core: convert vec::{head,head_opt} to return references

src/librustdoc/config.rs

@@ -132,7 +132,7 @@ pub fn parse_config_(
     match getopts::getopts(args, opts) {
         result::Ok(matches) => {
             if matches.free.len() == 1 {
-                let input_crate = Path(vec::head(matches.free));
+                let input_crate = Path(copy *matches.free.head());
                 config_from_opts(&input_crate, &matches, program_output)
             } else if matches.free.is_empty() {
                 result::Err(~"no crates specified")

src/librustdoc/desc_to_brief_pass.rs

@@ -144,14 +144,14 @@ fn parse_desc(desc: ~str) -> Option<~str> {
 fn first_sentence(s: ~str) -> Option<~str> {
     let paras = paragraphs(s);
     if !paras.is_empty() {
-        let first_para = vec::head(paras);
-        Some(str::replace(first_sentence_(first_para), ~"\n", ~" "))
+        let first_para = paras.head();
+        Some(str::replace(first_sentence_(*first_para), ~"\n", ~" "))
     } else {
         None
     }
 }
 
-fn first_sentence_(s: ~str) -> ~str {
+fn first_sentence_(s: &str) -> ~str {
     let mut dotcount = 0;
     // The index of the character following a single dot. This allows
     // Things like [0..1) to appear in the brief description
@@ -169,16 +169,16 @@ fn first_sentence_(s: ~str) -> ~str {
         }
     };
     match idx {
-      Some(idx) if idx > 2u => {
-        str::slice(s, 0u, idx - 1u)
-      }
-      _ => {
-        if str::ends_with(s, ~".") {
-            str::slice(s, 0u, str::len(s))
-        } else {
-            copy s
+        Some(idx) if idx > 2u => {
+            str::from_slice(str::view(s, 0, idx - 1))
+        }
+        _ => {
+            if str::ends_with(s, ~".") {
+                str::from_slice(s)
+            } else {
+                str::from_slice(s)
+            }
         }
-      }
     }
 }
 

src/librustdoc/unindent_pass.rs

@@ -78,7 +78,7 @@ fn unindent(s: &str) -> ~str {
     };
 
     if !lines.is_empty() {
-        let unindented = ~[str::trim(vec::head(lines))]
+        let unindented = ~[lines.head().trim()]
             + do vec::tail(lines).map |line| {
             if str::is_whitespace(*line) {
                 copy *line