Analysis of the use of regular expressions in Ruby, analysis of ruby Regular Expressions

Analysis of the use of regular expressions in Ruby, analysis of ruby Regular Expressions

If you only need to search for the text of a string, do not use a regular expression: string ['text']

You can use string [/RE/] to query a simple structure.

  match = string[/regexp/]       # get content of matched regexp  first_group = string[/text(grp)/, 1] # get content of captured group  string[/text (grp)/, 1] = 'replace' # string => 'text replace'

When you do not need to group results, use non-group groups.

  /(first|second)/  # bad  /(?:first|second)/ # good

Do not use Perl legacy variables to represent matched regular groups (such as $1, $2, etc.). Use Regexp. last_match [n] as an alternative.

  /(regexp)/ =~ string  ...  # bad  process $1  # good  process Regexp.last_match[1]

It is difficult to understand what they mean by using digital naming groups. Naming groups to replace.

  # bad  /(regexp)/ =~ string  ...  process Regexp.last_match[1]  # good  /(?<meaningful_var>regexp)/ =~ string  ...  process meaningful_var

Character classes have the following special keywords worth noting: ^,-, \,]. Therefore, do not escape. Or brackets in.

Note: ^ and $ match the beginning and end of A line, instead of the end of A string. If you want to match the entire string, use \ A and \ Z.

  string = "some injection\nusername"  string[/^username$/]  # matches  string[/\Ausername\Z/] # don't match

The x modifier is used for complex regular expressions. It can improve readability and add useful comments. Note that the white space characters are ignored.

  regexp = %r{   start     # some text   \s      # white space char   (group)    # first group   (?:alt1|alt2) # some alternation   end  }x

Sub/gsub also supports hash and code block syntax, which can be used for replacement operations in complex situations.