auto merge of #20990 : estsauver/rust/playpen_20732, r=alexcrichton

In #20732, that all links in some modules point to the same code
examples was reported. The ID's generated for documents in
librustdoc are not all unique, which means the code rendered as
text is not being properly selected.

This change makes the link to the code section that is next to
the current link.

src/librustdoc/html/markdown.rs

@@ -30,7 +30,7 @@
 use libc;
 use std::ascii::AsciiExt;
 use std::ffi::CString;
-use std::cell::{RefCell, Cell};
+use std::cell::RefCell;
 use std::collections::HashMap;
 use std::fmt;
 use std::slice;
@@ -155,7 +155,6 @@ fn stripped_filtered_line<'a>(s: &'a str) -> Option<&'a str> {
 thread_local!(static USED_HEADER_MAP: RefCell<HashMap<String, uint>> = {
     RefCell::new(HashMap::new())
 });
-thread_local!(static TEST_IDX: Cell<uint> = Cell::new(0));
 
 thread_local!(pub static PLAYGROUND_KRATE: RefCell<Option<Option<String>>> = {
     RefCell::new(None)
@@ -195,26 +194,19 @@ pub fn render(w: &mut fmt::Formatter, s: &str, print_toc: bool) -> fmt::Result {
             if rendered { return }
             PLAYGROUND_KRATE.with(|krate| {
                 let mut s = String::new();
-                let id = krate.borrow().as_ref().map(|krate| {
-                    let idx = TEST_IDX.with(|slot| {
-                        let i = slot.get();
-                        slot.set(i + 1);
-                        i
-                    });
-
+                krate.borrow().as_ref().map(|krate| {
                     let test = origtext.lines().map(|l| {
                         stripped_filtered_line(l).unwrap_or(l)
                     }).collect::<Vec<&str>>().connect("\n");
                     let krate = krate.as_ref().map(|s| s.as_slice());
                     let test = test::maketest(test.as_slice(), krate, false, false);
-                    s.push_str(format!("<span id='rust-example-raw-{}' \
-                                         class='rusttest'>{}</span>",
-                                       idx, Escape(test.as_slice())).as_slice());
-                    format!("rust-example-rendered-{}", idx)
+                    s.push_str(format!("<span class='rusttest'>{}</span>",
+                                         Escape(test.as_slice())).as_slice());
                 });
-                let id = id.as_ref().map(|a| a.as_slice());
-                s.push_str(highlight::highlight(text.as_slice(), None, id)
-                                     .as_slice());
+                s.push_str(highlight::highlight(text.as_slice(),
+                                                None,
+                                                Some("rust-example-rendered"))
+                             .as_slice());
                 let output = CString::from_vec(s.into_bytes());
                 hoedown_buffer_puts(ob, output.as_ptr());
             })
@@ -432,7 +424,6 @@ impl LangString {
 /// previous state (if any).
 pub fn reset_headers() {
     USED_HEADER_MAP.with(|s| s.borrow_mut().clear());
-    TEST_IDX.with(|s| s.set(0));
 }
 
 impl<'a> fmt::String for Markdown<'a> {

src/librustdoc/html/static/playpen.js

@@ -14,10 +14,8 @@
 (function() {
     if (window.playgroundUrl) {
         $('pre.rust').hover(function() {
-            if (!$(this).attr('id')) { return; }
-            var id = '#' + $(this).attr('id').replace('rendered', 'raw');
             var a = $('<a>').text('⇱').attr('class', 'test-arrow');
-            var code = $(id).text();
+            var code = $(this).siblings(".rusttest").text();
             a.attr('href', window.playgroundUrl + '?code=' +
                            encodeURIComponent(code));
             a.attr('target', '_blank');