split engine/ into manifold/ (backend oriented) and unfold/ (the UI)

[unfold.git] / unfold / prelude.py

diff --git a/unfold/prelude.py b/unfold/prelude.py
new file mode 100644 (file)
index 0000000..20beb7d
--- /dev/null
+++ b/unfold/prelude.py
@@ -0,0 +1,72 @@
+from types import StringTypes, ListType
+
+from django.template.loader import render_to_string
+
+debug=True
+
+class Prelude:
+
+    """A class for collecting dependencies on js/css files or fragments"""
+
+    keys=[ 'js_files','css_files','js_chunks', 'css_chunks' ]
+    def __init__ (self, js_files=None, css_files=None, js_chunks=None, css_chunks=None):
+        # it's tempting to use sets but sets are not ordered..
+        self.js_files  = Prelude._normalize(js_files)
+        self.css_files = Prelude._normalize(css_files)
+        self.js_chunks = Prelude._normalize(js_chunks)
+        self.css_chunks= Prelude._normalize(css_chunks)
+
+    @staticmethod
+    def _normalize (input):
+        if not input:                           return []
+        elif isinstance (input, ListType):      return input
+        elif isinstance (input, StringTypes):   return [ input ]
+        else:                                   return list (input)
+
+    def add_js_files (self, x):
+        for i in Prelude._normalize (x):
+            if i not in self.js_files: self.js_files.append(i)
+    def add_css_files (self, x):
+        for i in Prelude._normalize (x):
+            if i not in self.css_files: self.css_files.append(i)
+    def add_js_chunks (self, x):
+        self.js_chunks += Prelude._normalize (x)
+    def add_css_chunks (self, x):
+        self.css_chunks += Prelude._normalize (x)
+
+    def inspect_string (self,msg):
+        result =  'Prelude.inspect %s (%s) with '%(msg,self)
+        result += ",".join( [ "%s->%s"%(k,len(getattr(self,k))) for k in ['js_files','js_chunks','css_files','css_chunks'] ] )
+        return result
+    def inspect (self,msg):
+        print self.inspect_string(msg)
+
+    # first attempt was to use a simple dict like this
+    #    env={}
+    #    env['js_files']=  self.js_files
+    #    env['css_files']= self.css_files
+    #    env['js_chunks']= '\n'.join(self.js_chunks)
+    #    env['css_chunks']='\n'.join(self.css_chunks)
+    #    return env
+    # together with this in layout-myslice.html
+    # {% for js_file in js_files %} {% insert_str prelude js_file %} {% endfor %}
+    # {% for css_file in css_files %} {% insert_str prelude css_file %} {% endfor %}
+    # somehow however this would not work too well, 
+    # probably insert_above is not powerful enough to handle that
+    # 
+    # so a much simpler and safer approach is for use to compute the html header directly
+    def template_env (self): 
+        env={}
+        env['js_files']=  self.js_files
+        env['css_files']= self.css_files
+        env['js_chunks']= self.js_chunks
+        env['css_chunks']=self.css_chunks
+        if debug:
+            print "prelude has %d js_files, %d css files, %d js chunks and %d css_chunks"%\
+                (len(self.js_files),len(self.css_files),len(self.js_chunks),len(self.css_chunks),)
+        # not sure how this should be done more cleanly
+        from myslice.settings import STATIC_URL
+        env ['STATIC_URL'] = STATIC_URL
+        # render this with prelude.html and put the result in header_prelude
+        header_prelude = render_to_string ('header-prelude.html',env)
+        return { 'header_prelude' : header_prelude }