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95 lines
2.7 KiB
95 lines
2.7 KiB
4 years ago
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from ast import literal_eval
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from itertools import chain
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from itertools import islice
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from . import nodes
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from ._compat import text_type
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from .compiler import CodeGenerator
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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(nodes):
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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 nodes: Iterable of nodes to concatenate.
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"""
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head = list(islice(nodes, 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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else:
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raw = u"".join([text_type(v) for v in chain(head, nodes)])
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try:
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return literal_eval(raw)
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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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``to_string()`` around output nodes.
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"""
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@staticmethod
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def _default_finalize(value):
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return value
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def _output_const_repr(self, group):
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return repr(u"".join([text_type(v) for v in group]))
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def _output_child_to_const(self, node, frame, finalize):
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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(self, node, frame, finalize):
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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(self, node, frame, finalize):
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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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class NativeTemplate(Template):
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environment_class = NativeEnvironment
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def render(self, *args, **kwargs):
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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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vars = dict(*args, **kwargs)
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try:
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return native_concat(self.root_render_func(self.new_context(vars)))
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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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