text and language "see jack hack hackjackhackin one form or anotherprocessing text-based information is one of the more common tasks that applications need to perform this can include anything from scanning text file by columns to analyzing statements in language defined by formal grammar such processing usually is called parsing--analyzing the structure of text string in this we'll explore ways to handle language and text-based information and summarize some python development concepts in sidebars along the way in the processwe'll meet string methodstext pattern matchingxml and html parsersand other tools some of this material is advancedbut the examples are small to keep this short for instancerecursive descent parsing is illustrated with simple example to show how it can be implemented in python we'll also see that it' often unnecessary to write custom parsers for each language processing task in python they can usually be replaced by exporting apis for use in python programsand sometimes by single builtin function call finallythis closes by presenting pycalc-- calculator gui written in pythonand the last major python coding example in this text as we'll seewriting calculators isn' much more difficult than juggling stacks while scanning text strategies for processing text in python in the grand scheme of thingsthere are variety of ways to handle text processing and language analysis in pythonexpressions built-in string object expressions methods built-in string object method calls patterns regular expression pattern matching