new module to generate templated RTF files

calebasse/doc_templates.py

@@ -0,0 +1,70 @@
+import os
+import os.path
+import re
+import contextlib
+
+__ALL__ = [ 'DocTemplateError', 'replace_variables', 'make_doc_from_template' ]
+
+VARIABLE_RE = re.compile(r'@[A-Z]{2,3}[0-9]{0,2}')
+
+class DocTemplateError(RuntimeError):
+    def __str__(self):
+        return ' '.join(self.args)
+
+@contextlib.contextmanager
+def delete_on_error(f):
+    '''Context manager which deletes a file if an exception occur'''
+    try:
+        yield
+    except:
+        os.remove(f.name)
+        raise
+
+def replace_variables(template, variables):
+    '''Lookup all substring looking like @XXX9 in the string template, and
+       replace them by the value of the key XXX9 in the dictionary variables.
+
+       Returns a new :class:str
+
+       :param template: string containing the variables references
+       :param variables: dictionary containing the variables values
+
+    '''
+    needed_vars = set([v[1:] for v in re.findall(VARIABLE_RE, template)])
+    given_vars = set(variables.keys())
+    if given_vars != needed_vars:
+        missing = needed_vars - given_vars
+        unused = given_vars - needed_vars
+        raise DocTemplateError(
+            'Mismatch between given and needed variables: missing={0} unused={1}'
+            .format(map(repr, missing), map(repr, unused)))
+    def variable_replacement(match_obj):
+        return variables[match_obj.group(0)[1:]]
+    return re.sub(VARIABLE_RE, variable_replacement, template)
+
+def make_doc_from_template(from_path, to_path, variables):
+    '''Use file from_path as a template to combine with the variables
+       dictionary and place the result in the file to_path.
+
+       :param from_path: the template file path
+       :param to_path: the newly created file containing the result of the templating
+       :param variables: the dictionary of variables to replace
+    '''
+
+    if not os.path.exists(from_path):
+        raise DocTemplateError('Template file does not exist', repr(from_path))
+    if os.path.exists(to_path):
+        raise DocTemplateError('Destination file already exists', repr(to_path))
+    with open(to_path, 'w') as to_file:
+        with open(from_path) as from_file:
+            with delete_on_error(to_file):
+                to_file.write(replace_variables(from_file.read(), variables))
+
+if __name__ == '__main__':
+    import sys
+    try:
+        variables = dict((arg.split('=') for arg in sys.argv[3:]))
+        make_doc_from_template(sys.argv[1], sys.argv[2], variables)
+    except Exception, e:
+        print 'Error:', e
+        print 'Usage: python doc_template.py <template.rtf> <output.rtf> [KEY1=value1 KEY2=value2 ...]'