280 lines
9.3 KiB
Python
280 lines
9.3 KiB
Python
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from typing import Dict, List, Union, Tuple, Any, cast
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from typing_extensions import Final
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# Supported Python literal types. All tuple items must have supported
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# literal types as well, but we can't represent the type precisely.
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LiteralValue = Union[str, bytes, int, bool, float, complex, Tuple[object, ...], None]
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# Some literals are singletons and handled specially (None, False and True)
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NUM_SINGLETONS: Final = 3
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class Literals:
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"""Collection of literal values used in a compilation group and related helpers."""
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def __init__(self) -> None:
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# Each dict maps value to literal index (0, 1, ...)
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self.str_literals: Dict[str, int] = {}
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self.bytes_literals: Dict[bytes, int] = {}
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self.int_literals: Dict[int, int] = {}
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self.float_literals: Dict[float, int] = {}
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self.complex_literals: Dict[complex, int] = {}
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self.tuple_literals: Dict[Tuple[object, ...], int] = {}
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def record_literal(self, value: LiteralValue) -> None:
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"""Ensure that the literal value is available in generated code."""
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if value is None or value is True or value is False:
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# These are special cased and always present
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return
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if isinstance(value, str):
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str_literals = self.str_literals
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if value not in str_literals:
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str_literals[value] = len(str_literals)
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elif isinstance(value, bytes):
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bytes_literals = self.bytes_literals
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if value not in bytes_literals:
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bytes_literals[value] = len(bytes_literals)
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elif isinstance(value, int):
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int_literals = self.int_literals
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if value not in int_literals:
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int_literals[value] = len(int_literals)
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elif isinstance(value, float):
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float_literals = self.float_literals
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if value not in float_literals:
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float_literals[value] = len(float_literals)
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elif isinstance(value, complex):
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complex_literals = self.complex_literals
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if value not in complex_literals:
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complex_literals[value] = len(complex_literals)
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elif isinstance(value, tuple):
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tuple_literals = self.tuple_literals
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if value not in tuple_literals:
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for item in value:
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self.record_literal(cast(Any, item))
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tuple_literals[value] = len(tuple_literals)
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else:
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assert False, 'invalid literal: %r' % value
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def literal_index(self, value: LiteralValue) -> int:
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"""Return the index to the literals array for given value."""
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# The array contains first None and booleans, followed by all str values,
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# followed by bytes values, etc.
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if value is None:
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return 0
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elif value is False:
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return 1
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elif value is True:
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return 2
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n = NUM_SINGLETONS
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if isinstance(value, str):
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return n + self.str_literals[value]
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n += len(self.str_literals)
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if isinstance(value, bytes):
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return n + self.bytes_literals[value]
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n += len(self.bytes_literals)
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if isinstance(value, int):
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return n + self.int_literals[value]
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n += len(self.int_literals)
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if isinstance(value, float):
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return n + self.float_literals[value]
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n += len(self.float_literals)
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if isinstance(value, complex):
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return n + self.complex_literals[value]
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n += len(self.complex_literals)
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if isinstance(value, tuple):
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return n + self.tuple_literals[value]
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assert False, 'invalid literal: %r' % value
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def num_literals(self) -> int:
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# The first three are for None, True and False
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return (NUM_SINGLETONS + len(self.str_literals) + len(self.bytes_literals) +
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len(self.int_literals) + len(self.float_literals) + len(self.complex_literals) +
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len(self.tuple_literals))
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# The following methods return the C encodings of literal values
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# of different types
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def encoded_str_values(self) -> List[bytes]:
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return _encode_str_values(self.str_literals)
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def encoded_int_values(self) -> List[bytes]:
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return _encode_int_values(self.int_literals)
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def encoded_bytes_values(self) -> List[bytes]:
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return _encode_bytes_values(self.bytes_literals)
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def encoded_float_values(self) -> List[str]:
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return _encode_float_values(self.float_literals)
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def encoded_complex_values(self) -> List[str]:
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return _encode_complex_values(self.complex_literals)
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def encoded_tuple_values(self) -> List[str]:
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"""Encode tuple values into a C array.
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The format of the result is like this:
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<number of tuples>
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<length of the first tuple>
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<literal index of first item>
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...
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<literal index of last item>
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<length of the second tuple>
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...
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"""
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values = self.tuple_literals
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value_by_index = {}
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for value, index in values.items():
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value_by_index[index] = value
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result = []
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num = len(values)
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result.append(str(num))
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for i in range(num):
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value = value_by_index[i]
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result.append(str(len(value)))
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for item in value:
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index = self.literal_index(cast(Any, item))
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result.append(str(index))
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return result
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def _encode_str_values(values: Dict[str, int]) -> List[bytes]:
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value_by_index = {}
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for value, index in values.items():
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value_by_index[index] = value
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result = []
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line: List[bytes] = []
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line_len = 0
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for i in range(len(values)):
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value = value_by_index[i]
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c_literal = format_str_literal(value)
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c_len = len(c_literal)
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if line_len > 0 and line_len + c_len > 70:
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result.append(format_int(len(line)) + b''.join(line))
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line = []
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line_len = 0
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line.append(c_literal)
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line_len += c_len
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if line:
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result.append(format_int(len(line)) + b''.join(line))
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result.append(b'')
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return result
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def _encode_bytes_values(values: Dict[bytes, int]) -> List[bytes]:
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value_by_index = {}
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for value, index in values.items():
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value_by_index[index] = value
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result = []
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line: List[bytes] = []
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line_len = 0
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for i in range(len(values)):
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value = value_by_index[i]
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c_init = format_int(len(value))
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c_len = len(c_init) + len(value)
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if line_len > 0 and line_len + c_len > 70:
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result.append(format_int(len(line)) + b''.join(line))
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line = []
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line_len = 0
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line.append(c_init + value)
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line_len += c_len
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if line:
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result.append(format_int(len(line)) + b''.join(line))
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result.append(b'')
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return result
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def format_int(n: int) -> bytes:
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"""Format an integer using a variable-length binary encoding."""
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if n < 128:
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a = [n]
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else:
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a = []
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while n > 0:
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a.insert(0, n & 0x7f)
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n >>= 7
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for i in range(len(a) - 1):
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# If the highest bit is set, more 7-bit digits follow
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a[i] |= 0x80
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return bytes(a)
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def format_str_literal(s: str) -> bytes:
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utf8 = s.encode('utf-8')
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return format_int(len(utf8)) + utf8
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def _encode_int_values(values: Dict[int, int]) -> List[bytes]:
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"""Encode int values into C strings.
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Values are stored in base 10 and separated by 0 bytes.
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"""
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value_by_index = {}
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for value, index in values.items():
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value_by_index[index] = value
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result = []
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line: List[bytes] = []
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line_len = 0
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for i in range(len(values)):
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value = value_by_index[i]
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encoded = b'%d' % value
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if line_len > 0 and line_len + len(encoded) > 70:
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result.append(format_int(len(line)) + b'\0'.join(line))
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line = []
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line_len = 0
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line.append(encoded)
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line_len += len(encoded)
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if line:
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result.append(format_int(len(line)) + b'\0'.join(line))
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result.append(b'')
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return result
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def float_to_c(x: float) -> str:
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"""Return C literal representation of a float value."""
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s = str(x)
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if s == 'inf':
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return 'INFINITY'
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elif s == '-inf':
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return '-INFINITY'
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return s
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def _encode_float_values(values: Dict[float, int]) -> List[str]:
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"""Encode float values into a C array values.
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The result contains the number of values followed by individual values.
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"""
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value_by_index = {}
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for value, index in values.items():
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value_by_index[index] = value
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result = []
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num = len(values)
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result.append(str(num))
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for i in range(num):
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value = value_by_index[i]
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result.append(float_to_c(value))
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return result
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def _encode_complex_values(values: Dict[complex, int]) -> List[str]:
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"""Encode float values into a C array values.
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The result contains the number of values followed by pairs of doubles
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representing complex numbers.
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"""
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value_by_index = {}
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for value, index in values.items():
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value_by_index[index] = value
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result = []
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num = len(values)
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result.append(str(num))
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for i in range(num):
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value = value_by_index[i]
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result.append(float_to_c(value.real))
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result.append(float_to_c(value.imag))
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return result
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