prog-language

Full interpreter written in python, from lexing to interpreting.

interpreter portion heavily based on course textbook: https://github.com/ebonelli/PLaF/

Includes

Lexing: Converts string to list of tokens
Parser: Parses list of tokens to Concrete Syntax Tree (CST, dictionary tree-based)
AST: Converts CST to Abstract Syntax Tree (stacked function-based)
Interpreter: Interprets AST and returns final result
Ds: extended functions for cleaner interpreter, including Environment for variable handling

CST

Concrete Syntax:

<Exp> ::= <ID> | <NUMBER> | {bool}
<Exp> ::= (<Exp>) | (-<Exp>)
<Exp> ::= <Exp> <OP> <Exp>
<Exp> ::= <Exp>
<Exp> ::= <Exp> and <Exp> | <Exp> or <Exp> | not <Exp>
<Exp> ::= iszero(<Exp>)
<Exp> ::= abs(<Exp>)
<Exp> ::= max(<Exp>,<Exp>) | min(<Exp>,<Exp>)
<Exp> ::= begin <Exp> ... <Exp> end
<Exp> ::= for <Exp>:<Exp> <Exp> endf
<Exp> ::= while <Exp> <Exp> endw

<Exp> ::= [<Exp>, ..., <Exp>]
<Exp> ::= <Exp>[<Exp>]
<Exp> ::= len(<Exp>)
<Exp> ::= append(<Exp>, <Exp>)
<Exp> ::= pop(<Exp>)
<Exp> ::= push(<Exp>, <Exp>)

<Exp> ::= newref(<Exp>) | deref(<Exp>) | setref(<Exp>, <Exp>)

<Exp> ::= print(<Exp>)

bool = true | false
<BOp> ::= <+|-|*|/|%>


Precendence:
1 - (), func()
2 - Mult/Div/Mod
3 - Add/Sub
4 - begin end

Testing

Via execute folder in command line:

$ python3.10 runlang.py filename [interp|parse|CST|tokens] (py)

Note: optional "py" tag puts a begin end wrapper between the input file, alike to pythonic code

Via interp.py:

Tokens

shows tokens formed from string

>>> string_to_tokens("3+2*4")
[{'NUMBER': 3}, {'PLUS': '+'}, {'NUMBER': 2}, {'MULT': '*'}, {'NUMBER': 4}]

CST

displays dictionary tree of CST via pprint printing

display_CST(s)

>>> display_CST("3+2*4")
[{'EXP': [{'EXP': {'NUMBER': 3}},
          {'OP': {'PLUS': '+'}},
          {'EXP': [{'EXP': {'NUMBER': 2}},
                   {'OP': {'MULT': '*'}},
                   {'EXP': {'NUMBER': 4}}]}]}]

Parse

shows parsed results of input, (to-be run on interpreter code)

parse(s)

>>> parse("3+2*4")
'Parse: Add(Int 3, Mul(Int 2, Int 4))'

Interp

interprets input and returns result, or error if invalid string given

interp(s)

>>> interp("3+2*4")
'Result: Ok (Int 11)'

Requires Python 3.10 and pprint to run