#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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# ship.py
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#
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# Licensed under the Apache 2 License as is the rest of the project
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# Copyright (c) 2011 Jeff Schiller
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#
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# This script has very little real-world application. It is only used in our pure-client web app
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# served on GoogleCode so we can have one HTML file, run a build script and generate a 'release'
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# version without having to maintain two separate HTML files. It does this by evaluating
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# 'processing comments' that are suspicously similar to IE conditional comments and then outputting
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# a new HTML file after evaluating particular variables.
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#
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# This script takes the following inputs:
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#
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# * a HTML file (--i=in.html)
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# * a series of flag names (--on=Foo --on=Bar)
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#
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# Example:
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#
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# in.html:
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# <!--{if foo}>
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# FOO!
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# <!{else}-->
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# BAR!
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# <!--{endif}-->
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#
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# $ ship.py --i in.html --on foo
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#
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# out.html:
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# <!--{if foo}-->
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# FOO!
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# <!--{else}>
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# BAR!
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# <!{endif}-->
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#
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# It has the following limitations:
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#
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# 1) Only if-else-endif are currently supported.
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# 2) All processing comments must be on one line with no other non-whitespace characters.
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# 3) Comments cannot be nested.
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import optparse
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import os
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inside_if = False
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last_if_true = False
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_options_parser = optparse.OptionParser(
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usage='%prog --i input.html [--on flag1]',
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description=('Rewrites an HTML file based on conditional comments and flags'))
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_options_parser.add_option('--i',
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action='store', dest='input_html_file', help='Input HTML filename')
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_options_parser.add_option('--on',
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action='append', type='string', dest='enabled_flags',
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help='name of flag to enable')
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def parse_args(args=None):
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options, rargs = _options_parser.parse_args(args)
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return options, (None, None)
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def parseComment(line, line_num, enabled_flags):
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global inside_if
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global last_if_true
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start = line.find('{')
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end = line.find('}')
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statement = line[start+1:end].strip()
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if statement.startswith('if '):
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if inside_if == True:
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print 'Fatal Error: Nested {if} found on line ' + str(line_num)
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print line
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quit()
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# Evaluate whether the expression is true/false.
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# only one variable name allowed for now
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variable_name = statement[3:].strip()
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if variable_name in enabled_flags:
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last_if_true = True
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line = '<!--{if ' + variable_name + '}-->'
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else:
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last_if_true = False
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line = '<!--{if ' + variable_name + '}>'
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inside_if = True
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elif statement == 'else':
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if inside_if == False:
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print 'Fatal Error: {else} found without {if} on line ' + str(line_num)
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print line
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quit()
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if inside_if == 'else':
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print 'Fatal Error: Multiple {else} clauses found in the same if on line ' + str(line_num)
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print line
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quit()
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if last_if_true:
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line = '<!--{else}>'
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else:
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line = '<!{else}-->'
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# invert the logic so the endif clause is closed properly
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last_if_true = not last_if_true
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# ensure we don't have two else statements in the same if
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inside_if = 'else'
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elif statement == 'endif':
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if inside_if == False:
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print 'Fatal Error: {endif} found without {if} on line ' + str(line_num)
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print line
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quit()
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if last_if_true:
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line = '<!--{endif}-->'
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else:
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line = '<!{endif}-->'
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inside_if = False
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return line
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def ship(inFileName, enabled_flags):
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# read in HTML file
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lines = file(inFileName, 'r').readlines()
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out_lines = []
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i = 0
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# loop for each line of markup
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for line in lines:
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strline = line.strip()
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# if we find a comment, process it and print out
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if strline.startswith('<!--{') or strline.startswith('<!{'):
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# using the same indentation as the previous line
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start = line.find('<')
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out_lines.append(line[:start] \
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+ parseComment(strline, i, enabled_flags) \
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+ os.linesep)
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else: # else append line to the output list
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out_lines.append(line)
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i += 1
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return ''.join(out_lines)
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if __name__ == '__main__':
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options, (input, output) = parse_args()
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if options.input_html_file != None:
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enabled_flags = []
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if options.enabled_flags != None:
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enabled_flags.extend(options.enabled_flags)
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out_file = ship(options.input_html_file, enabled_flags)
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print out_file
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