frontend: Show feature flags in topbar

So far features were stored only in database.
Show them in the topbar menu.

src/db/types.rs

@@ -1,3 +1,4 @@
+use failure::_core::fmt::Formatter;
 use postgres_types::{FromSql, ToSql};
 use serde::Serialize;
 
@@ -12,4 +13,14 @@ impl Feature {
     pub fn new(name: String, subfeatures: Vec<String>) -> Self {
         Feature { name, subfeatures }
     }
+
+    pub fn is_private(&self) -> bool {
+        self.name.starts_with('_')
+    }
+}
+
+impl std::fmt::Display for Feature {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{} = {:?}", self.name, self.subfeatures)
+    }
 }

src/test/fakes.rs

@@ -210,6 +210,11 @@ impl<'a> FakeRelease<'a> {
         self
     }
 
+    pub(crate) fn features(mut self, features: HashMap<String, Vec<String>>) -> Self {
+        self.package.features = features;
+        self
+    }
+
     /// Returns the release_id
     pub(crate) fn create(self) -> Result<i32, Error> {
         use std::fs;

src/web/crate_details.rs

@@ -103,6 +103,7 @@ impl CrateDetails {
                 releases.license,
                 releases.documentation_url,
                 releases.default_target,
+                releases.features,
                 doc_coverage.total_items,
                 doc_coverage.documented_items,
                 doc_coverage.total_items_needing_examples,
@@ -148,6 +149,7 @@ impl CrateDetails {
             default_target: krate.get("default_target"),
             doc_targets: MetaData::parse_doc_targets(krate.get("doc_targets")),
             yanked: krate.get("yanked"),
+            features: MetaData::parse_features(krate.get("features")),
         };
 
         let documented_items: Option<i32> = krate.get("documented_items");
@@ -325,6 +327,7 @@ mod tests {
     use crate::test::{wrapper, TestDatabase};
     use failure::Error;
     use kuchiki::traits::TendrilSink;
+    use std::collections::HashMap;
 
     fn assert_last_successful_build_equals(
         db: &TestDatabase,
@@ -741,4 +744,42 @@ mod tests {
             Ok(())
         });
     }
+
+    #[test]
+    fn feature_flags_is_hidden_when_empty() {
+        wrapper(|env| {
+            env.fake_release()
+                .name("binary")
+                .version("0.1.0")
+                .binary(true)
+                .features(HashMap::new())
+                .create()?;
+
+            let page = kuchiki::parse_html()
+                .one(env.frontend().get("/crate/binary/0.1.0").send()?.text()?);
+            assert!(page.select_first(r#"a[aria-label="Feature"]"#).is_err());
+            Ok(())
+        });
+    }
+
+    #[test]
+    fn feature_private_feature_flags_are_hidden() {
+        wrapper(|env| {
+            let features = [("_private".into(), Vec::new())]
+                .iter()
+                .cloned()
+                .collect::<HashMap<String, Vec<String>>>();
+            env.fake_release()
+                .name("binary")
+                .version("0.1.0")
+                .binary(true)
+                .features(features)
+                .create()?;
+
+            let page = kuchiki::parse_html()
+                .one(env.frontend().get("/crate/binary/0.1.0").send()?.text()?);
+            assert!(page.select_first(r#"a[aria-label="Feature"]"#).is_err());
+            Ok(())
+        });
+    }
 }

src/web/mod.rs

@@ -90,6 +90,7 @@ mod sitemap;
 mod source;
 mod statics;
 
+use crate::db::types::Feature;
 use crate::{impl_webpage, Context};
 use chrono::{DateTime, Utc};
 use error::Nope;
@@ -519,6 +520,7 @@ pub(crate) struct MetaData {
     pub(crate) default_target: String,
     pub(crate) doc_targets: Vec<String>,
     pub(crate) yanked: bool,
+    pub(crate) features: Option<Vec<String>>,
 }
 
 impl MetaData {
@@ -532,7 +534,8 @@ impl MetaData {
                        releases.rustdoc_status,
                        releases.default_target,
                        releases.doc_targets,
-                       releases.yanked
+                       releases.yanked,
+                       releases.features
                 FROM releases
                 INNER JOIN crates ON crates.id = releases.crate_id
                 WHERE crates.name = $1 AND releases.version = $2",
@@ -551,6 +554,7 @@ impl MetaData {
             default_target: row.get(5),
             doc_targets: MetaData::parse_doc_targets(row.get(6)),
             yanked: row.get(7),
+            features: MetaData::parse_features(row.get(8)),
         })
     }
 
@@ -565,6 +569,15 @@ impl MetaData {
             })
             .unwrap_or_else(Vec::new)
     }
+
+    fn parse_features(features: Option<Vec<Feature>>) -> Option<Vec<String>> {
+        features.map(|vec| {
+            vec.iter()
+                .filter(|feature| !feature.is_private())
+                .map(|feature| feature.to_string())
+                .collect()
+        })
+    }
 }
 
 #[derive(Debug, Clone, PartialEq, Serialize)]
@@ -843,6 +856,7 @@ mod test {
                 "arm64-unknown-linux-gnu".to_string(),
             ],
             yanked: false,
+            features: None,
         };
 
         let correct_json = json!({
@@ -857,6 +871,7 @@ mod test {
                 "arm64-unknown-linux-gnu",
             ],
             "yanked": false,
+            "features": null
         });
 
         assert_eq!(correct_json, serde_json::to_value(&metadata).unwrap());
@@ -874,6 +889,7 @@ mod test {
                 "arm64-unknown-linux-gnu",
             ],
             "yanked": false,
+            "features": null,
         });
 
         assert_eq!(correct_json, serde_json::to_value(&metadata).unwrap());
@@ -891,6 +907,7 @@ mod test {
                 "arm64-unknown-linux-gnu",
             ],
             "yanked": false,
+            "features": null,
         });
 
         assert_eq!(correct_json, serde_json::to_value(&metadata).unwrap());

src/web/source.rs

@@ -58,7 +58,8 @@ impl FileList {
                         releases.files,
                         releases.default_target,
                         releases.doc_targets,
-                        releases.yanked
+                        releases.yanked,
+                        releases.features
                 FROM releases
                 LEFT OUTER JOIN crates ON crates.id = releases.crate_id
                 WHERE crates.name = $1 AND releases.version = $2",
@@ -137,6 +138,7 @@ impl FileList {
                     default_target: rows[0].get(6),
                     doc_targets: MetaData::parse_doc_targets(rows[0].get(7)),
                     yanked: rows[0].get(8),
+                    features: MetaData::parse_features(rows[0].get(9)),
                 },
                 files: file_list,
             })

templates/rustdoc/topbar.html

@@ -226,7 +226,26 @@
                 </li>
             {%- endfor -%}
         </ul>
-    </li>
+    </li>{#
+    Display the features available in current build
+    #}
+    {%- if metadata.features -%}
+        <li class="pure-menu-item pure-menu-has-children">
+            <a href="#" class="pure-menu-link" aria-label="Features">
+                {{ "flag" | fas }}
+                <span class="title">Feature flags</span>
+            </a>
+
+            {# Build the dropdown list showing available features #}
+            <ul class="pure-menu-children">
+                {%- for feature in metadata.features -%}
+                    <li class="pure-menu-item">
+                        <span class="pure-menu-link">{{ feature }}</span>
+                    </li>
+                {%- endfor -%}
+            </ul>
+        </li>
+    {%- endif -%}
 </ul>
 
 {%- include "header/topbar_end.html" -%}