v8 147.4.0

Rust bindings to V8
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130

import typing as t
from ast import literal_eval
from ast import parse
from itertools import chain
from itertools import islice
from types import GeneratorType

from . import nodes
from .compiler import CodeGenerator
from .compiler import Frame
from .compiler import has_safe_repr
from .environment import Environment
from .environment import Template


def native_concat(values: t.Iterable[t.Any]) -> t.Optional[t.Any]:
    """Return a native Python type from the list of compiled nodes. If
    the result is a single node, its value is returned. Otherwise, the
    nodes are concatenated as strings. If the result can be parsed with
    :func:`ast.literal_eval`, the parsed value is returned. Otherwise,
    the string is returned.

    :param values: Iterable of outputs to concatenate.
    """
    head = list(islice(values, 2))

    if not head:
        return None

    if len(head) == 1:
        raw = head[0]
        if not isinstance(raw, str):
            return raw
    else:
        if isinstance(values, GeneratorType):
            values = chain(head, values)
        raw = "".join([str(v) for v in values])

    try:
        return literal_eval(
            # In Python 3.10+ ast.literal_eval removes leading spaces/tabs
            # from the given string. For backwards compatibility we need to
            # parse the string ourselves without removing leading spaces/tabs.
            parse(raw, mode="eval")
        )
    except (ValueError, SyntaxError, MemoryError):
        return raw


class NativeCodeGenerator(CodeGenerator):
    """A code generator which renders Python types by not adding
    ``str()`` around output nodes.
    """

    @staticmethod
    def _default_finalize(value: t.Any) -> t.Any:
        return value

    def _output_const_repr(self, group: t.Iterable[t.Any]) -> str:
        return repr("".join([str(v) for v in group]))

    def _output_child_to_const(
        self, node: nodes.Expr, frame: Frame, finalize: CodeGenerator._FinalizeInfo
    ) -> t.Any:
        const = node.as_const(frame.eval_ctx)

        if not has_safe_repr(const):
            raise nodes.Impossible()

        if isinstance(node, nodes.TemplateData):
            return const

        return finalize.const(const)  # type: ignore

    def _output_child_pre(
        self, node: nodes.Expr, frame: Frame, finalize: CodeGenerator._FinalizeInfo
    ) -> None:
        if finalize.src is not None:
            self.write(finalize.src)

    def _output_child_post(
        self, node: nodes.Expr, frame: Frame, finalize: CodeGenerator._FinalizeInfo
    ) -> None:
        if finalize.src is not None:
            self.write(")")


class NativeEnvironment(Environment):
    """An environment that renders templates to native Python types."""

    code_generator_class = NativeCodeGenerator
    concat = staticmethod(native_concat)  # type: ignore


class NativeTemplate(Template):
    environment_class = NativeEnvironment

    def render(self, *args: t.Any, **kwargs: t.Any) -> t.Any:
        """Render the template to produce a native Python type. If the
        result is a single node, its value is returned. Otherwise, the
        nodes are concatenated as strings. If the result can be parsed
        with :func:`ast.literal_eval`, the parsed value is returned.
        Otherwise, the string is returned.
        """
        ctx = self.new_context(dict(*args, **kwargs))

        try:
            return self.environment_class.concat(  # type: ignore
                self.root_render_func(ctx)  # type: ignore
            )
        except Exception:
            return self.environment.handle_exception()

    async def render_async(self, *args: t.Any, **kwargs: t.Any) -> t.Any:
        if not self.environment.is_async:
            raise RuntimeError(
                "The environment was not created with async mode enabled."
            )

        ctx = self.new_context(dict(*args, **kwargs))

        try:
            return self.environment_class.concat(  # type: ignore
                [n async for n in self.root_render_func(ctx)]  # type: ignore
            )
        except Exception:
            return self.environment.handle_exception()


NativeEnvironment.template_class = NativeTemplate