Syntactic highlighting of NAME_REF for injections

This commit adds a function that tries to determine the syntax highlighting class of NAME_REFs based on the usage.
It is used for highlighting injections (such as highlighting of doctests) as the semantic logic will most of the time result in unresolved references.
It also adds a color to unresolved references in HTML encoding.

1 files changed, 17 insertions, 6 deletions

diff --git a/crates/ra_ide/src/snapshots/highlight_doctest.html b/crates/ra_ide/src/snapshots/highlight_doctest.html
index 0ae8c7efc..5228df267 100644
--- a/crates/ra_ide/src/snapshots/highlight_doctest.html
+++ b/crates/ra_ide/src/snapshots/highlight_doctest.html
@@ -25,22 +25,29 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 .variable           { color: #DCDCCC; }
 .format_specifier   { color: #CC696B; }
 .mutable            { text-decoration: underline; }
+.unresolved_reference { color: #FC5555; }
 
 .keyword            { color: #F0DFAF; font-weight: bold; }
 .keyword.unsafe     { color: #BC8383; font-weight: bold; }
 .control            { font-style: italic; }
 </style>
-<pre><code><span class="keyword">impl</span> <span class="unresolved_reference">Foo</span> {
+<pre><code><span class="keyword">struct</span> <span class="struct declaration">Foo</span> {
+    <span class="field declaration">bar</span>: <span class="builtin_type">bool</span>,
+}
+
+<span class="keyword">impl</span> <span class="struct">Foo</span> {
+    <span class="keyword">pub</span> <span class="keyword">const</span> <span class="constant declaration">bar</span>: <span class="builtin_type">bool</span> = <span class="bool_literal">true</span>;
+
     <span class="comment">/// Constructs a new `Foo`.</span>
     <span class="comment">///</span>
     <span class="comment">/// # Examples</span>
     <span class="comment">///</span>
     <span class="comment">/// ```</span>
     <span class="comment">/// #</span> <span class="attribute">#![</span><span class="function attribute">allow</span><span class="attribute">(unused_mut)]</span>
-    <span class="comment">/// </span><span class="keyword">let</span> <span class="keyword">mut</span> <span class="variable declaration mutable">foo</span>: <span class="unresolved_reference">Foo</span> = <span class="unresolved_reference">Foo</span>::<span class="unresolved_reference">new</span>();
+    <span class="comment">/// </span><span class="keyword">let</span> <span class="keyword">mut</span> <span class="variable declaration mutable">foo</span>: <span class="struct">Foo</span> = <span class="struct">Foo</span>::<span class="function">new</span>();
     <span class="comment">/// ```</span>
-    <span class="keyword">pub</span> <span class="keyword">const</span> <span class="keyword">fn</span> <span class="function declaration">new</span>() -&gt; <span class="unresolved_reference">Foo</span> {
-        <span class="unresolved_reference">Foo</span> { }
+    <span class="keyword">pub</span> <span class="keyword">const</span> <span class="keyword">fn</span> <span class="function declaration">new</span>() -&gt; <span class="struct">Foo</span> {
+        <span class="struct">Foo</span> { <span class="field">bar</span>: <span class="bool_literal">true</span> }
     }
 
     <span class="comment">/// `bar` method on `Foo`.</span>
@@ -48,11 +55,15 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <span class="comment">/// # Examples</span>
     <span class="comment">///</span>
     <span class="comment">/// ```</span>
-    <span class="comment">/// </span><span class="keyword">let</span> <span class="variable declaration">foo</span> = <span class="unresolved_reference">Foo</span>::<span class="unresolved_reference">new</span>();
+    <span class="comment">/// </span><span class="keyword">use</span> <span class="module">x</span>::<span class="module">y</span>;
+    <span class="comment">///</span>
+    <span class="comment">/// </span><span class="keyword">let</span> <span class="variable declaration">foo</span> = <span class="struct">Foo</span>::<span class="function">new</span>();
     <span class="comment">///</span>
     <span class="comment">/// </span><span class="comment">// calls bar on foo</span>
     <span class="comment">/// </span><span class="macro">assert!</span>(foo.bar());
     <span class="comment">///</span>
+    <span class="comment">/// </span><span class="keyword">let</span> <span class="variable declaration">bar</span> = <span class="variable">foo</span>.<span class="field">bar</span> || <span class="struct">Foo</span>::<span class="constant">bar</span>;
+    <span class="comment">///</span>
     <span class="comment">/// </span><span class="comment">/* multi-line
     </span><span class="comment">/// </span><span class="comment">       comment */</span>
     <span class="comment">///</span>
@@ -63,7 +74,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <span class="comment">/// ```</span>
     <span class="comment">///</span>
     <span class="comment">/// ```</span>
-    <span class="comment">/// </span><span class="keyword">let</span> <span class="variable declaration">foobar</span> = <span class="unresolved_reference">Foo</span>::<span class="unresolved_reference">new</span>().<span class="unresolved_reference">bar</span>();
+    <span class="comment">/// </span><span class="keyword">let</span> <span class="variable declaration">foobar</span> = <span class="struct">Foo</span>::<span class="function">new</span>().<span class="function">bar</span>();
     <span class="comment">/// ```</span>
     <span class="keyword">pub</span> <span class="keyword">fn</span> <span class="function declaration">foo</span>(&<span class="self_keyword">self</span>) -&gt; <span class="builtin_type">bool</span> {
         <span class="bool_literal">true</span>