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Diffstat (limited to 'lib/python2.7/pipes.py')
| -rw-r--r-- | lib/python2.7/pipes.py | 278 |
1 files changed, 0 insertions, 278 deletions
diff --git a/lib/python2.7/pipes.py b/lib/python2.7/pipes.py deleted file mode 100644 index 26750f6..0000000 --- a/lib/python2.7/pipes.py +++ /dev/null @@ -1,278 +0,0 @@ -"""Conversion pipeline templates. - -The problem: ------------- - -Suppose you have some data that you want to convert to another format, -such as from GIF image format to PPM image format. Maybe the -conversion involves several steps (e.g. piping it through compress or -uuencode). Some of the conversion steps may require that their input -is a disk file, others may be able to read standard input; similar for -their output. The input to the entire conversion may also be read -from a disk file or from an open file, and similar for its output. - -The module lets you construct a pipeline template by sticking one or -more conversion steps together. It will take care of creating and -removing temporary files if they are necessary to hold intermediate -data. You can then use the template to do conversions from many -different sources to many different destinations. The temporary -file names used are different each time the template is used. - -The templates are objects so you can create templates for many -different conversion steps and store them in a dictionary, for -instance. - - -Directions: ------------ - -To create a template: - t = Template() - -To add a conversion step to a template: - t.append(command, kind) -where kind is a string of two characters: the first is '-' if the -command reads its standard input or 'f' if it requires a file; the -second likewise for the output. The command must be valid /bin/sh -syntax. If input or output files are required, they are passed as -$IN and $OUT; otherwise, it must be possible to use the command in -a pipeline. - -To add a conversion step at the beginning: - t.prepend(command, kind) - -To convert a file to another file using a template: - sts = t.copy(infile, outfile) -If infile or outfile are the empty string, standard input is read or -standard output is written, respectively. The return value is the -exit status of the conversion pipeline. - -To open a file for reading or writing through a conversion pipeline: - fp = t.open(file, mode) -where mode is 'r' to read the file, or 'w' to write it -- just like -for the built-in function open() or for os.popen(). - -To create a new template object initialized to a given one: - t2 = t.clone() -""" # ' - - -import re -import os -import tempfile -import string - -__all__ = ["Template"] - -# Conversion step kinds - -FILEIN_FILEOUT = 'ff' # Must read & write real files -STDIN_FILEOUT = '-f' # Must write a real file -FILEIN_STDOUT = 'f-' # Must read a real file -STDIN_STDOUT = '--' # Normal pipeline element -SOURCE = '.-' # Must be first, writes stdout -SINK = '-.' # Must be last, reads stdin - -stepkinds = [FILEIN_FILEOUT, STDIN_FILEOUT, FILEIN_STDOUT, STDIN_STDOUT, \ - SOURCE, SINK] - - -class Template: - """Class representing a pipeline template.""" - - def __init__(self): - """Template() returns a fresh pipeline template.""" - self.debugging = 0 - self.reset() - - def __repr__(self): - """t.__repr__() implements repr(t).""" - return '<Template instance, steps=%r>' % (self.steps,) - - def reset(self): - """t.reset() restores a pipeline template to its initial state.""" - self.steps = [] - - def clone(self): - """t.clone() returns a new pipeline template with identical - initial state as the current one.""" - t = Template() - t.steps = self.steps[:] - t.debugging = self.debugging - return t - - def debug(self, flag): - """t.debug(flag) turns debugging on or off.""" - self.debugging = flag - - def append(self, cmd, kind): - """t.append(cmd, kind) adds a new step at the end.""" - if type(cmd) is not type(''): - raise TypeError, \ - 'Template.append: cmd must be a string' - if kind not in stepkinds: - raise ValueError, \ - 'Template.append: bad kind %r' % (kind,) - if kind == SOURCE: - raise ValueError, \ - 'Template.append: SOURCE can only be prepended' - if self.steps and self.steps[-1][1] == SINK: - raise ValueError, \ - 'Template.append: already ends with SINK' - if kind[0] == 'f' and not re.search(r'\$IN\b', cmd): - raise ValueError, \ - 'Template.append: missing $IN in cmd' - if kind[1] == 'f' and not re.search(r'\$OUT\b', cmd): - raise ValueError, \ - 'Template.append: missing $OUT in cmd' - self.steps.append((cmd, kind)) - - def prepend(self, cmd, kind): - """t.prepend(cmd, kind) adds a new step at the front.""" - if type(cmd) is not type(''): - raise TypeError, \ - 'Template.prepend: cmd must be a string' - if kind not in stepkinds: - raise ValueError, \ - 'Template.prepend: bad kind %r' % (kind,) - if kind == SINK: - raise ValueError, \ - 'Template.prepend: SINK can only be appended' - if self.steps and self.steps[0][1] == SOURCE: - raise ValueError, \ - 'Template.prepend: already begins with SOURCE' - if kind[0] == 'f' and not re.search(r'\$IN\b', cmd): - raise ValueError, \ - 'Template.prepend: missing $IN in cmd' - if kind[1] == 'f' and not re.search(r'\$OUT\b', cmd): - raise ValueError, \ - 'Template.prepend: missing $OUT in cmd' - self.steps.insert(0, (cmd, kind)) - - def open(self, file, rw): - """t.open(file, rw) returns a pipe or file object open for - reading or writing; the file is the other end of the pipeline.""" - if rw == 'r': - return self.open_r(file) - if rw == 'w': - return self.open_w(file) - raise ValueError, \ - 'Template.open: rw must be \'r\' or \'w\', not %r' % (rw,) - - def open_r(self, file): - """t.open_r(file) and t.open_w(file) implement - t.open(file, 'r') and t.open(file, 'w') respectively.""" - if not self.steps: - return open(file, 'r') - if self.steps[-1][1] == SINK: - raise ValueError, \ - 'Template.open_r: pipeline ends width SINK' - cmd = self.makepipeline(file, '') - return os.popen(cmd, 'r') - - def open_w(self, file): - if not self.steps: - return open(file, 'w') - if self.steps[0][1] == SOURCE: - raise ValueError, \ - 'Template.open_w: pipeline begins with SOURCE' - cmd = self.makepipeline('', file) - return os.popen(cmd, 'w') - - def copy(self, infile, outfile): - return os.system(self.makepipeline(infile, outfile)) - - def makepipeline(self, infile, outfile): - cmd = makepipeline(infile, self.steps, outfile) - if self.debugging: - print cmd - cmd = 'set -x; ' + cmd - return cmd - - -def makepipeline(infile, steps, outfile): - # Build a list with for each command: - # [input filename or '', command string, kind, output filename or ''] - - list = [] - for cmd, kind in steps: - list.append(['', cmd, kind, '']) - # - # Make sure there is at least one step - # - if not list: - list.append(['', 'cat', '--', '']) - # - # Take care of the input and output ends - # - [cmd, kind] = list[0][1:3] - if kind[0] == 'f' and not infile: - list.insert(0, ['', 'cat', '--', '']) - list[0][0] = infile - # - [cmd, kind] = list[-1][1:3] - if kind[1] == 'f' and not outfile: - list.append(['', 'cat', '--', '']) - list[-1][-1] = outfile - # - # Invent temporary files to connect stages that need files - # - garbage = [] - for i in range(1, len(list)): - lkind = list[i-1][2] - rkind = list[i][2] - if lkind[1] == 'f' or rkind[0] == 'f': - (fd, temp) = tempfile.mkstemp() - os.close(fd) - garbage.append(temp) - list[i-1][-1] = list[i][0] = temp - # - for item in list: - [inf, cmd, kind, outf] = item - if kind[1] == 'f': - cmd = 'OUT=' + quote(outf) + '; ' + cmd - if kind[0] == 'f': - cmd = 'IN=' + quote(inf) + '; ' + cmd - if kind[0] == '-' and inf: - cmd = cmd + ' <' + quote(inf) - if kind[1] == '-' and outf: - cmd = cmd + ' >' + quote(outf) - item[1] = cmd - # - cmdlist = list[0][1] - for item in list[1:]: - [cmd, kind] = item[1:3] - if item[0] == '': - if 'f' in kind: - cmd = '{ ' + cmd + '; }' - cmdlist = cmdlist + ' |\n' + cmd - else: - cmdlist = cmdlist + '\n' + cmd - # - if garbage: - rmcmd = 'rm -f' - for file in garbage: - rmcmd = rmcmd + ' ' + quote(file) - trapcmd = 'trap ' + quote(rmcmd + '; exit') + ' 1 2 3 13 14 15' - cmdlist = trapcmd + '\n' + cmdlist + '\n' + rmcmd - # - return cmdlist - - -# Reliably quote a string as a single argument for /bin/sh - -# Safe unquoted -_safechars = frozenset(string.ascii_letters + string.digits + '@%_-+=:,./') - -def quote(file): - """Return a shell-escaped version of the file string.""" - for c in file: - if c not in _safechars: - break - else: - if not file: - return "''" - return file - # use single quotes, and put single quotes into double quotes - # the string $'b is then quoted as '$'"'"'b' - return "'" + file.replace("'", "'\"'\"'") + "'" |