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compiler.py
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# -*- coding: utf-8 -*- """Compiles nodes from the parser into Python code.""" from collections import namedtuple from functools import update_wrapper from itertools import chain from keyword import iskeyword as is_python_keyword from markupsafe import escape from markupsafe import Markup from . import nodes from ._compat import imap from ._compat import iteritems from ._compat import izip from ._compat import NativeStringIO from ._compat import range_type from ._compat import string_types from ._compat import text_type from .exceptions import TemplateAssertionError from .idtracking import Symbols from .idtracking import VAR_LOAD_ALIAS from .idtracking import VAR_LOAD_PARAMETER from .idtracking import VAR_LOAD_RESOLVE from .idtracking import VAR_LOAD_UNDEFINED from .nodes import EvalContext from .optimizer import Optimizer from .utils import concat from .visitor import NodeVisitor operators = { "eq": "==", "ne": "!=", "gt": ">", "gteq": ">=", "lt": "<", "lteq": "<=", "in": "in", "notin": "not in", } # what method to iterate over items do we want to use for dict iteration # in generated code? on 2.x let's go with iteritems, on 3.x with items if hasattr(dict, "iteritems"): dict_item_iter = "iteritems" else: dict_item_iter = "items" code_features = ["division"] # does this python version support generator stops? (PEP 0479) try: exec("from __future__ import generator_stop") code_features.append("generator_stop") except SyntaxError: pass # does this python version support yield from? try: exec("def f(): yield from x()") except SyntaxError: supports_yield_from = False else: supports_yield_from = True def optimizeconst(f): def new_func(self, node, frame, **kwargs): # Only optimize if the frame is not volatile if self.optimized and not frame.eval_ctx.volatile: new_node = self.optimizer.visit(node, frame.eval_ctx) if new_node != node: return self.visit(new_node, frame) return f(self, node, frame, **kwargs) return update_wrapper(new_func, f) def generate( node, environment, name, filename, stream=None, defer_init=False, optimized=True ): """Generate the python source for a node tree.""" if not isinstance(node, nodes.Template): raise TypeError("Can't compile non template nodes") generator = environment.code_generator_class( environment, name, filename, stream, defer_init, optimized ) generator.visit(node) if stream is None: return generator.stream.getvalue() def has_safe_repr(value): """Does the node have a safe representation?""" if value is None or value is NotImplemented or value is Ellipsis: return True if type(value) in (bool, int, float, complex, range_type, Markup) + string_types: return True if type(value) in (tuple, list, set, frozenset): for item in value: if not has_safe_repr(item): return False return True elif type(value) is dict: for key, value in iteritems(value): if not has_safe_repr(key): return False if not has_safe_repr(value): return False return True return False def find_undeclared(nodes, names): """Check if the names passed are accessed undeclared. The return value is a set of all the undeclared names from the sequence of names found. """ visitor = UndeclaredNameVisitor(names) try: for node in nodes: visitor.visit(node) except VisitorExit: pass return visitor.undeclared class MacroRef(object): def __init__(self, node): self.node = node self.accesses_caller = False self.accesses_kwargs = False self.accesses_varargs = False class Frame(object): """Holds compile time information for us.""" def __init__(self, eval_ctx, parent=None, level=None): self.eval_ctx = eval_ctx self.symbols = Symbols(parent and parent.symbols or None, level=level) # a toplevel frame is the root + soft frames such as if conditions. self.toplevel = False # the root frame is basically just the outermost frame, so no if # conditions. This information is used to optimize inheritance # situations. self.rootlevel = False # in some dynamic inheritance situations the compiler needs to add # write tests around output statements. self.require_output_check = parent and parent.require_output_check # inside some tags we are using a buffer rather than yield statements. # this for example affects {% filter %} or {% macro %}. If a frame # is buffered this variable points to the name of the list used as # buffer. self.buffer = None # the name of the block we're in, otherwise None. self.block = parent and parent.block or None # the parent of this frame self.parent = parent if parent is not None: self.buffer = parent.buffer def copy(self): """Create a copy of the current one.""" rv = object.__new__(self.__class__) rv.__dict__.update(self.__dict__) rv.symbols = self.symbols.copy() return rv def inner(self, isolated=False): """Return an inner frame.""" if isolated: return Frame(self.eval_ctx, level=self.symbols.level + 1) return Frame(self.eval_ctx, self) def soft(self): """Return a soft frame. A soft frame may not be modified as standalone thing as it shares the resources with the frame it was created of, but it's not a rootlevel frame any longer. This is only used to implement if-statements. """ rv = self.copy() rv.rootlevel = False return rv __copy__ = copy class VisitorExit(RuntimeError): """Exception used by the `UndeclaredNameVisitor` to signal a stop.""" class DependencyFinderVisitor(NodeVisitor): """A visitor that collects filter and test calls.""" def __init__(self): self.filters = set() self.tests = set() def visit_Filter(self, node): self.generic_visit(node) self.filters.add(node.name) def visit_Test(self, node): self.generic_visit(node) self.tests.add(node.name) def visit_Block(self, node): """Stop visiting at blocks.""" class UndeclaredNameVisitor(NodeVisitor): """A visitor that checks if a name is accessed without being declared. This is different from the frame visitor as it will not stop at closure frames. """ def __init__(self, names): self.names = set(names) self.undeclared = set() def visit_Name(self, node): if node.ctx == "load" and node.name in self.names: self.undeclared.add(node.name) if self.undeclared == self.names: raise VisitorExit() else: self.names.discard(node.name) def visit_Block(self, node): """Stop visiting a blocks.""" class CompilerExit(Exception): """Raised if the compiler encountered a situation where it just doesn't make sense to further process the code. Any block that raises such an exception is not further processed. """ class CodeGenerator(NodeVisitor): def __init__( self, environment, name, filename, stream=None, defer_init=False, optimized=True ): if stream is None: stream = NativeStringIO() self.environment = environment self.name = name self.filename = filename self.stream = stream self.created_block_context = False self.defer_init = defer_init self.optimized = optimized if optimized: self.optimizer = Optimizer(environment) # aliases for imports self.import_aliases = {} # a registry for all blocks. Because blocks are moved out # into the global python scope they are registered here self.blocks = {} # the number of extends statements so far self.extends_so_far = 0 # some templates have a rootlevel extends. In this case we # can safely assume that we're a child template and do some # more optimizations. self.has_known_extends = False # the current line number self.code_lineno = 1 # registry of all filters and tests (global, not block local) self.tests = {} self.filters = {} # the debug information self.debug_info = [] self._write_debug_info = None # the number of new lines before the next write() self._new_lines = 0 # the line number of the last written statement self._last_line = 0 # true if nothing was written so far. self._first_write = True # used by the `temporary_identifier` method to get new # unique, temporary identifier self._last_identifier = 0 # the current indentation self._indentation = 0 # Tracks toplevel assignments self._assign_stack = [] # Tracks parameter definition blocks self._param_def_block = [] # Tracks the current context. self._context_reference_stack = ["context"] # -- Various compilation helpers def fail(self, msg, lineno): """Fail with a :exc:`TemplateAssertionError`.""" raise TemplateAssertionError(msg, lineno, self.name, self.filename) def temporary_identifier(self): """Get a new unique identifier.""" self._last_identifier += 1 return "t_%d" % self._last_identifier def buffer(self, frame): """Enable buffering for the frame from that point onwards.""" frame.buffer = self.temporary_identifier() self.writeline("%s = []" % frame.buffer) def return_buffer_contents(self, frame, force_unescaped=False): """Return the buffer contents of the frame.""" if not force_unescaped: if frame.eval_ctx.volatile: self.writeline("if context.eval_ctx.autoescape:") self.indent() self.writeline("return Markup(concat(%s))" % frame.buffer) self.outdent() self.writeline("else:") self.indent() self.writeline("return concat(%s)" % frame.buffer) self.outdent() return elif frame.eval_ctx.autoescape: self.writeline("return Markup(concat(%s))" % frame.buffer) return self.writeline("return concat(%s)" % frame.buffer) def indent(self): """Indent by one.""" self._indentation += 1 def outdent(self, step=1): """Outdent by step.""" self._indentation -= step def start_write(self, frame, node=None): """Yield or write into the frame buffer.""" if frame.buffer is None: self.writeline("yield ", node) else: self.writeline("%s.append(" % frame.buffer, node) def end_write(self, frame): """End the writing process started by `start_write`.""" if frame.buffer is not None: self.write(")") def simple_write(self, s, frame, node=None): """Simple shortcut for start_write + write + end_write.""" self.start_write(frame, node) self.write(s) self.end_write(frame) def blockvisit(self, nodes, frame): """Visit a list of nodes as block in a frame. If the current frame is no buffer a dummy ``if 0: yield None`` is written automatically. """ try: self.writeline("pass") for node in nodes: self.visit(node, frame) except CompilerExit: pass def write(self, x): """Write a string into the output stream.""" if self._new_lines: if not self._first_write: self.stream.write("\n" * self._new_lines) self.code_lineno += self._new_lines if self._write_debug_info is not None: self.debug_info.append((self._write_debug_info, self.code_lineno)) self._write_debug_info = None self._first_write = False self.stream.write(" " * self._indentation) self._new_lines = 0 self.stream.write(x) def writeline(self, x, node=None, extra=0): """Combination of newline and write.""" self.newline(node, extra) self.write(x) def newline(self, node=None, extra=0): """Add one or more newlines before the next write.""" self._new_lines = max(self._new_lines, 1 + extra) if node is not None and node.lineno != self._last_line: self._write_debug_info = node.lineno self._last_line = node.lineno def signature(self, node, frame, extra_kwargs=None): """Writes a function call to the stream for the current node. A leading comma is added automatically. The extra keyword arguments may not include python keywords otherwise a syntax error could occur. The extra keyword arguments should be given as python dict. """ # if any of the given keyword arguments is a python keyword # we have to make sure that no invalid call is created. kwarg_workaround = False for kwarg in chain((x.key for x in node.kwargs), extra_kwargs or ()): if is_python_keyword(kwarg): kwarg_workaround = True break for arg in node.args: self.write(", ") self.visit(arg, frame) if not kwarg_workaround: for kwarg in node.kwargs: self.write(", ") self.visit(kwarg, frame) if extra_kwargs is not None: for key, value in iteritems(extra_kwargs): self.write(", %s=%s" % (key, value)) if node.dyn_args: self.write(", *") self.visit(node.dyn_args, frame) if kwarg_workaround: if node.dyn_kwargs is not None: self.write(", **dict({") else: self.write(", **{") for kwarg in node.kwargs: self.write("%r: " % kwarg.key) self.visit(kwarg.value, frame) self.write(", ") if extra_kwargs is not None: for key, value in iteritems(extra_kwargs): self.write("%r: %s, " % (key, value)) if node.dyn_kwargs is not None: self.write("}, **") self.visit(node.dyn_kwargs, frame) self.write(")") else: self.write("}") elif node.dyn_kwargs is not None: self.write(", **") self.visit(node.dyn_kwargs, frame) def pull_dependencies(self, nodes): """Pull all the dependencies.""" visitor = DependencyFinderVisitor() for node in nodes: visitor.visit(node) for dependency in "filters", "tests": mapping = getattr(self, dependency) for name in getattr(visitor, dependency): if name not in mapping: mapping[name] = self.temporary_identifier() self.writeline( "%s = environment.%s[%r]" % (mapping[name], dependency, name) ) def enter_frame(self, frame): undefs = [] for target, (action, param) in iteritems(frame.symbols.loads): if action == VAR_LOAD_PARAMETER: pass elif action == VAR_LOAD_RESOLVE: self.writeline("%s = %s(%r)" % (target, self.get_resolve_func(), param)) elif action == VAR_LOAD_ALIAS: self.writeline("%s = %s" % (target, param)) elif action == VAR_LOAD_UNDEFINED: undefs.append(target) else: raise NotImplementedError("unknown load instruction") if undefs: self.writeline("%s = missing" % " = ".join(undefs)) def leave_frame(self, frame, with_python_scope=False): if not with_python_scope: undefs = [] for target, _ in iteritems(frame.symbols.loads): undefs.append(target) if undefs: self.writeline("%s = missing" % " = ".join(undefs)) def func(self, name): if self.environment.is_async: return "async def %s" % name return "def %s" % name def macro_body(self, node, frame): """Dump the function def of a macro or call block.""" frame = frame.inner() frame.symbols.analyze_node(node) macro_ref = MacroRef(node) explicit_caller = None skip_special_params = set() args = [] for idx, arg in enumerate(node.args): if arg.name == "caller": explicit_caller = idx if arg.name in ("kwargs", "varargs"): skip_special_params.add(arg.name) args.append(frame.symbols.ref(arg.name)) undeclared = find_undeclared(node.body, ("caller", "kwargs", "varargs")) if "caller" in undeclared: # In older Jinja versions there was a bug that allowed caller # to retain the special behavior even if it was mentioned in # the argument list. However thankfully this was only really # working if it was the last argument. So we are explicitly # checking this now and error out if it is anywhere else in # the argument list. if explicit_caller is not None: try: node.defaults[explicit_caller - len(node.args)] except IndexError: self.fail( "When defining macros or call blocks the " 'special "caller" argument must be omitted ' "or be given a default.", node.lineno, ) else: args.append(frame.symbols.declare_parameter("caller")) macro_ref.accesses_caller = True if "kwargs" in undeclared and "kwargs" not in skip_special_params: args.append(frame.symbols.declare_parameter("kwargs")) macro_ref.accesses_kwargs = True if "varargs" in undeclared and "varargs" not in skip_special_params: args.append(frame.symbols.declare_parameter("varargs")) macro_ref.accesses_varargs = True # macros are delayed, they never require output checks frame.require_output_check = False frame.symbols.analyze_node(node) self.writeline("%s(%s):" % (self.func("macro"), ", ".join(args)), node) self.indent() self.buffer(frame) self.enter_frame(frame) self.push_parameter_definitions(frame) for idx, arg in enumerate(node.args): ref = frame.symbols.ref(arg.name) self.writeline("if %s is missing:" % ref) self.indent() try: default = node.defaults[idx - len(node.args)] except IndexError: self.writeline( "%s = undefined(%r, name=%r)" % (ref, "parameter %r was not provided" % arg.name, arg.name) ) else: self.writeline("%s = " % ref) self.visit(default, frame) self.mark_parameter_stored(ref) self.outdent() self.pop_parameter_definitions() self.blockvisit(node.body, frame) self.return_buffer_contents(frame, force_unescaped=True) self.leave_frame(frame, with_python_scope=True) self.outdent() return frame, macro_ref def macro_def(self, macro_ref, frame): """Dump the macro definition for the def created by macro_body.""" arg_tuple = ", ".join(repr(x.name) for x in macro_ref.node.args) name = getattr(macro_ref.node, "name", None) if len(macro_ref.node.args) == 1: arg_tuple += "," self.write( "Macro(environment, macro, %r, (%s), %r, %r, %r, " "context.eval_ctx.autoescape)" % ( name, arg_tuple, macro_ref.accesses_kwargs, macro_ref.accesses_varargs, macro_ref.accesses_caller, ) ) def position(self, node): """Return a human readable position for the node.""" rv = "line %d" % node.lineno if self.name is not None: rv += " in " + repr(self.name) return rv def dump_local_context(self, frame): return "{%s}" % ", ".join( "%r: %s" % (name, target) for name, target in iteritems(frame.symbols.dump_stores()) ) def write_commons(self): """Writes a common preamble that is used by root and block functions. Primarily this sets up common local helpers and enforces a generator through a dead branch. """ self.writeline("resolve = context.resolve_or_missing") self.writeline("undefined = environment.undefined") # always use the standard Undefined class for the implicit else of # conditional expressions self.writeline("cond_expr_undefined = Undefined") self.writeline("if 0: yield None") def push_parameter_definitions(self, frame): """Pushes all parameter targets from the given frame into a local stack that permits tracking of yet to be assigned parameters. In particular this enables the optimization from `visit_Name` to skip undefined expressions for parameters in macros as macros can reference otherwise unbound parameters. """ self._param_def_block.append(frame.symbols.dump_param_targets()) def pop_parameter_definitions(self): """Pops the current parameter definitions set.""" self._param_def_block.pop() def mark_parameter_stored(self, target): """Marks a parameter in the current parameter definitions as stored. This will skip the enforced undefined checks. """ if self._param_def_block: self._param_def_block[-1].discard(target) def push_context_reference(self, target): self._context_reference_stack.append(target) def pop_context_reference(self): self._context_reference_stack.pop() def get_context_ref(self): return self._context_reference_stack[-1] def get_resolve_func(self): target = self._context_reference_stack[-1] if target == "context": return "resolve" return "%s.resolve" % target def derive_context(self, frame): return "%s.derived(%s)" % ( self.get_context_ref(), self.dump_local_context(frame), ) def parameter_is_undeclared(self, target): """Checks if a given target is an undeclared parameter.""" if not self._param_def_block: return False return target in self._param_def_block[-1] def push_assign_tracking(self): """Pushes a new layer for assignment tracking.""" self._assign_stack.append(set()) def pop_assign_tracking(self, frame): """Pops the topmost level for assignment tracking and updates the context variables if necessary. """ vars = self._assign_stack.pop() if not frame.toplevel or not vars: return public_names = [x for x in vars if x[:1] != "_"] if len(vars) == 1: name = next(iter(vars)) ref = frame.symbols.ref(name) self.writeline("context.vars[%r] = %s" % (name, ref)) else: self.writeline("context.vars.update({") for idx, name in enumerate(vars): if idx: self.write(", ") ref = frame.symbols.ref(name) self.write("%r: %s" % (name, ref)) self.write("})") if public_names: if len(public_names) == 1: self.writeline("context.exported_vars.add(%r)" % public_names[0]) else: self.writeline( "context.exported_vars.update((%s))" % ", ".join(imap(repr, public_names)) ) # -- Statement Visitors def visit_Template(self, node, frame=None): assert frame is None, "no root frame allowed" eval_ctx = EvalContext(self.environment, self.name) from .runtime import exported self.writeline("from __future__ import %s" % ", ".join(code_features)) self.writeline("from jinja2.runtime import " + ", ".join(exported)) if self.environment.is_async: self.writeline( "from jinja2.asyncsupport import auto_await, " "auto_aiter, AsyncLoopContext" ) # if we want a deferred initialization we cannot move the # environment into a local name envenv = not self.defer_init and ", environment=environment" or "" # do we have an extends tag at all? If not, we can save some # overhead by just not processing any inheritance code. have_extends = node.find(nodes.Extends) is not None # find all blocks for block in node.find_all(nodes.Block): if block.name in self.blocks: self.fail("block %r defined twice" % block.name, block.lineno) self.blocks[block.name] = block # find all imports and import them for import_ in node.find_all(nodes.ImportedName): if import_.importname not in self.import_aliases: imp = import_.importname self.import_aliases[imp] = alias = self.temporary_identifier() if "." in imp: module, obj = imp.rsplit(".", 1) self.writeline("from %s import %s as %s" % (module, obj, alias)) else: self.writeline("import %s as %s" % (imp, alias)) # add the load name self.writeline("name = %r" % self.name) # generate the root render function. self.writeline( "%s(context, missing=missing%s):" % (self.func("root"), envenv), extra=1 ) self.indent() self.write_commons() # process the root frame = Frame(eval_ctx) if "self" in find_undeclared(node.body, ("self",)): ref = frame.symbols.declare_parameter("self") self.writeline("%s = TemplateReference(context)" % ref) frame.symbols.analyze_node(node) frame.toplevel = frame.rootlevel = True frame.require_output_check = have_extends and not self.has_known_extends if have_extends: self.writeline("parent_template = None") self.enter_frame(frame) self.pull_dependencies(node.body) self.blockvisit(node.body, frame) self.leave_frame(frame, with_python_scope=True) self.outdent() # make sure that the parent root is called. if have_extends: if not self.has_known_extends: self.indent() self.writeline("if parent_template is not None:") self.indent() if supports_yield_from and not self.environment.is_async: self.writeline("yield from parent_template.root_render_func(context)") else: self.writeline( "%sfor event in parent_template." "root_render_func(context):" % (self.environment.is_async and "async " or "") ) self.indent() self.writeline("yield event") self.outdent() self.outdent(1 + (not self.has_known_extends)) # at this point we now have the blocks collected and can visit them too. for name, block in iteritems(self.blocks): self.writeline( "%s(context, missing=missing%s):" % (self.func("block_" + name), envenv), block, 1, ) self.indent() self.write_commons() # It's important that we do not make this frame a child of the # toplevel template. This would cause a variety of # interesting issues with identifier tracking. block_frame = Frame(eval_ctx) undeclared = find_undeclared(block.body, ("self", "super")) if "self" in undeclared: ref = block_frame.symbols.declare_parameter("self") self.writeline("%s = TemplateReference(context)" % ref) if "super" in undeclared: ref = block_frame.symbols.declare_parameter("super") self.writeline("%s = context.super(%r, block_%s)" % (ref, name, name)) block_frame.symbols.analyze_node(block) block_frame.block = name self.enter_frame(block_frame) self.pull_dependencies(block.body) self.blockvisit(block.body, block_frame) self.leave_frame(block_frame, with_python_scope=True) self.outdent() self.writeline( "blocks = {%s}" % ", ".join("%r: block_%s" % (x, x) for x in self.blocks), extra=1, ) # add a function that returns the debug info self.writeline( "debug_info = %r" % "&".join("%s=%s" % x for x in self.debug_info) ) def visit_Block(self, node, frame): """Call a block and register it for the template.""" level = 0 if frame.toplevel: # if we know that we are a child template, there is no need to # check if we are one if self.has_known_extends: return if self.extends_so_far > 0: self.writeline("if parent_template is None:") self.indent() level += 1 if node.scoped: context = self.derive_context(frame) else: context = self.get_context_ref() if ( supports_yield_from and not self.environment.is_async and frame.buffer is None ): self.writeline( "yield from context.blocks[%r][0](%s)" % (node.name, context), node ) else: loop = self.environment.is_async and "async for" or "for" self.writeline( "%s event in context.blocks[%r][0](%s):" % (loop, node.name, context), node, ) self.indent() self.simple_write("event", frame) self.outdent() self.outdent(level) def visit_Extends(self, node, frame): """Calls the extender.""" if not frame.toplevel: self.fail("cannot use extend from a non top-level scope", node.lineno) # if the number of extends statements in general is zero so # far, we don't have to add a check if something extended # the template before this one. if self.extends_so_far > 0: # if we have a known extends we just add a template runtime # error into the generated code. We could catch that at compile # time too, but i welcome it not to confuse users by throwing the # same error at different times just "because we can". if not self.has_known_extends: self.writeline("if parent_template is not None:") self.indent() self.writeline("raise TemplateRuntimeError(%r)" % "extended multiple times") # if we have a known extends already we don't need that code here # as we know that the template execution will end here. if self.has_known_extends: raise CompilerExit() else: self.outdent() self.writeline("parent_template = environment.get_template(", node) self.visit(node.template, frame) self.write(", %r)" % self.name) self.writeline( "for name, parent_block in parent_template.blocks.%s():" % dict_item_iter ) self.indent() self.writeline("context.blocks.setdefault(name, []).append(parent_block)") self.outdent() # if this extends statement was in the root level we can take # advantage of that information and simplify the generated code # in the top level from this point onwards if frame.rootlevel: self.has_known_extends = True # and now we have one more self.extends_so_far += 1 def visit_Include(self, node, frame): """Handles includes.""" if node.ignore_missing: self.writeline("try:") self.indent() func_name = "get_or_select_template" if isinstance(node.template, nodes.Const): if isinstance(node.template.value, string_types): func_name = "get_template" elif isinstance(node.template.value, (tuple, list)): func_name = "select_template" elif isinstance(node.template, (nodes.Tuple, nodes.List)): func_name = "select_template" self.writeline("template = environment.%s(" % func_name, node) self.visit(node.template, frame) self.write(", %r)" % self.name) if node.ignore_missing: self.outdent() self.writeline("except TemplateNotFound:") self.indent() self.writeline("pass") self.outdent() self.writeline("else:") self.indent() skip_event_yield = False if node.with_context: loop = self.environment.is_async and "async for" or "for" self.writeline( "%s event in template.root_render_func(" "template.new_context(context.get_all(), True, " "%s)):" % (loop, self.dump_local_context(frame)) ) elif self.environment.is_async: self.writeline( "for event in (await " "template._get_default_module_async())" "._body_stream:" ) else: if supports_yield_from: self.writeline("yield from template._get_default_module()._body_stream") skip_event_yield = True else: self.writeline( "for event in template._get_default_module()._body_stream:" ) if not skip_event_yield: self.indent() self.simple_write("event", frame) self.outdent() if node.ignore_missing: self.outdent() def visit_Import(self, node, frame): """Visit regular imports.""" self.writeline("%s = " % frame.symbols.ref(node.target), node) if frame.toplevel: self.write("context.vars[%r] = " % node.target) if self.environment.is_async: self.write("await ") self.write("environment.get_template(") self.visit(node.template, frame) self.write(", %r)." % self.name) if node.with_context: self.write( "make_module%s(context.get_all(), True, %s)" % ( self.environment.is_async and "_async" or "", self.dump_local_context(frame), ) ) elif self.environment.is_async: self.write("_get_default_module_async()") else: self.write("_get_default_module()") if frame.toplevel and not node.target.startswith("_"): self.writeline("context.exported_vars.discard(%r)" % node.target) def visit_FromImport(self, node, frame): """Visit named imports.""" self.newline(node) self.write( "included_template = %senvironment.get_template(" % (self.environment.is_async and "await " or "") ) self.visit(node.template, frame) self.write(", %r)." % self.name) if node.with_context: self.write( "make_module%s(context.get_all(), True, %s)" % ( self.environment.is_async and "_async" or "", self.dump_local_context(frame), ) ) elif self.environment.is_async: self.write("_get_default_module_async()") else: self.write("_get_default_module()") var_names = [] discarded_names = [] for name in node.names: if isinstance(name, tuple): name, alias = name else: alias = name self.writeline( "%s = getattr(included_template, " "%r, missing)" % (frame.symbols.ref(alias), name) ) self.writeline("if %s is missing:" % frame.symbols.ref(alias)) self.indent() self.writeline( "%s = undefined(%r %% " "included_template.__name__, " "name=%r)" % ( frame.symbols.ref(alias), "the template %%r (imported on %s) does " "not export the requested name %s" % (self.position(node), repr(name)), name, ) ) self.outdent() if frame.toplevel: var_names.append(alias) if not alias.startswith("_"): discarded_names.append(alias) if var_names: if len(var_names) == 1: name = var_names[0] self.writeline( "context.vars[%r] = %s" % (name, frame.symbols.ref(name)) ) else: self.writeline( "context.vars.update({%s})" % ", ".join( "%r: %s" % (name, frame.symbols.ref(name)) for name in var_names ) ) if discarded_names: if len(discarded_names) == 1: self.writeline("context.exported_vars.discard(%r)" % discarded_names[0]) else: self.writeline( "context.exported_vars.difference_" "update((%s))" % ", ".join(imap(repr, discarded_names)) ) def visit_For(self, node, frame): loop_frame = frame.inner() test_frame = frame.inner() else_frame = frame.inner() # try to figure out if we have an extended loop. An extended loop # is necessary if the loop is in recursive mode if the special loop # variable is accessed in the body. extended_loop = node.recursive or "loop" in find_undeclared( node.iter_child_nodes(only=("body",)), ("loop",) ) loop_ref = None if extended_loop: loop_ref = loop_frame.symbols.declare_parameter("loop") loop_frame.symbols.analyze_node(node, for_branch="body") if node.else_: else_frame.symbols.analyze_node(node, for_branch="else") if node.test: loop_filter_func = self.temporary_identifier() test_frame.symbols.analyze_node(node, for_branch="test") self.writeline("%s(fiter):" % self.func(loop_filter_func), node.test) self.indent() self.enter_frame(test_frame) self.writeline(self.environment.is_async and "async for " or "for ") self.visit(node.target, loop_frame) self.write(" in ") self.write(self.environment.is_async and "auto_aiter(fiter)" or "fiter") self.write(":") self.indent() self.writeline("if ", node.test) self.visit(node.test, test_frame) self.write(":") self.indent() self.writeline("yield ") self.visit(node.target, loop_frame) self.outdent(3) self.leave_frame(test_frame, with_python_scope=True) # if we don't have an recursive loop we have to find the shadowed # variables at that point. Because loops can be nested but the loop # variable is a special one we have to enforce aliasing for it. if node.recursive: self.writeline( "%s(reciter, loop_render_func, depth=0):" % self.func("loop"), node ) self.indent() self.buffer(loop_frame) # Use the same buffer for the else frame else_frame.buffer = loop_frame.buffer # make sure the loop variable is a special one and raise a template # assertion error if a loop tries to write to loop if extended_loop: self.writeline("%s = missing" % loop_ref) for name in node.find_all(nodes.Name): if name.ctx == "store" and name.name == "loop": self.fail( "Can't assign to special loop variable in for-loop target", name.lineno, ) if node.else_: iteration_indicator = self.temporary_identifier() self.writeline("%s = 1" % iteration_indicator) self.writeline(self.environment.is_async and "async for " or "for ", node) self.visit(node.target, loop_frame) if extended_loop: if self.environment.is_async: self.write(", %s in AsyncLoopContext(" % loop_ref) else: self.write(", %s in LoopContext(" % loop_ref) else: self.write(" in ") if node.test: self.write("%s(" % loop_filter_func) if node.recursive: self.write("reciter") else: if self.environment.is_async and not extended_loop: self.write("auto_aiter(") self.visit(node.iter, frame) if self.environment.is_async and not extended_loop: self.write(")") if node.test: self.write(")") if node.recursive: self.write(", undefined, loop_render_func, depth):") else: self.write(extended_loop and ", undefined):" or ":") self.indent() self.enter_frame(loop_frame) self.blockvisit(node.body, loop_frame) if node.else_: self.writeline("%s = 0" % iteration_indicator) self.outdent() self.leave_frame( loop_frame, with_python_scope=node.recursive and not node.else_ ) if node.else_: self.writeline("if %s:" % iteration_indicator) self.indent() self.enter_frame(else_frame) self.blockvisit(node.else_, else_frame) self.leave_frame(else_frame) self.outdent() # if the node was recursive we have to return the buffer contents # and start the iteration code if node.recursive: self.return_buffer_contents(loop_frame) self.outdent() self.start_write(frame, node) if self.environment.is_async: self.write("await ") self.write("loop(") if self.environment.is_async: self.write("auto_aiter(") self.visit(node.iter, frame) if self.environment.is_async: self.write(")") self.write(", loop)") self.end_write(frame) def visit_If(self, node, frame): if_frame = frame.soft() self.writeline("if ", node) self.visit(node.test, if_frame) self.write(":") self.indent() self.blockvisit(node.body, if_frame) self.outdent() for elif_ in node.elif_: self.writeline("elif ", elif_) self.visit(elif_.test, if_frame) self.write(":") self.indent() self.blockvisit(elif_.body, if_frame) self.outdent() if node.else_: self.writeline("else:") self.indent() self.blockvisit(node.else_, if_frame) self.outdent() def visit_Macro(self, node, frame): macro_frame, macro_ref = self.macro_body(node, frame) self.newline() if frame.toplevel: if not node.name.startswith("_"): self.write("context.exported_vars.add(%r)" % node.name) self.writeline("context.vars[%r] = " % node.name) self.write("%s = " % frame.symbols.ref(node.name)) self.macro_def(macro_ref, macro_frame) def visit_CallBlock(self, node, frame): call_frame, macro_ref = self.macro_body(node, frame) self.writeline("caller = ") self.macro_def(macro_ref, call_frame) self.start_write(frame, node) self.visit_Call(node.call, frame, forward_caller=True) self.end_write(frame) def visit_FilterBlock(self, node, frame): filter_frame = frame.inner() filter_frame.symbols.analyze_node(node) self.enter_frame(filter_frame) self.buffer(filter_frame) self.blockvisit(node.body, filter_frame) self.start_write(frame, node) self.visit_Filter(node.filter, filter_frame) self.end_write(frame) self.leave_frame(filter_frame) def visit_With(self, node, frame): with_frame = frame.inner() with_frame.symbols.analyze_node(node) self.enter_frame(with_frame) for target, expr in izip(node.targets, node.values): self.newline() self.visit(target, with_frame) self.write(" = ") self.visit(expr, frame) self.blockvisit(node.body, with_frame) self.leave_frame(with_frame) def visit_ExprStmt(self, node, frame): self.newline(node) self.visit(node.node, frame) _FinalizeInfo = namedtuple("_FinalizeInfo", ("const", "src")) #: The default finalize function if the environment isn't configured #: with one. Or if the environment has one, this is called on that #: function's output for constants. _default_finalize = text_type _finalize = None def _make_finalize(self): """Build the finalize function to be used on constants and at runtime. Cached so it's only created once for all output nodes. Returns a ``namedtuple`` with the following attributes: ``const`` A function to finalize constant data at compile time. ``src`` Source code to output around nodes to be evaluated at runtime. """ if self._finalize is not None: return self._finalize finalize = default = self._default_finalize src = None if self.environment.finalize: src = "environment.finalize(" env_finalize = self.environment.finalize def finalize(value): return default(env_finalize(value)) if getattr(env_finalize, "contextfunction", False) is True: src += "context, " finalize = None # noqa: F811 elif getattr(env_finalize, "evalcontextfunction", False) is True: src += "context.eval_ctx, " finalize = None elif getattr(env_finalize, "environmentfunction", False) is True: src += "environment, " def finalize(value): return default(env_finalize(self.environment, value)) self._finalize = self._FinalizeInfo(finalize, src) return self._finalize def _output_const_repr(self, group): """Given a group of constant values converted from ``Output`` child nodes, produce a string to write to the template module source. """ return repr(concat(group)) def _output_child_to_const(self, node, frame, finalize): """Try to optimize a child of an ``Output`` node by trying to convert it to constant, finalized data at compile time. If :exc:`Impossible` is raised, the node is not constant and will be evaluated at runtime. Any other exception will also be evaluated at runtime for easier debugging. """ const = node.as_const(frame.eval_ctx) if frame.eval_ctx.autoescape: const = escape(const) # Template data doesn't go through finalize. if isinstance(node, nodes.TemplateData): return text_type(const) return finalize.const(const) def _output_child_pre(self, node, frame, finalize): """Output extra source code before visiting a child of an ``Output`` node. """ if frame.eval_ctx.volatile: self.write("(escape if context.eval_ctx.autoescape else to_string)(") elif frame.eval_ctx.autoescape: self.write("escape(") else: self.write("to_string(") if finalize.src is not None: self.write(finalize.src) def _output_child_post(self, node, frame, finalize): """Output extra source code after visiting a child of an ``Output`` node. """ self.write(")") if finalize.src is not None: self.write(")") def visit_Output(self, node, frame): # If an extends is active, don't render outside a block. if frame.require_output_check: # A top-level extends is known to exist at compile time. if self.has_known_extends: return self.writeline("if parent_template is None:") self.indent() finalize = self._make_finalize() body = [] # Evaluate constants at compile time if possible. Each item in # body will be either a list of static data or a node to be # evaluated at runtime. for child in node.nodes: try: if not ( # If the finalize function requires runtime context, # constants can't be evaluated at compile time. finalize.const # Unless it's basic template data that won't be # finalized anyway. or isinstance(child, nodes.TemplateData) ): raise nodes.Impossible() const = self._output_child_to_const(child, frame, finalize) except (nodes.Impossible, Exception): # The node was not constant and needs to be evaluated at # runtime. Or another error was raised, which is easier # to debug at runtime. body.append(child) continue if body and isinstance(body[-1], list): body[-1].append(const) else: body.append([const]) if frame.buffer is not None: 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): # A group of constant data to join and output. val = self._output_const_repr(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) # A node to be evaluated at runtime. self._output_child_pre(item, frame, finalize) self.visit(item, frame) self._output_child_post(item, frame, finalize) if frame.buffer is not None: self.write(",") if frame.buffer is not None: self.outdent() self.writeline(")" if len(body) == 1 else "))") if frame.require_output_check: self.outdent() def visit_Assign(self, node, frame): self.push_assign_tracking() self.newline(node) self.visit(node.target, frame) self.write(" = ") self.visit(node.node, frame) self.pop_assign_tracking(frame) def visit_AssignBlock(self, node, frame): self.push_assign_tracking() block_frame = frame.inner() # This is a special case. Since a set block always captures we # will disable output checks. This way one can use set blocks # toplevel even in extended templates. block_frame.require_output_check = False block_frame.symbols.analyze_node(node) self.enter_frame(block_frame) self.buffer(block_frame) self.blockvisit(node.body, block_frame) self.newline(node) self.visit(node.target, frame) self.write(" = (Markup if context.eval_ctx.autoescape else identity)(") if node.filter is not None: self.visit_Filter(node.filter, block_frame) else: self.write("concat(%s)" % block_frame.buffer) self.write(")") self.pop_assign_tracking(frame) self.leave_frame(block_frame) # -- Expression Visitors def visit_Name(self, node, frame): if node.ctx == "store" and frame.toplevel: if self._assign_stack: self._assign_stack[-1].add(node.name) ref = frame.symbols.ref(node.name) # If we are looking up a variable we might have to deal with the # case where it's undefined. We can skip that case if the load # instruction indicates a parameter which are always defined. if node.ctx == "load": load = frame.symbols.find_load(ref) if not ( load is not None and load[0] == VAR_LOAD_PARAMETER and not self.parameter_is_undeclared(ref) ): self.write( "(undefined(name=%r) if %s is missing else %s)" % (node.name, ref, ref) ) return self.write(ref) def visit_NSRef(self, node, frame): # NSRefs can only be used to store values; since they use the normal # `foo.bar` notation they will be parsed as a normal attribute access # when used anywhere but in a `set` context ref = frame.symbols.ref(node.name) self.writeline("if not isinstance(%s, Namespace):" % ref) self.indent() self.writeline( "raise TemplateRuntimeError(%r)" % "cannot assign attribute on non-namespace object" ) self.outdent() self.writeline("%s[%r]" % (ref, node.attr)) def visit_Const(self, node, frame): val = node.as_const(frame.eval_ctx) if isinstance(val, float): self.write(str(val)) else: self.write(repr(val)) def visit_TemplateData(self, node, frame): try: self.write(repr(node.as_const(frame.eval_ctx))) except nodes.Impossible: self.write( "(Markup if context.eval_ctx.autoescape else identity)(%r)" % node.data ) def visit_Tuple(self, node, frame): self.write("(") idx = -1 for idx, item in enumerate(node.items): if idx: self.write(", ") self.visit(item, frame) self.write(idx == 0 and ",)" or ")") def visit_List(self, node, frame): self.write("[") for idx, item in enumerate(node.items): if idx: self.write(", ") self.visit(item, frame) self.write("]") def visit_Dict(self, node, frame): self.write("{") for idx, item in enumerate(node.items): if idx: self.write(", ") self.visit(item.key, frame) self.write(": ") self.visit(item.value, frame) self.write("}") def binop(operator, interceptable=True): # noqa: B902 @optimizeconst def visitor(self, node, frame): if ( self.environment.sandboxed and operator in self.environment.intercepted_binops ): self.write("environment.call_binop(context, %r, " % operator) self.visit(node.left, frame) self.write(", ") self.visit(node.right, frame) else: self.write("(") self.visit(node.left, frame) self.write(" %s " % operator) self.visit(node.right, frame) self.write(")") return visitor def uaop(operator, interceptable=True): # noqa: B902 @optimizeconst def visitor(self, node, frame): if ( self.environment.sandboxed and operator in self.environment.intercepted_unops ): self.write("environment.call_unop(context, %r, " % operator) self.visit(node.node, frame) else: self.write("(" + operator) self.visit(node.node, frame) self.write(")") return visitor visit_Add = binop("+") visit_Sub = binop("-") visit_Mul = binop("*") visit_Div = binop("/") visit_FloorDiv = binop("//") visit_Pow = binop("**") visit_Mod = binop("%") visit_And = binop("and", interceptable=False) visit_Or = binop("or", interceptable=False) visit_Pos = uaop("+") visit_Neg = uaop("-") visit_Not = uaop("not ", interceptable=False) del binop, uaop @optimizeconst def visit_Concat(self, node, frame): if frame.eval_ctx.volatile: func_name = "(context.eval_ctx.volatile and markup_join or unicode_join)" elif frame.eval_ctx.autoescape: func_name = "markup_join" else: func_name = "unicode_join" self.write("%s((" % func_name) for arg in node.nodes: self.visit(arg, frame) self.write(", ") self.write("))") @optimizeconst def visit_Compare(self, node, frame): self.write("(") self.visit(node.expr, frame) for op in node.ops: self.visit(op, frame) self.write(")") def visit_Operand(self, node, frame): self.write(" %s " % operators[node.op]) self.visit(node.expr, frame) @optimizeconst def visit_Getattr(self, node, frame): if self.environment.is_async: self.write("(await auto_await(") self.write("environment.getattr(") self.visit(node.node, frame) self.write(", %r)" % node.attr) if self.environment.is_async: self.write("))") @optimizeconst def visit_Getitem(self, node, frame): # slices bypass the environment getitem method. if isinstance(node.arg, nodes.Slice): self.visit(node.node, frame) self.write("[") self.visit(node.arg, frame) self.write("]") else: if self.environment.is_async: self.write("(await auto_await(") self.write("environment.getitem(") self.visit(node.node, frame) self.write(", ") self.visit(node.arg, frame) self.write(")") if self.environment.is_async: self.write("))") def visit_Slice(self, node, frame): if node.start is not None: self.visit(node.start, frame) self.write(":") if node.stop is not None: self.visit(node.stop, frame) if node.step is not None: self.write(":") self.visit(node.step, frame) @optimizeconst def visit_Filter(self, node, frame): if self.environment.is_async: self.write("await auto_await(") self.write(self.filters[node.name] + "(") func = self.environment.filters.get(node.name) if func is None: self.fail("no filter named %r" % node.name, node.lineno) if getattr(func, "contextfilter", False) is True: self.write("context, ") elif getattr(func, "evalcontextfilter", False) is True: self.write("context.eval_ctx, ") elif getattr(func, "environmentfilter", False) is True: self.write("environment, ") # if the filter node is None we are inside a filter block # and want to write to the current buffer if node.node is not None: self.visit(node.node, frame) elif frame.eval_ctx.volatile: self.write( "(context.eval_ctx.autoescape and" " Markup(concat(%s)) or concat(%s))" % (frame.buffer, frame.buffer) ) elif frame.eval_ctx.autoescape: self.write("Markup(concat(%s))" % frame.buffer) else: self.write("concat(%s)" % frame.buffer) self.signature(node, frame) self.write(")") if self.environment.is_async: self.write(")") @optimizeconst def visit_Test(self, node, frame): self.write(self.tests[node.name] + "(") if node.name not in self.environment.tests: self.fail("no test named %r" % node.name, node.lineno) self.visit(node.node, frame) self.signature(node, frame) self.write(")") @optimizeconst def visit_CondExpr(self, node, frame): def write_expr2(): if node.expr2 is not None: return self.visit(node.expr2, frame) self.write( "cond_expr_undefined(%r)" % ( "the inline if-" "expression on %s evaluated to false and " "no else section was defined." % self.position(node) ) ) self.write("(") self.visit(node.expr1, frame) self.write(" if ") self.visit(node.test, frame) self.write(" else ") write_expr2() self.write(")") @optimizeconst def visit_Call(self, node, frame, forward_caller=False): if self.environment.is_async: self.write("await auto_await(") if self.environment.sandboxed: self.write("environment.call(context, ") else: self.write("context.call(") self.visit(node.node, frame) extra_kwargs = forward_caller and {"caller": "caller"} or None self.signature(node, frame, extra_kwargs) self.write(")") if self.environment.is_async: self.write(")") def visit_Keyword(self, node, frame): self.write(node.key + "=") self.visit(node.value, frame) # -- Unused nodes for extensions def visit_MarkSafe(self, node, frame): self.write("Markup(") self.visit(node.expr, frame) self.write(")") def visit_MarkSafeIfAutoescape(self, node, frame): self.write("(context.eval_ctx.autoescape and Markup or identity)(") self.visit(node.expr, frame) self.write(")") def visit_EnvironmentAttribute(self, node, frame): self.write("environment." + node.name) def visit_ExtensionAttribute(self, node, frame): self.write("environment.extensions[%r].%s" % (node.identifier, node.name)) def visit_ImportedName(self, node, frame): self.write(self.import_aliases[node.importname]) def visit_InternalName(self, node, frame): self.write(node.name) def visit_ContextReference(self, node, frame): self.write("context") def visit_DerivedContextReference(self, node, frame): self.write(self.derive_context(frame)) def visit_Continue(self, node, frame): self.writeline("continue", node) def visit_Break(self, node, frame): self.writeline("break", node) def visit_Scope(self, node, frame): scope_frame = frame.inner() scope_frame.symbols.analyze_node(node) self.enter_frame(scope_frame) self.blockvisit(node.body, scope_frame) self.leave_frame(scope_frame) def visit_OverlayScope(self, node, frame): ctx = self.temporary_identifier() self.writeline("%s = %s" % (ctx, self.derive_context(frame))) self.writeline("%s.vars = " % ctx) self.visit(node.context, frame) self.push_context_reference(ctx) scope_frame = frame.inner(isolated=True) scope_frame.symbols.analyze_node(node) self.enter_frame(scope_frame) self.blockvisit(node.body, scope_frame) self.leave_frame(scope_frame) self.pop_context_reference() def visit_EvalContextModifier(self, node, frame): for keyword in node.options: self.writeline("context.eval_ctx.%s = " % keyword.key) self.visit(keyword.value, frame) try: val = keyword.value.as_const(frame.eval_ctx) except nodes.Impossible: frame.eval_ctx.volatile = True else: setattr(frame.eval_ctx, keyword.key, val) def visit_ScopedEvalContextModifier(self, node, frame): old_ctx_name = self.temporary_identifier() saved_ctx = frame.eval_ctx.save() self.writeline("%s = context.eval_ctx.save()" % old_ctx_name) self.visit_EvalContextModifier(node, frame) for child in node.body: self.visit(child, frame) frame.eval_ctx.revert(saved_ctx) self.writeline("context.eval_ctx.revert(%s)" % old_ctx_name)