Module 0x1::from_bcs

This module provides a number of functions to convert primitive types from their representation in std::bcs to values. This is the opposite of bcs::to_bytes. Note that it is not safe to define a generic public from_bytes function because this can violate implicit struct invariants, therefore only primitive types are offered. If a general conversion back-and-force is needed, consider the aptos_std::Any type which preserves invariants.

Example:

use std::bcs;
use aptos_std::from_bcs;

assert!(from_bcs::to_address(bcs::to_bytes(&@0xabcdef)) == @0xabcdef, 0);

• Constants
• Function to_bool
• Function to_u8
• Function to_u16
• Function to_u32
• Function to_u64
• Function to_u128
• Function to_u256
• Function to_address
• Function to_bytes
• Function to_string
• Function from_bytes
• Specification
  • Function from_bytes

use 0x1::string;

Constants

UTF8 check failed in conversion from bytes to string

const EINVALID_UTF8: u64 = 1;

Function to_bool

public fun to_bool(v: vector<u8>): bool

public fun to_bool(v: vector<u8>): bool {
    from_bytes<bool>(v)
}

Function to_u8

public fun to_u8(v: vector<u8>): u8

public fun to_u8(v: vector<u8>): u8 {
    from_bytes<u8>(v)
}

Function to_u16

public fun to_u16(v: vector<u8>): u16

public fun to_u16(v: vector<u8>): u16 {
    from_bytes<u16>(v)
}

Function to_u32

public fun to_u32(v: vector<u8>): u32

public fun to_u32(v: vector<u8>): u32 {
    from_bytes<u32>(v)
}

Function to_u64

public fun to_u64(v: vector<u8>): u64

public fun to_u64(v: vector<u8>): u64 {
    from_bytes<u64>(v)
}

Function to_u128

public fun to_u128(v: vector<u8>): u128

public fun to_u128(v: vector<u8>): u128 {
    from_bytes<u128>(v)
}

Function to_u256

public fun to_u256(v: vector<u8>): u256

public fun to_u256(v: vector<u8>): u256 {
    from_bytes<u256>(v)
}

Function to_address

public fun to_address(v: vector<u8>): address

public fun to_address(v: vector<u8>): address {
    from_bytes<address>(v)
}

Function to_bytes

public fun to_bytes(v: vector<u8>): vector<u8>

public fun to_bytes(v: vector<u8>): vector<u8> {
    from_bytes<vector<u8>>(v)
}

Function to_string

public fun to_string(v: vector<u8>): string::String

public fun to_string(v: vector<u8>): String {
    // To make this safe, we need to evaluate the utf8 invariant.
    let s = from_bytes<String>(v);
    assert!(string::internal_check_utf8(s.bytes()), EINVALID_UTF8);
    s
}

Function from_bytes

Package private native function to deserialize a type T.

Note that this function does not put any constraint on T. If code uses this function to deserialize a linear value, its their responsibility that the data they deserialize is owned.

Function would abort if T has signer in it.

public(friend) fun from_bytes<T>(bytes: vector<u8>): T

native friend fun from_bytes<T>(bytes: vector<u8>): T;

Specification

fun deserialize<T>(bytes: vector<u8>): T;

fun deserializable<T>(bytes: vector<u8>): bool;
axiom<T> forall b1: vector<u8>, b2: vector<u8>:
    ( b1 == b2 ==> deserializable<T>(b1) == deserializable<T>(b2) );
axiom<T> forall b1: vector<u8>, b2: vector<u8>:
    ( b1 == b2 ==> deserialize<T>(b1) == deserialize<T>(b2) );

Function from_bytes

public(friend) fun from_bytes<T>(bytes: vector<u8>): T

pragma opaque;
aborts_if !deserializable<T>(bytes);
ensures result == deserialize<T>(bytes);