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| 1 | +"""Shared ECMAScript value operations for the supported runtime subset.""" |
| 2 | + |
| 3 | +from __future__ import annotations |
| 4 | + |
| 5 | +import inspect |
| 6 | +import math |
| 7 | +import re |
| 8 | +from collections.abc import Mapping |
| 9 | +from decimal import Decimal |
| 10 | + |
| 11 | + |
| 12 | +class _Undefined: |
| 13 | + __slots__ = () |
| 14 | + _instance = None |
| 15 | + |
| 16 | + def __new__(cls): |
| 17 | + if cls._instance is None: |
| 18 | + cls._instance = super().__new__(cls) |
| 19 | + return cls._instance |
| 20 | + |
| 21 | + def __repr__(self) -> str: |
| 22 | + return "undefined" |
| 23 | + |
| 24 | + def __bool__(self) -> bool: |
| 25 | + return False |
| 26 | + |
| 27 | + def __reduce__(self): |
| 28 | + return (_Undefined, ()) |
| 29 | + |
| 30 | + |
| 31 | +undefined = _Undefined() |
| 32 | +null = None |
| 33 | +NaN = math.nan |
| 34 | +Infinity = math.inf |
| 35 | + |
| 36 | +# ECMAScript WhiteSpace and LineTerminator code points, including BOM. |
| 37 | +WHITESPACE = "\u0009\u000b\u000c\u0020\u00a0\u1680\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200a\u202f\u205f\u3000\ufeff\u000a\u000d\u2028\u2029" |
| 38 | +_DECIMAL = re.compile(r"[+-]?(?:(?:[0-9]+(?:\.[0-9]*)?|\.[0-9]+)(?:[eE][+-]?[0-9]+)?|Infinity)\Z") |
| 39 | + |
| 40 | + |
| 41 | +def is_number(value) -> bool: |
| 42 | + return isinstance(value, (int, float)) and not isinstance(value, bool) |
| 43 | + |
| 44 | + |
| 45 | +def truthy(value=undefined) -> bool: |
| 46 | + """JavaScript Boolean conversion; empty containers are true.""" |
| 47 | + if value is undefined or value is None or value is False: |
| 48 | + return False |
| 49 | + if is_number(value): |
| 50 | + return value != 0 and not math.isnan(to_number(value)) |
| 51 | + if isinstance(value, str): |
| 52 | + return len(value) != 0 |
| 53 | + return True |
| 54 | + |
| 55 | + |
| 56 | +def primitive(value): |
| 57 | + if value is undefined or value is None or isinstance(value, (str, bool, int, float)): |
| 58 | + return value |
| 59 | + method = getattr(type(value), "_js_primitive", None) |
| 60 | + if method is not None: |
| 61 | + result = method(value) |
| 62 | + if result is undefined or result is None or isinstance(result, (str, bool, int, float)): |
| 63 | + return result |
| 64 | + raise TypeError("Cannot convert object to a primitive value") |
| 65 | + if isinstance(value, (list, tuple)): |
| 66 | + return ",".join("" if item is None or item is undefined else to_string(item) for item in value) |
| 67 | + if isinstance(value, Mapping): |
| 68 | + return "[object Object]" |
| 69 | + raise TypeError(f"Unsupported JavaScript value: {type(value).__name__}") |
| 70 | + |
| 71 | + |
| 72 | +def to_number(value=undefined) -> float: |
| 73 | + value = primitive(value) |
| 74 | + if value is undefined: |
| 75 | + return NaN |
| 76 | + if value is None: |
| 77 | + return 0.0 |
| 78 | + if isinstance(value, (bool, int, float)): |
| 79 | + try: |
| 80 | + return float(value) |
| 81 | + except OverflowError: |
| 82 | + return -Infinity if value < 0 else Infinity |
| 83 | + text = value.strip(WHITESPACE) |
| 84 | + if not text: |
| 85 | + return 0.0 |
| 86 | + if re.fullmatch(r"0[xX][0-9a-fA-F]+|0[bB][01]+|0[oO][0-7]+", text): |
| 87 | + return to_number(int(text, 0)) |
| 88 | + if not _DECIMAL.fullmatch(text): |
| 89 | + return NaN |
| 90 | + return float(text) |
| 91 | + |
| 92 | + |
| 93 | +def number_string(value) -> str: |
| 94 | + number = to_number(value) |
| 95 | + if math.isnan(number): |
| 96 | + return "NaN" |
| 97 | + if math.isinf(number): |
| 98 | + return "-Infinity" if number < 0 else "Infinity" |
| 99 | + if number == 0: |
| 100 | + return "0" |
| 101 | + text = repr(number) |
| 102 | + if 1e-6 <= abs(number) < 1e21: |
| 103 | + text = format(Decimal(text), "f") |
| 104 | + return text.rstrip("0").rstrip(".") if "." in text else text |
| 105 | + mantissa, exponent = text.split("e") |
| 106 | + exponent = int(exponent) |
| 107 | + return f"{mantissa.removesuffix('.0')}e{'+' if exponent >= 0 else '-'}{abs(exponent)}" |
| 108 | + |
| 109 | + |
| 110 | +def to_string(value=undefined) -> str: |
| 111 | + value = primitive(value) |
| 112 | + if value is undefined: |
| 113 | + return "undefined" |
| 114 | + if value is None: |
| 115 | + return "null" |
| 116 | + if value is True: |
| 117 | + return "true" |
| 118 | + if value is False: |
| 119 | + return "false" |
| 120 | + if isinstance(value, str): |
| 121 | + return str(value) |
| 122 | + return number_string(value) |
| 123 | + |
| 124 | + |
| 125 | +def integer(value=undefined): |
| 126 | + number = to_number(value) |
| 127 | + if math.isnan(number) or number == 0: |
| 128 | + return 0 |
| 129 | + return number if math.isinf(number) else math.trunc(number) |
| 130 | + |
| 131 | + |
| 132 | +def relative_index(value, length: int) -> int: |
| 133 | + index = integer(value) |
| 134 | + if index < 0: |
| 135 | + return max(length + index, 0) |
| 136 | + return min(index, length) |
| 137 | + |
| 138 | + |
| 139 | +def strictEqual(left, right) -> bool: |
| 140 | + """ECMAScript strict equality for supported values (objects use identity).""" |
| 141 | + if is_number(left) and is_number(right): |
| 142 | + return to_number(left) == to_number(right) |
| 143 | + if isinstance(left, str) and isinstance(right, str): |
| 144 | + return str(left) == str(right) |
| 145 | + return left is right |
| 146 | + |
| 147 | + |
| 148 | +def same_value(left, right) -> bool: |
| 149 | + if is_number(left) and is_number(right): |
| 150 | + a, b = to_number(left), to_number(right) |
| 151 | + if math.isnan(a) and math.isnan(b): |
| 152 | + return True |
| 153 | + if a == b == 0: |
| 154 | + return math.copysign(1, a) == math.copysign(1, b) |
| 155 | + return strictEqual(left, right) |
| 156 | + |
| 157 | + |
| 158 | +def same_value_zero(left, right) -> bool: |
| 159 | + return strictEqual(left, right) or (is_number(left) and is_number(right) and math.isnan(to_number(left)) and math.isnan(to_number(right))) |
| 160 | + |
| 161 | + |
| 162 | +def typeof(value=undefined) -> str: |
| 163 | + if value is undefined: |
| 164 | + return "undefined" |
| 165 | + if value is None: |
| 166 | + return "object" |
| 167 | + if isinstance(value, bool): |
| 168 | + return "boolean" |
| 169 | + if is_number(value): |
| 170 | + return "number" |
| 171 | + if isinstance(value, str): |
| 172 | + return "string" |
| 173 | + return "function" if callable(value) else "object" |
| 174 | + |
| 175 | + |
| 176 | +def isNaN(value=undefined) -> bool: |
| 177 | + return math.isnan(to_number(value)) |
| 178 | + |
| 179 | + |
| 180 | +def isFinite(value=undefined) -> bool: |
| 181 | + return math.isfinite(to_number(value)) |
| 182 | + |
| 183 | + |
| 184 | +def callback(function): |
| 185 | + """Adapt declared positional arity once, without retrying callback errors.""" |
| 186 | + if not callable(function): |
| 187 | + raise TypeError("Callback must be callable") |
| 188 | + try: |
| 189 | + parameters = inspect.signature(function).parameters.values() |
| 190 | + except (TypeError, ValueError): |
| 191 | + return function |
| 192 | + if any(p.kind == p.VAR_POSITIONAL for p in parameters): |
| 193 | + return function |
| 194 | + count = sum(p.kind in (p.POSITIONAL_ONLY, p.POSITIONAL_OR_KEYWORD) for p in parameters) |
| 195 | + return lambda *args: function(*args[:count]) |
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