'''PX stands for *P*ython *X*ML. It is a templating engine that reuses the pod engine to produce XML (including XHTML) from templates written as a mix of Python and XML.''' # ------------------------------------------------------------------------------ import xml.sax from px_parser import PxParser, PxEnvironment from appy.pod.buffers import MemoryBuffer # Exception class -------------------------------------------------------------- class PxError(Exception): pass # ------------------------------------------------------------------------------ class Px: '''Represents a (chunk of) PX code.''' xhtmlPrologue = '\n' def __init__(self, content, isFileName=False, partial=True, template=None, hook=None, prologue=None): '''p_content is the PX code, as a string, or a file name if p_isFileName is True. If this code represents a complete XML file, p_partial is False. Else, we must surround p_content with a root tag to be able to parse it with a SAX parser. If this PX is based on another PX template, specify the PX template in p_template and the name of the p_hook where to insert this PX into the template PX. If a p_prologue is specified, it will be rendered at the start of the PX result. ''' # Get the PX content if isFileName: f = file(content) self.content = f.read() f.close() else: self.content = content # It this content a complete XML file, or just some part of it? if partial: # Surround the partial chunk with a root tag: it must be valid XML. self.content = '%s' % self.content self.partial = partial # Create a PX parser self.parser = PxParser(PxEnvironment(), self) # Parses self.content (a PX code in a string) with self.parser, to # produce a tree of memory buffers. try: self.parser.parse(self.content) except xml.sax.SAXParseException, spe: self.completeErrorMessage(spe) raise spe # Is this PX based on a template PX? self.template = template self.hook = hook # Is there some (XML, XHTML...) prologue to dump? self.prologue = prologue def completeErrorMessage(self, parsingError): '''A p_parsingError occurred. Complete the error message with the erroneous line from self.content.''' # Split lines from self.content splitted = self.content.split('\n') i = parsingError.getLineNumber() - 1 # Get the erroneous line, and add a subsequent line for indicating # the erroneous column. column = ' ' * (parsingError.getColumnNumber()-1) + '^' lines = [splitted[i], column] # Get the previous and next lines when present. if i > 0: lines.insert(0, splitted[i-1]) if i < len(splitted)-1: lines.append(splitted[i+1]) parsingError._msg += '\n%s' % '\n'.join(lines) def __call__(self, context, applyTemplate=True): '''Renders the PX. If the PX is based on a template PX, we have 2 possibilities. 1. p_applyTemplate is True. This case corresponds to the initial call to the current PX. In this case we call the template with a context containing, in the hook variable, the current PX. 2. p_applyTemplate is False. In this case, we are currently executing the PX template, and, at the hook, we must include the current PX, as is, without re-applying the template (else, an infinite recursion would occur). ''' if self.hook and applyTemplate: # Call the template PX, filling the hook with the current PX. context[self.hook] = self return self.template(context) else: # Create a Memory buffer for storing the result. env = self.parser.env result = MemoryBuffer(env, None) env.ast.evaluate(result, context) res = result.content if self.prologue: res = self.prologue + res return res # ------------------------------------------------------------------------------