bravo - v4.0.1

bravo/uset

This module provides functions to work with USets

Types

USet

opaque </>

An unordered set. Keys may only occur once per table, and keys are unordered.

In order for a lookup match to occur, entries must have the same value and type.

pub opaque type USet(t)

Functions

delete

</> 
pub fn delete(with uset: USet(a)) -> Bool

Deletes a USet.

Table lifetime is static, and memory is only freed when the owner process is killed! Don’t forget to call this function!

The input USet is completely useless after it is deleted. Even if another table is created with the same name, the old handle will not work.

delete_all_objects

</> 
pub fn delete_all_objects(with uset: USet(a)) -> Nil

Deletes all objects in the USet. This is atomic and isolated.

delete_key

</> 
pub fn delete_key(with uset: USet(a), at key: b) -> Nil

Deletes the object addressed by key, if it exists. If it doesn’t, this does nothing.

delete_object

</> 
pub fn delete_object(with uset: USet(a), target object: a) -> Nil

Deletes a specific object in the USet. This is more useful in Bags and DBags.

file2tab

</> 
pub fn file2tab(
  from filename: String,
  verify verify: Bool,
  using decoder: fn(Dynamic) -> Result(a, b),
) -> Result(USet(a), BravoError)

Creates a USet from file filename that was previously created by tab2file.

For type safety reasons, a dynamic decoder must be provided, and the decoder must not fail for all objects in the table.

If the flag verify is set, then checks are performed to ensure the data is correct. This can be slow if tab2file was ran with md5sum enabled.

Size-1 tuples are handled uniquely internally and are treated as non-tuples when saved to disk, so you must decode the non-tuple version of the type.

Can have error types DecodeFailure and ErlangError.

first

</> 
pub fn first(with uset: USet(a)) -> Result(b, Nil)

Returns the first key (not the object!) in the table, if it exists.

USets are unordered, so the order of keys is unknown.

insert

</> 
pub fn insert(
  with uset: USet(a),
  insert objects: List(a),
) -> Bool

Inserts a list of tuples into a USet.

Returns a Bool representing if the inserting succeeded.

  • If True, all objects in the list were inserted.
  • If False, none of the objects in the list were inserted. This may occur if the keypos of the USet is greater than the object tuple size or if the input list is empty.

If an object with the same key already exists, then the old object will be overwritten with the new one.

insert_new

</> 
pub fn insert_new(
  with uset: USet(a),
  insert objects: List(a),
) -> Bool

Inserts a list of tuples into a USet. Unlike insert, this cannot overwrite objects and will return false if it tries to do so.

Returns a Bool representing if the inserting succeeded.

  • If True, all objects in the list were inserted.
  • If False, none of the objects in the list were inserted. This may occur if the keypos of the USet is greater than the object tuple size or if the input list is empty.

last

</> 
pub fn last(with uset: USet(a)) -> Result(b, Nil)

Returns the last key (not the object!) in the table, if it exists.

USets are unordered, so the order of keys is unknown.

lookup

</> 
pub fn lookup(with uset: USet(a), at key: b) -> Result(a, Nil)

Gets an object from a USet.

Returns an Result containing the object, if it exists.

member

</> 
pub fn member(with uset: USet(a), at key: b) -> Bool

Returns whether a USet contains an object at key.

new

</> 
pub fn new(
  name name: String,
  keypos keypos: Int,
  access access: Access,
) -> Result(USet(a), BravoError)

Creates a new ETS table configured as a set: keys may only occur once per table, and objects are unordered.

name: An atom representing the name of the USet. There may only be one ETS table associated with an atom. keypos: The index (1-indexed) that represents the key position of the object. This function fails if this is less than 1. access: Determines how visible the table is to other processes.

  • Public: Any process can read or write to the USet.
  • Protected: Any process can read the USet. Only the owner process can write to it.
  • Private: Only the parent process can read or write to the USet.

Returns a result of the created USet, which can be used by other functions in this module. Can have error types ErlangError and NonPositiveKeypos.

next

</> 
pub fn next(with uset: USet(a), from key: b) -> Result(b, Nil)

Given a key, returns the next key (not the object!) after it in the table, if it exists.

USets are unordered, so the order of keys is unknown.

prev

</> 
pub fn prev(with uset: USet(a), from key: b) -> Result(b, Nil)

Given a key, returns the previous key (not the object!) before it in the table, if it exists.

USets are unordered, so the order of keys is unknown.

tab2file

</> 
pub fn tab2file(
  with uset: USet(a),
  to filename: String,
  object_count object_count: Bool,
  md5sum md5sum: Bool,
  sync sync: Bool,
) -> Result(Nil, BravoError)

Saves a USet as file filename that can later be read back into memory using file2tab.

There are three configuration flags with this function:

  • object_count: Stores the number of objects in the table in the footer. This can detect truncation.
  • md5sum: Stores a md5 checksum of the table and its objects. This can detect even single bitflips, but is computationally expensive.
  • sync: Blocks the process until the file has been successfully written.

Can have error type ErlangError.

tab2list

</> 
pub fn tab2list(with uset: USet(a)) -> List(a)

Returns a list containing all of the objects in the USet.

take

</> 
pub fn take(with uset: USet(a), at key: b) -> Result(a, Nil)

Returns and removes an object at key in the USet, if such object exists.

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