Properly implement pto tag so that tag not found errors are not r…

…aised.

src/z3c/rml/flowable.py

@@ -1067,38 +1067,6 @@ def process(self):
             self.klass(img, flow.flow, **args))
 
 
-class IPTO(interfaces.IRMLDirectiveSignature):
-    '''A container for flowables decorated with trailer & header lists.
-    If the split operation would be called then the trailer and header
-    lists are injected before and after the split. This allows specialist
-    "please turn over" and "continued from previous" like behaviours.'''
-
-class PTO(Flowable):
-    signature = IPTO
-    klass = reportlab.platypus.flowables.PTOContainer
-
-    def process(self):
-        # Get Content
-        flow = Flow(self.element, self.parent)
-        flow.process()
-        # Get the header
-        ptoHeader = self.element.find('pto_header')
-        header = None
-        if ptoHeader is not None:
-            header = Flow(ptoHeader, self.parent)
-            header.process()
-            header = header.flow
-        # Get the trailer
-        ptoTrailer = self.element.find('pto_trailer')
-        trailer = None
-        if ptoTrailer is not None:
-            trailer = Flow(ptoTrailer, self.parent)
-            trailer.process()
-            trailer = trailer.flow
-        # Create and add the PTO Container
-        self.parent.flow.append(self.klass(flow.flow, trailer, header))
-
-
 class IIndent(interfaces.IRMLDirectiveSignature):
     """Indent the contained flowables."""
 
@@ -1112,6 +1080,7 @@ class IIndent(interfaces.IRMLDirectiveSignature):
         description=u'The indentation to the right.',
         required=False)
 
+
 class Indent(Flowable):
     signature = IIndent
 
@@ -1568,7 +1537,6 @@ class IFlow(interfaces.IRMLDirectiveSignature):
         occurence.ZeroOrMore('keepTogether', IKeepTogether),
         occurence.ZeroOrMore('img', IImage),
         occurence.ZeroOrMore('imageAndFlowables', IImageAndFlowables),
-        occurence.ZeroOrMore('pto', IPTO),
         occurence.ZeroOrMore('indent', IIndent),
         occurence.ZeroOrMore('fixedSize', IFixedSize),
         occurence.ZeroOrMore('bookmarkPage', IBookmarkPage),
@@ -1637,7 +1605,6 @@ class Flow(directive.RMLDirective):
         'keepTogether': KeepTogether,
         'img': Image,
         'imageAndFlowables': ImageAndFlowables,
-        'pto': PTO,
         'indent': Indent,
         'fixedSize': FixedSize,
         'bookmarkPage': BookmarkPage,
@@ -1665,3 +1632,57 @@ def __init__(self, *args, **kw):
     def process(self):
         self.processSubDirectives()
         return self.flow
+
+
+class IPTOHeader(IFlow):
+    """A container for flowables used at the beginning of a frame.
+    """
+
+
+class PTOHeader(Flow):
+
+    def process(self):
+        self.parent.header = super(PTOHeader, self).process()
+
+
+class IPTOTrailer(IFlow):
+    """A container for flowables used at the end of a frame.
+    """
+
+
+class PTOTrailer(Flow):
+
+    def process(self):
+        self.parent.trailer = super(PTOTrailer, self).process()
+
+
+class IPTO(IFlow):
+    """A container for flowables decorated with trailer & header lists.
+
+    If the split operation would be called then the trailer and header
+    lists are injected before and after the split. This allows specialist
+    "please turn over" and "continued from previous" like behaviours.
+    """
+    occurence.containing(
+        occurence.ZeroOrOne('pto_header', IPTOHeader),
+        occurence.ZeroOrOne('pto_trailer', IPTOTrailer),
+    )
+
+
+class PTO(Flow):
+    signature = IPTO
+    klass = reportlab.platypus.flowables.PTOContainer
+
+    factories = dict(
+        pto_header=PTOHeader,
+        pto_trailer=PTOTrailer,
+        **Flow.factories
+    )
+
+    header = None
+    trailer = None
+
+    def process(self):
+        flow = super(PTO, self).process()
+        self.parent.flow.append(
+            self.klass(flow, self.trailer, self.header))

src/z3c/rml/template.py

@@ -23,6 +23,7 @@
 class IStory(flowable.IFlow):
     """The story of the PDF file."""
     occurence.containing(
+        occurence.ZeroOrMore('pto', flowable.IPTO),
         *flowable.IFlow.getTaggedValue('directives'))
 
     firstPageTemplate = attr.Text(
@@ -31,9 +32,15 @@ class IStory(flowable.IFlow):
         default=None,
         required=False)
 
+
 class Story(flowable.Flow):
     signature = IStory
 
+    factories = dict(
+        pto=flowable.PTO,
+        **flowable.Flow.factories
+    )
+
     def process(self):
         self.parent.flowables = super(Story, self).process()
         self.parent.doc._firstPageTemplateIndex = self.getFirstPTIndex()
@@ -123,7 +130,8 @@ def process(self):
         args = dict(self.getAttributeValues())
         # Deal with percentages
         for name, dir in (('x1', 0), ('y1', 1), ('width', 0), ('height', 1)):
-            if isinstance(args[name], six.string_types) and args[name].endswith('%'):
+            if (isinstance(args[name], six.string_types) and
+                    args[name].endswith('%')):
                 args[name] = float(args[name][:-1])/100*size[dir]
         frame = platypus.Frame(**args)
         self.parent.frames.append(frame)