Rollup merge of rust-lang#56709 - GuillaumeGomez:reduce-search-index,…

… r=QuietMisdreavus

Remove unneeded extra chars to reduce search-index size

Before:

```
2013782 Dec 11 10:16 build/x86_64-unknown-linux-gnu/doc/search-index.js
```

After:

```
1736597 Dec 11 10:50 build/x86_64-unknown-linux-gnu/doc/search-index.js
```

No changes in the output of the search.

r? @QuietMisdreavus

src/librustdoc/html/markdown.rs

@@ -806,6 +806,10 @@ impl<'a> fmt::Display for MarkdownSummaryLine<'a> {
 }
 
 pub fn plain_summary_line(md: &str) -> String {
+    plain_summary_line_full(md, false)
+}
+
+pub fn plain_summary_line_full(md: &str, limit_length: bool) -> String {
     struct ParserWrapper<'a> {
         inner: Parser<'a>,
         is_in: isize,
@@ -852,7 +856,21 @@ pub fn plain_summary_line(md: &str) -> String {
             s.push_str(&t);
         }
     }
-    s
+    if limit_length && s.chars().count() > 60 {
+        let mut len = 0;
+        let mut ret = s.split_whitespace()
+                       .take_while(|p| {
+                           // + 1 for the added character after the word.
+                           len += p.chars().count() + 1;
+                           len < 60
+                       })
+                       .collect::<Vec<_>>()
+                       .join(" ");
+        ret.push('…');
+        ret
+    } else {
+        s
+    }
 }
 
 pub fn markdown_links(md: &str) -> Vec<(String, Option<Range<usize>>)> {

src/librustdoc/html/render.rs

@@ -698,7 +698,7 @@ fn build_index(krate: &clean::Crate, cache: &mut Cache) -> String {
                 ty: item.type_(),
                 name: item.name.clone().unwrap(),
                 path: fqp[..fqp.len() - 1].join("::"),
-                desc: plain_summary_line(item.doc_value()),
+                desc: plain_summary_line_short(item.doc_value()),
                 parent: Some(did),
                 parent_idx: None,
                 search_type: get_index_search_type(&item),
@@ -736,7 +736,7 @@ fn build_index(krate: &clean::Crate, cache: &mut Cache) -> String {
     }
 
     let crate_doc = krate.module.as_ref().map(|module| {
-        plain_summary_line(module.doc_value())
+        plain_summary_line_short(module.doc_value())
     }).unwrap_or(String::new());
 
     let mut crate_data = BTreeMap::new();
@@ -1481,7 +1481,7 @@ impl DocFolder for Cache {
                             ty: item.type_(),
                             name: s.to_string(),
                             path: path.join("::"),
-                            desc: plain_summary_line(item.doc_value()),
+                            desc: plain_summary_line_short(item.doc_value()),
                             parent,
                             parent_idx: None,
                             search_type: get_index_search_type(&item),
@@ -1673,7 +1673,7 @@ impl<'a> Cache {
                                 ty: item.type_(),
                                 name: item_name.to_string(),
                                 path: path.clone(),
-                                desc: plain_summary_line(item.doc_value()),
+                                desc: plain_summary_line_short(item.doc_value()),
                                 parent: None,
                                 parent_idx: None,
                                 search_type: get_index_search_type(&item),
@@ -2388,7 +2388,13 @@ fn shorter<'a>(s: Option<&'a str>) -> String {
 #[inline]
 fn plain_summary_line(s: Option<&str>) -> String {
     let line = shorter(s).replace("\n", " ");
-    markdown::plain_summary_line(&line[..])
+    markdown::plain_summary_line_full(&line[..], false)
+}
+
+#[inline]
+fn plain_summary_line_short(s: Option<&str>) -> String {
+    let line = shorter(s).replace("\n", " ");
+    markdown::plain_summary_line_full(&line[..], true)
 }
 
 fn document(w: &mut fmt::Formatter, cx: &Context, item: &clean::Item) -> fmt::Result {