Merge rust-bitcoin/rust-bitcoin#3743: Refactor predict weight

0135cddc32 Refactor non_input_size (Tobin C. Harding)
f42f13cd8d Simplify closures in call to fold (Tobin C. Harding)

Pull request description:

  Two refactorings to make the code easier to read. No logic changes.

ACKs for top commit:
  apoelstra:
    ACK 0135cddc32462490528dea549fd8db4c0a30646e; successfully ran local tests

Tree-SHA512: 747cfe1212283a62545cb86a5af0be46592ab3b41f94ab0a2dad8f06b094c04eb9265520ece595d2aab303fddf55a652e7ef977911439602550c264bedd4385b
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merge-script 2024-12-13 23:58:31 +00:00
commit 7ab569388b
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1 changed files with 15 additions and 28 deletions

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@ -842,29 +842,20 @@ where
I: IntoIterator<Item = InputWeightPrediction>,
O: IntoIterator<Item = usize>,
{
// sum input_weights, input_count and count of inputs with witness data
let (input_count, input_weight, inputs_with_witnesses) = inputs.into_iter().fold(
(0, 0, 0),
|(count, input_weight, inputs_with_witnesses), prediction| {
let (input_count, input_weight, inputs_with_witnesses) =
inputs.into_iter().fold((0, 0, 0), |(count, weight, with_witnesses), prediction| {
(
count + 1,
input_weight + prediction.total_weight().to_wu() as usize,
inputs_with_witnesses + (prediction.witness_size > 0) as usize,
weight + prediction.total_weight().to_wu() as usize,
with_witnesses + (prediction.witness_size > 0) as usize,
)
},
);
});
let (output_count, output_scripts_size) =
output_script_lens.into_iter().fold((0, 0), |(count, scripts_size), script_len| {
(count + 1, scripts_size + script_len + compact_size::encoded_size(script_len))
});
// This fold() does two things:
// 1) Counts the outputs and returns the sum as `output_count`.
// 2) Sums the output script sizes and returns the sum as `output_scripts_size`.
// script_len + the length of a VarInt struct that stores the value of script_len
let (output_count, output_scripts_size) = output_script_lens.into_iter().fold(
(0, 0),
|(output_count, total_scripts_size), script_len| {
let script_size = script_len + compact_size::encoded_size(script_len);
(output_count + 1, total_scripts_size + script_size)
},
);
predict_weight_internal(
input_count,
input_weight,
@ -883,15 +874,11 @@ const fn predict_weight_internal(
) -> Weight {
// The value field of a TxOut is 8 bytes.
let output_size = 8 * output_count + output_scripts_size;
let non_input_size =
// version:
4 +
// count varints:
compact_size::encoded_size_const(input_count as u64) +
compact_size::encoded_size_const(output_count as u64) +
output_size +
// lock_time
4;
let non_input_size = 4 // version
+ compact_size::encoded_size_const(input_count as u64) // Can't use ToU64 in const context.
+ compact_size::encoded_size_const(output_count as u64)
+ output_size
+ 4; // locktime
let weight = if inputs_with_witnesses == 0 {
non_input_size * 4 + input_weight
} else {