katagami - a very simple xml template engine.
Project description
setup…skip to next chapter:
>>> def testfile(file):
... if not hasattr(file, 'read'):
... with open(file) as fp:
... result = render(fp)
... else:
... result = render(file)
... if sys.platform != 'cli': # IronPython doesn't implement unicode.
... result = result.encode()
... return result
>>> def teststr(t):
... return testfile(StringIO('<html><body>%s</body></html>' % t))
>>> def echo(name, body):
... with open(os.path.join(tmpdir, name), 'w') as fp:
... fp.write(body)
>>> def echoxml(name, body):
... echo(name, '<html><body>%s</body></html>' % body)
Pythonic evaluation
Dump the value (call eval with attribute value):
>>> teststr('''<python value="'hello, world'"/>''')
'<html><body>hello, world</body></html>'
By the default, xml entities are escaped in value attribute of python element:
>>> teststr('''<python value="'<p>hello, world</p>'" escape="false"/>''')
'<html><body><p>hello, world</p></body></html>'
By the default, exceptions are suppressed:
>>> teststr('''<python value="not_found"/>''')
'<html><body></body></html>'
Use __mode__ for dump exceptions (and see a helpful traceback):
>>> teststr('''<python __mode__="strict" value="not_found"/>''') # fails in IronPython
'<html><pre>Traceback (most recent call last):\n File "<string>", line 1, in Element "body"\n File "<string>", line 1, in Element "python"\n File "<string>", line 1, in Element "python" at line 1-1\n not_found\nNameError: name \'not_found\' is not defined\n</pre></html>'
Attribute evaluation (attribute value starts with ‘python:’):
>>> teststr('''<p class="python:'python-expr'">hello, world</p>''')
'<html><body><p class="python-expr">hello, world</p></body></html>'
Pythonic statements
All statements are available in all elements.
if, elif, else statements:
>>> teststr('''
... <p if="0"/>
... <p elif="0"/>
... <p else="">output here</p>
... ''')
'<html><body><p>output here</p></body></html>'
for statement (attribute value is Pythonic for style):
>>> teststr('''<p for_="i, j in enumerate(range(3))"><python value="i, j"/></p>''')
'<html><body><p>(0, 0)</p><p>(1, 1)</p><p>(2, 2)</p></body></html>'
while statement:
>>> teststr('''
... <python><![CDATA[ i = [1, 2, 3] ]]></python>
... <p while="i">
... <python value="i[0]"/>
... <python><![CDATA[ i = i[1:] ]]></python>
... </p>
... ''')
'<html><body><p>1</p><p>2</p><p>3</p></body></html>'
except statement:
>>> teststr('''
... <python except="StandardError as e"><![CDATA[ not_found ]]></python>
... <python value="e"/>
... <python except="StandardError"><![CDATA[ not_found ]]></python>
... ''')
"<html><body>name 'not_found' is not defined</body></html>"
with statement:
>>> echo('msg.txt', 'hello, world')
>>> teststr('''
... <python with="open(r'%s') as fp">
... <p><python value="fp.read()"/></p>
... <p><python value="fp.closed"/></p>
... </python>
... <p><python value="fp.closed"/></p>
... ''' % os.path.join(tmpdir, 'msg.txt'))
'<html><body><p>hello, world</p><p>False</p><p>True</p></body></html>'
Multi items are supported (ex. ‘with a, b: pass’).
>>> echo('msg2.txt', 'hello, world')
>>> teststr('''
... <python with="open(r'%s') as fp, open(r'%s') as fp2">
... <p><python value="fp.read()"/></p>
... <p><python value="fp2.read()"/></p>
... </python>
... ''' % (os.path.join(tmpdir, 'msg.txt'), os.path.join(tmpdir, 'msg2.txt')))
'<html><body><p>hello, world</p><p>hello, world</p></body></html>'
def statement (give context by keyword arguments):
>>> teststr('''
... <p def="myfunc">hello, <python value="msg"/></p>
... <python value="myfunc(msg='world')" escape="false"/>
... ''')
'<html><body><p>hello,world</p></body></html>'
Embedded python script
CDATA is required and write is function:
>>> teststr('''
... <python><![CDATA[
... write('<p>hello, world</p>')
... ]]></python>
... ''')
'<html><body><p>hello, world</p></body></html>'
and escape xml entities:
>>> teststr('''
... <python><![CDATA[
... write('<p>', 'hello, world', '</p>', escape=True)
... ]]></python>
... ''')
'<html><body><p>hello, world</p></body></html>'
Include python script file:
>>> echo('sub-script.py', '''write('hello, world')''')
>>> echoxml('template.html', '''
... <p><python src="sub-script.py"/></p>
... ''')
>>> testfile(os.path.join(tmpdir, 'template.html'))
'<html><body><p>hello, world</p></body></html>'
and share variables:
>>> echo('sub-script.py', '''
... global msg
... msg = 'hello, world'
... msg2 = 'hello, world'
... global myfunc
... def myfunc(name):
... return 'hello, ' + name
... ''')
>>> echoxml('template.html', '''
... <python src="sub-script.py"/>
... <p><python value="msg"/></p>
... <p>
... <python value="msg2" __mode__="strict" except="NameError as e"/>
... <python value="e"/>
... </p>
... <p><python value="myfunc('world')"/></p>
... ''')
>>> testfile(os.path.join(tmpdir, 'template.html'))
"<html><body><p>hello, world</p><p>name 'msg2' is not defined</p><p>hello, world</p></body></html>"
Include another template
Simply, include all elements:
>>> echoxml('sub-template.html', '<p>hello, world</p>')
>>> echoxml('template.html', '<python template="sub-template.html"/>')
>>> testfile(os.path.join(tmpdir, 'template.html'))
'<html><body><html><body><p>hello, world</p></body></html></body></html>'
Then include a part of elements:
>>> echoxml('sub-template.html', '<p id="myid">hello, world</p>')
>>> echoxml('template.html',
... '<python template="sub-template.html" fragment="myid"/>')
>>> testfile(os.path.join(tmpdir, 'template.html'))
'<html><body><p id="myid">hello, world</p></body></html>'
And share variables:
>>> echoxml('sub-template.html', '''
... <p id="myid">hello, world</p>
... <python><![CDATA[
... global msg
... msg = 'hello, world'
... ]]></python>
... <p def="global myfunc"><python value="text"/></p>
... ''')
>>> echoxml('template.html', '''
... <python template="sub-template.html" fragment="myid"/>
... <p><python value="msg"/></p>
... <python value="myfunc(text='hello, world')" escape="false"/>
... ''')
>>> testfile(os.path.join(tmpdir, 'template.html'))
'<html><body><p id="myid">hello, world</p><p>hello, world</p><p>hello, world</p></body></html>'
Techniques and notices
This module is wrote under assuming that sys.setdefaultencoding(‘utf-8’).
This module works with null xml namespace, but doesn’t remove any namespace:
>>> testfile(StringIO('''<?xml version="1.0"?>
... <root xmlns = "http://default-namespace.org/"
... xmlns:py = "http://www.python.org/ns/">
... <py:elem1 py:if="0"/>
... <elem2 xmlns="" />
... <py:elem3 if="0"/>
... </root>'''))
'<?xml version="1.0"?>\n<root xmlns="http://default-namespace.org/" xmlns:py="http://www.python.org/ns/"><py:elem1 py:if="0"/><elem2 xmlns=""/></root>'
The namespace is flat like python module and nested in function:
>>> teststr('''
... <python><![CDATA[ a = b = 0 ]]></python>
... <python def="myfunc"><![CDATA[
... global a
... write('a = %d\\n' % a)
... write('b = %d\\n' % b)
... a = b = 1
... ]]></python>
... <python value="myfunc()"/>
... <python value="a, b"/>
... ''')
'<html><body>a = 0\nb = 0\n(1, 0)</body></html>'
By the default, White spaces and comments are stripped:
>>> teststr('''<p><!-- comment --> hello, world </p>''')
'<html><body><p>hello, world</p></body></html>'
Use direct mode:
>>> teststr('''<p __mode__="direct"><!-- comment --> hello, world </p>''')
'<html><body><p><!-- comment --> hello, world </p></body></html>'
The attribute order is important:
>>> teststr('''
... <p if="0" for_="i in range(2)"><python value="i"/></p>
... <p for_="i in range(2)" if="i > 0"><python value="i"/></p>
... ''')
'<html><body><p>1</p></body></html>'
If you need closing tag such as textarea, then write below:
>>> teststr('''<textarea><python/></textarea>''')
'<html><body><textarea></textarea></body></html>'
Entities will not be expanded:
>>> teststr(''' &unknown_entity;''')
'<html><body> &unknown_entity;</body></html>'
- Special variables are available in some cases:
__file__ = str -> path of file (template or script)
- __noloop__ = bool -> whether loop statements executed
(and when not strict mode)
_ = object -> temporary value when extracting variables
Special utility functions are available, see default_namespace.
- Special string codecs:
percent, uri - known as encodeURIComponent, decodeURIComponent
xml - escape ‘<’, ‘>’, ‘&’
For more information, see Element class implementation.
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