Regular Expression Generator

The Regular Expression Generator helps you to create a regular expression to include in your AQL extractor.

Procedure

Use the Regular Expression Generator, to select a suggested expression and refine the expression by examining and modifying the subexpressions that make up the expression.
Remember: The generated regular expression adds an escape character to the forward slash character (//). This adjustment facilitates the use of the forward slash directly in the AQL file. If you use the regular expression in other tools, remove the escape character on the forward slash to properly capture your input examples.
Regular expression selector
The Regular Expression Generator algorithm suggests one or more regular expressions that match example strings that you provide.
  1. Click Load samples from file.
  2. After you load your samples, select the expression that best matches your query, and click Next.
  3. If you are not satisfied with the results of this regular expression produces, click Back, and select another expression.
  4. If you want to modify the samples in the table, change them, and then click Generate regular expression to refresh the regular expressions.
  5. Use the slider to generate more general or specific regular expressions.
Regular expression refinement
  1. You can see the regular expression in the Regular Expression text box at the top of the regular expression refinement page of the wizard. Each regular expression consists of several subexpressions. For example,
    								\d{1,2} or (N|S) 
    							
    are subexpressions of the following regular expression:
    								(\d{1,2}(-)( )\d{1,2}(')( )(N|S)(,)( )\d{1,3}(-)( )\d{2}(')( )(E|W))
    							
    .
  2. Refine the individual subexpressions. The subexpression that you refine is highlighted in the text box.
  3. Click Next and Back to navigate to the next or prior subexpression within your regular expression.
Samples table
  1. View the Samples table to see the examples that you entered in the last wizard page.

    The first column (Match) indicates whether the current regular expression matches the example of this row.

  2. The part of the example that is matched by the current subexpression is highlighted.
Current® subexpression refinement
  1. The section that is labeled Refine the current subexpression shows some information about the current subexpression and its character class. For more information about character classes, see the Regular expression constructs and characters. When you refine the subexpression, you can:
    • Make a subexpression optional.
    • Change the type of the current subexpression.
Make a subexpression optional

Select the This subexpression is optional check box to make a subexpression optional. This action adds a ? after the current subexpression, which means {0, 1}. In other words, the subexpression can occur zero or one time. Use caution when you make an optional subexpression a mandatory expression. This action might result in a regular expression that does not match some of your samples.

Change the type of the current subexpression
Consider the following constraints when you refine your subexpression by selecting one of the following options:
Any of the symbols in this character class
By selecting this option, any of the symbols that belong to this character class can occur at this position. Each character class comprises certain characters. Refer to the table in Regular expression constructs and characters. You can define the minimum and maximum number of characters that occur at this position, which adds {min, max} after your subexpression, and that means that this subexpression must occur at least min times and can be repeated up to max times. Be careful when you increase the minimum number or decrease the maximum number because this action might result in a regular expression that does not match some of your samples. Ensure that all of your examples are still matching after you modify these numbers.
One of the samples in the table must occur
The Samples of this Subexpression table shows all values of this subexpression that occur in the samples that you provided. If you select this option, one of the elements in this table must occur at this position. In other words, the resulting regular expression contains an alternation of these examples at this position.
An integer number within a certain range can occur
If the character class is Digit, you can also select more options to define that an integer number can occur within a certain range. If you select this option, click the corresponding radio button and provide a minimum and maximum integer number for the range. You might also want to allow leading zeros.
Test samples
You can validate the generated regular expression by manually entering text into the lower right text area, or you can click Import to load a text file (*.txt) that contains samples. After some text is entered, the generator highlights the text in the text area that matches with the regular expression that is generated.