Support multiple input files with -o being a directory

This change makes it possible for scour to consume multiple input
files in one command invocation.  E.g.

     $ scour file1.svg file2.svgz ... output-directory
     # xargs friendly variant
     $ scour -o output-directory file1.svg file2.svgz ...

This avoids most of the "startup" overhead in python and scour when
many files are being processed.  On about a 100 of (already scour'ed)
gnuplot svg graphs, this change provides an almost 40% speed up compared
to a shell alternative:

     # Original shell pipeline (~29s)
     # Note; for bash, rewriting this without the "basename"-call does
     # not seem to improve performance considerably.
     $ for FILE in input/[01]* ; do \
         python3 -m scour.scour "$FILE" output/"$(basename "$FILE")" > /dev/null ; \
       done
    # With this patch (~16s)
    $ python3 -m scour.scour input/[01]* output > /dev/null

Signed-off-by: Niels Thykier <niels@thykier.net>

scour/scour.py

@@ -3630,10 +3630,12 @@ class HeaderedFormatter(optparse.IndentedHelpFormatter):
 # GZ: would prefer this to be in a function or class scope, but tests etc need
 #     access to the defaults anyway
 _options_parser = optparse.OptionParser(
-    usage="%prog [INPUT.SVG [OUTPUT.SVG]] [OPTIONS]",
+    usage="%prog [INPUT.SVG [[... INPUT.SVG] OUTPUT]] [OPTIONS]",
     description=("If the input/output files are not specified, stdin/stdout are used. "
                  "If the input/output files are specified with a svgz extension, "
-                 "then compressed SVG is assumed."),
+                 "then compressed SVG is assumed.  Multiple input files can be specified "
+                 "when output is a directory.  The ouput files will be the basename of "
+                 "the input files."),
     formatter=HeaderedFormatter(max_help_position=33),
     version=VER)
 
@@ -3648,11 +3650,11 @@ _options_parser.add_option("-v", "--verbose",
                            action="store_true", dest="verbose", default=False,
                            help="verbose output (statistics, etc.)")
 _options_parser.add_option("-i",
-                           action="store", dest="infilename", metavar="INPUT.SVG",
+                           action="append", dest="infilenames", metavar="INPUT.SVG",
-                           help="alternative way to specify input filename")
+                           help="alternative way to specify input filenames")
 _options_parser.add_option("-o",
-                           action="store", dest="outfilename", metavar="OUTPUT.SVG",
+                           action="store", dest="outfilename", metavar="OUTPUT",
-                           help="alternative way to specify output filename")
+                           help="alternative way to specify output (either a file or a directory)")
 
 _option_group_optimization = optparse.OptionGroup(_options_parser, "Optimization")
 _option_group_optimization.add_option("--set-precision",
@@ -3766,10 +3768,11 @@ def parse_args(args=None, ignore_additional_args=False):
     options, rargs = _options_parser.parse_args(args)
 
     if rargs:
-        if not options.infilename:
+        if not options.outfilename and len(rargs) > 1:
-            options.infilename = rargs.pop(0)
+            options.outfilename = rargs.pop()
-        if not options.outfilename and rargs:
+        if not options.infilenames:
-            options.outfilename = rargs.pop(0)
+            options.infilenames = rargs
+            rargs = []
         if not ignore_additional_args and rargs:
             _options_parser.error("Additional arguments not handled: %r, see --help" % rargs)
     if options.digits < 1:
@@ -3782,8 +3785,15 @@ def parse_args(args=None, ignore_additional_args=False):
         _options_parser.error("Invalid value for --indent, see --help")
     if options.indent_depth < 0:
         _options_parser.error("Value for --nindent should be positive (or zero), see --help")
-    if options.infilename and options.outfilename and options.infilename == options.outfilename:
+    if options.infilenames:
-        _options_parser.error("Input filename is the same as output filename")
+        if len(options.infilenames) > 1:
+            if not options.outfilename or not os.path.isdir(options.outfilename):
+                _options_parser.error("Multiple input files requires an directory as output (-o)")
+        elif len(options.infilenames) == 0 and options.outfilename and options.infilenames[0] == options.outfilename:
+            _options_parser.error("Input filename is the same as output filename")
+    else:
+        if options.outfilename and os.path.isdir(options.outfilename):
+            _options_parser.error("Cannot use a directory as output when input is stdin")
 
     return options
 
@@ -3811,12 +3821,12 @@ def maybe_gziped_file(filename, mode="r"):
     return open(filename, mode)
 
 
-def getInOut(options):
+def getInOut(input_file, options):
     references_relative_to = None
-    if options.infilename:
+    if input_file is not None:
-        infile = maybe_gziped_file(options.infilename, "rb")
+        infile = maybe_gziped_file(input_file, "rb")
         # GZ: could catch a raised IOError here and report
-        references_relative_to = os.path.dirname(options.infilename)
+        references_relative_to = os.path.dirname(input_file)
     else:
         # GZ: could sniff for gzip compression here
         #
@@ -3830,7 +3840,11 @@ def getInOut(options):
             _options_parser.error("No input file specified, see --help for detailed usage information")
 
     if options.outfilename:
-        outfile = maybe_gziped_file(options.outfilename, "wb")
+        dest = options.outfilename
+        if os.path.isdir(dest):
+            assert input_file is not None
+            dest = os.path.join(dest, os.path.basename(input_file))
+        outfile = maybe_gziped_file(dest, "wb")
     else:
         # open the binary buffer of stdout as the output is already encoded
         try:
@@ -3901,8 +3915,14 @@ def start(options, input, output, references_relative_to=None):
 
 def run():
     options = parse_args()
-    (input, input_relative_to, output) = getInOut(options)
+    input_files = options.infilenames if options.infilenames is not None else []
-    start(options, input, output, input_relative_to)
+    if input_files and input_files[0] is not None:
+        for filename in input_files:
+            (input, input_relative_to, output) = getInOut(filename, options)
+            start(options, input, output, input_relative_to)
+    else:
+        (input, input_relative_to, output) = getInOut(None, options)
+        start(options, input, output, input_relative_to)
 
 
 if __name__ == '__main__':

testscour.py

@@ -2358,7 +2358,7 @@ class DoNotStripXmlSpaceAttribute(unittest.TestCase):
 
 class CommandLineUsage(unittest.TestCase):
 
-    USAGE_STRING = "Usage: scour [INPUT.SVG [OUTPUT.SVG]] [OPTIONS]"
+    USAGE_STRING = "Usage: scour [INPUT.SVG [[... INPUT.SVG] OUTPUT]] [OPTIONS]"
     MINIMAL_SVG = '<?xml version="1.0" encoding="UTF-8"?>\n' \
                   '<svg xmlns="http://www.w3.org/2000/svg"/>\n'
     TEMP_SVG_FILE = 'testscour_temp.svg'