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""" A small templating language This implements a small templating language for use internally in Paste and Paste Script. This language implements if/elif/else, for/continue/break, expressions, and blocks of Python code. The syntax is:: {{any expression (function calls etc)}} {{any expression | filter}} {{for x in y}}...{{endfor}} {{if x}}x{{elif y}}y{{else}}z{{endif}} {{py:x=1}} {{py: def foo(bar): return 'baz' }} {{default var = default_value}} {{# comment}} You use this with the ``Template`` class or the ``sub`` shortcut. The ``Template`` class takes the template string and the name of the template (for errors) and a default namespace. Then (like ``string.Template``) you can call the ``tmpl.substitute(**kw)`` method to make a substitution (or ``tmpl.substitute(a_dict)``). ``sub(content, **kw)`` substitutes the template immediately. You can use ``__name='tmpl.html'`` to set the name of the template. If there are syntax errors ``TemplateError`` will be raised. """ import re import sys import cgi import urllib from paste.util.looper import looper __all__ = ['TemplateError', 'Template', 'sub', 'HTMLTemplate', 'sub_html', 'html', 'bunch'] token_re = re.compile(r'\{\{|\}\}') in_re = re.compile(r'\s+in\s+') var_re = re.compile(r'^[a-z_][a-z0-9_]*$', re.I) class TemplateError(Exception): """Exception raised while parsing a template """ def __init__(self, message, position, name=None): self.message = message self.position = position self.name = name def __str__(self): msg = '%s at line %s column %s' % ( self.message, self.position[0], self.position[1]) if self.name: msg += ' in %s' % self.name return msg class _TemplateContinue(Exception): pass class _TemplateBreak(Exception): pass class Template(object): default_namespace = { 'start_braces': '{{', 'end_braces': '}}', 'looper': looper, } default_encoding = 'utf8' def __init__(self, content, name=None, namespace=None): self.content = content self._unicode = isinstance(content, unicode) self.name = name self._parsed = parse(content, name=name) if namespace is None: namespace = {} self.namespace = namespace def from_filename(cls, filename, namespace=None, encoding=None): f = open(filename, 'rb') c = f.read() f.close() if encoding: c = c.decode(encoding) return cls(content=c, name=filename, namespace=namespace) from_filename = classmethod(from_filename) def __repr__(self): return '<%s %s name=%r>' % ( self.__class__.__name__, hex(id(self))[2:], self.name) def substitute(self, *args, **kw): if args: if kw: raise TypeError( "You can only give positional *or* keyword arguments") if len(args) > 1: raise TypeError( "You can only give on positional argument") kw = args[0] ns = self.default_namespace.copy() ns.update(self.namespace) ns.update(kw) result = self._interpret(ns) return result def _interpret(self, ns): __traceback_hide__ = True parts = [] self._interpret_codes(self._parsed, ns, out=parts) return ''.join(parts) def _interpret_codes(self, codes, ns, out): __traceback_hide__ = True for item in codes: if isinstance(item, basestring): out.append(item) else: self._interpret_code(item, ns, out) def _interpret_code(self, code, ns, out): __traceback_hide__ = True name, pos = code[0], code[1] if name == 'py': self._exec(code[2], ns, pos) elif name == 'continue': raise _TemplateContinue() elif name == 'break': raise _TemplateBreak() elif name == 'for': vars, expr, content = code[2], code[3], code[4] expr = self._eval(expr, ns, pos) self._interpret_for(vars, expr, content, ns, out) elif name == 'cond': parts = code[2:] self._interpret_if(parts, ns, out) elif name == 'expr': parts = code[2].split('|') base = self._eval(parts[0], ns, pos) for part in parts[1:]: func = self._eval(part, ns, pos) base = func(base) out.append(self._repr(base, pos)) elif name == 'default': var, expr = code[2], code[3] if var not in ns: result = self._eval(expr, ns, pos) ns[var] = result elif name == 'comment': return else: assert 0, "Unknown code: %r" % name def _interpret_for(self, vars, expr, content, ns, out): __traceback_hide__ = True for item in expr: if len(vars) == 1: ns[vars[0]] = item else: if len(vars) != len(item): raise ValueError( 'Need %i items to unpack (got %i items)' % (len(vars), len(item))) for name, value in zip(vars, item): ns[name] = value try: self._interpret_codes(content, ns, out) except _TemplateContinue: continue except _TemplateBreak: break def _interpret_if(self, parts, ns, out): __traceback_hide__ = True # @@: if/else/else gets through for part in parts: assert not isinstance(part, basestring) name, pos = part[0], part[1] if name == 'else': result = True else: result = self._eval(part[2], ns, pos) if result: self._interpret_codes(part[3], ns, out) break def _eval(self, code, ns, pos): __traceback_hide__ = True try: value = eval(code, ns) return value except: exc_info = sys.exc_info() e = exc_info[1] if getattr(e, 'args'): arg0 = e.args[0] else: arg0 = str(e) e.args = (self._add_line_info(arg0, pos),) raise exc_info[0], e, exc_info[2] def _exec(self, code, ns, pos): __traceback_hide__ = True try: exec code in ns except: exc_info = sys.exc_info() e = exc_info[1] e.args = (self._add_line_info(e.args[0], pos),) raise exc_info[0], e, exc_info[2] def _repr(self, value, pos): __traceback_hide__ = True try: if value is None: return '' if self._unicode: try: value = unicode(value) except UnicodeDecodeError: value = str(value) else: value = str(value) except: exc_info = sys.exc_info() e = exc_info[1] e.args = (self._add_line_info(e.args[0], pos),) raise exc_info[0], e, exc_info[2] else: if self._unicode and isinstance(value, str): if not self.decode_encoding: raise UnicodeDecodeError( 'Cannot decode str value %r into unicode ' '(no default_encoding provided)' % value) value = value.decode(self.default_encoding) elif not self._unicode and isinstance(value, unicode): if not self.decode_encoding: raise UnicodeEncodeError( 'Cannot encode unicode value %r into str ' '(no default_encoding provided)' % value) value = value.encode(self.default_encoding) return value def _add_line_info(self, msg, pos): msg = "%s at line %s column %s" % ( msg, pos[0], pos[1]) if self.name: msg += " in file %s" % self.name return msg def sub(content, **kw): name = kw.get('__name') tmpl = Template(content, name=name) return tmpl.substitute(kw) return result def paste_script_template_renderer(content, vars, filename=None): tmpl = Template(content, name=filename) return tmpl.substitute(vars) class bunch(dict): def __init__(self, **kw): for name, value in kw.items(): setattr(self, name, value) def __setattr__(self, name, value): self[name] = value def __getattr__(self, name): try: return self[name] except KeyError: raise AttributeError(name) def __getitem__(self, key): if 'default' in self: try: return dict.__getitem__(self, key) except KeyError: return dict.__getitem__(self, 'default') else: return dict.__getitem__(self, key) def __repr__(self): items = [ (k, v) for k, v in self.items()] items.sort() return '<%s %s>' % ( self.__class__.__name__, ' '.join(['%s=%r' % (k, v) for k, v in items])) ############################################################ ## HTML Templating ############################################################ class html(object): def __init__(self, value): self.value = value def __str__(self): return self.value def __repr__(self): return '<%s %r>' % ( self.__class__.__name__, self.value) def html_quote(value): if value is None: return '' if not isinstance(value, basestring): if hasattr(value, '__unicode__'): value = unicode(value) else: value = str(value) value = cgi.escape(value, 1) if isinstance(value, unicode): value = value.encode('ascii', 'xmlcharrefreplace') return value def url(v): if not isinstance(v, basestring): if hasattr(v, '__unicode__'): v = unicode(v) else: v = str(v) if isinstance(v, unicode): v = v.encode('utf8') return urllib.quote(v) def attr(**kw): kw = kw.items() kw.sort() parts = [] for name, value in kw: if value is None: continue if name.endswith('_'): name = name[:-1] parts.append('%s="%s"' % (html_quote(name), html_quote(value))) return html(' '.join(parts)) class HTMLTemplate(Template): default_namespace = Template.default_namespace.copy() default_namespace.update(dict( html=html, attr=attr, url=url, )) def _repr(self, value, pos): plain = Template._repr(self, value, pos) if isinstance(value, html): return plain else: return html_quote(plain) def sub_html(content, **kw): name = kw.get('__name') tmpl = HTMLTemplate(content, name=name) return tmpl.substitute(kw) return result ############################################################ ## Lexing and Parsing ############################################################ def lex(s, name=None, trim_whitespace=True): """ Lex a string into chunks: >>> lex('hey') ['hey'] >>> lex('hey {{you}}') ['hey ', ('you', (1, 7))] >>> lex('hey {{') Traceback (most recent call last): ... TemplateError: No }} to finish last expression at line 1 column 7 >>> lex('hey }}') Traceback (most recent call last): ... TemplateError: }} outside expression at line 1 column 7 >>> lex('hey {{ {{') Traceback (most recent call last): ... TemplateError: {{ inside expression at line 1 column 10 """ in_expr = False chunks = [] last = 0 last_pos = (1, 1) for match in token_re.finditer(s): expr = match.group(0) pos = find_position(s, match.end()) if expr == '{{' and in_expr: raise TemplateError('{{ inside expression', position=pos, name=name) elif expr == '}}' and not in_expr: raise TemplateError('}} outside expression', position=pos, name=name) if expr == '{{': part = s[last:match.start()] if part: chunks.append(part) in_expr = True else: chunks.append((s[last:match.start()], last_pos)) in_expr = False last = match.end() last_pos = pos if in_expr: raise TemplateError('No }} to finish last expression', name=name, position=last_pos) part = s[last:] if part: chunks.append(part) if trim_whitespace: chunks = trim_lex(chunks) return chunks statement_re = re.compile(r'^(?:if |elif |else |for |py:)') single_statements = ['endif', 'endfor', 'continue', 'break'] trail_whitespace_re = re.compile(r'\n[\t ]*$') lead_whitespace_re = re.compile(r'^[\t ]*\n') def trim_lex(tokens): r""" Takes a lexed set of tokens, and removes whitespace when there is a directive on a line by itself: >>> tokens = lex('{{if x}}\nx\n{{endif}}\ny', trim_whitespace=False) >>> tokens [('if x', (1, 3)), '\nx\n', ('endif', (3, 3)), '\ny'] >>> trim_lex(tokens) [('if x', (1, 3)), 'x\n', ('endif', (3, 3)), 'y'] """ for i in range(len(tokens)): current = tokens[i] if isinstance(tokens[i], basestring): # we don't trim this continue item = current[0] if not statement_re.search(item) and item not in single_statements: continue if not i: prev = '' else: prev = tokens[i-1] if i+1 >= len(tokens): next = '' else: next = tokens[i+1] if (not isinstance(next, basestring) or not isinstance(prev, basestring)): continue if ((not prev or trail_whitespace_re.search(prev)) and (not next or lead_whitespace_re.search(next))): if prev: m = trail_whitespace_re.search(prev) # +1 to leave the leading \n on: prev = prev[:m.start()+1] tokens[i-1] = prev if next: m = lead_whitespace_re.search(next) next = next[m.end():] tokens[i+1] = next return tokens def find_position(string, index): """Given a string and index, return (line, column)""" leading = string[:index].splitlines() return (len(leading), len(leading[-1])+1) def parse(s, name=None): r""" Parses a string into a kind of AST >>> parse('{{x}}') [('expr', (1, 3), 'x')] >>> parse('foo') ['foo'] >>> parse('{{if x}}test{{endif}}') [('cond', (1, 3), ('if', (1, 3), 'x', ['test']))] >>> parse('series->{{for x in y}}x={{x}}{{endfor}}') ['series->', ('for', (1, 11), ('x',), 'y', ['x=', ('expr', (1, 27), 'x')])] >>> parse('{{for x, y in z:}}{{continue}}{{endfor}}') [('for', (1, 3), ('x', 'y'), 'z', [('continue', (1, 21))])] >>> parse('{{py:x=1}}') [('py', (1, 3), 'x=1')] >>> parse('{{if x}}a{{elif y}}b{{else}}c{{endif}}') [('cond', (1, 3), ('if', (1, 3), 'x', ['a']), ('elif', (1, 12), 'y', ['b']), ('else', (1, 23), None, ['c']))] Some exceptions:: >>> parse('{{continue}}') Traceback (most recent call last): ... TemplateError: continue outside of for loop at line 1 column 3 >>> parse('{{if x}}foo') Traceback (most recent call last): ... TemplateError: No {{endif}} at line 1 column 3 >>> parse('{{else}}') Traceback (most recent call last): ... TemplateError: else outside of an if block at line 1 column 3 >>> parse('{{if x}}{{for x in y}}{{endif}}{{endfor}}') Traceback (most recent call last): ... TemplateError: Unexpected endif at line 1 column 25 >>> parse('{{if}}{{endif}}') Traceback (most recent call last): ... TemplateError: if with no expression at line 1 column 3 >>> parse('{{for x y}}{{endfor}}') Traceback (most recent call last): ... TemplateError: Bad for (no "in") in 'x y' at line 1 column 3 >>> parse('{{py:x=1\ny=2}}') Traceback (most recent call last): ... TemplateError: Multi-line py blocks must start with a newline at line 1 column 3 """ tokens = lex(s, name=name) result = [] while tokens: next, tokens = parse_expr(tokens, name) result.append(next) return result def parse_expr(tokens, name, context=()): if isinstance(tokens[0], basestring): return tokens[0], tokens[1:] expr, pos = tokens[0] expr = expr.strip() if expr.startswith('py:'): expr = expr[3:].lstrip(' \t') if expr.startswith('\n'): expr = expr[1:] else: if '\n' in expr: raise TemplateError( 'Multi-line py blocks must start with a newline', position=pos, name=name) return ('py', pos, expr), tokens[1:] elif expr in ('continue', 'break'): if 'for' not in context: raise TemplateError( 'continue outside of for loop', position=pos, name=name) return (expr, pos), tokens[1:] elif expr.startswith('if '): return parse_cond(tokens, name, context) elif (expr.startswith('elif ') or expr == 'else'): raise TemplateError( '%s outside of an if block' % expr.split()[0], position=pos, name=name) elif expr in ('if', 'elif', 'for'): raise TemplateError( '%s with no expression' % expr, position=pos, name=name) elif expr in ('endif', 'endfor'): raise TemplateError( 'Unexpected %s' % expr, position=pos, name=name) elif expr.startswith('for '): return parse_for(tokens, name, context) elif expr.startswith('default '): return parse_default(tokens, name, context) elif expr.startswith('#'): return ('comment', pos, tokens[0][0]), tokens[1:] return ('expr', pos, tokens[0][0]), tokens[1:] def parse_cond(tokens, name, context): start = tokens[0][1] pieces = [] context = context + ('if',) while 1: if not tokens: raise TemplateError( 'Missing {{endif}}', position=start, name=name) if (isinstance(tokens[0], tuple) and tokens[0][0] == 'endif'): return ('cond', start) + tuple(pieces), tokens[1:] next, tokens = parse_one_cond(tokens, name, context) pieces.append(next) def parse_one_cond(tokens, name, context): (first, pos), tokens = tokens[0], tokens[1:] content = [] if first.endswith(':'): first = first[:-1] if first.startswith('if '): part = ('if', pos, first[3:].lstrip(), content) elif first.startswith('elif '): part = ('elif', pos, first[5:].lstrip(), content) elif first == 'else': part = ('else', pos, None, content) else: assert 0, "Unexpected token %r at %s" % (first, pos) while 1: if not tokens: raise TemplateError( 'No {{endif}}', position=pos, name=name) if (isinstance(tokens[0], tuple) and (tokens[0][0] == 'endif' or tokens[0][0].startswith('elif ') or tokens[0][0] == 'else')): return part, tokens next, tokens = parse_expr(tokens, name, context) content.append(next) def parse_for(tokens, name, context): first, pos = tokens[0] tokens = tokens[1:] context = ('for',) + context content = [] assert first.startswith('for ') if first.endswith(':'): first = first[:-1] first = first[3:].strip() match = in_re.search(first) if not match: raise TemplateError( 'Bad for (no "in") in %r' % first, position=pos, name=name) vars = first[:match.start()] if '(' in vars: raise TemplateError( 'You cannot have () in the variable section of a for loop (%r)' % vars, position=pos, name=name) vars = tuple([ v.strip() for v in first[:match.start()].split(',') if v.strip()]) expr = first[match.end():] while 1: if not tokens: raise TemplateError( 'No {{endfor}}', position=pos, name=name) if (isinstance(tokens[0], tuple) and tokens[0][0] == 'endfor'): return ('for', pos, vars, expr, content), tokens[1:] next, tokens = parse_expr(tokens, name, context) content.append(next) def parse_default(tokens, name, context): first, pos = tokens[0] assert first.startswith('default ') first = first.split(None, 1)[1] parts = first.split('=', 1) if len(parts) == 1: raise TemplateError( "Expression must be {{default var=value}}; no = found in %r" % first, position=pos, name=name) var = parts[0].strip() if ',' in var: raise TemplateError( "{{default x, y = ...}} is not supported", position=pos, name=name) if not var_re.search(var): raise TemplateError( "Not a valid variable name for {{default}}: %r" % var, position=pos, name=name) expr = parts[1].strip() return ('default', pos, var, expr), tokens[1:] _fill_command_usage = """\ %prog [OPTIONS] TEMPLATE arg=value Use py:arg=value to set a Python value; otherwise all values are strings. """ def fill_command(args=None): import sys, optparse, pkg_resources, os if args is None: args = sys.argv[1:] dist = pkg_resources.get_distribution('Paste') parser = optparse.OptionParser( version=str(dist), usage=_fill_command_usage) parser.add_option( '-o', '--output', dest='output', metavar="FILENAME", help="File to write output to (default stdout)") parser.add_option( '--html', dest='use_html', action='store_true', help="Use HTML style filling (including automatic HTML quoting)") parser.add_option( '--env', dest='use_env', action='store_true', help="Put the environment in as top-level variables") options, args = parser.parse_args(args) if len(args) < 1: print 'You must give a template filename' print dir(parser) assert 0 template_name = args[0] args = args[1:] vars = {} if options.use_env: vars.update(os.environ) for value in args: if '=' not in value: print 'Bad argument: %r' % value sys.exit(2) name, value = value.split('=', 1) if name.startswith('py:'): name = name[:3] value = eval(value) vars[name] = value if template_name == '-': template_content = sys.stdin.read() template_name = '<stdin>' else: f = open(template_name, 'rb') template_content = f.read() f.close() if options.use_html: TemplateClass = HTMLTemplate else: TemplateClass = Template template = TemplateClass(template_content, name=template_name) result = template.substitute(vars) if options.output: f = open(options.output, 'wb') f.write(result) f.close() else: sys.stdout.write(result) if __name__ == '__main__': from paste.util.template import fill_command fill_command()