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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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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) |
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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) |
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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( |
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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( |
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[n async for n in 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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NativeEnvironment.template_class = NativeTemplate |
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