RPAL Interpreter

This repository contains an implementation of a RPAL Interpreter, which includes a lexical analyzer, parser, abstract syntax tree (AST) generation, conversion to Standardized Tree (ST), and a CSE machine. It is defined by lexical rules and grammar detailed in RPAL_Lex.pdf and RPAL_Grammar.pdf under docs respectively.

Usage

The program can execute using the following

C/C++

$ ./myrpal file_name

Replace file_name with the name of the file containing the RPAL program.

The following sequence of commands can be used in the root of the project directory to compile the program and execute rpal programs:

> make
> ./myrpal file_name

To generate the Abstract Syntax Tree:

> ./myrpal -ast file_name

To generate the Standardized Tree:

> ./myrpal -st file_name

Required Switch

• -ast: This switch prints the abstract syntax tree and nothing else.

Input Format

The input RPAL program should adhere to the following format:

let Sum(A) = Psum (A,Order A ) 
where rec Psum (T,N) = N eq 0 -> 0
 | Psum(T,N-1)+T N
in Print ( Sum (1,2,3,4,5) ) 

Output Format

When the -ast switch is used, the output format should match the following:

let
.function_form
..<ID:Sum>
..<ID:A>
..where
...gamma
....<ID:Psum>
....tau
.....<ID:A>
.....gamma
......<ID:Order>
......<ID:A>
...rec
....function_form
.....<ID:Psum>
.....,
......<ID:T>
......<ID:N>
.....->
......eq
.......<ID:N>
.......<INT:0>
......<INT:0>
......+
.......gamma
........<ID:Psum>
........tau
.........<ID:T>
.........-
..........<ID:N>
..........<INT:1>
.......gamma
........<ID:T>
........<ID:N>
.gamma
..<ID:Print>
..gamma
...<ID:Sum>
...tau
....<INT:1>
....<INT:2>
....<INT:3>
....<INT:4>
....<INT:5>

When the -ast switch is not used, the output format should display the result of the RPAL program execution:

Output of the above program is: 15

Components

1. Lexical Analyzer: Tokenizes the input RPAL program.
2. Parser: Parses the tokens and constructs the abstract syntax tree (AST).
3. Abstract Syntax Tree (AST): Represents the parsed program as a tree structure.
4. Standardized Tree (ST): Converts the AST into a standardized tree.
5. CSE Machine: Executes the RPAL program.

Contributors

• Niruksha Sandeepa @NirukshaSandeepa
• Lakshani Manamperi @LRManamperi

License

This project is licensed under the MIT License