验证该字符串仅包含 Ruby 中允许的字符

Question

如何测试一个 Ruby 字符串是否只包含一组特定的字符？

例如，如果我的允许字符集是"AGHTM" 加上数字0-9，

• 字符串"MT3G22AH"是有效的；

• 字符串"TAR34" 无效（因为R）。

Answer 1

一个非常惯用的非正则表达式解决方案是使用String#count：

"MT3G22AH".count("^AGHTM0-9").zero?  # => true
"TAR34".count("^AGHTM0-9").zero?     # => false

如果你觉得它更易读，反之亦然：

"MT3G22AH".count('AGHTM0-9') == "MT3G22AH".size  # => true

任你选。

对于较长的字符串，这两种方法的性能都明显优于基于正则表达式的选项。

Answer 2

allowed = "AGHTM"
allowed = /\A[\d#{allowed}]+\z/i

"MT3G22AH" =~ allowed #⇒ truthy
"TAR34" =~ allowed #⇒ falsey

Answer 3

字符串#delete

一种可能性是删除所有允许的字符并检查结果字符串是否为空：

"MT3G22AH".delete("AGHTM0-9").empty?
#=> true
"TAR34".delete("AGHTM0-9").empty?
#=> false

性能

短字符串

对于短字符串，@steenslag 是最快的方法，其次是@Jesse 和我的方法。

def mudasobwa(string)
  allowed = 'AGHTM'
  allowed = /\A[\d#{allowed}]+\z/i
  string.match? allowed
end

def eric(string)
  string.delete('AGHTM1-9').empty?
end

def meagar(string)
  allowed = 'AGHTM0123456789'
  string.chars.uniq.all? { |c| allowed.include?(c) }
end

def jesse(string)
  string.count('^AGHTM0-9').zero?
end

def steenslag(string)
  !string.match?(/[^AGHTM0-9]/) 
end

require 'fruity'

n = 1
str1 = 'MT3G22AH' * n
str2 = 'TAR34' * n
compare do
  _jesse { [jesse(str1), jesse(str2)] }
  _eric { [eric(str1), eric(str2)] }
  _mudasobwa { [mudasobwa(str1), mudasobwa(str2)] }
  _meagar { [meagar(str1), meagar(str2)] }
  _steenslag { [steenslag(str1), steenslag(str2)] }
end

它输出：

Running each test 1024 times. Test will take about 2 seconds.
_steenslag is faster than _jesse by 2.2x ± 0.1
_jesse is faster than _eric by 8.000000000000007% ± 1.0%
_eric is faster than _meagar by 4.3x ± 0.1
_meagar is faster than _mudasobwa by 2.4x ± 0.1

更长的字符串

对于较长的字符串 (n=5000)，@Jesse 成为最快的方法。

Running each test 32 times. Test will take about 12 seconds.
_jesse is faster than _eric by 2.5x ± 0.01
_eric is faster than _mudasobwa by 4x ± 1.0
_mudasobwa is faster than _steenslag by 2x ± 0.1
_steenslag is faster than _meagar by 11x ± 0.1

Answer 4

这似乎比之前所有的基准测试都要快（@Eric Duminil）（ruby 2.4）：

!string.match?(/[^AGHTM0-9]/)