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# Generated by re2py
# re2py $INPUT -o $OUTPUT -f
from enum import Enum
import os
# Use a small buffer to cover the case when a lexeme doesn't fit.
# In real world use a larger buffer.
BUFSIZE = 10
DEBUG = False
class State:
def __init__(self, file):
self.file = file
self.yyinput = bytearray(BUFSIZE)
self.yylimit = BUFSIZE - 1 # exclude terminating null
self.yycursor = self.yylimit
self.yymarker = self.yylimit
self.token = self.yylimit
self.yystate = -1
class Status(Enum):
END = 0
READY = 1
WAITING = 2
BIG_PACKET = 3
BAD_PACKET = 4
def fill(st):
# Error: lexeme too long. In real life could reallocate a larger buffer.
if st.token < 1:
return Status.BIG_PACKET
# Shift buffer contents (discard everything up to the current token).
st.yyinput = st.yyinput[st.token:st.yylimit]
st.yycursor -= st.token;
st.yymarker -= st.token;
st.yylimit -= st.token;
st.token = 0;
# Fill free space at the end of buffer with new data from file.
bytes = st.file.read(BUFSIZE - st.yylimit - 1) # -1 for sentinel
if bytes:
st.yylimit += len(bytes);
st.yyinput += bytes
st.yyinput += b'\0' # append sentinel
return Status.READY
def lex(yyrecord, recv):
while True:
yyrecord.token = yyrecord.yycursor
yystate = yyrecord.yystate
while True:
match yystate:
case -1|0:
yych = yyrecord.yyinput[yyrecord.yycursor]
if yych <= 0x00:
if yyrecord.yylimit <= yyrecord.yycursor:
yyrecord.yystate = 8
return Status.WAITING, recv
yyrecord.yycursor += 1
yystate = 1
continue
if yych <= 0x60:
yyrecord.yycursor += 1
yystate = 1
continue
if yych <= 0x7A:
yyrecord.yycursor += 1
yystate = 3
continue
yyrecord.yycursor += 1
yystate = 1
continue
case 1:
yystate = 2
continue
case 2:
yyrecord.yystate = -1
return Status.BAD_PACKET, recv
case 3:
yyrecord.yymarker = yyrecord.yycursor
yych = yyrecord.yyinput[yyrecord.yycursor]
if yych <= 0x3B:
if yych <= 0x00:
if yyrecord.yylimit <= yyrecord.yycursor:
yyrecord.yystate = 9
return Status.WAITING, recv
yystate = 2
continue
if yych <= 0x3A:
yystate = 2
continue
yyrecord.yycursor += 1
yystate = 4
continue
else:
if yych <= 0x60:
yystate = 2
continue
if yych <= 0x7A:
yyrecord.yycursor += 1
yystate = 5
continue
yystate = 2
continue
case 4:
yyrecord.yystate = -1
recv += 1
break
case 5:
yych = yyrecord.yyinput[yyrecord.yycursor]
if yych <= 0x3B:
if yych <= 0x00:
if yyrecord.yylimit <= yyrecord.yycursor:
yyrecord.yystate = 10
return Status.WAITING, recv
yystate = 6
continue
if yych >= 0x3B:
yyrecord.yycursor += 1
yystate = 4
continue
yystate = 6
continue
else:
if yych <= 0x60:
yystate = 6
continue
if yych <= 0x7A:
yyrecord.yycursor += 1
yystate = 5
continue
yystate = 6
continue
case 6:
yyrecord.yycursor = yyrecord.yymarker
yystate = 2
continue
case 7:
yyrecord.yystate = -1
return Status.END, recv
case 8:
if yyrecord.yylimit <= yyrecord.yycursor:
yystate = 7
continue
yystate = 0
continue
case 9:
if yyrecord.yylimit <= yyrecord.yycursor:
yystate = 2
continue
yystate = 3
continue
case 10:
if yyrecord.yylimit <= yyrecord.yycursor:
yystate = 6
continue
yystate = 5
continue
case _:
raise "internal lexer error"
def test(packets, expect):
# Create a pipe (open the same file for reading and writing).
fname = "pipe"
fw = open(fname, "wb")
fr = open(fname, "rb")
# Initialize lexer state
st = State(fr)
# Main loop. The buffer contains incomplete data which appears packet by
# packet. When the lexer needs more input it saves its internal state and
# returns to the caller which should provide more input and resume lexing.
send = 0
recv = 0
while True:
status, recv = lex(st, recv)
if status == Status.END:
if DEBUG: print("done: got {} packets".format(recv))
break
elif status == Status.WAITING:
if DEBUG: print("waiting...");
if send < len(packets):
if DEBUG: print("sent packet {}: {}".format(send, packets[send]))
fw.write(packets[send])
fw.flush()
send += 1
status = fill(st)
if DEBUG: print("queue: '{}', status: {}".format(st.yyinput, status))
if status == Status.BIG_PACKET:
if DEBUG: print("error: packet too big")
break
assert status == Status.READY
else:
assert status == Status.BAD_PACKET
if DEBUG: print("error: ill-formed packet")
break
# Check results.
assert status == expect
if status == Status.END:
assert recv == send
# Cleanup: remove input file.
fr.close()
fw.close()
os.remove(fname)
def main():
test([], Status.END)
test([b"zero;", b"one;", b"two;", b"three;", b"four;"], Status.END)
test([b"zer0;"], Status.BAD_PACKET)
test([b"goooooooooogle;"], Status.BIG_PACKET)
if __name__ == '__main__':
main()
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