forked from bton/matekasse
191 lines
6.2 KiB
Python
191 lines
6.2 KiB
Python
import sys
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import typing as t
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from types import CodeType
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from types import TracebackType
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from .exceptions import TemplateSyntaxError
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from .utils import internal_code
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from .utils import missing
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if t.TYPE_CHECKING:
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from .runtime import Context
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def rewrite_traceback_stack(source: t.Optional[str] = None) -> BaseException:
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"""Rewrite the current exception to replace any tracebacks from
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within compiled template code with tracebacks that look like they
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came from the template source.
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This must be called within an ``except`` block.
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:param source: For ``TemplateSyntaxError``, the original source if
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known.
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:return: The original exception with the rewritten traceback.
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"""
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_, exc_value, tb = sys.exc_info()
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exc_value = t.cast(BaseException, exc_value)
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tb = t.cast(TracebackType, tb)
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if isinstance(exc_value, TemplateSyntaxError) and not exc_value.translated:
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exc_value.translated = True
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exc_value.source = source
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# Remove the old traceback, otherwise the frames from the
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# compiler still show up.
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exc_value.with_traceback(None)
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# Outside of runtime, so the frame isn't executing template
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# code, but it still needs to point at the template.
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tb = fake_traceback(
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exc_value, None, exc_value.filename or "<unknown>", exc_value.lineno
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)
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else:
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# Skip the frame for the render function.
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tb = tb.tb_next
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stack = []
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# Build the stack of traceback object, replacing any in template
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# code with the source file and line information.
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while tb is not None:
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# Skip frames decorated with @internalcode. These are internal
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# calls that aren't useful in template debugging output.
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if tb.tb_frame.f_code in internal_code:
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tb = tb.tb_next
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continue
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template = tb.tb_frame.f_globals.get("__jinja_template__")
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if template is not None:
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lineno = template.get_corresponding_lineno(tb.tb_lineno)
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fake_tb = fake_traceback(exc_value, tb, template.filename, lineno)
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stack.append(fake_tb)
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else:
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stack.append(tb)
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tb = tb.tb_next
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tb_next = None
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# Assign tb_next in reverse to avoid circular references.
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for tb in reversed(stack):
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tb.tb_next = tb_next
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tb_next = tb
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return exc_value.with_traceback(tb_next)
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def fake_traceback( # type: ignore
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exc_value: BaseException, tb: t.Optional[TracebackType], filename: str, lineno: int
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) -> TracebackType:
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"""Produce a new traceback object that looks like it came from the
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template source instead of the compiled code. The filename, line
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number, and location name will point to the template, and the local
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variables will be the current template context.
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:param exc_value: The original exception to be re-raised to create
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the new traceback.
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:param tb: The original traceback to get the local variables and
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code info from.
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:param filename: The template filename.
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:param lineno: The line number in the template source.
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"""
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if tb is not None:
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# Replace the real locals with the context that would be
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# available at that point in the template.
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locals = get_template_locals(tb.tb_frame.f_locals)
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locals.pop("__jinja_exception__", None)
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else:
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locals = {}
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globals = {
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"__name__": filename,
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"__file__": filename,
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"__jinja_exception__": exc_value,
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}
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# Raise an exception at the correct line number.
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code: CodeType = compile(
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"\n" * (lineno - 1) + "raise __jinja_exception__", filename, "exec"
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)
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# Build a new code object that points to the template file and
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# replaces the location with a block name.
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location = "template"
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if tb is not None:
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function = tb.tb_frame.f_code.co_name
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if function == "root":
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location = "top-level template code"
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elif function.startswith("block_"):
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location = f"block {function[6:]!r}"
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if sys.version_info >= (3, 8):
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code = code.replace(co_name=location)
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else:
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code = CodeType(
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code.co_argcount,
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code.co_kwonlyargcount,
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code.co_nlocals,
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code.co_stacksize,
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code.co_flags,
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code.co_code,
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code.co_consts,
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code.co_names,
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code.co_varnames,
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code.co_filename,
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location,
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code.co_firstlineno,
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code.co_lnotab,
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code.co_freevars,
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code.co_cellvars,
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)
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# Execute the new code, which is guaranteed to raise, and return
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# the new traceback without this frame.
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try:
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exec(code, globals, locals)
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except BaseException:
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return sys.exc_info()[2].tb_next # type: ignore
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def get_template_locals(real_locals: t.Mapping[str, t.Any]) -> t.Dict[str, t.Any]:
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"""Based on the runtime locals, get the context that would be
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available at that point in the template.
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"""
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# Start with the current template context.
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ctx: "t.Optional[Context]" = real_locals.get("context")
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if ctx is not None:
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data: t.Dict[str, t.Any] = ctx.get_all().copy()
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else:
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data = {}
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# Might be in a derived context that only sets local variables
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# rather than pushing a context. Local variables follow the scheme
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# l_depth_name. Find the highest-depth local that has a value for
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# each name.
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local_overrides: t.Dict[str, t.Tuple[int, t.Any]] = {}
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for name, value in real_locals.items():
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if not name.startswith("l_") or value is missing:
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# Not a template variable, or no longer relevant.
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continue
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try:
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_, depth_str, name = name.split("_", 2)
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depth = int(depth_str)
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except ValueError:
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continue
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cur_depth = local_overrides.get(name, (-1,))[0]
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if cur_depth < depth:
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local_overrides[name] = (depth, value)
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# Modify the context with any derived context.
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for name, (_, value) in local_overrides.items():
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if value is missing:
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data.pop(name, None)
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else:
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data[name] = value
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return data
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