We can use JavaCC file to generate lexers.

Files:

• simple lexer for polynomials: polyTokens.jj
• simple main file: PolyTokenTest.java
• simple test input for lexer: TestPolyInput.poly

Instructions:

javacc polyTokens.jj
javac *.java
java -cp . PolyTokenTest < TestPolyInput.poly

Note:

• still must e.g. manually convert digit sequence into an integer
• but easier once you know that you have correct token (we know its beginning and end)