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December 2, 2012 06:28
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python calculator
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| #!/usr/bin/python | |
| # | |
| # by Erik Osheim | |
| # | |
| # This program uses a recursive descent, LL1 parser to generate a Code object | |
| # for the given input. Code objects are pure expressions whose behavior can | |
| # only be controlled via a dictionary of strings-to-numbers provided to run. | |
| # | |
| # Syntax: | |
| # | |
| # * decimal numbers (e.g. 3, 4.52) | |
| # * simple names (foo, qux13). | |
| # * built-in constants: pi, e, i | |
| # * arithmetic operators: + - * / % // ^ ! | |
| # * parenthesis and absolute value: (2 + 3) * |4 - x| | |
| # * built-in functions: | |
| # abs, ceil, cos, degrees, floor, log, log10, | |
| # log2, max, min, radians, round, sin, tan | |
| # | |
| # You can test this program out on the command-line. For instance: | |
| # | |
| # python calc.py "2 + 2" | |
| # | |
| # python calc.py "9!" | |
| # | |
| # python calc.py "2^foo - 1" foo=8 | |
| # | |
| # python calc.py "e^(i*pi) + 1" | |
| import math | |
| import re | |
| import sys | |
| import time | |
| # private expression cache | |
| _cache = {} | |
| # public methods | |
| def prepare(s): | |
| "Prepare the given expression 's' and return a Code object." | |
| global _cache | |
| if s not in _cache: | |
| _cache[s] = Code.gen(Parser(s).parse()) | |
| return _cache[s] | |
| def run(s, d): | |
| "Run the given expression 's' using the variables from 'd'." | |
| return prepare(s).run(d) | |
| def flush(): | |
| "Clear the expression cache." | |
| global _cache | |
| _cache = {} | |
| # everything below here is semi-private, except the Code class, which is | |
| # returned from prepare(). | |
| class Lexeme(object): | |
| def __init__(self, name, pos, data): | |
| self.name = name | |
| self.pos = pos | |
| self.data = data | |
| def __repr__(self): | |
| return 'Lexeme(%r, %d, %r)' % (self.name, self.pos, self.data) | |
| class Lexer(object): | |
| num_re = re.compile(r'(?:0|[1-9][0-9]*)(?:\.[0-9]+)?') | |
| def __init__(self, data): | |
| self.data = data | |
| self.lexs = [] | |
| def lexid(self, i): | |
| j = i + 1 | |
| while j < len(self.data) and self.data[j].isalnum(): j += 1 | |
| self.lexs.append(Lexeme('id', i, self.data[i:j])) | |
| return j | |
| def lexnum(self, i): | |
| j = i + 1 | |
| while j < len(self.data) and self.data[j].isdigit(): j += 1 | |
| k = j | |
| if k < len(self.data) and self.data[k] == '.': | |
| k += 1 | |
| while k < len(self.data) and self.data[k].isdigit(): k += 1 | |
| if k > j + 1: | |
| self.lexs.append(Lexeme('num', i, self.data[i:k])) | |
| return k | |
| else: | |
| self.lexs.append(Lexeme('num', i, self.data[i:j])) | |
| return j | |
| def lex(self): | |
| i = 0 | |
| while i < len(self.data): | |
| c = self.data[i] | |
| if c.isspace(): | |
| i += 1 | |
| elif c.isalpha(): | |
| i = self.lexid(i) | |
| elif c.isdigit(): | |
| i = self.lexnum(i) | |
| elif c == '/' and self.data[i:i + 2] == '//': | |
| self.lexs.append(Lexeme('//', i, '//')) | |
| i += 2 | |
| else: | |
| self.lexs.append(Lexeme(c, i, c)) | |
| i += 1 | |
| self.lexs.append(Lexeme('$', i, None)) | |
| return self.lexs | |
| class Expr(object): | |
| def __init__(self, op, *args): | |
| self.op = op | |
| self.args = args | |
| def __repr__(self): | |
| return 'Expr(%r, %r)' % (self.op, self.args) | |
| def lisp(self): | |
| if self.op == 'num': | |
| return self.args[0] | |
| elif self.op == 'id': | |
| return self.args[0] | |
| elif self.op == 'apply': | |
| return '(%s %s)' % (self.args[0], ' '.join([a.lisp() for a in self.args[1:]])) | |
| elif self.args: | |
| return '(%s %s)' % (self.op, ' '.join([a.lisp() for a in self.args])) | |
| else: | |
| return self.op | |
| class Parser(object): | |
| debug = False | |
| def error(self): | |
| if self.debug: | |
| raise Exception("parse error at %r" % self.cur) | |
| else: | |
| raise Exception("parse error at %r (byte %d)" % (self.cur.data, self.cur.pos)) | |
| def __init__(self, data): | |
| self.lexer = Lexer(data) | |
| def next(self): | |
| self.k += 1 | |
| self.cur = self.lexs[self.k] | |
| def parse(self): | |
| self.k = 0 | |
| self.lexs = self.lexer.lex() | |
| self.cur = self.lexs[0] | |
| return self.parseP() | |
| def lxin(self, names): | |
| return self.cur.name in names | |
| pnames = set(['num', 'id', '(', '|', '-']) | |
| def parseP(self): | |
| return self.parseE1() | |
| def parseEx(self, names, f1, f2, right=False): | |
| lhs = f1() | |
| lst = f2() | |
| if not lst: | |
| return lhs | |
| elif right: | |
| lst = [lhs] + lst | |
| expr = lst[-1] | |
| i = len(lst) - 3 | |
| while i >= 0: | |
| expr = Expr(lst[i + 1], lst[i], expr) | |
| i -= 2 | |
| return expr | |
| else: | |
| expr = lhs | |
| i = 0 | |
| while i < len(lst) - 1: | |
| expr = Expr(lst[i], expr, lst[i + 1]) | |
| i += 2 | |
| return expr | |
| def parseE1(self): | |
| return self.parseEx(self.pnames, self.parseE2, self.parseE1_) | |
| def parseE2(self): | |
| return self.parseEx(self.pnames, self.parseE3, self.parseE2_) | |
| dash = set(['-']) | |
| e3names = set(['num', 'id', '(', '|']) | |
| def parseE3(self): | |
| if self.cur.name == '-': | |
| self.next() | |
| expr = self.parseE3() | |
| return Expr('-', expr) | |
| else: | |
| return self.parseE4() | |
| def parseE4(self): | |
| return self.parseEx(self.e3names, self.parseE5, self.parseE4_, right=True) | |
| def parseE5(self): | |
| expr = self.parseE6() | |
| if self.parseE5_() is None: | |
| return expr | |
| else: | |
| return Expr('!', expr) | |
| lpar = set(['(']) | |
| pipe = set(['|']) | |
| rpar = set([')']) | |
| def parseE6(self): | |
| c = self.cur | |
| if c.name == 'num': | |
| self.next() | |
| return Expr('num', c.data) | |
| elif c.name == 'id': | |
| self.next() | |
| a = self.parseA() | |
| if a is None: | |
| return Expr('id', c.data) | |
| else: | |
| return Expr('apply', c.data, *a) | |
| elif c.name == '(': | |
| self.next() | |
| e1 = self.parseE1() | |
| if self.lxin(self.rpar): | |
| self.next() | |
| return e1 | |
| else: | |
| self.error() | |
| elif c.name == '|': | |
| self.next() | |
| e1 = self.parseE1() | |
| if self.lxin(self.pipe): | |
| self.next() | |
| return Expr('abs', e1) | |
| else: | |
| self.error() | |
| else: | |
| self.error() | |
| anames = set(['!', '$', '^', '*', '/', '//', '%', '+', '-', ')', '|', ',']) | |
| def parseA(self): | |
| if self.lxin(self.lpar): | |
| self.next() | |
| ll = self.parseL() | |
| if self.lxin(self.rpar): | |
| self.next() | |
| return ll | |
| else: | |
| self.error() | |
| else: | |
| return None | |
| lnames = set(['num', 'id', '(', '|', '-']) | |
| def parseL(self): | |
| e1 = self.parseE1() | |
| l_ = self.parseL_() | |
| if l_ is None: | |
| return [e1] | |
| else: | |
| return [e1] + l_ | |
| comma = set([',']) | |
| def parseL_(self): | |
| if self.lxin(self.comma): | |
| self.next() | |
| e1 = self.parseE1() | |
| l_ = self.parseL_() | |
| if l_ is None: | |
| return [e1] | |
| else: | |
| return [e1] + l_ | |
| else: | |
| return None | |
| def parseEx_(self, names, skips, f1): | |
| if self.lxin(names): | |
| c = self.cur | |
| self.next() | |
| lhs = f1() | |
| lst = self.parseEx_(names, skips, f1) | |
| return [c.name, lhs] + lst | |
| else: | |
| return [] | |
| e1_names = set(['+', '-']) | |
| e1_skips = set([')', '|', ',', '$']) | |
| def parseE1_(self): | |
| return self.parseEx_(self.e1_names, self.e1_skips, self.parseE2) | |
| e2_names = set(['*', '/', '//', '%']) | |
| e2_skips = set(['+', '-', '$', ')', '|', ',']) | |
| def parseE2_(self): | |
| return self.parseEx_(self.e2_names, self.e2_skips, self.parseE3) | |
| e4_names = set(['^']) | |
| e4_skips = set(['*', '/', '//', '%', '$', '+', '-', ')', '|', ',']) | |
| def parseE4_(self): | |
| #return self.parseEx_(self.e4_names, self.e4_skips, self.parseE5) | |
| if self.cur.name == '^': | |
| self.next() | |
| #lhs = self.parseE5() | |
| lhs = self.parseE3() | |
| lst = self.parseE4_() | |
| return ['^', lhs] + lst | |
| else: | |
| return [] | |
| bang = set(['!']) | |
| e5names = set(['^', '$', '*', '/', '//', '%', '+', '-', ')', '|', ',']) | |
| def parseE5_(self): | |
| if self.lxin(self.bang): | |
| self.next() | |
| if self.parseE5_() is None: | |
| return '!' | |
| else: | |
| return None | |
| else: | |
| return None | |
| class Code(object): | |
| # semi-private. you should probably not build these by-hand. | |
| def __init__(self, f, names): | |
| "Construct a Code instance from function 'f' and a list 'names'." | |
| self.f = f | |
| self.names = names | |
| # public | |
| def run(self, kw): | |
| "Run the given Code instance using the dictionary 'kw'." | |
| return self.f(kw) | |
| # semi-private. requires knowledge of the AST structure. | |
| @classmethod | |
| def gen(cls, e): | |
| "Generate a Code instance given a parse tree 'e'." | |
| if e.op == 'num': | |
| if '.' in e.args[0]: | |
| n = float(e.args[0]) | |
| else: | |
| n = int(e.args[0]) | |
| return cls(lambda kw: n, []) | |
| elif e.op == 'id': | |
| s = e.args[0] | |
| if s == 'e': | |
| return cls(lambda kw: math.e, []) | |
| elif s == 'pi': | |
| return cls(lambda kw: math.pi, []) | |
| elif s == 'i': | |
| return cls(lambda kw: 1j, []) | |
| else: | |
| return cls(lambda kw: kw[s], [s]) | |
| elif e.op == '+': | |
| lhs = Code.gen(e.args[0]) | |
| rhs = Code.gen(e.args[1]) | |
| names = lhs.names + rhs.names | |
| return cls(lambda kw: lhs.run(kw) + rhs.run(kw), names) | |
| elif e.op == '-': | |
| lhs = Code.gen(e.args[0]) | |
| if len(e.args) == 1: | |
| return cls(lambda kw: -lhs.run(kw), lhs.names) | |
| else: | |
| rhs = Code.gen(e.args[1]) | |
| names = lhs.names + rhs.names | |
| return cls(lambda kw: lhs.run(kw) - rhs.run(kw), names) | |
| elif e.op == '*': | |
| lhs = Code.gen(e.args[0]) | |
| rhs = Code.gen(e.args[1]) | |
| names = lhs.names + rhs.names | |
| return cls(lambda kw: lhs.run(kw) * rhs.run(kw), names) | |
| elif e.op == '/': | |
| lhs = Code.gen(e.args[0]) | |
| rhs = Code.gen(e.args[1]) | |
| names = lhs.names + rhs.names | |
| return cls(lambda kw: float(lhs.run(kw)) / rhs.run(kw), names) | |
| elif e.op == '%': | |
| lhs = Code.gen(e.args[0]) | |
| rhs = Code.gen(e.args[1]) | |
| names = lhs.names + rhs.names | |
| return cls(lambda kw: lhs.run(kw) % rhs.run(kw), names) | |
| elif e.op == '//': | |
| lhs = Code.gen(e.args[0]) | |
| rhs = Code.gen(e.args[1]) | |
| names = lhs.names + rhs.names | |
| return cls(lambda kw: lhs.run(kw) // rhs.run(kw), names) | |
| elif e.op == '^': | |
| lhs = Code.gen(e.args[0]) | |
| rhs = Code.gen(e.args[1]) | |
| names = lhs.names + rhs.names | |
| return cls(lambda kw: lhs.run(kw) ** rhs.run(kw), names) | |
| elif e.op == '!': | |
| lhs = Code.gen(e.args[0]) | |
| return cls(lambda kw: math.factorial(lhs.run(kw)), lhs.names) | |
| elif e.op == 'abs': | |
| lhs = Code.gen(e.args[0]) | |
| return cls(lambda kw: abs(lhs.run(kw)), lhs.names) | |
| elif e.op == 'apply': | |
| fn = e.args[0] | |
| if fn == 'abs': | |
| lhs = Code.gen(e.args[1]) | |
| return cls(lambda kw: abs(lhs.run(kw)), lhs.names) | |
| elif fn == 'ceil': | |
| lhs = Code.gen(e.args[1]) | |
| return cls(lambda kw: math.ceil(lhs.run(kw)), lhs.names) | |
| elif fn == 'cos': | |
| lhs = Code.gen(e.args[1]) | |
| return cls(lambda kw: math.cos(lhs.run(kw)), lhs.names) | |
| elif fn == 'degrees': | |
| lhs = Code.gen(e.args[1]) | |
| return cls(lambda kw: math.degrees(lhs.run(kw)), lhs.names) | |
| elif fn == 'floor': | |
| lhs = Code.gen(e.args[1]) | |
| return cls(lambda kw: math.floor(lhs.run(kw)), lhs.names) | |
| elif fn == 'log': | |
| lhs = Code.gen(e.args[1]) | |
| return cls(lambda kw: math.log(lhs.run(kw)), lhs.names) | |
| elif fn == 'log10': | |
| lhs = Code.gen(e.args[1]) | |
| return cls(lambda kw: math.log10(lhs.run(kw)), lhs.names) | |
| elif fn == 'log2': | |
| lhs = Code.gen(e.args[1]) | |
| return cls(lambda kw: math.log(lhs.run(kw), 2), lhs.names) | |
| elif fn == 'max': | |
| args = [Code.gen(arg) for arg in e.args[1:]] | |
| names = [] | |
| for arg in args: names.extend(arg.names) | |
| return cls(lambda kw: min([a.run(kw) for a in args]), names) | |
| elif fn == 'min': | |
| args = [Code.gen(arg) for arg in e.args[1:]] | |
| names = [] | |
| for arg in args: names.extend(arg.names) | |
| return cls(lambda kw: min([a.run(kw) for a in args]), names) | |
| elif fn == 'radians': | |
| lhs = Code.gen(e.args[1]) | |
| return cls(lambda kw: math.radians(lhs.run(kw)), lhs.names) | |
| elif fn == 'round': | |
| lhs = Code.gen(e.args[1]) | |
| return cls(lambda kw: round(lhs.run(kw)), lhs.names) | |
| elif fn == 'sin': | |
| lhs = Code.gen(e.args[1]) | |
| return cls(lambda kw: math.sin(lhs.run(kw)), lhs.names) | |
| elif fn == 'tan': | |
| lhs = Code.gen(e.args[1]) | |
| return cls(lambda kw: math.tan(lhs.run(kw)), lhs.names) | |
| else: | |
| raise Exception("function %r is not defined" % e.args[0]) | |
| else: | |
| raise Exception("can't handle %r" % e) | |
| # just for playing around or building a REPL. nothing to see here... | |
| class Main(object): | |
| def tplize(self, s): | |
| k, v = s.split('=') | |
| if '.' in v: | |
| return (k, float(v)) | |
| else: | |
| return (k, int(v)) | |
| def argdict(self): | |
| return dict([self.tplize(arg) for arg in sys.argv[2:]]) | |
| def gen(self, s): | |
| return Code.gen(Parser(s).parse()) | |
| def execute(self, s, d): | |
| return self.gen(s).run(d) | |
| def bench(self, s, d, r): | |
| print s, d, r | |
| n = 10000 | |
| t0 = time.time() | |
| x = 0 | |
| for i in xrange(0, n): | |
| x += len(Lexer(s).lex()) | |
| t1 = time.time() | |
| print "lexed: %s ms" % (t1 - t0) | |
| e = Parser(s).parse() | |
| t0 = time.time() | |
| for i in xrange(0, n): | |
| c = Code.gen(e) | |
| t1 = time.time() | |
| print "code-gen: %s ms" % (t1 - t0) | |
| t0 = time.time() | |
| c = self.gen(s) | |
| for i in xrange(0, n): | |
| assert(c.run(d) == r) | |
| t1 = time.time() | |
| print "execution only: %s ms" % (t1 - t0) | |
| t0 = time.time() | |
| for i in xrange(0, n): | |
| assert(self.execute(s, d) == r) | |
| t1 = time.time() | |
| print "full run: %s ms" % (t1 - t0) | |
| def cmdrun(self): | |
| s = sys.argv[1] | |
| print "input: %s" % s | |
| d = self.argdict() | |
| e = Parser(s).parse() | |
| print "lisp: %s" % e.lisp() | |
| c = Code.gen(e) | |
| if c.names: | |
| print "variables used: %s" % ', '.join(c.names) | |
| else: | |
| print "no variables" | |
| try: | |
| r = c.run(d) | |
| print "result: %r" % r | |
| except KeyError, k: | |
| print "missing variable: %r" % k.message | |
| def main(self): | |
| mode = 'run' | |
| if mode == 'debug': | |
| self.cmdrun() | |
| elif mode == 'bench': | |
| self.bench("1", {}, 1) | |
| self.bench("1 + 1", {}, 2) | |
| self.bench("1 + x", {'x': 9}, 10) | |
| self.bench("1 + x * 2 + 999", {'x': 3}, 1006) | |
| self.bench("1 + x * 2 + 999 / y", {'x': 1, 'y': 3}, 336) | |
| self.bench("log2(2 ^ n * x)", {'n': 8, 'x': 0.5}, 7) | |
| self.bench("(60 * mapLevel + 3 * mapLevel^2) / 500", {'mapLevel': 1}, 63.0 / 500) | |
| else: | |
| print run(sys.argv[1], self.argdict()) | |
| if __name__ == "__main__": | |
| Main().main() | |
| # Calculator Grammar: | |
| # | |
| # non-terminal productions | |
| # P -> E1 | |
| # E1 -> E2 E1_ | |
| # E1_ -> + E2 E1_ | - E2 E1_ | e | |
| # E2 -> E3 E2_ | |
| # E2_ -> * E3 E2_ | / E3 E2_ | // E3 E2_ | % E3 E2_ | e | |
| # E3 -> E4 | - E4 | |
| # E4 -> E5 E4_ | |
| # E4_ -> ^ E5 E4_ | e | |
| # E5 -> E6 E5_ | |
| # E5_ -> ! E5_ | e | |
| # E6 -> num | id A | ( E1 ) | bar E1 bar | |
| # A -> ( L ) | e | |
| # L -> E1 L_ | |
| # L_ -> , E1 L_ | e | |
| # | |
| # terminal definitions | |
| # bar = "|" | |
| # id = [a-zA-Z][a-zA-Z0-9]* | |
| # num = (0|[1-9][0-9]*)(\.[0-9]+)? | |
| # (plus other literal characters, e.g. +) | |
| # | |
| # first sets | |
| # Fi(A) = ( e | |
| # Fi(E6) = num id ( bar | |
| # Fi(E5_) = ! e | |
| # Fi(E5) = Fi(E6) = num id ( bar | |
| # Fi(E4_) = ^ e | |
| # Fi(E4) = Fi(E5) = num id ( bar | |
| # Fi(E3) = Fi(E4) - = num id ( bar - | |
| # Fi(E2_) = * / // % e | |
| # Fi(E2) = Fi(E3) = num id ( bar - | |
| # Fi(E1_) = + - e | |
| # Fi(E1) = Fi(E2) = num id ( bar - | |
| # Fi(P) = Fi(E1) = num id ( bar - | |
| # Fi(L) = Fi(E1) = num id ( bar - | |
| # Fi(L_) = , e | |
| # | |
| # follow sets | |
| # Fo(E1) = ) bar Fi(L_) Fo(L) = ) bar , e | |
| # Fo(E1_) = Fo(E1) = ) bar , e | |
| # Fo(E2) = Fi(E1_) Fo(E1) = + - e ) bar , | |
| # Fo(E2_) = Fo(E2) = + - e ) bar , | |
| # Fo(E3) = Fi(E2_) Fo(E2) = * / // % e + - ) bar , | |
| # Fo(E4) = Fo(E3) = * / // % e + - ) bar , | |
| # Fo(E4_) = Fo(E4) = * / // % e + - ) bar , | |
| # Fo(E5) = Fi(E4_) Fo(E4) = ^ e * / // % + - ) bar , | |
| # Fo(E5_) = Fo(E5) = ^ e * / // % + - ) bar , | |
| # Fo(E6) = Fi(E5_) Fo(E5) = ! e ^ * / // % + - ) bar , | |
| # Fo(A) = Fo(E6) = ! e ^ * / // % + - ) bar , | |
| # Fo(L) = ) | |
| # Fo(L_) = Fo(L) = ) | |
| # | |
| # parse table (non-terminal, list of terminals = production) | |
| # P num id ( bar - = E1 | |
| # E1 num id ( bar - = E2 E1_ | |
| # E1_ + - = [c] E2 E1_ | |
| # E1_ ) bar , $ = e | |
| # E2 num id ( bar - = E3 E2_ | |
| # E2_ * / // % = [c] E3 E2_ | |
| # E2_ + - $ ) bar , = e | |
| # E3 - = - E3 | |
| # E3 num id ( bar = E4 | |
| # E4 num id ( bar = E5 E4_ | |
| # E4_ ^ = ^ E5 E4_ | |
| # E4_ * / // % $ + - ) bar , = e | |
| # E5 num id ( bar = E6 E5_ | |
| # E5_ ! = ! E5_ | |
| # E5_ ^ $ * / // % + - ) bar , = e | |
| # E6 num = num | |
| # E6 id = id A | |
| # E6 ( = ( E1 ) | |
| # E6 bar = bar E1 bar | |
| # A ( = ( L ) | |
| # A ! e ^ * / // % + - ) bar , = e | |
| # L num id ( bar - = E1 L_ | |
| # L_ , = , E1 L_ | |
| # L_ ) = e |
(this is not part of the code): here is a very simple calculator:
while 1<2:
print("this is a simple two digit calculator made on python, enjoy :)")
#this detects when uesr is ready:
start=int(input("press any number to start"))
#user inputs:
if start:
x=int(input("print first number"))
y=int(input("print second number"))
a=input("type +,-,*, or /")
#some simple if and elif, with some math:
if a=="+":
print(x+y)
elif a=="-":
print(x-y)
elif a=="*":
print(x*y)
elif a=="/":
#if the user tries to divide by zero we avoid the console from crashing and send them an error message:
try:
print("HERE")
print(x/y)
except ZeroDivisionError:
print("Oops! Error 870...You can't divide by zero!!")
else:
print("That's not an operation! Check your spelling and try again")
hello, by hoping it would run I copied and pasted the codes block for calculator to Pychar, but I met the following error:
line 476
print "lexed: %s ms" % (t1 - t0)
^
SyntaxError: invalid syntax
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Doesn't work :( Says print statement for ,s doesn't work