sra@google.com
fc20e9356e
Lines starting with //$ are removed during preprocessing of the template. This allows comments in the templates that are not copied to the generated text. Update copyright in template file in anticipation of new uses. Review URL: https://chromiumcodereview.appspot.com//10694169 git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@9616 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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