class LogicalLines:
def __init__(self, fileobj, continued=None):
# self.seq: the underlying line-sequence
# self.phys_num: current index into self.seq (physical line number)
# self.logi_num: current index into self (logical line number)
import xreadlines
try: self.seq = fileobj.xreadlines()
except AttributeError: self.seq = xreadlines.xreadlines(fileobj)
self.phys_num = 0
self.logi_num = 0
# allow for optional passing of continued-function
if not callable(continued):
def continued(line):
if line.endswith('\\\n'): return 1,line[:-2]
else: return 0, line
self.continued = continued
def __getitem__(self, index):
if index != self.logi_num:
raise TypeError, "Only sequential access supported"
self.logi_num += 1
result = []
while 1:
# Note: we must intercept IndexError, since we may not
# be finished, even when the underlying sequence is --
# we may have one or more lines in result to be returned
try: line = self.seq[self.phys_num]
except IndexError:
if result: break
else: raise
self.phys_num += 1
continues, line = self.continued(line)
result.append(line)
if not continues: break
# return string result
return ''.join(result)
# here's an example function, showing off usage:
def show_logicals(fileob,numlines=5):
ll = LogicalLines(fileob)
for l in ll:
print "Log#%d, phys# %d: %s" % (
ll.logi_num, ll.phys_num, repr(l))
if ll.logi_num>numlines: break
if __name__=='__main__':
from cStringIO import StringIO
ff = StringIO(
"""prima \seconda \terza
quarta \quinta
sesta
settima \ottava
""")
show_logicals( ff )
# a simpler approach, if the need is of a 1-off kind, might be:
# logical_line = []
# for physical_line in fileobj.xreadlines():
# if physical_line.endswith('\\\n'):
# logical_line.append(physical_line[:-2])
# else:
# logical_line = ''.join(logical_line) + physical_line
# process_full_record(logical_line)
# logical_line = []
# if logical_line: process_full_record(''.join(logical_line))
