byte_span
local byte_span = require 'byte_span'A span of bytes. In Emilua, they’re used as network buffers.
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Plugin authors
This class is intended for network buffers in a proactor-based network API (i.e. true asynchronous IO). A NIC could be writing to this memory region while the program is running. This has the same effect of another thread writing to the same memory region. If you’re writing state machines, do not construct the state machine on top of
the memory region pointed by a A future Emilua release could introduce read-write locks, but as of now I’m unconvinced of their advantages here. |
It’s modeled after Golang’s slices. However 1-indexed access is used.
Functions
new(length: integer[, capacity: integer]) → byte_span
Constructor.
When the capacity argument is omitted, it defaults to the specified length.
slice(self[, start: integer, end: integer]) → byte_span
Returns a new byte_span that points to a slice of the same memory region.
The start and end indices are optional; they default to 1 and the
byte_span's length respectively.
We can grow a byte_span to its capacity by slicing it again.
Invalid ranges (e.g. start below 1, a byte_span running beyond its
capacity, negative indexes, …) will raise EINVAL.
copy(self, src: byte_span|string) → integer
Copy src into self.
Returns the number of elements copied.
Copying between slices of different lengths is supported (it’ll copy only up to the smaller number of elements). In addition it can handle source and destination spans that share the same underlying memory, handling overlapping spans correctly.
append() → byte_span
function append(self, ...: byte_span|string|nil) -> byte_span (1)
function append(...: byte_span|string|nil) -> byte_span (2)Returns a new byte_span by appending trailing arguments into self. If
self's capacity is enough to hold all data, the underlying memory is
modified in place. Otherwise the returned byte_span will point to newly
allocated memory[1].
For the second overload (non-member function), a new byte span is created from scratch.
Functions (string algorithms)
These functions operate in terms of octets/bytes (kinda like an 8-bit ASCII) and have no concept of UTF-8 encoding.
find(self, tgt: string|byte_span[, start: integer]) → integer|nil
Finds the first substring equals to tgt and returns its index, or nil if not
found.
rfind(self, tgt: string|byte_span[, end_: integer]) → integer|nil
Finds the last substring equals to tgt and returns its index, or nil if not
found.
find_first_of(self, strlist: string|byte_span[, start: integer]) → integer|nil
Finds the first octet equals to any of the octets within strlist and returns
its index, or nil if not found.
find_last_of(self, strlist: string|byte_span[, end_: integer]) → integer|nil
Finds the last octet equals to any of the octets within strlist and returns
its index, or nil if not found.
find_first_not_of(self, strlist: string|byte_span[, start: integer]) → integer|nil
Finds the first octet not equals to any of the octets within strlist and
returns its index, or nil if not found.
Metamethods
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__tostring() -
__len() -
__index() -
__newindex() -
__eq()
You can index the spans by numerical valued keys and the numerical (ASCII)
value for the underlying byte will be returned (or assigned on __newindex()).
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byte_span's capacity) is left unspecified and may change among Emilua releases.