Pascal To Smalltalk

Pascal to Smalltalk Barry Haynes April 11, 1985 Current Status A new class, PascalCodeParser has been created. lt is a subclass of Parser that parses Pascal source code to produce a Smalltalk parse tree. From this parse tree, Smalltalk source is created and each method is added to the Smalltalk class that should include that method. Currently, the user must create the Smalltalk class manually. All methods are automatically placed in a category called pascal source. PascalCodeParser can now handle parsing procedures and functions and converting Pascal formal parameters into Smalltalk keyword parameters. lt converts simple local variables from Pascal to Smalltalk. Pascal expressions and assignment statements are correctly converted into equivalent Smalltalk statements. Handling function return results is also implemented. At this point, we know the basic conversion mechanism works. All that is required ·to do complete conversion from Pascal to Smalltalk is Smalltalk methods and a scheme for each of the parts of the Pascal railroad diagrams that have not yet been · implemented. The rest of this memo deals with these issues and problems that must be resolved to finish the job. lssues for the Rest of the Conversion 1. In general it is assumed the Object Pascal that is being translated has been compiled, has no syntax errors and is correct, complete Object Pascal in every way. 2.lt will be assumed that real numbers are not used in the Pascal that is being translated. · 3.Globals could be handled in the following way. For MacApp itself, global variables and constants can be added as class variables to class TObject. For the case of constants, code will be added to TObject initialize toset the constants to the correct values. Fora particular application, globals and constants declared in the interface and implementation of that application will be stored in a shared pool shared by all classes of that application. The shared pool will be initialized by the initialize method of whatever class the parser comes comes across first. lt is generally assumed this will be a sub-class of TApplication. 4. There will be a symbol table that will remember needed information about particular types and variables, like if it is an array or a PascalRecord. Variables that require a PascalRecord will have code generated in either the appropriate class initialize method or the local method, depending on where the Variable is located, to create the PascalRecord. 5.Both the interface and implementation of MacApp or a specific application will have to be parsed. This will allow the parser to know about the types of all variables. The parser will need to know about global procedures as well as methods that haven't yet been parsed. Only by parsing the interfaces first can this information be obtained. Procedures that are global to MacApp will be defined as class methods of TObject. Procedures that are global to a particular application will be defined as class methods of the …