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python一个简单的lisp实

python 水墨上仙 1303次浏览 已收录 手机上查看

python一个简单的lisp实

#coding=utf-8
import types,sys
import operator as op
from functools import reduce
from inspect import getargspec
##########################
def quote(code):
    return code
def atom(code):
    if type(code) is list and code != []:
        return []
    return True
def eq(car, cdr):
    if car==cdr:
        return True
    return []
def noteq(car, cdr):
    if car != cdr:
        return True
    return []
def and2(car, cdr):#用lisp实现一个and吧
    if car!=[] and cdr!=[]:
        return True
    return []
def car(code):
    if code == [] or code == '':#fix map func error
        return []
    return code[0]
def cdr(code):
    return code[1:]
def cons(arg1, arg2):
    res = [arg1]
    res.extend(arg2);
    return res
def cond(code):pass
def define():pass
def fun():pass
def fun_seq():pass
class S(str):pass
#extra
def lt(car, cdr):#<
    if car < cdr:
        return True
    return []
def gt(car, cdr):#>
    if car > cdr:
        return True
    return []
def mul(*args):#*
    return reduce(op.mul, args)
def div(*args):#/
    return reduce(op.div, args)
def sub(*args):#-
    return reduce(op.sub, args)
def add(*args):#+
    return reduce(op.add, args)
def mod(car, cdr):#%
    return car % cdr
def show(code):
    print( code)
    return code
def seti(key, val):
    pass
# def yf():
#     pass
# def yd():
#     pass
def nexti(sq, n):
    if not hasattr(sq, '__next__'):
        sq = iter(sq)
    while n:
        if n == 1:
            return next(sq)
        next(sq)
        n = n - 1
        
def use(pg, _as=None):
    try:
        mod = __import__(pg)
        return mod, _as
    except Exception as e:
        print('<No this Package: '+ str(e) +'>')
        return None, None
def attr(obj, prop):
    return getattr(obj, prop)
        
###############################
class Env(dict):
    def __init__(self, outer, params=None, args=None):
        params = params if params else []
        args = args if args else []
        #for currying
        for i in range(len(args),len(params)):
            args.append([])
        #end
        self.update(zip(params,args))#
        self.outer = outer
    def find(self, key):
        ks = key.split('.')
        if len(ks) > 1:
            if ks[0] in self:
                for k in ks[1:]:
                    ks[0] = getattr(self[ks[0]], k)
                return ks[0]
            return self.outer[key]
        else:
            if key in self:
                return self[key]
            return self.outer.find(key)
    def seti(self, key,value):
        if key in self:
            self[key] = value
        else:
            self.outer.seti(key,value)
#############################
lisp_env = {'quote':quote,'_':quote,'atom':atom,'eq':eq,'car':car, \
        'cdr':cdr,'cons':cons,'cond':cond,'define':define,'fun':fun, \
        'lt':lt,'mul':mul,'sub':sub,'gt':gt,'div':div,'mod':mod, \
        'add':add,'noteq':noteq,'and2':and2, 'next':next, 'nexti':nexti, \
        'show':show, 'seti':seti, 'True':True, 'False':False, \
        'use':use, 'attr':attr }#
############################
def run(code,env):
    # print '===code===', code, '======'
    # print '===env===', env, '======'
    # print '===outer===', env.outer, '======'
    #return S('val'),变量
    if type(code) is S:
        try:
            return env.find(code)
        except:
            print( '<Undefined variable %s...>' % code, '')
            raise RuntimeError
    #常量
    #for empty list and no list
    elif code==[] or type(code) is not list:
        return code
    #设置变量的值
    elif code[0] is seti:
        if type(code[1]) is not S:
            print ("<Can't assign a value to %s...>" % code[1], '')
            raise RuntimeError
        try:
            key = env.seti(code[1], run(code[2], env))
            return env.find(code[1])
        except:
            print( "<Can't variable %s...>" % code[1], '')
            raise RuntimeError
    #变量引用,for quote exp
    elif code[0] is quote:
        return code[0](*code[1:])
    #特别函数,for def, fun, let
    elif code[0] is define:
        env[ code[1]] = run(code[2],env)
        # if code[1] == 'inner' or code[1]=='E':
        #     print '--define--', code[1], code[2], env
        return env[ code[1]]
    #执行function体
    elif code[0] is fun_seq:
        last = None
        codelen = len(code[1:]) - 1
        for i, c in enumerate(code[1:]):
            res = run(c, env)
            if i == codelen:
                last = res
        return last
    elif code[0] is fun:
        # if code[1] and code[1][-1] == 'ident' or code[1] and code[1][-1] == '__outer__':
        #     print '--eval--', env
        if len(code[1]) == 0:
            return lambda *args: run([fun_seq]+code[2:], Env(env, ['args'], [list(args)]))
        if type(code[1]) is S:
            return lambda *args: run( [fun_seq]+code[2:], Env(env, [code[1]], [list(args)]))
        return lambda *args: run([fun_seq]+code[2:], Env(env, code[1], list(args)))#name,value
        
    #条件,for cond, [cond [p1,e1],[p2,e2],...]
    elif code[0] is cond:
        for c in code[1:]:
            if run(c[0], env):
                res = [run(ii, env) for ii in c[1:]]
                return res[-1]
                
    elif code[0] is use:
        mod, _as = None,None
        if len(code) > 2:
            mod, _as = use(code[1], code[2])
        else:
            mod, _as = use(code[1])
            
        if not mod:
            raise RuntimeError
        if _as:
            env[_as] = mod 
        else:
            env[code[1]] = mod
        return env[_as] if _as else env[code[1]]
    #[S]
    elif type(code[0]) is S and len(code) == 1:
        try:
            return run(env.find(code[0]), env)
        except:
            print( '<Undefined variable %s...>' % code[0], '')
            raise RuntimeError
    else:
        exps = [ run(exp, env) for exp in code]
        f = exps.pop(0)
        if not (type(f) is types.FunctionType) and not (type(f) is types.BuiltinFunctionType) and not f is type:
            return [f]+exps
        try:
            #print f, exps
            return f(*exps)
        except TypeError as e:#pass arg for next(), if not a iterator
            print ('<StopIteration!>')
        raise RuntimeError


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