Golden Rule of Regex Matching

• Longest match rule:

  • "When consuming its input, the scanner determines the regular expression that matches the longest portion of the input."

Is = "is"

Island = "island"

%%

{Is} { System.out.println("Got an 'is'"); }

{Island} { System.out.println("Got an 'island'"); }

mylexer.flex

See example12

Input:

island

Output:

Got an 'island'

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