bjoernager/rust
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Estimate path length instead of hardcoding 64 bytes

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This commit is contained in:
Noah Lev 2022-01-10 12:23:58 -08:00
parent 53f1bed83a
commit 8f59eb6da0
2 changed files with 10 additions and 2 deletions
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4
src/librustdoc/html/format.rs
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@ -30,6 +30,7 @@ use crate::formats::item_type::ItemType;
use crate::html::escape::Escape; use crate::html::escape::Escape;
use crate::html::render::Context; use crate::html::render::Context;
use super::url_parts_builder::estimate_item_path_byte_length;
use super::url_parts_builder::UrlPartsBuilder; use super::url_parts_builder::UrlPartsBuilder;
crate trait Print { crate trait Print {
@ -505,8 +506,7 @@ crate enum HrefError {
// Panics if `syms` is empty. // Panics if `syms` is empty.
crate fn join_with_double_colon(syms: &[Symbol]) -> String { crate fn join_with_double_colon(syms: &[Symbol]) -> String {
// 64 bytes covers 99.9%+ of cases. let mut s = String::with_capacity(estimate_item_path_byte_length(syms.len()));
let mut s = String::with_capacity(64);
s.push_str(&syms[0].as_str()); s.push_str(&syms[0].as_str());
for sym in &syms[1..] { for sym in &syms[1..] {
s.push_str("::"); s.push_str("::");

8
src/librustdoc/html/url_parts_builder.rs
View file

@ -110,6 +110,14 @@ impl UrlPartsBuilder {
/// This is intentionally on the lower end to avoid overallocating. /// This is intentionally on the lower end to avoid overallocating.
const AVG_PART_LENGTH: usize = 5; const AVG_PART_LENGTH: usize = 5;
/// Estimate the number of bytes in an item's path, based on how many segments it has.
///
/// **Note:** This is only to be used with, e.g., [`String::with_capacity()`];
/// the return value is just a rough estimate.
crate const fn estimate_item_path_byte_length(segment_count: usize) -> usize {
AVG_PART_LENGTH * segment_count
}
impl<'a> FromIterator<&'a str> for UrlPartsBuilder { impl<'a> FromIterator<&'a str> for UrlPartsBuilder {
fn from_iter<T: IntoIterator<Item = &'a str>>(iter: T) -> Self { fn from_iter<T: IntoIterator<Item = &'a str>>(iter: T) -> Self {
let iter = iter.into_iter(); let iter = iter.into_iter();