bottle template

tmpl.py

import functools
from urllib2 import *

TEMPLATE_PATH = ['./', './views/']
TEMPLATES = {}

#------------------------------------------utils------------------------------------------
def tob(s, enc='utf8'):
    return s.encode(enc) if isinstance(s, unicode) else bytes(s)

def touni(s, enc='utf8', err='strict'):
    return s.decode(enc, err) if isinstance(s, bytes) else unicode(s)

def depr(message):
    warnings.warn(message, DeprecationWarning, stacklevel=3)

def makelist(data): # This is just to handy
    if isinstance(data, (tuple, list, set, dict)): return list(data)
    elif data: return [data]
    else: return []


class DictProperty(object):
    ''' Property that maps to a key in a local dict-like attribute. '''
    def __init__(self, attr, key=None, read_only=False):
        self.attr, self.key, self.read_only = attr, key, read_only

    def __call__(self, func):
        functools.update_wrapper(self, func, updated=[])
        self.getter, self.key = func, self.key or func.__name__
        return self

    def __get__(self, obj, cls):
        if obj is None: return self
        key, storage = self.key, getattr(obj, self.attr)
        if key not in storage: storage[key] = self.getter(obj)
        return storage[key]

    def __set__(self, obj, value):
        if self.read_only: raise AttributeError("Read-Only property.")
        getattr(obj, self.attr)[self.key] = value

    def __delete__(self, obj):
        if self.read_only: raise AttributeError("Read-Only property.")
        del getattr(obj, self.attr)[self.key]

class cached_property(object):
    ''' A property that is only computed once per instance and then replaces
        itself with an ordinary attribute. Deleting the attribute resets the
        property. '''

    def __init__(self, func):
        self.func = func

    def __get__(self, obj, cls):
        if obj is None: return self
        value = obj.__dict__[self.func.__name__] = self.func(obj)
        return value

def html_escape(string):
    ''' Escape HTML special characters ``&<>`` and quotes ``'"``. '''
    return string.replace('&','&amp;').replace('<','&lt;').replace('>','&gt;')\
                 .replace('"','&quot;').replace("'",'&#039;')

def html_quote(string):
    ''' Escape and quote a string to be used as an HTTP attribute.'''
    return '"%s"' % html_escape(string).replace('\n','%#10;')\
                    .replace('\r','&#13;').replace('\t','&#9;')

class lazy_attribute(object):
    ''' A property that caches itself to the class object. '''
    def __init__(self, func):
        functools.update_wrapper(self, func, updated=[])
        self.getter = func

    def __get__(self, obj, cls):
        value = self.getter(cls)
        setattr(cls, self.__name__, value)
        return value


class TemplateError(HTTPError):
    def __init__(self, message):
        HTTPError.__init__(self, 500, message)


class BaseTemplate(object):
    """ Base class and minimal API for template adapters """
    extensions = ['tpl','html','thtml','stpl']
    settings = {} #used in prepare()
    defaults = {} #used in render()

    def __init__(self, source=None, name=None, lookup=[], encoding='utf8', **settings):
        """ Create a new template.
        If the source parameter (str or buffer) is missing, the name argument
        is used to guess a template filename. Subclasses can assume that
        self.source and/or self.filename are set. Both are strings.
        The lookup, encoding and settings parameters are stored as instance
        variables.
        The lookup parameter stores a list containing directory paths.
        The encoding parameter should be used to decode byte strings or files.
        The settings parameter contains a dict for engine-specific settings.
        """
        self.name = name
        self.source = source.read() if hasattr(source, 'read') else source
        self.filename = source.filename if hasattr(source, 'filename') else None
        self.lookup = [os.path.abspath(x) for x in lookup]
        self.encoding = encoding
        self.settings = self.settings.copy() # Copy from class variable
        self.settings.update(settings) # Apply
        if not self.source and self.name:
            self.filename = self.search(self.name, self.lookup)
            if not self.filename:
                raise TemplateError('Template %s not found.' % repr(name))
        if not self.source and not self.filename:
            raise TemplateError('No template specified.')
        self.prepare(**self.settings)

    @classmethod
    def search(cls, name, lookup=[]):
        """ Search name in all directories specified in lookup.
        First without, then with common extensions. Return first hit. """
        if not lookup:
            depr('The template lookup path list should not be empty.')
            lookup = ['.']

        if os.path.isabs(name) and os.path.isfile(name):
            depr('Absolute template path names are deprecated.')
            return os.path.abspath(name)

        for spath in lookup:
            spath = os.path.abspath(spath) + os.sep
            fname = os.path.abspath(os.path.join(spath, name))
            if not fname.startswith(spath): continue
            if os.path.isfile(fname): return fname
            for ext in cls.extensions:
                if os.path.isfile('%s.%s' % (fname, ext)):
                    return '%s.%s' % (fname, ext)

    @classmethod
    def global_config(cls, key, *args):
        ''' This reads or sets the global settings stored in class.settings. '''
        if args:
            cls.settings = cls.settings.copy() # Make settings local to class
            cls.settings[key] = args[0]
        else:
            return cls.settings[key]

    def prepare(self, **options):
        """ Run preparations (parsing, caching, ...).
        It should be possible to call this again to refresh a template or to
        update settings.
        """
        raise NotImplementedError

    def render(self, *args, **kwargs):
        """ Render the template with the specified local variables and return
        a single byte or unicode string. If it is a byte string, the encoding
        must match self.encoding. This method must be thread-safe!
        Local variables may be provided in dictionaries (*args)
        or directly, as keywords (**kwargs).
        """
        raise NotImplementedError



class SimpleTemplate(BaseTemplate):
    blocks = ('if', 'elif', 'else', 'try', 'except', 'finally', 'for', 'while',
              'with', 'def', 'class')
    dedent_blocks = ('elif', 'else', 'except', 'finally')

    @lazy_attribute
    def re_pytokens(cls):
        ''' This matches comments and all kinds of quoted strings but does
            NOT match comments (#...) within quoted strings. (trust me) '''
        return re.compile(r'''
            (''(?!')|""(?!")|'{6}|"{6}    # Empty strings (all 4 types)
             |'(?:[^\\']|\\.)+?'          # Single quotes (')
             |"(?:[^\\"]|\\.)+?"          # Double quotes (")
             |'{3}(?:[^\\]|\\.|\n)+?'{3}  # Triple-quoted strings (')
             |"{3}(?:[^\\]|\\.|\n)+?"{3}  # Triple-quoted strings (")
             |\#.*                        # Comments
            )''', re.VERBOSE)

    def prepare(self, escape_func=html_escape, noescape=False, **kwargs):
        self.cache = {}
        enc = self.encoding
        self._str = lambda x: touni(x, enc)
        self._escape = lambda x: escape_func(touni(x, enc))
        if noescape:
            self._str, self._escape = self._escape, self._str

    @classmethod
    def split_comment(cls, code):
        """ Removes comments (#...) from python code. """
        if '#' not in code: return code
        #: Remove comments only (leave quoted strings as they are)
        subf = lambda m: '' if m.group(0)[0]=='#' else m.group(0)
        return re.sub(cls.re_pytokens, subf, code)

    @cached_property
    def co(self):
        return compile(self.code, self.filename or '<string>', 'exec')

    @cached_property
    def code(self):
        stack = [] # Current Code indentation
        lineno = 0 # Current line of code
        ptrbuffer = [] # Buffer for printable strings and token tuple instances
        codebuffer = [] # Buffer for generated python code
        multiline = dedent = oneline = False
        template = self.source or open(self.filename, 'rb').read()

        def yield_tokens(line):
            for i, part in enumerate(re.split(r'\{\{(.*?)\}\}', line)):
                if i % 2:
                    if part.startswith('!'): yield 'RAW', part[1:]
                    else: yield 'CMD', part
                else: yield 'TXT', part

        def flush(): # Flush the ptrbuffer
            if not ptrbuffer: return
            cline = ''
            for line in ptrbuffer:
                for token, value in line:
                    if token == 'TXT': cline += repr(value)
                    elif token == 'RAW': cline += '_str(%s)' % value
                    elif token == 'CMD': cline += '_escape(%s)' % value
                    cline +=  ', '
                cline = cline[:-2] + '\\\n'
            cline = cline[:-2]
            if cline[:-1].endswith('\\\\\\\\\\n'):
                cline = cline[:-7] + cline[-1] # 'nobr\\\\\n' --> 'nobr'
            cline = '_printlist([' + cline + '])'
            del ptrbuffer[:] # Do this before calling code() again
            code(cline)

        def code(stmt):
            for line in stmt.splitlines():
                codebuffer.append('  ' * len(stack) + line.strip())

        for line in template.splitlines(True):
            lineno += 1
            line = touni(line, self.encoding)
            sline = line.lstrip()
            if lineno <= 2:
                m = re.match(r"%\s*#.*coding[:=]\s*([-\w.]+)", sline)
                if m: self.encoding = m.group(1)
                if m: line = line.replace('coding','coding (removed)')
            if sline and sline[0] == '%' and sline[:2] != '%%':
                line = line.split('%',1)[1].lstrip() # Full line following the %
                cline = self.split_comment(line).strip()
                cmd = re.split(r'[^a-zA-Z0-9_]', cline)[0]
                flush() # You are actually reading this? Good luck, it's a mess :)
                if cmd in self.blocks or multiline:
                    cmd = multiline or cmd
                    dedent = cmd in self.dedent_blocks # "else:"
                    if dedent and not oneline and not multiline:
                        cmd = stack.pop()
                    code(line)
                    oneline = not cline.endswith(':') # "if 1: pass"
                    multiline = cmd if cline.endswith('\\') else False
                    if not oneline and not multiline:
                        stack.append(cmd)
                elif cmd == 'end' and stack:
                    code('#end(%s) %s' % (stack.pop(), line.strip()[3:]))
                elif cmd == 'include':
                    p = cline.split(None, 2)[1:]
                    if len(p) == 2:
                        code("_=_include(%s, _stdout, %s)" % (repr(p[0]), p[1]))
                    elif p:
                        code("_=_include(%s, _stdout)" % repr(p[0]))
                    else: # Empty %include -> reverse of %rebase
                        code("_printlist(_base)")
                elif cmd == 'rebase':
                    p = cline.split(None, 2)[1:]
                    if len(p) == 2:
                        code("globals()['_rebase']=(%s, dict(%s))" % (repr(p[0]), p[1]))
                    elif p:
                        code("globals()['_rebase']=(%s, {})" % repr(p[0]))
                else:
                    code(line)
            else: # Line starting with text (not '%') or '%%' (escaped)
                if line.strip().startswith('%%'):
                    line = line.replace('%%', '%', 1)
                ptrbuffer.append(yield_tokens(line))
        flush()
        return '\n'.join(codebuffer) + '\n'

    def subtemplate(self, _name, _stdout, *args, **kwargs):
        for dictarg in args: kwargs.update(dictarg)
        if _name not in self.cache:
            self.cache[_name] = self.__class__(name=_name, lookup=self.lookup)
        return self.cache[_name].execute(_stdout, kwargs)

    def execute(self, _stdout, *args, **kwargs):
        for dictarg in args: kwargs.update(dictarg)
        env = self.defaults.copy()
        env.update({'_stdout': _stdout, '_printlist': _stdout.extend,
               '_include': self.subtemplate, '_str': self._str,
               '_escape': self._escape, 'get': env.get,
               'setdefault': env.setdefault, 'defined': env.__contains__})
        env.update(kwargs)
        eval(self.co, env)
        if '_rebase' in env:
            subtpl, rargs = env['_rebase']
            rargs['_base'] = _stdout[:] #copy stdout
            del _stdout[:] # clear stdout
            return self.subtemplate(subtpl,_stdout,rargs)
        return env

    def render(self, *args, **kwargs):
        """ Render the template using keyword arguments as local variables. """
        for dictarg in args: kwargs.update(dictarg)
        stdout = []
        self.execute(stdout, kwargs)
        return ''.join(stdout)

def template(*args, **kwargs):
    '''
    Get a rendered template as a string iterator.
    You can use a name, a filename or a template string as first parameter.
    Template rendering arguments can be passed as dictionaries
    or directly (as keyword arguments).
    '''
    tpl = args[0] if args else None
    adapter = kwargs.pop('template_adapter', SimpleTemplate)
    lookup = kwargs.pop('template_lookup', TEMPLATE_PATH)
    tplid = (id(lookup), tpl)
    if tplid not in TEMPLATES or DEBUG:
        settings = kwargs.pop('template_settings', {})
        if isinstance(tpl, adapter):
            TEMPLATES[tplid] = tpl
            if settings: TEMPLATES[tplid].prepare(**settings)
        elif "\n" in tpl or "{" in tpl or "%" in tpl or '$' in tpl:
            TEMPLATES[tplid] = adapter(source=tpl, lookup=lookup, **settings)
        else:
            TEMPLATES[tplid] = adapter(name=tpl, lookup=lookup, **settings)
    if not TEMPLATES[tplid]:
        abort(500, 'Template (%s) not found' % tpl)
    for dictarg in args[1:]: kwargs.update(dictarg)
    return TEMPLATES[tplid].render(kwargs)

def main():
    print template("hello {{name}}", name="world")

if __name__ == '__main__':
    main()