Implement debug commands, like saving and loading state

.gitignore

@@ -1 +1,2 @@
 /challenge.bin
+/dumps

README.md

@@ -1,3 +1,23 @@
 # synacor.py
 
 My sort-of-OOP, ~~poorly-documented~~concise response to the Synacor challenge
+
+## Debug commands
+
+At any time the program is waiting for input, a string of the following form may be input:
+
+    .<cmd> <args>
+
+This will execute the file `<cmd>.py` with `dbg_args[0]` set to `<cmd>` and `<args>` stored in `dbg_args[1..n]`.
+
+For example, the self-test and decryption at the beginning of the program takes a comparatively long time. To save the state to the `dumps/init` file, enter:
+
+    .dbg_dump dumps/init
+
+Similarly, debug commands may be passed as command-line arguments to `synacor.py` in the form:
+
+    ./synacor.py <cmd> <args>
+
+For example, to load the `dumps/init` state to skip the self-test and decryption, run:
+
+    ./synacor.py dbg_load dumps/init

dbg_dump.py

@@ -0,0 +1,30 @@
+#    synacor.py - An implementation of the Synacor Challenge
+#    Copyright © 2016  RunasSudo
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU Affero General Public License as published by
+#    the Free Software Foundation, either version 3 of the License, or
+#    (at your option) any later version.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU Affero General Public License for more details.
+#
+#    You should have received a copy of the GNU Affero General Public License
+#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import pickle
+
+if len(dbg_args) < 2:
+	print('Usage: .{} <file>'.format(dbg_args[0]))
+else:
+	model = {
+		'SYN_PTR': SYN_PTR,
+		'SYN_MEM': SYN_MEM,
+		'SYN_REG': SYN_REG,
+		'SYN_STK': SYN_STK
+	}
+	
+	with open(dbg_args[1], 'wb') as f:
+		pickle.dump(model, f)

dbg_load.py

@@ -0,0 +1,28 @@
+#    synacor.py - An implementation of the Synacor Challenge
+#    Copyright © 2016  RunasSudo
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU Affero General Public License as published by
+#    the Free Software Foundation, either version 3 of the License, or
+#    (at your option) any later version.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU Affero General Public License for more details.
+#
+#    You should have received a copy of the GNU Affero General Public License
+#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import pickle
+
+if len(dbg_args) < 2:
+	print('Usage: {} {} <file>'.format(sys.argv[0], dbg_args[0]))
+else:
+	with open(dbg_args[1], 'rb') as f:
+		model = pickle.load(f)
+	
+	SYN_PTR = model['SYN_PTR']
+	SYN_MEM = model['SYN_MEM']
+	SYN_REG = model['SYN_REG']
+	SYN_STK = model['SYN_STK']

synacor.py

@@ -22,6 +22,7 @@ SYN_PTR = 0
 SYN_MEM = [0] * 32768
 SYN_REG = [0] * 8
 SYN_STK = []
+SYN_STDIN_BUF = []
 
 class OpLiteral:
 	def __init__(self, value):
@@ -52,16 +53,20 @@ def swallowOp():
 	SYN_PTR += 1
 	return op
 
-# Read code into memory
+if len(sys.argv) > 1:
-with open('challenge.bin', 'rb') as data:
+	dbg_args = sys.argv[1:]
+	with open(dbg_args[0] + '.py', 'r') as f:
+		exec(f.read(), globals(), locals())
+else:
+	# Read code into memory
+	with open('challenge.bin', 'rb') as data:
 		while True:
 			byteData = data.read(2)
 			if len(byteData) < 2:
 				break
 			SYN_MEM[SYN_PTR] = struct.unpack('<H', byteData)[0]
 			SYN_PTR += 1
-
+	SYN_PTR = 0
-SYN_PTR = 0
 
 # Begin execution
 while True:
@@ -120,6 +125,15 @@ while True:
 	elif instruction == 19: #OUT
 		print(chr(swallowOp().get()), end='')
 	elif instruction == 20: #IN
-		swallowOp().set(ord(sys.stdin.read(1))) # the spec says a whole line will be read, so ¯\_(ツ)_/¯
+		while len(SYN_STDIN_BUF) == 0:
+			line = sys.stdin.readline()
+			if line.startswith('.'): # debug command
+				dbg_args = line.rstrip()[1:].split()
+				with open(dbg_args[0] + '.py', 'r') as f:
+					SYN_PTR -= 1; exec(f.read(), globals(), locals()); SYN_PTR += 1
+			else:
+				SYN_STDIN_BUF = list(line)
+		
+		swallowOp().set(ord(SYN_STDIN_BUF.pop(0)))
 	else:
 		raise Exception('Unimplemented opcode {} at {}'.format(instruction, SYN_PTR))