efortuna@google.com
880f4d814a
Review URL: https://chromiumcodereview.appspot.com//10913125 git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@12082 260f80e4-7a28-3924-810f-c04153c831b5
117 lines
3.4 KiB
Python
117 lines
3.4 KiB
Python
#!/usr/bin/python
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# Copyright (c) 2011, the Dart project authors. Please see the AUTHORS file
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# for details. All rights reserved. Use of this source code is governed by a
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# BSD-style license that can be found in the LICENSE file.
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# Template loader and preprocessor.
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#
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# Preprocessor language:
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#
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# //$ Comment line removed by preprocessor
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# $if VAR
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# $else
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# $endif
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#
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# VAR must be defined in the conditions dictionary.
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import os
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class TemplateLoader(object):
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"""Loads template files from a path."""
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def __init__(self, root, subpaths, conditions = {}):
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"""Initializes loader.
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Args:
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root - a string, the directory under which the templates are stored.
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subpaths - a list of strings, subpaths of root in search order.
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conditions - a dictionay from strings to booleans. Any conditional
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expression must be a key in the map.
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"""
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self._root = root
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self._subpaths = subpaths
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self._conditions = conditions
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self._cache = {}
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def TryLoad(self, name):
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"""Returns content of template file as a string, or None of not found."""
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if name in self._cache:
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return self._cache[name]
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for subpath in self._subpaths:
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template_file = os.path.join(self._root, subpath, name)
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if os.path.exists(template_file):
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template = ''.join(open(template_file).readlines())
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template = self._Preprocess(template, template_file)
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self._cache[name] = template
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return template
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return None
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def Load(self, name):
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"""Returns contents of template file as a string, or raises an exception."""
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template = self.TryLoad(name)
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if template is not None: # Can be empty string
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return template
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raise Exception("Could not find template '%s' on %s / %s" % (
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name, self._root, self._subpaths))
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def _Preprocess(self, template, filename):
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def error(lineno, message):
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raise Exception('%s:%s: %s' % (filename, lineno, message))
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lines = template.splitlines(True)
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out = []
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condition_stack = []
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active = True
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seen_else = False
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for (lineno, full_line) in enumerate(lines):
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line = full_line.strip()
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if line.startswith('$'):
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words = line.split()
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directive = words[0]
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if directive == '$if':
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if len(words) != 2:
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error(lineno, '$if does not have single variable')
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variable = words[1]
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if variable in self._conditions:
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condition_stack.append((active, seen_else))
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active = self._conditions[variable]
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seen_else = False
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else:
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error(lineno, "Unknown $if variable '%s'" % variable)
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elif directive == '$else':
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if not condition_stack:
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error(lineno, '$else without $if')
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if seen_else:
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raise error(lineno, 'Double $else')
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seen_else = True
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active = not active
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elif directive == '$endif':
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if not condition_stack:
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error(lineno, '$endif without $if')
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(active, seen_else) = condition_stack.pop()
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else:
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# Something else, like '$!MEMBERS'
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if active:
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out.append(full_line)
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elif line.startswith('//$'):
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pass # Ignore pre-processor comment.
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else:
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if active:
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out.append(full_line)
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continue
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if condition_stack:
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error(len(lines), 'Unterminated $if')
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return ''.join(out)
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