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131 lines
4.1 KiB
131 lines
4.1 KiB
import typing as t
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from ast import literal_eval
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from ast import parse
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from itertools import chain
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from itertools import islice
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from types import GeneratorType
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from . import nodes
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from .compiler import CodeGenerator
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from .compiler import Frame
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from .compiler import has_safe_repr
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from .environment import Environment
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from .environment import Template
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def native_concat(values: t.Iterable[t.Any]) -> t.Optional[t.Any]:
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"""Return a native Python type from the list of compiled nodes. If
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the result is a single node, its value is returned. Otherwise, the
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nodes are concatenated as strings. If the result can be parsed with
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:func:`ast.literal_eval`, the parsed value is returned. Otherwise,
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the string is returned.
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:param values: Iterable of outputs to concatenate.
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"""
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head = list(islice(values, 2))
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if not head:
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return None
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if len(head) == 1:
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raw = head[0]
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if not isinstance(raw, str):
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return raw
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else:
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if isinstance(values, GeneratorType):
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values = chain(head, values)
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raw = "".join([str(v) for v in values])
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try:
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return literal_eval(
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# In Python 3.10+ ast.literal_eval removes leading spaces/tabs
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# from the given string. For backwards compatibility we need to
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# parse the string ourselves without removing leading spaces/tabs.
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parse(raw, mode="eval")
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)
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except (ValueError, SyntaxError, MemoryError):
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return raw
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class NativeCodeGenerator(CodeGenerator):
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"""A code generator which renders Python types by not adding
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``str()`` around output nodes.
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"""
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@staticmethod
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def _default_finalize(value: t.Any) -> t.Any:
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return value
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def _output_const_repr(self, group: t.Iterable[t.Any]) -> str:
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return repr("".join([str(v) for v in group]))
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def _output_child_to_const(
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self, node: nodes.Expr, frame: Frame, finalize: CodeGenerator._FinalizeInfo
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) -> t.Any:
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const = node.as_const(frame.eval_ctx)
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if not has_safe_repr(const):
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raise nodes.Impossible()
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if isinstance(node, nodes.TemplateData):
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return const
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return finalize.const(const) # type: ignore
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def _output_child_pre(
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self, node: nodes.Expr, frame: Frame, finalize: CodeGenerator._FinalizeInfo
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) -> None:
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if finalize.src is not None:
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self.write(finalize.src)
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def _output_child_post(
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self, node: nodes.Expr, frame: Frame, finalize: CodeGenerator._FinalizeInfo
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) -> None:
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if finalize.src is not None:
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self.write(")")
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class NativeEnvironment(Environment):
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"""An environment that renders templates to native Python types."""
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code_generator_class = NativeCodeGenerator
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concat = staticmethod(native_concat) # type: ignore
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class NativeTemplate(Template):
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environment_class = NativeEnvironment
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def render(self, *args: t.Any, **kwargs: t.Any) -> t.Any:
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"""Render the template to produce a native Python type. If the
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result is a single node, its value is returned. Otherwise, the
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nodes are concatenated as strings. If the result can be parsed
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with :func:`ast.literal_eval`, the parsed value is returned.
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Otherwise, the string is returned.
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"""
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ctx = self.new_context(dict(*args, **kwargs))
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try:
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return self.environment_class.concat( # type: ignore
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self.root_render_func(ctx)
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)
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except Exception:
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return self.environment.handle_exception()
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async def render_async(self, *args: t.Any, **kwargs: t.Any) -> t.Any:
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if not self.environment.is_async:
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raise RuntimeError(
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"The environment was not created with async mode enabled."
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)
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ctx = self.new_context(dict(*args, **kwargs))
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try:
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return self.environment_class.concat( # type: ignore
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[n async for n in self.root_render_func(ctx)] # type: ignore
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)
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except Exception:
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return self.environment.handle_exception()
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NativeEnvironment.template_class = NativeTemplate
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