|1|2|3|4|5|6|7|8|9|zero|one|two|three|four|five|six|seven|eight|nine))/
reg3 = /0|1|2|3|4|5|6|7|8|9|zero|one|two|three|four|five|six|seven|eight|nine/

values = {
    '0' => 0,
    '1' => 1,
    '2' => 2,
    '3' => 3,
    '4' => 4,
    '5' => 5,
    '6' => 6,
    '7' => 7,
    '8' => 8,
    '9' => 9,
    'zero' => 0,
    'one' => 1,
    'two' => 2,
    'three' => 3,
    'four' => 4,
    'five' => 5,
    'six' => 6,
    'seven' => 7,
    'eight' => 8,
    'nine' => 9
}


# Pipe the file line by line and do per line
File.foreach("../resources/input.txt", chomp: true) do |line|
    # Get the first and last digits as their values
    numbers = line.scan(reg3)

    firstDigitValue = values[numbers[0]] * 10
    lastDigitValue = values[numbers[-1]]

    # accumulate
    sum += (firstDigitValue+lastDigitValue)

end

puts sum