StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
text
Body
copied!<p>Use the standard <a href="http://docs.python.org/library/xml.etree.elementtree.html" rel="nofollow">xml.etree.Element</a> tree to extract the information from XML to Python objects (or the more enhanced third party <a href="http://lxml.de/" rel="nofollow">lxml</a> with the same API). </p> <p>I recommend to read the Mark Pilrim's <em>Dive Into Python 3</em>, Chapter 12. XML (<a href="http://getpython3.com/diveintopython3/xml.html" rel="nofollow">http://getpython3.com/diveintopython3/xml.html</a>).</p> <p>Here is the core of how the parser/compiler could be written. The idea is to go recursively through the elements, collect the neccessary information and output the code when it is possible:</p> <pre><code>import xml.etree.ElementTree as ET class Parser: def __init__(self): self.output_list = [] # collected output lines self.il = 0 # indentation level def __iter__(self): return iter(self.output_list) def out(self, s): '''Output the indented string to the output list.''' self.output_list.append(' ' * self.il + s) def indent(self, num=1): '''Increase the indentation level.''' self.il += num def dedent(self, num=1): '''Decrease the indentation level.''' self.il -= num def parse(self, elem): '''Call the parser of the elem.tag name. The tag name appended to "parse_" and then the name of that function is called. If the function is not defined, then self.parse_undefined() is called.''' fn_name = 'parse_' + elem.tag try: fn = getattr(self, fn_name) except AttributeError: fn = self.parse_undefined return fn(elem) def loop(self, elem): '''Helper method to loop through the child elements.''' for e in elem: self.parse(e) def parseXMLfile(self, fname): '''Reads the XML file and starts parsing from the root element.''' tree = ET.parse(fname) script = tree.getroot() assert script.tag == 'script' self.parse(script) ###################### ELEMENT PARSERS ####################### def parse_undefined(self, elem): '''Called for the element that has no parser defined.''' self.out('PARSING UNDEFINED for ' + elem.tag) def parse_script(self, elem): self.loop(elem) def parse_stage(self, elem): self.out('') self.out('Parsing the stage: ' + elem.attrib['id']) self.indent() self.loop(elem) self.dedent() def parse_initialise(self, elem): self.out('') self.out('#---------- ' + elem.tag + ' ----------') self.loop(elem) def parse_variable(self, elem): tt = str # default type if elem.attrib['type'] == 'Integer': tt = int # elif ... etc for other types # Conversion of the value to the type because of the later repr(). value = tt(elem.attrib['value']) id_ = elem.attrib['id'] # Produce the line of the output. self.out('{0} = {1}'.format(id_, repr(value))) def parse_execute(self, elem): self.out('') self.out('#---------- ' + elem.tag + ' ----------') self.loop(elem) def parse_if(self, elem): assert elem[0].tag == 'condition' condition = self.parse(elem[0]) self.out('if ' + condition + ':') self.indent() self.loop(elem[1:]) self.dedent() def parse_condition(self, elem): assert len(elem) == 0 return elem.text def parse_then(self, elem): self.loop(elem) def parse_else(self, elem): self.dedent() self.out('else:') self.indent() self.loop(elem) def parse_error(self, elem): assert len(elem) == 0 errorID = elem.attrib.get('errorID', None) fieldID = elem.attrib.get('fieldID', None) self.out('error({0}, {1})'.format(errorID, fieldID)) def parse_setNextStage(self, elem): assert len(elem) == 0 self.out('setNextStage --> ' + elem.text) if __name__ == '__main__': parser = Parser() parser.parseXMLfile('data.xml') for s in parser: print s </code></pre> <p>When used with the data pasted here <a href="http://pastebin.com/vRRxfWiA" rel="nofollow">http://pastebin.com/vRRxfWiA</a>, the script produces the following output:</p> <pre><code>Parsing the stage: stage1 #---------- initialise ---------- taxyear = 2012 taxyearstart = '06/04/2012' taxyearend = '05/04/2013' previousemergencytaxcode = '747L' emergencytaxcode = '810L' nextemergencytaxcode = '810L' ... maxLimitAmount = 0 PARSING UNDEFINED for executeMethod if $maxLimitReached$ == True: employeepayrecord = 'N' employeepayrecordstate = '2' else: employeepayrecordstate = '1' gender = '' genderstate = '1' title = '' forename = '' forename2 = '' surname = '' dob = '' dobinvalid = '' #---------- execute ---------- if $dobstring$ != "": validDOBCheck = 'False' PARSING UNDEFINED for executeMethod if $validDOBCheck$ == False: error(224, dob) else: minimumDOBDate = '' PARSING UNDEFINED for executeMethod validDOBCheck = 'False' PARSING UNDEFINED for executeMethod if $validDOBCheck$ == False: error(3007161, dob) if $dobstring$ == "01/01/1901": error(231, dob) else: error(231, dob) Parsing the stage: stage2 #---------- initialise ---------- address1 = '' ... </code></pre>

Querying!

Guidance

An individual column

Larger individual text columns get their own page to allow for proper reading.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload