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Parsing using regular expression

Kowshik Nandagudi
Ranch Hand

Joined: Dec 09, 2010
Posts: 57
Hi All,

I need to parse a formula which can have comments. A valid formula will be something like this.
B = rescale(A,'monthly') +33 ; 'this is a comment

The formula should end with semicolon ";" and a comments can start with single quote(').

If a formula does not end with semi colon then i should throw an Exception (Syntax error)

Invalid formula :
B = rescale(A,'monthly') +33 'this is a formula which does not terminate with semicolon

I need to strip the 'this is a comment in the above example.

I tried with the regular expression like this ['](.*) to strip but it also strips the 'monthly') +33

Can anybody help me in doing this using regular expression?

Some of the valid example of formula in my project

B = abs(A);
A = 2;
C =abs(A)+pow(A,2);

Thanks in advance
Rob Spoor

Joined: Oct 27, 2005
Posts: 20179

Regular expressions are a bad tool for parsing like this. You need a proper parser, and that involves writing a grammar that specifies what is and what isn't allowed. JavaCC or ANTLR can be used for creating this parser.

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