GGGGGG

import sys, time

cachesize = 1000

cache = [0] * cachesize
pointer = 0
codeindex = 0
loopindices = []

valid = [
    'G',
    ' '
    ]

loop = False
f_ = False

debug = not "-nodebug" in sys.argv
numbers = "-numeric" in sys.argv

print "ICE'S GGGGGG INTERPRETER v1.0\n-------------------------\n"

if len(sys.argv) < 2:
    coderaw = raw_input("No program selected; input code: ")
else:
    try:
        f = open(sys.argv[1], 'r')
    except IOError:
        print "File not found, aborting."
        raw_input()
        exit()
    f_ = True

    coderaw = f.read()

for char in coderaw:
    if char not in valid:
        print "Invalid characters, aborting."
        raw_input()
        exit()

code = coderaw.split(" ")

codelength = len(code)

starttime = int(round(time.time() * 1000))

while codeindex < codelength:
    char = code[codeindex]

    if len(char) == 1:
        pointer += 1
        if pointer > cachesize:
            print "Error: attempted to exceed cache size"
            raw_input()
            exit()
    elif len(char) == 2:
        pointer = pointer - 1
        if pointer < 0:
            print "Error: attempted to go below index 0"
            raw_input()
            exit()
    elif len(char) == 3:
        if not numbers:
            sys.stdout.write(str(chr(cache[pointer])))
        else:
            sys.stdout.write(str(cache[pointer]) + " ")
    elif len(char) == 4:
        cache[pointer] += 1
        if cache[pointer] > 255:
            print "Error: location " + str(pointer) + " attempted to exceed byte value"
            raw_input()
            exit()
    elif len(char) == 5:
        cache[pointer] -= 1
        if cache[pointer] < -255:
            print "Error: location " + str(pointer) + " attempted attempted to create negative value"
            raw_input()
            exit()
    elif len(char) == 6:
        inp = raw_input("Input: ")
        if len(inp) > 0:
            cache[pointer] = ord(inp[0])
        else:
            cache[pointer] = 0
    elif len(char) == 7:
        loop = True
        loopindices.append(codeindex)
    elif len(char) == 8:
        if not loop:
            print "Error: ended non-existent loop"
            raw_input()
            exit()
        elif cache[pointer] > 0:
            codeindex = loopindices.pop()
            continue
        else:
            loopindices.pop()
            cache[pointer] = 0
    else:
        pointer = len(char) - 9
        if pointer > cachesize:
            print "Error: attempted to exceed cache size"
            raw_input()
            exit()
        if pointer < 0:
            print "Error: attempted to go below index 0"
            raw_input()
            exit()

    codeindex += 1

print "\n\nProgram terminated after " + str(int(round(time.time() * 1000) - starttime)) + " milliseconds at index " + str(pointer) + "\n"
if debug:
    print "Memory locations:\n"
    for i in xrange(0, 10):
        print "Location " + str(i) + ": " + str(cache[i])

if f_:
    f.close()
raw_input()