## [Pyparsing] Parse variables with indexes

 [Pyparsing] Parse variables with indexes From: Alexander Bruy - 2010-01-08 09:37:06 ```Hi list I need to parse and evaluate algebraic expressions with variables. Some of variables is simply variable name which replaced with it value when evaluating, but some variables is complex variable with index part (like array indexing). For example variable{1} For this kind of variables I need to do additional actions (based on variable name and index) before evaluating. For example, I have variable "layer", when this variable found without index part I need to return one value, when index is 2 (in expression this looks as layer{2}) I need to return second value, index is 1 (in expression this looks as layer{1}) I need to return third value. Is it possible with pyparsing? I look at manuals and example SimpleCalc.py and this looks very similar for what I want. I think, that index part must be described with Optional class. But I can't understand what I must add to the SimpleCalc.py for parsing and evaluating variables with indexes. Can anyone help me with this? Thanks and sorry for my bad English, I'm Ukrainian -- Alexander Bruy mailto: alexander.bruy@... ```

 [Pyparsing] Parse variables with indexes From: Alexander Bruy - 2010-01-08 09:37:06 ```Hi list I need to parse and evaluate algebraic expressions with variables. Some of variables is simply variable name which replaced with it value when evaluating, but some variables is complex variable with index part (like array indexing). For example variable{1} For this kind of variables I need to do additional actions (based on variable name and index) before evaluating. For example, I have variable "layer", when this variable found without index part I need to return one value, when index is 2 (in expression this looks as layer{2}) I need to return second value, index is 1 (in expression this looks as layer{1}) I need to return third value. Is it possible with pyparsing? I look at manuals and example SimpleCalc.py and this looks very similar for what I want. I think, that index part must be described with Optional class. But I can't understand what I must add to the SimpleCalc.py for parsing and evaluating variables with indexes. Can anyone help me with this? Thanks and sorry for my bad English, I'm Ukrainian -- Alexander Bruy mailto: alexander.bruy@... ```
 Re: [Pyparsing] Parse variables with indexes From: Alexander Bruy - 2010-01-08 09:59:23 ```Hi again I found a solution, when we poped from stack an index (number with {}) than we need to pop next operand from stack - so we have variable name and index and can analyse this values. Thanks -- Alexander Bruy mailto: alexander.bruy@... ```