gte/gte/mutator.py

import copy
from random import randint

from .rpnlib import RpnExpr, RpnSymbol

ADD = (10, 100)
DEL = (5,100)
UPDVAL = (25, 100)
UPDTYPE = (25,100)

def mutate(expr, force = True, mutcount = 1):
    ''' @brief Introduce a mutation in expr
        @param expr RpnExpr : an RPN expression
        @param force bool : if force a mutation occur each time
        @param mutcount int : count of time
        @return a muatated copy of expr
    '''
    if force:
        return mutatef(expr, mutcount)

    res = copy.copy(expr)
    for _ in range(mutcount):
        rep = randint(*ADD)
        if rep <= ADD[0]:
            mutadd(res)

        rep = randint(*DEL)
        if rep <= DEL[0]:
            mutdel(res)

        rep = randint(*UPDTYPE)
        if rep <= UPDTYPE[0]:
            mutupdtype(res)
        
        rep = randint(*UPDVAL)
        if rep <= UPDVAL[0]:
            mutupdval(res)

    return res

def mutatef(expr, mutcount = 1):
    mutations = [mutadd, mutdel]
    mutations += [mutupdtype for _ in range(3)]
    mutations += [mutupdval for _ in range(6)]
    res = copy.copy(expr)
    for _ in range(mutcount):
        mutations[randint(0, len(mutations)-1)](res)
    return res

def mutadd(expr):
    pos = randint(0, len(expr))
    expr.insert(pos, RpnSymbol.random())
    return expr

def mutdel(expr):
    pos = randint(0, len(expr)-1)
    del(expr[pos])
    return expr

def mutupdtype(expr):
    pos = randint(0, len(expr) - 1)
    optype = [RpnSymbol.OPERATION, RpnSymbol.VALUE, RpnSymbol.VARIABLE]
    del(optype[optype.index(expr[pos].optype)])
    expr[pos] = RpnSymbol.random(optype[randint(0,1)])
    return expr

def mutupdval(expr):
    pos = randint(0, len(expr) - 1)
    expr[pos] = RpnSymbol(randint(0, 0xFFFF), expr[pos].optype)
    return expr