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cursor.py
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cursor.py
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#!/usr/bin/env python
# BSD 3-Clause License; see https://github.com/scikit-hep/uproot/blob/master/LICENSE
from __future__ import absolute_import
import struct
import string
import numpy
class Cursor(object):
# makes __doc__ attribute mutable before Python 3.3
__metaclass__ = type.__new__(type, "type", (type,), {})
def __init__(self, index, origin=0, refs=None):
self.index = index
self.origin = origin
if refs is None:
self.refs = {}
else:
self.refs = refs
def copied(self, index=None, origin=None, refs=None):
if index is None:
index = self.index
if origin is None:
origin = self.origin
if refs is None:
refs = self.refs
return Cursor(index, origin, refs)
def skipped(self, numbytes, origin=None, refs=None):
if origin is None:
origin = self.origin
if refs is None:
refs = self.refs
return Cursor(self.index + numbytes, origin, refs)
def skip(self, numbytes):
self.index += numbytes
def fields(self, source, format):
start = self.index
stop = self.index = start + format.size
return format.unpack(source.data(start, stop))
def field(self, source, format):
return self.fields(source, format)[0]
def bytes(self, source, length):
start = self.index
stop = self.index = start + length
return source.data(start, stop)
def array(self, source, length, dtype):
if not isinstance(dtype, numpy.dtype):
dtype = numpy.dtype(dtype)
start = self.index
stop = self.index = start + length*dtype.itemsize
return source.data(start, stop, dtype)
def string(self, source):
start = self.index
stop = self.index = start + 1
length = source.data(start, stop)[0]
if length == 255:
start = self.index
stop = self.index = start + 4
length = source.data(start, stop, numpy.dtype(">u4"))[0]
start = self.index
stop = self.index = start + length
return source.data(start, stop).tostring()
def cstring(self, source):
char = None
chars = []
while char != 0:
char = source.data(self.index, self.index + 1)
if char != 0:
chars.append(chr(char[0]).encode("ascii"))
self.index += 1
return b"".join(chars)
def skipstring(self, source):
length = source.data(self.index, self.index + 1)[0]
self.index += 1
if length == 255:
length = source.data(self.index, self.index + 4, numpy.dtype(">u4"))[0]
self.index += 4
self.index += length
def hexdump(self, source, size=160, offset=0, format="%02x"):
pos = self.index + offset
out = []
for linepos in range(pos, pos + size, 16):
data = source.data(linepos, min(linepos + 16, pos + size))
line = [format % x for x in data]
text = [chr(x) if chr(x) in string.printable[:-5] else "." for x in data]
if len(line) < 16:
diff = 16 - len(line)
line.extend([" "] * diff)
text.extend([" "] * diff)
out.append("{0:08o} {1} {2} |{3}|".format(linepos, " ".join(line[:8]), " ".join(line[8:]), "".join(text)))
return "\n".join(out)