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Diffstat (limited to 'python/jinja2/nativetypes.py')
| -rw-r--r-- | python/jinja2/nativetypes.py | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/python/jinja2/nativetypes.py b/python/jinja2/nativetypes.py new file mode 100644 index 0000000..fe17e41 --- /dev/null +++ b/python/jinja2/nativetypes.py @@ -0,0 +1,220 @@ +import sys +from ast import literal_eval +from itertools import islice, chain +from jinja2 import nodes +from jinja2._compat import text_type +from jinja2.compiler import CodeGenerator, has_safe_repr +from jinja2.environment import Environment, Template +from jinja2.utils import concat, escape + + +def native_concat(nodes): + """Return a native Python type from the list of compiled nodes. If the + result is a single node, its value is returned. Otherwise, the nodes are + concatenated as strings. If the result can be parsed with + :func:`ast.literal_eval`, the parsed value is returned. Otherwise, the + string is returned. + """ + head = list(islice(nodes, 2)) + + if not head: + return None + + if len(head) == 1: + out = head[0] + else: + out = u''.join([text_type(v) for v in chain(head, nodes)]) + + try: + return literal_eval(out) + except (ValueError, SyntaxError, MemoryError): + return out + + +class NativeCodeGenerator(CodeGenerator): + """A code generator which avoids injecting ``to_string()`` calls around the + internal code Jinja uses to render templates. + """ + + def visit_Output(self, node, frame): + """Same as :meth:`CodeGenerator.visit_Output`, but do not call + ``to_string`` on output nodes in generated code. + """ + if self.has_known_extends and frame.require_output_check: + return + + finalize = self.environment.finalize + finalize_context = getattr(finalize, 'contextfunction', False) + finalize_eval = getattr(finalize, 'evalcontextfunction', False) + finalize_env = getattr(finalize, 'environmentfunction', False) + + if finalize is not None: + if finalize_context or finalize_eval: + const_finalize = None + elif finalize_env: + def const_finalize(x): + return finalize(self.environment, x) + else: + const_finalize = finalize + else: + def const_finalize(x): + return x + + # If we are inside a frame that requires output checking, we do so. + outdent_later = False + + if frame.require_output_check: + self.writeline('if parent_template is None:') + self.indent() + outdent_later = True + + # Try to evaluate as many chunks as possible into a static string at + # compile time. + body = [] + + for child in node.nodes: + try: + if const_finalize is None: + raise nodes.Impossible() + + const = child.as_const(frame.eval_ctx) + if not has_safe_repr(const): + raise nodes.Impossible() + except nodes.Impossible: + body.append(child) + continue + + # the frame can't be volatile here, because otherwise the as_const + # function would raise an Impossible exception at that point + try: + if frame.eval_ctx.autoescape: + if hasattr(const, '__html__'): + const = const.__html__() + else: + const = escape(const) + + const = const_finalize(const) + except Exception: + # if something goes wrong here we evaluate the node at runtime + # for easier debugging + body.append(child) + continue + + if body and isinstance(body[-1], list): + body[-1].append(const) + else: + body.append([const]) + + # if we have less than 3 nodes or a buffer we yield or extend/append + if len(body) < 3 or frame.buffer is not None: + if frame.buffer is not None: + # for one item we append, for more we extend + if len(body) == 1: + self.writeline('%s.append(' % frame.buffer) + else: + self.writeline('%s.extend((' % frame.buffer) + + self.indent() + + for item in body: + if isinstance(item, list): + val = repr(native_concat(item)) + + if frame.buffer is None: + self.writeline('yield ' + val) + else: + self.writeline(val + ',') + else: + if frame.buffer is None: + self.writeline('yield ', item) + else: + self.newline(item) + + close = 0 + + if finalize is not None: + self.write('environment.finalize(') + + if finalize_context: + self.write('context, ') + + close += 1 + + self.visit(item, frame) + + if close > 0: + self.write(')' * close) + + if frame.buffer is not None: + self.write(',') + + if frame.buffer is not None: + # close the open parentheses + self.outdent() + self.writeline(len(body) == 1 and ')' or '))') + + # otherwise we create a format string as this is faster in that case + else: + format = [] + arguments = [] + + for item in body: + if isinstance(item, list): + format.append(native_concat(item).replace('%', '%%')) + else: + format.append('%s') + arguments.append(item) + + self.writeline('yield ') + self.write(repr(concat(format)) + ' % (') + self.indent() + + for argument in arguments: + self.newline(argument) + close = 0 + + if finalize is not None: + self.write('environment.finalize(') + + if finalize_context: + self.write('context, ') + elif finalize_eval: + self.write('context.eval_ctx, ') + elif finalize_env: + self.write('environment, ') + + close += 1 + + self.visit(argument, frame) + self.write(')' * close + ', ') + + self.outdent() + self.writeline(')') + + if outdent_later: + self.outdent() + + +class NativeTemplate(Template): + def render(self, *args, **kwargs): + """Render the template to produce a native Python type. If the result + is a single node, its value is returned. Otherwise, the nodes are + concatenated as strings. If the result can be parsed with + :func:`ast.literal_eval`, the parsed value is returned. Otherwise, the + string is returned. + """ + vars = dict(*args, **kwargs) + + try: + return native_concat(self.root_render_func(self.new_context(vars))) + except Exception: + exc_info = sys.exc_info() + + return self.environment.handle_exception(exc_info, True) + + +class NativeEnvironment(Environment): + """An environment that renders templates to native Python types.""" + + code_generator_class = NativeCodeGenerator + template_class = NativeTemplate |