19: Improve performance of solution for Rust track exercise "Beer Song" at the cost of duplication.

[?]

Aaw9nJhsNmfzFih9mKyNw9mV8CgERXJkRa1kK1Kx3LQH

Aug 24, 2021, 12:24 PM

Z4YP3EEKPFAFPS7F3UUOHECS65V3QFBQPAGXMHY3HEWQA2R6PA4QC

Dependencies

[2] 7NUHCTMK 16: Apply `cargo fmt` and `cargo clippy` to the solution for Rust track exercise "Beer Song". Also add previous versions.
[3] QK6XE5XF 13: Add Rust track exercises "Beer Song", "Proverb", "Difference Of Squares", "Sum Of Multiples", "Grains", "Prime Factors", "Armstrong Numbers" and "Reverse String".
[4] 6DOVDD66 15: Add solution for Rust track exercise "Beer Song".

Change contents

replacement in rust/beer-song/src/lib.rs at line 3

[3.1565]→[3.1565:1592](∅→∅),[3.1592]→[2.10762:10852](∅→∅),[2.10852]→[3.1657:1675](∅→∅),[3.1657]→[3.1657:1675](∅→∅),[3.1675]→[2.10853:11191](∅→∅),[2.11191]→[3.1931:1934](∅→∅),[3.1931]→[3.1931:1934](∅→∅)

const DICT: [&str; 24] = [
"N", // 0
"o m", // 1
"ore", // 2
" bottle", // 3
"s", // 4
" of beer", // 5
" on", // 6
" th", // 7
"e ", // 8
"wall", // 9
", ", // 10
"n", // 11
".\n", // 12
"Go to", // 13
"st", // 14
" and ", // 15
"buy som", // 16
"m", // 17
"99", // 18
"Take", // 19
" it ", // 20
"down", // 21
"pass", // 22
"around", // 23
];

[3.1565]

[3.1934]

pub fn verse(n: u32) -> String {
match n {
0 => "No more bottles of beer on the wall, no more bottles of beer.\nGo to the store and buy some more, 99 bottles of beer on the wall.\n".to_string(),
1 => "1 bottle of beer on the wall, 1 bottle of beer.\nTake it down and pass it around, no more bottles of beer on the wall.\n".to_string(),
2 => "2 bottles of beer on the wall, 2 bottles of beer.\nTake one down and pass it around, 1 bottle of beer on the wall.\n".to_string(),
_ => format!("{0} bottles of beer on the wall, {0} bottles of beer.\nTake one down and pass it around, {1} bottles of beer on the wall.\n", n, n - 1),
}
}
edit in rust/beer-song/src/lib.rs at line 18

[3.2193]→[3.2193:2256](∅→∅)

struct IndicesWithPrefixes<'a>(&'a [(&'a str, &'a [usize])]);
replacement in rust/beer-song/src/lib.rs at line 19

[3.2257]→[3.2257:2467](∅→∅),[3.2467]→[2.11192:11223](∅→∅),[2.11223]→[3.2494:2648](∅→∅),[3.2494]→[3.2494:2648](∅→∅),[3.2648]→[3.37669:37702](∅→∅),[3.37668]→[3.37669:37702](∅→∅),[3.37702]→[3.2649:2721](∅→∅),[3.2721]→[2.11224:11428](∅→∅),[2.11428]→[3.2903:2956](∅→∅),[3.2903]→[3.2903:2956](∅→∅),[3.2956]→[2.11429:11653](∅→∅),[2.11653]→[3.3131:3212](∅→∅),[3.3131]→[3.3131:3212](∅→∅),[3.3212]→[2.11654:11862](∅→∅),[2.11862]→[3.3398:3479](∅→∅),[3.3398]→[3.3398:3479](∅→∅),[3.3479]→[2.11863:12074](∅→∅),[2.12074]→[3.3668:3678](∅→∅),[3.3668]→[3.3668:3678](∅→∅)

impl IndicesWithPrefixes<'_> {
fn generate_verse(&self, n: u32) -> String {
let n = n as usize;
let mut out = String::with_capacity(if n > 2 {
LENGTHS[3] + 2 * integer_length(n) + integer_length(n - 1)
} else {
LENGTHS[n]
});
self.0.iter().for_each(|(prefix, indices)| {
out.push_str(prefix);
indices.iter().for_each(|index| out.push_str(DICT[*index]));
});
out
}
}

pub fn verse(n: u32) -> String {
match n {
0 => {
let mut out = String::with_capacity(LENGTHS[0]);
[
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 1, 2, 3, 4, 5, 12, 13, 7, 8, 14, 2, 15, 16,
8, 17, 2, 10, 18, 3, 4, 5, 6, 7, 8, 9, 12,
]
.iter()
.for_each(|index| out.push_str(DICT[*index]));
out
}
1 => {
let n_string = n.to_string();
IndicesWithPrefixes(&[
(&n_string, &[3, 5, 6, 7, 8, 9, 10]),
(
&n_string,
&[
3, 5, 12, 19, 20, 21, 15, 22, 20, 23, 10, 11, 1, 2, 3, 4, 5, 6, 7, 8, 9, 12,
],
),
])
.generate_verse(n)
}
2 => {
let (n_string, m_string) = (n.to_string(), (n - 1).to_string());
IndicesWithPrefixes(&[
(&n_string, &[3, 4, 5, 6, 7, 8, 9, 10]),
(&n_string, &[3, 4, 5, 12, 19, 6, 8, 21, 15, 22, 20, 23, 10]),
(&m_string, &[3, 5, 6, 7, 8, 9, 12]),
])
.generate_verse(n)
}
_ => {
let (n_string, m_string) = (n.to_string(), (n - 1).to_string());
IndicesWithPrefixes(&[
(&n_string, &[3, 4, 5, 6, 7, 8, 9, 10]),
(&n_string, &[3, 4, 5, 12, 19, 6, 8, 21, 15, 22, 20, 23, 10]),
(&m_string, &[3, 4, 5, 6, 7, 8, 9, 12]),
])
.generate_verse(n)
}
}
}

[3.2257]

[3.3678]

// Might not work properly if results of `powi`s don't fit into the `usize` casts.
replacement in rust/beer-song/src/lib.rs at line 60

[3.4795]→[3.4795:4875](∅→∅)

if start < end {
out.push_str(&verse(e));
(e + 1..=s).for_each(|a| {

[3.4795]

[2.12733]

if start > end {
out.push_str(&verse(s));
(e..=s - 1).rev().for_each(|a| {
replacement in rust/beer-song/src/lib.rs at line 67

[3.4950]→[3.4950:5016](∅→∅)

out.push_str(&verse(s));
(e..=s - 1).rev().for_each(|a| {

[3.4950]

[2.12755]

out.push_str(&verse(e));
(e + 1..=s).for_each(|a| {