Added pure-python pycalc implementation and unit tests

Author: daniildavydzik

final_task/pycalc/__init__.py

@@ -0,0 +1,72 @@
+from pycalc.operators import Operator, Function, Constant
+from pycalc.parser import Parser
+from pycalc.importmodules import FunctionParser
+from pycalc.validator import Validator
+
+
+def infix_to_postfix(parsed_exp):
+    stack = []
+    postfix_list = []
+    for token in parsed_exp:
+        if isinstance(token, Operator) or isinstance(token, Function):
+            if token.name == '(':
+                stack.append(token)
+            elif token.name == ')':
+                while stack and stack[-1].name != '(':
+                    postfix_list.append(stack.pop())
+                if stack:
+                    stack.pop()
+            else:
+                if not token.associativity == 1:
+                    while stack and token.priority < stack[-1].priority:
+                        postfix_list.append(stack.pop())
+                else:
+                    while stack and token.priority <= stack[-1].priority:
+                        postfix_list.append(stack.pop())
+                stack.append(token)
+        elif isinstance(token, Function):
+            stack.append(token)
+        elif isinstance(token, Constant):
+            postfix_list.append(token)
+        elif Parser.is_number(token):
+            postfix_list.append(token)
+        else:
+            raise ValueError(f'name {token} is not defined')
+    while stack:
+        postfix_list.append(stack.pop())
+    return postfix_list
+
+
+def calculate(exp):
+    stack = []
+    parser = Parser()
+    parsed_exp = parser.parse_expression(exp)
+    polish = infix_to_postfix(parsed_exp)
+    if all(isinstance(token, Operator) for token in polish):
+        raise ValueError('not valid input')
+    for token in polish:
+        if isinstance(token, Operator) or isinstance(token, Function) or isinstance(token, Constant):
+            if isinstance(token, Function) and len(polish) == 1:
+                stack.append(token.func())
+            elif isinstance(token, Function):
+                x = stack.pop()
+                if type(x) is list:
+                    res = token.func(*x)
+                else:
+                    res = token.func(*[x])
+                stack.append(res)
+            elif isinstance(token, Constant):
+                stack.append(token.func)
+            elif not token.is_binary:
+                x = stack.pop()
+                stack.append(token.func(x))
+            else:
+                try:
+                    y, x = stack.pop(), stack.pop()
+                    stack.append(token.func(x, y))
+                except Exception as e:
+                    raise ValueError(f' binary operation must have two operands {e}')
+
+        else:
+            stack.append(float(token))
+    return stack[0]

final_task/pycalc/evaluator.py

@@ -0,0 +1,27 @@
+import importlib
+from pycalc.operators import Function, Constant
+
+
+class FunctionParser:
+    functions_dict = {}
+    constants_dict = {}
+
+    def __init__(self):
+        self.parse_modules(['math'])
+        self.functions_dict['pow'] = Function(object, 6, 1, True, pow)
+        self.functions_dict['abs'] = Function(object, 6, 1, True, abs)
+        self.functions_dict['round'] = Function(object, 6, 1, True, round)
+
+    def parse_modules(self, modules):
+        ''' Method that parse module names array and add to dictionary their name as a key and
+            callable object as a value.
+            :param modules: Array of modules names.
+        '''
+        for module in modules:
+            modul = importlib.import_module(module)
+            for object in vars(modul):
+                if object[0:2] != '__':
+                    if isinstance(vars(modul)[object], (int, float, complex)):
+                        self.constants_dict[object] = Constant(object, 6, 1, True, vars(modul)[object])
+                    else:
+                        self.functions_dict[object] = Function(object, 6, 1, True, vars(modul)[object])

final_task/pycalc/importmodules.py

@@ -0,0 +1,48 @@
+class Operator:
+    def __init__(self, name, priority, associativity, is_binary,  func):
+        self.priority = priority
+        self.associativity = associativity
+        self.func = func
+        self.name = name
+        self.is_binary = is_binary
+
+
+class Function:
+    def __init__(self, name, priority, associativity, is_binary,  func):
+        self.priority = priority
+        self.associativity = associativity
+        self.func = func
+        self.name = name
+        self.is_binary = is_binary
+
+
+class Constant:
+    def __init__(self, name, priority, associativity, is_binary,  func):
+        self.priority = priority
+        self.associativity = associativity
+        self.func = func
+        self.name = name
+        self.is_binary = is_binary
+
+
+operators_dict = {
+    '>=': Operator('>=', 0, 1, True, lambda x, y: x >= y),
+    '<=': Operator('<=', 0, 1, True, lambda x, y: x <= y),
+    '==': Operator('==', 0, 1, True, lambda x, y: x == y),
+    '!=': Operator('!=', 0, 1, True, lambda x, y: x != y),
+    '>': Operator('>', 0, 1, True, lambda x, y: x > y),
+    '<': Operator('<', 0, 1, True, lambda x, y: x >= y),
+    ',': Operator(',', 1, 1, True, lambda x, y: [x, y]),
+    '+': Operator('+', 2, 1, True, lambda x, y: x+y),
+    '-': Operator('-', 2, 1,  True, lambda x, y: x-y),
+    ')': Operator(')', -1, 1, False, None),
+    '(': Operator('(', -1, 1, False, None),
+    '*': Operator('*', 3, 1, True, lambda x, y: x*y),
+    '/': Operator('/', 3, 1, True, lambda x, y: x/y),
+    '%': Operator('%', 3, 1, True, lambda x, y: x % y),
+    '//': Operator('//',3, 1,True, lambda x, y: x // y),
+    'unary_minus': Operator('unary_minus', 4, 1, False, lambda x: -x),
+    'unary_plus': Operator('unary_plus', 4, 1, False, lambda x: x),
+    '^': Operator('^', 5, 2, True, lambda x, y: x**y),
+}
+

final_task/pycalc/operators.py

@@ -0,0 +1,105 @@
+from pycalc.operators import operators_dict, Operator, Function, Constant
+from pycalc.validator import Validator
+from pycalc.importmodules import FunctionParser
+functions_dict = {}
+const_dict = {}
+
+
+class Parser:
+    def __init__(self):
+        self.func_parser = FunctionParser()
+
+    @staticmethod
+    def is_number(s):
+        """ Returns True is string is a number. """
+        if isinstance(s, Operator) or isinstance(s, Function) or isinstance(s, Constant) or s == 'pow':
+            return False
+        return s.replace('.', '', 1).isdigit()
+
+    @staticmethod
+    def is_operator(s):
+        return s in operators_dict
+
+    @staticmethod
+    def is_function(s):
+        return s in FunctionParser.functions_dict
+
+    @staticmethod
+    def is_constant(s):
+        return s in FunctionParser.constants_dict
+
+    @staticmethod
+    def add_multiply_sign(lexem_list):
+        for i in range(1, len(lexem_list)):
+            if isinstance(lexem_list[i], Function) and not isinstance(lexem_list[i-1], Operator):
+                lexem_list.insert(i, operators_dict['*'])
+            elif isinstance(lexem_list[i], Function) and isinstance(lexem_list[i-1], Operator) and lexem_list[i-1].name == ')':
+                lexem_list.insert(i, operators_dict['*'])
+            elif isinstance(lexem_list[i], Operator) and lexem_list[i].name == '(' and (isinstance(lexem_list[i-1], Constant) or Parser.is_number(lexem_list[i-1])):
+                lexem_list.insert(i, operators_dict['*'])
+            elif isinstance(lexem_list[i], Operator) and lexem_list[i].name == '(' and isinstance(lexem_list[i-1], Operator) and lexem_list[i-1].name == ')':
+                lexem_list.insert(i, operators_dict['*'])
+            elif isinstance(lexem_list[i], Operator) and lexem_list[i].name == '(' and not isinstance(lexem_list[i-1], Operator) and not isinstance(lexem_list[i-1], Function):
+                lexem_list.insert(i, operators_dict['*'])
+        return lexem_list
+
+    def parse_expression(self, exp):
+        exp = Validator.pre_tokinaze(exp)
+        exp.replace(" ", "")
+        lexem_array = []
+        start_index = 0
+        end_index = len(exp)
+        while start_index != len(exp):
+            substring = exp[start_index:end_index]
+            if Parser.is_number(substring):
+                lexem_array.append(substring)
+                start_index, end_index = end_index, len(exp)
+            elif Parser.is_operator(substring):
+                operator = operators_dict[substring]
+                lexem_array.append(operator)
+
+                start_index, end_index = end_index, len(exp)
+            elif Parser.is_constant(substring):
+                lexem_array.append(self.func_parser.constants_dict[substring])
+                start_index, end_index = end_index, len(exp)
+            elif Parser.is_function(substring):
+                lexem_array.append(self.func_parser.functions_dict[substring])
+                start_index, end_index = end_index, len(exp)
+            else:
+                end_index -= 1
+        lex_list =Parser.add_multiply_sign(lexem_array)
+        unary_signs = Parser.find_unary_signs(lex_list)
+        final_lexem_list = Parser.remove_redundant_unary_signs(unary_signs, lex_list)
+
+        return final_lexem_list
+
+    @staticmethod
+    def find_unary_signs(lexem_list):
+        final_list = []
+        for i in range(len(lexem_list)):
+            if i == 0 and isinstance(lexem_list[i], Operator) and lexem_list[i].name in ['+', '-']:
+                final_list.append(0)
+            elif (isinstance(lexem_list[i], Operator) and lexem_list[i].name in ['+', '-']) and not (Parser.is_constant(lexem_list[i-1]) or Parser.is_number(lexem_list[i-1])) \
+                    and not (isinstance(lexem_list[i-1], Operator) and lexem_list[i-1].name == ')'):
+                final_list.append(i)
+        lexems_with_indicies = enumerate(lexem_list)
+        lexems_filter = list(filter(lambda x: x[0] in final_list, lexems_with_indicies))
+        for unary_sign in lexems_filter:
+            lexem_list[unary_sign[0]] = operators_dict['unary_plus'] if unary_sign[1] == '+' else operators_dict['unary_minus']
+        return lexems_filter
+
+    @staticmethod
+    def remove_redundant_unary_signs(lexems_with_indicies, lex_list):
+        final_index = len(lexems_with_indicies)-1
+        while final_index != -1:
+            last_index, last_sign = lexems_with_indicies[final_index]
+            prev_index, prev_sign = lexems_with_indicies[final_index - 1]
+            if last_index - 1 == prev_index and last_sign.name == prev_sign.name:
+                lex_list[prev_index:last_index + 1] = [operators_dict['unary_plus']]
+                lexems_with_indicies[final_index - 1: final_index + 1] = [(prev_index,  operators_dict['+'])]
+            elif last_index - 1 == prev_index and last_sign != prev_sign:
+                lex_list[prev_index: last_index + 1] = [operators_dict['unary_minus']]
+                lexems_with_indicies[final_index - 1: final_index + 1] = [(prev_index,  operators_dict['-'])]
+            final_index -= 1
+        return lex_list
+

final_task/pycalc/parser.py

@@ -0,0 +1,34 @@
+import argparse
+import sys
+from pycalc.importmodules import FunctionParser
+from pycalc.evaluator import calculate
+
+
+def get_args():
+    '''This function parses and return arguments passed in'''
+    parser = argparse.ArgumentParser(
+        description='Script retrieves schedules from a given server')
+    parser.add_argument(
+        'expression',  help='')
+
+    parser.add_argument(
+         '-m', '--use-modules', nargs='+', help='', required=False)
+    return parser.parse_args()
+
+
+def main():
+    try:
+        # args = get_args()
+        # parser = FunctionParser()
+        # if args.use_modules:
+        #     parser.parse_modules(args.use_modules)
+        # parser.parse_modules(['time'])
+        # result = calculate(args.expression)
+        # print(calculate('time()'))
+        # print(f'{result}')
+
+
+    except Exception as e:
+        print(f"ERROR: {e}")
+        sys.exit(1)
+

final_task/pycalc/pycalc.py

@@ -0,0 +1,66 @@
+import re
+
+
+class Validator:
+    spaces_reg = '\s+'
+    sign_arr = ['<', '>', '=', '!']
+
+    @staticmethod
+    def normalize_string(str):
+        ''' Method that normalize string with expression. If we have more than one space between symbol,
+            it change multiply spaces with one space.
+            :param str: String with a math expression.
+            :return : Normalized string with a math expression.
+        '''
+        return re.sub(Validator.spaces_reg, ' ', str).strip()
+
+    @staticmethod
+    def pre_tokinaze(str):
+        ''' Method that do a number of operations before tokenization.
+            :param str: String with a math expression.
+            :return : Amended string with a math expression.
+        '''
+        str.lower()
+        if Validator.par_check(str):
+            normalize_str = Validator.normalize_string(str)
+            valid_string = Validator.validate_string(normalize_str).replace(" ", "")
+            return valid_string
+        else:
+            raise ValueError('Brackets not balanced')
+
+    @staticmethod
+    def par_check(expression):
+        ''' Method that check for validity of brackets.
+            :param expression: String with math expression.
+            :return : True or False, depends on validity of brackets of a given expression.
+        '''
+        mapping = dict(zip('({[', ')}]'))
+        queue = []
+        for letter in expression:
+            if letter in mapping:
+                queue.append(mapping[letter])
+            elif letter not in mapping.values():
+                continue
+            elif not (queue and letter == queue.pop()):
+                return False
+        return not queue
+
+
+    @staticmethod
+    def validate_string(str):
+        ''' Method that raise error if string with a math expression is not valid.
+            :param str: String with a math expression.
+            :return : string with a math expression if it is valid.
+        '''
+        indices = enumerate(str)
+        for i, char in indices:
+            if char in Validator.sign_arr:
+                if str[i + 1] == ' ' and str[i + 2] == '=':
+                    raise ValueError('invalid syntax')
+            elif char.isdigit() and i != len(str) - 1:
+                if str[i + 1] == ' ' and str[i + 2].isdigit():
+                    raise ValueError('invalid syntax')
+
+        return str
+
+