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Editing: pipes.pyc
� z fc @ s� d Z d d l Z d d l Z d d l Z d d l Z d g Z d Z d Z d Z d Z d Z d Z e e e e e e g Z d d d � � YZ d � Z e e j e j d � Z d � Z d S( s� 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 $OUT; otherwise, it must be possible to use the command in a pipeline. To add a conversion step at the beginning: t.prepend(command, kind) To convert a file to another file using a template: sts = t.copy(infile, outfile) If infile or outfile are the empty string, standard input is read or standard output is written, respectively. The return value is the exit status of the conversion pipeline. To open a file for reading or writing through a conversion pipeline: fp = t.open(file, mode) where mode is 'r' to read the file, or 'w' to write it -- just like for the built-in function open() or for os.popen(). To create a new template object initialized to a given one: t2 = t.clone() i����Nt Templatet ffs -fs f-s --s .-s -.c B sz e Z d Z d � Z d � Z d � Z d � Z d � Z d � Z d � Z d � Z d � Z d � Z d � Z d � Z RS( s' Class representing a pipeline template.c C s d | _ | j � d S( s- Template() returns a fresh pipeline template.i N( t debuggingt reset( t self( ( s /usr/lib64/python2.7/pipes.pyt __init__S s c C s d | j f S( s t.__repr__() implements repr(t).s <Template instance, steps=%r>( t steps( R ( ( s /usr/lib64/python2.7/pipes.pyt __repr__X s c C s g | _ d S( s< t.reset() restores a pipeline template to its initial state.N( R ( R ( ( s /usr/lib64/python2.7/pipes.pyR \ s c C s& t � } | j | _ | j | _ | S( sb t.clone() returns a new pipeline template with identical initial state as the current one.( R R R ( R t t( ( s /usr/lib64/python2.7/pipes.pyt clone` s c C s | | _ d S( s( t.debug(flag) turns debugging on or off.N( R ( R t flag( ( s /usr/lib64/python2.7/pipes.pyt debugh s c C s� t | � t d � k r$ t d � n | t k rC t d | f � n | t k r[ t d � n | j r� | j d d t k r� t d � n | d d k r� t j d | � r� t d � n | d d k r� t j d | � r� t d � n | j j | | f � d S( s/ t.append(cmd, kind) adds a new step at the end.t s% Template.append: cmd must be a strings Template.append: bad kind %rs- Template.append: SOURCE can only be prependedi����i s' Template.append: already ends with SINKi t fs \$IN\bs# Template.append: missing $IN in cmds \$OUT\bs$ Template.append: missing $OUT in cmdN( t typet TypeErrort stepkindst ValueErrort SOURCER t SINKt ret searcht append( R t cmdt kind( ( s /usr/lib64/python2.7/pipes.pyR l s& # # c C s t | � t d � k r$ t d � n | t k rC t d | f � n | t k r[ t d � n | j r� | j d d t k r� t d � n | d d k r� t j d | � r� t d � n | d d k r� t j d | � r� t d � n | j j d | | f � d S( s2 t.prepend(cmd, kind) adds a new step at the front.R s& Template.prepend: cmd must be a strings Template.prepend: bad kind %rs+ Template.prepend: SINK can only be appendedi i s, Template.prepend: already begins with SOURCER s \$IN\bs$ Template.prepend: missing $IN in cmds \$OUT\bs% Template.prepend: missing $OUT in cmdN( R R R R R R R R R t insert( R R R ( ( s /usr/lib64/python2.7/pipes.pyt prepend� s& # # c C sF | d k r | j | � S| d k r2 | j | � St d | f � d S( s~ t.open(file, rw) returns a pipe or file object open for reading or writing; the file is the other end of the pipeline.t rt ws, Template.open: rw must be 'r' or 'w', not %rN( t open_rt open_wR ( R t filet rw( ( s /usr/lib64/python2.7/pipes.pyt open� s c C s[ | j s t | d � S| j d d t k r9 t d � n | j | d � } t j | d � S( si t.open_r(file) and t.open_w(file) implement t.open(file, 'r') and t.open(file, 'w') respectively.R i����i s) Template.open_r: pipeline ends width SINKR ( R R! R R t makepipelinet ost popen( R R R ( ( s /usr/lib64/python2.7/pipes.pyR � s c C s[ | j s t | d � S| j d d t k r9 t d � n | j d | � } t j | d � S( NR i i s, Template.open_w: pipeline begins with SOURCER ( R R! R R R" R# R$ ( R R R ( ( s /usr/lib64/python2.7/pipes.pyR � s c C s t j | j | | � � S( N( R# t systemR" ( R t infilet outfile( ( s /usr/lib64/python2.7/pipes.pyt copy� s c C s4 t | | j | � } | j r0 | GHd | } n | S( Ns set -x; ( R" R R ( R R& R' R ( ( s /usr/lib64/python2.7/pipes.pyR" � s ( t __name__t __module__t __doc__R R R R R R R R! 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