Running user entered code

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Thread: Running user entered code

  1. #1
    Join Date
    Mar 2006

    Running user entered code

    I have an application that allows the user to place boxes of text on a page with special placeholders and then output a pdf where the placeholders are replaced but values from a database. Example: "My name is %NAME%" when composed results in "My name is Bob". Now I need a way to allow the user to enter some form of simple code to create a conditional statement which will be parsed when the document is composed. Example: if (%NAME% == "Joe") { return "Bob" } I have no idea how to even begin to approach this. Does anyone know of a way to turn a user entered string of text into actual Java code that the application will run?

  2. #2
    Join Date
    Feb 2006
    Cologne - Germany
    there are several possibilities.
    one elegant version is using a compiler of Java code at run-time, like, which also supports expression evaluation.
    another elegant approach would be to include a scripting language, like the ones listed at
    the third elegant approach is writing your own little scripting language with jflex, jcup or antlr. but this will assume knowledge on building languages and compilers.

  3. #3
    Join Date
    Mar 2005
    UK, London
    graviton is right, we will need to look into making a compiler, and you need to be able to detect syntax errors. I cant say that this is easy.

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