parseJsonNumber

Parse a JSON number literal and return the appropriate var type.

This function takes a number lexeme and parses it into the most appropriate numeric type according to JSON semantics:

• If the number is integral and fits in a long, use var.Type.LONG.
• If the number is integral, non-negative, and fits in ulong but not long, use var.Type.ULONG.
• Otherwise (decimals, exponents, overflow), use var.Type.DOUBLE.

With preferSigned = false, non-negative integers that fit are reported as var.Type.ULONG instead of var.Type.LONG (negative integers remain LONG; there is no unsigned representation).

Parameters

lexeme	The number literal lexeme from the lexer.
result	Output parameter for the parsed value.
errorMsg	Output parameter for error message on failure.
preferSigned	When true, prefer signed integers when value fits both; when false, prefer ulong for non-negative integers.

Returns

true on success, false on error (with errorMsg set).