This module is the Template Macro module. It preprocesses a web template in which variables and blocks are contained. This package plays an important role as an explicit boundary between web template designing and script implementation.
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#-*- coding: utf-8 -*-
'''
This module is the B{Template Macro} module. It preprocesses a web
template in which variables and blocks are contained. This package
plays an important role as an explicit boundary between web template
designing and script implementation.
@note: A block can be defined with block comment:
C{<!-- block }M{q}C{ start -->}
M{c}
C{<!-- block }M{q}C{ end -->},
where M{q} is the block name and M{c} is the content of this block.
@note: It should be noted that each subblock symbol is necessary to
differ from its superblock's name. This is owing to the block pattern.
@author: Prachya Boonkwan
@organization: NAI{i}ST Laboratory, Kasetsart University, Thailand
@copyright: October 23, 2003
'''
########################################
import copy
import re
import string
########################################
class Template:
'''
Web template representation. As soon as the template instance is
constructed, the content is automatically analyzed and the symbol
table is afterward created.
@ivar path: Path to web template file.
@type path: str
@ivar content: Textual content of web template.
@type content: str
@ivar symtab: Symbol table of web template
@type symtab: dict
@cvar blkpat: Block declaration pattern (regular expression). It
should be noted that this pattern does I{not} greedily match the
block body.
'''
blkpat = re.compile(
r'\s*<!---*\s*block\s*(?P<blkname>\w+?)\s*(start|begin)\s*-*-->'
r'(?P<blkbody>\s*.*?)'
r'\s*<!---*\s*block\s*(?P=blkname)\s*end\s*-*-->',
re.DOTALL
)
def __init__(self, path = None, content = None, symtab = None):
'''
Construct a web template representation.
@param path: Path to web template file.
@type path: str
@param content: Textual content of web template
@type content: str
@param symtab: Symbol table of web template
@type symtab: dict
@note: It is recommended to specify only the path of the
template.
'''
if symtab is None: symtab = {}
self.path = path
self.content = content
self.symtab = symtab
if self.content is None or len(self.symtab) == 0:
if self.path is not None:
self.load()
self.content = self.analyze(self.content)
def __copy__(self):
'''
Copy a web template representation.
'''
return Template(
self.path, self.content, copy.copy(self.symtab)
)
def load(self):
'''
Load the content of the template from the specified path.
'''
fhdl = open(self.path)
self.content = fhdl.read()
fhdl.close()
def analyze(self, text, blkpath = None):
'''
Analyze the text to establish blocks.
@param text: Text to be analyzed.
@type text: str
@param blkpath: Block path to the text.
@type blkpath: list
@return: Content which blocks are replaced with symbols.
@rtype: str
@raise TemplateError: If symbol reassignment occurs.
'''
if blkpath is None: blkpath = []
result = text
while True:
matobj = Template.blkpat.search(result)
if matobj is None: break
blkname = matobj.group('blkname')
symbol = string.join(blkpath + [blkname], '.')
blkbody = matobj.group('blkbody')
(result, _) = Template.blkpat.subn(
'[[:%s:]]' % symbol, result, 1
)
value = self.analyze(blkbody, blkpath + [blkname])
if symbol not in self.symtab.keys():
self.symtab[symbol] = value
else:
raise TemplateError, \
'Reassigning the same symbol (%s).' % symbol
return result
def __getitem__(self, symbol):
'''
Get the value of the symbol.
@param symbol: Symbol name.
@type symbol: str
@return: Value of the symbol.
@rtype: str
'''
return self.symtab[symbol]
def repr(self):
'''
Represent this template with a string representation.
@return: String C{Template(path = }M{p}C{, content = }M{c}
C{, symtab = }M{s}C{)}, where M{p} is the path, M{c} is the
content of that template, and M{s} is the symbol table.
@rtype: str
'''
return 'Template(path = %r, content = %r, symtab = %r)' % (
self.path, self.content, self.symtab
)
__repr__ = __str__ = repr
########################################
class TemplateError(Exception):
'''
Error occurring in the class Template.
'''
pass
########################################
class PageMacro:
'''
Page Macro Expander. It enables users to define symbols in order
to be expanded to templates further. Moreover, also enables users
to expand consecutively blocks in templates.
@ivar symtab: Symbol table.
@type symtab: dict
@cvar KEEPMODE: Mode of keeping all undefined symbols.
@type KEEPMODE: int
@cvar DELMODE: Mode of deleting all undefined symbols.
@type DELMODE: int
@cvar varpat: Symbol pattern.
@cvar unkpat: Unknown symbol pattern.
'''
KEEPMODE = 0
DELMODE = 1
varpat = re.compile(r'\[\[:(?P<symname>(\w+\.)*\w+?):\]\]')
unkpat = re.compile(r'\[\[::(?P<synname>(\w+\.)*\w+?)::\]\]')
def __init__(self, mainsym, unkmthd = None, symtab = None):
'''
Construct a page macro expander.
@param mainsym: Main symbol to be displayed.
@type mainsym: str
@param unkmthd: Resolution method of undefined symbols
(C{PageMacro.KEEPMODE} or C{PageMacro.DELMODE}).
@type unkmthd: int
@param symtab: Symbol table.
@type symtab: dict
'''
if unkmthd is None: unkmthd = PageMacro.KEEPMODE
if symtab is None: symtab = {}
self.mainsym = mainsym
self.unkmthd = unkmthd
self.symtab = symtab
def __copy__(self):
'''
Copy a page macro expander.
'''
return PageMacro(
self.mainsym, self.unkmthd, copy.copy(self.symtab)
)
def repr(self):
'''
Represent a page macro expander with a string representation.
@return: String C{PageMacro(mainsym = }M{q}C{, unkmthd = }M{m}
C{, symtab = }M{s}C{)}, where M{q} is the main symbol, M{m} is
the resolution method of unknown or undefined symbols and M{s}
is the symbol table.
@rtype: str
'''
return 'PageMacro(mainsym = %s, unkmthd = %d, symtab = %r)' % (
self.mainsym, self.unkmthd, self.symtab
)
__repr__ = repr
def __getitem__(self, symbol):
'''
Get the value of a symbol.
@param symbol: Symbol name.
@type symbol: str
@return: Value of the symbol.
@rtype: Template
'''
return self.symtab[symbol]
def __setitem__(self, symbol, value):
'''
Set the value of a symbol.
@param symbol: Symbol name.
@type symbol: str
@param value: Value of the symbol.
@type value: str or Template
@note: The parameter C{value} of a symbol can be a string or a
template. If it is a string, it will be considered as the
content of the template and it will be wrapped with Template
class. On the contrary, if it is a template, it will be
directly assigned to the symbol.
@note: If users would like to assign to a symbol with the path
to a template file, please use C{pm[}M{s}C{] =
Template(path = }M{p}C{)}, where C{pm} is a C{PageMacro}
instance, M{s} is a symbol name, and M{p} is a path to
template. Users can alternatively use the method C{load} for
ease of use.
@note: If users would like to assign directly to a symbol with
the template content, please use C{pm[}M{s}C{] = }M{c}, where
C{pm} is a C{PageMacro} instance and M{c} is a content of
template.
'''
if isinstance(value, Template):
self.symtab[symbol] = value
elif type(value) is str:
self.symtab[symbol] = Template(content = value)
def load(self, symbol, filename):
'''
Load a template file to a symbol.
@param symbol: Symbol name.
@type symbol: str
@param filename: Template path.
@type filename: str
'''
self[symbol] = Template(path = filename)
def resolve(self, symbol):
'''
Resolve the specified symbol to absolute value.
@param symbol: Symbol name.
@type symbol: str
@return: Absolute value of the symbol.
@rtype: str
'''
if symbol not in self.symtab:
return '[[::%s::]]' % symbol
result = self.symtab[symbol].content
while True:
matobj = PageMacro.varpat.search(result)
if matobj is None: break
symname = matobj.group('symname')
if symname in self.symtab:
(result, _) = PageMacro.varpat.subn(
self.resolve(symname), result, 1
)
else:
(result, _) = PageMacro.varpat.subn(
'[[::%s::]]' % symname, result, 1
)
return self.handle_unk(result)
def handle_unk(self, text):
'''
Handle unknown symbols in the text.
@param text: Text.
@type text: str
@return: Unknown-handled text.
@rtype: str
'''
result = text
while True:
matobj = PageMacro.unkpat.search(result)
if matobj is None: break
if self.unkmthd == PageMacro.KEEPMODE:
result = PageMacro.unkpat.sub(
'[[:\g<synname>:]]', result
)
elif self.unkmthd == PageMacro.DELMODE:
result = PageMacro.unkpat.sub('', result)
return result
def envision(self, tempsym, blocksym, symdict):
'''
Resolve a block in a template with a symbol dictionary.
@param tempsym: Template symbol.
@type tempsym: str
@param blocksym: Block symbol in the template.
@type blocksym: str
@param symdict: Symbol dictionary.
@type symdict: dict
@raise PageMacroError: If unknown switch is to be resolved.
'''
self.expand(tempsym, blocksym, [symdict])
def expand(self, tempsym, blocksym, iterable):
'''
Expand consecutively a block in a template with an iterable.
@param tempsym: Template symbol.
@type tempsym: str
@param blocksym: Block symbol in the template.
@type blocksym: str
@param iterable: Iterable list of dictionaries whose keys and
values resemble correspondences among symbols and their
values. A value in the dictionary can be a list or an iterable
to expand recursively the block. In this case, the key of such
value is necessary to specify explicitly block hierarchy.
@type iterable: list or iter
@raise PageMacroError: If unknown block is to be resolved.
'''
if (
tempsym not in self.symtab
):
raise PageMacroError, \
'Unknown template (%s) cannot be resolved.' % tempsym
if (
blocksym not in self.symtab[tempsym].symtab
):
raise PageMacroError, \
'Unknown block (%s) cannot be resolved.' % blocksym
result = []
for symdict in iterable:
content = self.symtab[tempsym][blocksym]
while True:
matobj = PageMacro.varpat.search(content)
if matobj is None: break
symname = matobj.group('symname')
if symname in symdict:
if type(symdict[symname]) is str:
self[symname] = symdict[symname]
elif type(symdict[symname]) in [list, iter]:
self.expand(tempsym, symname, symdict[symname])
elif type(symdict[symname]) is dict:
self.expand(
tempsym, symname, [symdict[symname]]
)
(content, _) = PageMacro.varpat.subn(
self.resolve(symname), content, 1
)
result.append(content)
self[blocksym] = string.join(result, '')
def str(self):
'''
Represent a page macro expander with the expanded value of the
main symbol.
@return: Expanded value.
@rtype: str
'''
return self.resolve(self.mainsym)
__str__ = str
########################################
class PageMacroError(Exception):
'''
Error occurring in the class PageMacro.
'''
pass
########################################
def demo():
'''
Demonstrate this module.
'''
input = '''
<html>
This page was written by <b>[[:author:]]</b>.
<!-- block TableBlock start -->
<table>
<th>
<td>[[:h1:]]</td>
<td>[[:h2:]]</td>
<td>[[:h3:]]</td>
</th>
<!-- block RowBlock start -->
<tr>
<td>[[:c1:]]</td>
<td>[[:c2:]]</td>
<td>[[:c3:]]</td>
</tr>
<!-- block RowBlock end -->
</table>
<!-- block TableBlock end -->
</html>
'''
pm = PageMacro('Content', PageMacro.DELMODE)
pm['Content'] = input
pm['author'] = 'Prachya Boonkwan'
pm.expand('Content', 'TableBlock', [
{
'h1': 'Country', 'h2': 'President', 'h3': 'Population',
'TableBlock.RowBlock': [
{'c1': 'USA', 'c2': 'Bush', 'c3': '200m'},
{'c1': 'PRC', 'c2': 'Jintao', 'c3': '1,200m'}
]
},
{
'h1': 'Class', 'h2': 'Instructor', 'h3': 'Student No.',
'TableBlock.RowBlock': [
{'c1': 'AI', 'c2': 'AK', 'c3': '60'},
{'c1': 'NLP', 'c2': 'AK', 'c3': '50'}
]
}
])
print pm
if __name__ == '__main__':
demo()
|
This program is motivated by PHP Template macro of PHPLIB. The innovation is that blocks can be expanded consecutively be a list of nested dictionaries of variables and their values.
Tags: cgi
Documentation in the source code. In order to clarify all comments in the source code, kindly uses epydoc (http://epydoc.sourceforge.net) to generate a documentation.