Commits on Feb 10, 2022

1. String matcher …

   Most of the time when I'm using string scanner I am checking multiple patterns. In this case I usually have to join them in a single regex or I just check them with multiple elsif clauses. Instead, it would be nice to initialize a string scanner that could check multiple patterns and then return to me the value that I want. In this commit I introduce a `StringMatcher` object that does just that. For example:
   
   ```
   require "strmatch"
   
   NumberToken = Struct.new(:value, keyword_init: true)
   StringToken = Struct.new(:value, keyword_init: true)
   
   matcher = StringMatcher.new("12ab34")
   matcher.match(/\d+/) { |value| NumberToken.new(value: value.to_i) }
   matcher.match(/[a-z]+/) { |value| StringToken.new(value:) }
   
   until matcher.eos?
     case matcher.select
     in NumberToken[value:] if value >= 20
       puts "NUMBER: #{value.inspect} (big)"
     in NumberToken[value:] if value < 20
       puts "NUMBER: #{value.inspect} (small)"
     in StringToken[value:]
       puts "STRING: #{value.inspect}"
     end
   end
   ```
   
   Running the above example will produce:
   
   ```
   NUMBER: 12 (small)
   STRING: "ab"
   NUMBER: 34 (big)
   ```
   
   This is more ergonomic since you can now use pattern matching instead of a chain of if/elsif clauses.

   

   kddnewton committed Feb 10, 2022
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