PoPL/02_syntax/main.py

#!/bin/env python3

import argparse
import ply.lex as lex
import ply.yacc as yacc
import lexer

# Simple debuggin function to call from syntax rules
symbolnum = 0
def debug_print(p):
    global symbolnum
    symbolnum += 1
    p[0] = symbolnum
    msg = ''
    for i, s in enumerate(p.slice):
        if s is not None:
            if type(s) is lex.LexToken:
                msg += str(s.type) + '<' + str(s.value) + '> '
            else:
                msg += str(s) + '(' + str(p[i]) + ') '
        else:
            msg += '?? '
        if i == 0:
            msg += ':: '
    print(msg)

tokens = lexer.tokens

def p_program(p):
    '''program : statement_list
               | definitions program'''
    debug_print(p)

def p_statement_list(p):
    '''statement_list : statement
                      | statement COMMA statement_list'''
    debug_print(p)

def p_definitions(p):
    '''definitions : function_definition
                   | procedure_definition
                   | variable_definition'''
    debug_print(p)

def p_variable_definition(p):
    '''variable_definition : VAR IDENT EQ expression'''
    debug_print(p)

def p_empty(p):
    '''empty :'''
    debug_print(p)

def p_opt_formals(p):
    '''opt_formals : empty
                   | formals'''
    debug_print(p)

def p_opt_variable_defitions(p):
    '''opt_variable_definitions : empty
                                | variable_definition opt_variable_definitions'''
    debug_print(p)

def p_function_definition(p):
    '''function_definition : FUNCTION FUNC_IDENT LCURLY opt_formals RCURLY RETURN IDENT opt_variable_definitions IS rvalue END FUNCTION'''
    debug_print(p)

def p_procedure_definition(p):
    '''procedure_definition : PROCEDURE PROC_IDENT LCURLY opt_formals RCURLY opt_variable_definitions IS statement_list END PROCEDURE
                            | PROCEDURE PROC_IDENT LCURLY opt_formals RCURLY RETURN IDENT opt_variable_definitions IS statement_list END PROCEDURE'''
    debug_print(p)

def p_formals(p):
    '''formals : formal_arg
               | formal_arg COMMA formals'''
    debug_print(p)

def p_formal_arg(p):
    '''formal_arg : IDENT LSQUARE IDENT RSQUARE'''
    debug_print(p)

def p_procedure_call(p):
    '''procedure_call : PROC_IDENT LPAREN RPAREN
                      | PROC_IDENT LPAREN arguments RPAREN'''
    debug_print(p)

def p_arguments(p):
    '''arguments : expression
                 | expression COMMA arguments'''
    debug_print(p)

def p_assignment(p):
    '''assignment : lvalue EQ rvalue'''
    debug_print(p)

def p_lvalue(p):
    '''lvalue : IDENT
              | IDENT DOT IDENT'''
    debug_print(p)

def p_rvalue(p):
    '''rvalue : expression
              | unless_expression'''
    debug_print(p)

def p_print_statement(p):
    '''print_statement : PRINT print_item
                       | print_statement AMPERSAND print_item'''
    debug_print(p)

def p_print_item(p):
    '''print_item : STRING
                  | expression'''
    debug_print(p)

def p_statement(p):
    '''statement : procedure_call
                 | assignment
                 | print_statement
                 | DO statement_list UNTIL expression
                 | DO statement_list UNLESS expression DONE
                 | DO statement_list UNLESS expression OTHERWISE statement_list DONE
                 | RETURN expression'''
    debug_print(p)

def p_expression(p):
    '''expression : simple_expr
                  | expression EQ simple_expr
                  | expression LT simple_expr'''
    debug_print(p)

def p_simple_expr(p):
    '''simple_expr : term
                   | simple_expr PLUS term
                   | simple_expr MINUS term
       term : factor
            | term MULT factor
            | term DIV factor
       factor : atom
              | MINUS atom
              | PLUS atom
       atom : IDENT
            | IDENT APOSTROPHE IDENT
            | INT_LITERAL
            | DATE_LITERAL
            | function_call
            | procedure_call
            | LPAREN expression RPAREN'''
    debug_print(p)

def p_function_call(p):
    '''function_call : FUNC_IDENT LPAREN RPAREN
                     | FUNC_IDENT LPAREN arguments RPAREN'''
    debug_print(p)

def p_unless_expression(p):
    '''unless_expression : DO expression UNLESS expression OTHERWISE expression DONE'''
    debug_print(p)

def p_error(p):
    if p is not None:
        print(f"{{{p.lineno}}}:Syntax Error (token:'{p.value}')")
    else:
        print('Syntax Error at the end of file')
    raise SystemExit

def syntax_check_file(file_path: str, debug: bool):
    parser = yacc.yacc()
    with open(file_path, 'r', encoding='utf-8') as file:
        parser.parse(file.read(), lexer=lexer.lexer, debug=debug)
    print('syntax OK')

if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument('-d', '--debug', action='store_true', help='debug?')
    group = parser.add_mutually_exclusive_group(required=True)
    group.add_argument('--who', action='store_true', help='print out student IDs and NAMEs of authors')
    group.add_argument('-f', '--file', help='filename to process')

    args = parser.parse_args()

    if args.who:
        print('Author')
        print('  Student ID: 150189237')
        print('  Name:       Oskari Alaranta')
    else:
        syntax_check_file(args.file, args.debug)