Conditionally show compile warnings when running code

book-example/src/SUMMARY.md

@@ -14,7 +14,7 @@
     - [Configuration](format/config.md)
     - [Theme](format/theme/README.md)
         - [index.hbs](format/theme/index-hbs.md)
-        - [Syntax highlighting](format/theme/syntax-highlighting.md)
+        - [Code Blocks](format/theme/code-blocks.md)
         - [Editor](format/theme/editor.md)
     - [MathJax Support](format/mathjax.md)
     - [mdBook specific features](format/mdbook.md)

book-example/src/format/theme/syntax-highlighting.md → book-example/src/format/theme/code-blocks.md

@@ -1,17 +1,51 @@
-# Syntax Highlighting
-
-For syntax highlighting I use [Highlight.js](https://highlightjs.org) with a
-custom theme.
+# Code Blocks
 
+Syntax highlighted code blocks are supported using [Highlight.js](https://highlightjs.org)
+with a custom theme.  
 Automatic language detection has been turned off, so you will probably want to
 specify the programming language you use like this
-
 <pre><code class="language-markdown">```rust
 fn main() {
     // Some code
 }
 ```</code></pre>
 
+## Run Button
+Rust code blocks are runnable by default with a run button, for example:
+```rust
+fn main() {
+    println!("hello");
+}
+```
+Other languages are currently not supported.
+
+You can also diable the run button with `no_run`:
+<pre><code class="language-markdown">```rust,no_run
+fn main() {
+    println!("Not runnable.");
+}
+```</code></pre>
+
+```rust,no_run
+fn main() {
+    println!("Not runnable.");
+}
+```
+### Show Warnings
+
+It is possible to show warning when Rust code is run via adding `warn`:
+<pre><code class="language-markdown">```rust,warn
+fn main() {
+    let unused = 7;
+}
+```</code></pre>
+
+```rust,warn
+fn main() {
+    let unused = 7;
+}
+```
+
 ## Custom theme
 Like the rest of the theme, the files used for syntax highlighting can be
 overridden with your own.

src/theme/book.js

@@ -98,33 +98,45 @@ function playground_text(playground) {
     }
 
     function run_rust_code(code_block) {
-        var result_block = code_block.querySelector(".result");
+        var result_stderr_block = code_block.querySelector(".result.stderr");
+        if (!result_stderr_block) {
+            result_stderr_block = document.createElement('code');
+            result_stderr_block.className = 'result stderr hljs nohighlight';
+
+            code_block.append(result_stderr_block);
+        }
+        var result_block = code_block.querySelector(".result.stdout");
         if (!result_block) {
             result_block = document.createElement('code');
-            result_block.className = 'result hljs language-bash';
+            result_block.className = 'result stdout hljs nohighlight';
 
             code_block.append(result_block);
         }
 
         let text = playground_text(code_block);
         let classes = code_block.querySelector('code').classList;
         let has_2018 = classes.contains("edition2018");
+        let should_warn = classes.contains("warn")
         let edition = has_2018 ? "2018" : "2015";
 
         var params = {
-            version: "stable",
-            optimize: "0",
+            backtrace: true,
+            channel: "stable",
             code: text,
-            edition: edition
+            edition: edition,
+            mode: "debug",
+            tests: false,
+            crateType: "bin",
         };
 
         if (text.indexOf("#![feature") !== -1) {
             params.version = "nightly";
         }
 
+        result_stderr_block.classList.add("hidden");
         result_block.innerText = "Running...";
 
-        fetch_with_timeout("https://play.rust-lang.org/evaluate.json", {
+        fetch_with_timeout("https://play.rust-lang.org/execute", {
             headers: {
                 'Content-Type': "application/json",
             },
@@ -133,7 +145,15 @@ function playground_text(playground) {
             body: JSON.stringify(params)
         })
         .then(response => response.json())
-        .then(response => result_block.innerText = response.result)
+        .then(response => {
+            result_block.innerText = response.stdout;
+            var show_warnings = should_warn && response.stderr.includes("warning");
+            // show stderr block if there is compile error or warning
+            if (!response.success || show_warnings) {
+                result_stderr_block.innerText = response.stderr;
+                result_stderr_block.classList.remove("hidden");
+            }
+        })
         .catch(error => result_block.innerText = "Playground Communication: " + error.message);
     }
 

tests/summary_md_files/example_book.md

@@ -12,7 +12,7 @@
     - [Configuration](format/config.md)
     - [Theme](format/theme/theme.md)
         - [index.hbs](format/theme/index-hbs.md)
-        - [Syntax highlighting](format/theme/syntax-highlighting.md)
+        - [Code Blocks](format/theme/code-blocks.md)
     - [MathJax Support](format/mathjax.md)
     - [Rust code specific features](format/rust.md)
 - [Rust Library](lib/lib.md)