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May 17, 2022 07:07
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This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters. Learn more about bidirectional Unicode charactersOriginal file line number Diff line number Diff line change @@ -0,0 +1,278 @@ import sys import re VARIABLE_ASSIGNMENT_REGEX = r'[a-zA-Z_]*=' SQR = 'SQR' ABS = 'ABS' INI = '^' FIN = '$' QTM = '\"' EQO = '\=' OPP = '\(' CLP = '\)' ADD = '\+' SUB = '\-' MLT = '\*' DIV = '\/' VAR = '[a-zA-Z]([a-zA-Z0-9_]*)' INT = '\d+' FLT = '(((\d+)\.(\d+))|(\.(\d+))|((\d+)\.))' VAL = "(({})|({})|({}))".format(VAR, INT, FLT) variables = { "X": 0, "Y": 1, } def replace_spaces_in_non_string_literals(expression): in_string_literal = False cleaned_expression = "" for char in expression: append = char if char == '"' and not in_string_literal: in_string_literal = True elif char == '"' and in_string_literal: in_string_literal = False elif char == " " and not in_string_literal: append = "" cleaned_expression += append return cleaned_expression def evaluate(expression): expression = replace_spaces_in_non_string_literals(expression) # QUOTES if re.match(INI + QTM, expression): i = 1 q_expression = "" while i < len(expression) and expression[i] != '"': q_expression += expression[i] i += 1 if expression[i] != '"': raise(Exception("Unmatched quotation marks in {}").format(expression)) if i == len(expression)-1: return q_expression p_value = evaluate(p_expression) if i >= len(expression): return p_value elif expression[i] == "+": return evaluate(str(p_value) + "+" + expression[(i+1):]) elif expression[i] == "-": return evaluate(str(p_value) + "-" + expression[(i+1):]) elif expression[i] == "*": return evaluate(str(p_value) + "*" + expression[(i+1):]) elif expression[i] == "/": return evaluate(str(p_value) + "/" + expression[(i+1):]) else: raise(Exception("Syntax error: {}").format(expression)) # STRING LITERALS # if expression.startswith('"'): # if expression.endswith('"'): # return expression.strip('"') # else: # raise(Exception("Invalid expression: {}").format(expression)) # NOT A STRING, SO SAFE TO REMOVE SPACES # expression = replace_spaces_in_non_string_literals(expression) # NUMERIC LITERALS AND VARIABLES if re.match(INI+INT+FIN, expression): return int(expression) elif re.match(INI+FLT+FIN, expression): return float(expression) elif re.match(INI+VAR+FIN, expression): return variables[expression] # EQUALITY elif re.match(INI + VAL + EQO, expression): if re.match(INI + VAL + EQO + VAL + FIN, expression): lhs, rhs = expression.split("=", 1) return evaluate(lhs) == evaluate(rhs) if re.match(INI + VAL + EQO + OPP, expression): lhs, rhs = expression.split("=", 1) return evaluate(lhs) == evaluate(rhs) # ADDITION elif re.match(INI + VAL + ADD, expression): # GREEDY SUB-CASES: ADD IMMEDIATELY if re.match(INI + VAL + ADD + VAL + FIN, expression): lhs, rhs = expression.split("+", 1) return evaluate(lhs) + evaluate(rhs) if re.match(INI + VAL + ADD + VAL + ADD, expression): s1, s2 = expression.split("+", 1) s2, s3 = s2.split("+", 1) return evaluate(str(evaluate(s1) + evaluate(s2)) + "+" + s3) if re.match(INI + VAL + ADD + VAL + SUB, expression): s1, s2 = expression.split("+", 1) s2, s3 = s2.split("-", 1) return evaluate(str(evaluate(s1) + evaluate(s2)) + "-" + s3) # LAZY SUB-CASES: EVALUATE FIRST if re.match(INI + VAL + ADD + VAL + MLT, expression): s1, s2= expression.split("+", 1) return evaluate(s1) + evaluate(s2) if re.match(INI + VAL + ADD + VAL + DIV, expression): s1, s2 = expression.split("+", 1) return evaluate(s1) + evaluate(s2) if re.match(INI + VAL + ADD + VAL + OPP, expression): s1, s2 = expression.split("+", 1) return evaluate(s1) + evaluate(s2) # SUBTRACTION elif re.match(INI + VAL + SUB, expression): # GREEDY SUB-CASES: SUB IMMEDIATELY if re.match(INI + VAL + SUB + VAL + FIN, expression): lhs, rhs = expression.split("-", 1) return evaluate(lhs) - evaluate(rhs) if re.match(INI + VAL + SUB + VAL + ADD, expression): s1, s2 = expression.split("-", 1) s2, s3 = s2.split("+", 1) return evaluate(str(evaluate(s1) - evaluate(s2)) + "+" + s3) if re.match(INI + VAL + SUB + VAL + SUB, expression): s1, s2 = expression.split("-", 1) s2, s3 = s2.split("-", 1) return evaluate(str(evaluate(s1) - evaluate(s2)) + "-" + s3) # LAZY SUB-CASES: EVALUATE FIRST if re.match(INI + VAL + SUB + VAL + MLT, expression): s1, s2 = expression.split("-", 1) return evaluate(s1) - evaluate(s2) if re.match(INI + VAL + SUB + VAL + DIV, expression): s1, s2 = expression.split("-", 1) return evaluate(s1) + evaluate(s2) if re.match(INI + VAL + SUB + VAL + OPP, expression): s1, s2 = expression.split("-", 1) return evaluate(s1) + evaluate(s2) # MULTIPLICATION elif re.match(INI + VAL + MLT, expression): # GREEDY SUB-CASES: MLT IMMEDIATELY if re.match(INI + VAL + MLT + VAL + FIN, expression): lhs, rhs = expression.split("*", 1) return evaluate(lhs) * evaluate(rhs) if re.match(INI + VAL + MLT + VAL + ADD, expression): s1, s2 = expression.split("*", 1) s2, s3 = s2.split("+", 1) return evaluate(str(evaluate(s1) * evaluate(s2)) + "+" + s3) if re.match(INI + VAL + MLT + VAL + SUB, expression): s1, s2 = expression.split("*", 1) s2, s3 = s2.split("-", 1) return evaluate(str(evaluate(s1) * evaluate(s2)) + "-" + s3) if re.match(INI + VAL + MLT + VAL + MLT, expression): s1, s2 = expression.split("*", 1) s2, s3 = s2.split("*", 1) return evaluate(str(evaluate(s1) * evaluate(s2)) + "*" + s3) if re.match(INI + VAL + MLT + VAL + DIV, expression): s1, s2 = expression.split("*", 1) s2, s3 = s2.split("/", 1) return evaluate(str(evaluate(s1) * evaluate(s2)) + "/" + s3) # LAZY SUB-CASES: EVAL FIRST if re.match(INI + VAL + MLT + OPP, expression): s1, s2 = expression.split("*", 1) return evaluate(s1) * evaluate(s2) # DIVISION elif re.match(INI + VAL + DIV, expression): # GREEDY SUB-CASES: DIV IMMEDIATELY if re.match(INI + VAL + DIV + VAL + FIN, expression): lhs, rhs = expression.split("/", 1) return evaluate(lhs) / evaluate(rhs) if re.match(INI + VAL + DIV + VAL + ADD, expression): s1, s2 = expression.split("/", 1) s2, s3 = s2.split("+", 1) return evaluate(str(evaluate(s1) / evaluate(s2)) + "+" + s3) if re.match(INI + VAL + DIV + VAL + SUB, expression): s1, s2 = expression.split("/", 1) s2, s3 = s2.split("-", 1) return evaluate(str(evaluate(s1) * evaluate(s2)) + "-" + s3) if re.match(INI + VAL + DIV + VAL + MLT, expression): s1, s2 = expression.split("/", 1) s2, s3 = s2.split("*", 1) return evaluate(str(evaluate(s1) / evaluate(s2)) + "*" + s3) if re.match(INI + VAL + DIV + VAL + DIV, expression): s1, s2 = expression.split("/", 1) s2, s3 = s2.split("/", 1) return evaluate(str(evaluate(s1) / evaluate(s2)) + "/" + s3) # LAZY SUB-CASES: EVAL FIRST if re.match(INI + VAL + DIV + OPP, expression): s1, s2 = expression.split("/", 1) return evaluate(s1) / evaluate(s2) # PARENTHESES elif re.match(INI + OPP, expression): i = 1 stack = 1 p_expression = "" while stack and i < len(expression): if expression[i] == "(": stack += 1 if expression[i] == ")": stack -= 1 p_expression += expression[i] i += 1 if stack: raise(Exception("Unmatched parentheses in {}").format(expression)) p_expression = p_expression[:-1] if p_expression.endswith(")") else p_expression p_value = evaluate(p_expression) if i >= len(expression): return p_value elif expression[i] == "+": return evaluate(str(p_value) + "+" + expression[(i+1):]) elif expression[i] == "-": return evaluate(str(p_value) + "-" + expression[(i+1):]) elif expression[i] == "*": return evaluate(str(p_value) + "*" + expression[(i+1):]) elif expression[i] == "/": return evaluate(str(p_value) + "/" + expression[(i+1):]) else: raise(Exception("Syntax error: {}").format(expression)) test_expressions = [ ('""', "Empty string"), ('"1"', "Numeric string"), ('"A"', "Alpha string"), ('"A1"', "Alphanumeric string"), ('1', "integer"), ('1.', "float (nothing after decimal)"), ('.1', "float (nothing before decimal)"), ('1.1', "float (vals before and after decimal)"), ('2+3', "integer addition"), ('2-3', "integer subtraction"), ('2*3', "integer multiplication"), ('7/3', "integer division"), ('2.8+3.1', "float addition"), ('2-3', "float subtraction"), ('2*3', "float multiplication"), ('7/3', "float division"), ('2 + 3', "integer addition with spaces"), ('1=1', "identity with two ints"), ] successes = len(test_expressions) for test_expression, test_name in test_expressions: if evaluate(test_expression) != eval(test_expression): print("Failed test: {}".format(test_name)) successes -= 1 print("Passed {} of {} tests.".format(successes, len(test_expressions)))