rustdoc: format where clauses like rust-lang-nursery/fmt-rfcs#38

3 files changed, 55 insertions, 81 deletions

diff --git a/src/librustdoc/html/format.rs b/src/librustdoc/html/format.rs
index 3589cc8fac6..3fb90f407eb 100644
--- a/src/librustdoc/html/format.rs
+++ b/src/librustdoc/html/format.rs
@@ -49,14 +49,19 @@ pub struct MutableSpace(pub clean::Mutability);
 /// Similar to VisSpace, but used for mutability
 #[derive(Copy, Clone)]
 pub struct RawMutableSpace(pub clean::Mutability);
-/// Wrapper struct for emitting a where clause from Generics.
-pub struct WhereClause<'a>(pub &'a clean::Generics, pub usize);
 /// Wrapper struct for emitting type parameter bounds.
 pub struct TyParamBounds<'a>(pub &'a [clean::TyParamBound]);
 /// Wrapper struct for emitting a comma-separated list of items
 pub struct CommaSep<'a, T: 'a>(pub &'a [T]);
 pub struct AbiSpace(pub Abi);
 
+/// Wrapper struct for emitting a where clause from Generics.
+pub struct WhereClause<'a>{
+    pub gens: &'a clean::Generics,
+    pub indent: usize,
+    pub end_newline: bool,
+}
+
 pub struct HRef<'a> {
     pub did: DefId,
     pub text: &'a str,
@@ -167,24 +172,27 @@ impl fmt::Display for clean::Generics {
 
 impl<'a> fmt::Display for WhereClause<'a> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        let &WhereClause(gens, pad) = self;
+        let &WhereClause{ gens, indent, end_newline } = self;
         if gens.where_predicates.is_empty() {
             return Ok(());
         }
         let mut clause = String::new();
         if f.alternate() {
-            clause.push_str(" where ");
+            clause.push_str(" where");
         } else {
-            clause.push_str(" <span class=\"where fmt-newline\">where ");
+            if end_newline {
+                clause.push_str("<span class=\"where fmt-newline\">where");
+            } else {
+                clause.push_str("<span class=\"where\">where");
+            }
         }
         for (i, pred) in gens.where_predicates.iter().enumerate() {
-            if i > 0 {
-                if f.alternate() {
-                    clause.push_str(", ");
-                } else {
-                    clause.push_str(",<br>");
-                }
+            if f.alternate() {
+                clause.push(' ');
+            } else {
+                clause.push_str("<br>");
             }
+
             match pred {
                 &clean::WherePredicate::BoundPredicate { ref ty, ref bounds } => {
                     let bounds = bounds;
@@ -213,21 +221,18 @@ impl<'a> fmt::Display for WhereClause<'a> {
                     }
                 }
             }
+
+            if i < gens.where_predicates.len() - 1 || end_newline {
+                clause.push(',');
+            }
         }
         if !f.alternate() {
             clause.push_str("</span>");
-            let plain = format!("{:#}", self);
-            if plain.len() + pad > 80 {
-                // break it onto its own line regardless, but make sure method impls and trait
-                // blocks keep their fixed padding (2 and 9, respectively)
-                let padding = if pad > 10 {
-                    repeat("&nbsp;").take(8).collect::<String>()
-                } else {
-                    repeat("&nbsp;").take(pad + 6).collect::<String>()
-                };
-                clause = clause.replace("<br>", &format!("<br>{}", padding));
-            } else {
-                clause = clause.replace("<br>", " ");
+            let padding = repeat("&nbsp;").take(indent + 4).collect::<String>();
+            clause = clause.replace("<br>", &format!("<br>{}", padding));
+            clause.insert_str(0, &repeat("&nbsp;").take(indent).collect::<String>());
+            if !end_newline {
+                clause.insert_str(0, "<br>");
             }
         }
         write!(f, "{}", clause)
@@ -838,43 +843,35 @@ fn fmt_impl(i: &clean::Impl,
             f: &mut fmt::Formatter,
             link_trait: bool,
             use_absolute: bool) -> fmt::Result {
-    let mut plain = String::new();
-
     if f.alternate() {
         write!(f, "impl{:#} ", i.generics)?;
     } else {
         write!(f, "impl{} ", i.generics)?;
     }
-    plain.push_str(&format!("impl{:#} ", i.generics));
 
     if let Some(ref ty) = i.trait_ {
         if i.polarity == Some(clean::ImplPolarity::Negative) {
             write!(f, "!")?;
-            plain.push_str("!");
         }
 
         if link_trait {
             fmt::Display::fmt(ty, f)?;
-            plain.push_str(&format!("{:#}", ty));
         } else {
             match *ty {
                 clean::ResolvedPath { typarams: None, ref path, is_generic: false, .. } => {
                     let last = path.segments.last().unwrap();
                     fmt::Display::fmt(&last.name, f)?;
                     fmt::Display::fmt(&last.params, f)?;
-                    plain.push_str(&format!("{:#}{:#}", last.name, last.params));
                 }
                 _ => unreachable!(),
             }
         }
         write!(f, " for ")?;
-        plain.push_str(" for ");
     }
 
     fmt_type(&i.for_, f, use_absolute, true)?;
-    plain.push_str(&format!("{:#}", i.for_));
 
-    fmt::Display::fmt(&WhereClause(&i.generics, plain.len() + 1), f)?;
+    fmt::Display::fmt(&WhereClause{ gens: &i.generics, indent: 0, end_newline: true }, f)?;
     Ok(())
 }
 
diff --git a/src/librustdoc/html/render.rs b/src/librustdoc/html/render.rs
index c571bcb08e4..4eb228ce68f 100644
--- a/src/librustdoc/html/render.rs
+++ b/src/librustdoc/html/render.rs
@@ -2012,7 +2012,7 @@ fn item_function(w: &mut fmt::Formatter, cx: &Context, it: &clean::Item,
            abi = AbiSpace(f.abi),
            name = it.name.as_ref().unwrap(),
            generics = f.generics,
-           where_clause = WhereClause(&f.generics, 2),
+           where_clause = WhereClause { gens: &f.generics, indent: 0, end_newline: true },
            decl = Method(&f.decl, indent))?;
     document(w, cx, it)
 }
@@ -2047,8 +2047,7 @@ fn item_trait(w: &mut fmt::Formatter, cx: &Context, it: &clean::Item,
            it.name.as_ref().unwrap(),
            t.generics,
            bounds,
-           // Where clauses in traits are indented nine spaces, per rustdoc.css
-           WhereClause(&t.generics, 9))?;
+           WhereClause { gens: &t.generics, indent: 0, end_newline: true })?;
 
     let types = t.items.iter().filter(|m| m.is_associated_type()).collect::<Vec<_>>();
     let consts = t.items.iter().filter(|m| m.is_associated_const()).collect::<Vec<_>>();
@@ -2087,7 +2086,14 @@ fn item_trait(w: &mut fmt::Formatter, cx: &Context, it: &clean::Item,
         for m in &provided {
             write!(w, "    ")?;
             render_assoc_item(w, m, AssocItemLink::Anchor(None), ItemType::Trait)?;
-            write!(w, " {{ ... }}\n")?;
+            match m.inner {
+                clean::MethodItem(ref inner) if !inner.generics.where_predicates.is_empty() => {
+                    write!(w, ",\n    {{ ... }}\n")?;
+                },
+                _ => {
+                    write!(w, " {{ ... }}\n")?;
+                },
+            }
         }
         write!(w, "}}")?;
     }
@@ -2327,14 +2333,14 @@ fn render_assoc_item(w: &mut fmt::Formatter,
                              name,
                              *g);
         let mut indent = prefix.len();
-        let where_indent = if parent == ItemType::Trait {
+        let (where_indent, end_newline) = if parent == ItemType::Trait {
             indent += 4;
-            8
+            (4, false)
         } else if parent == ItemType::Impl {
-            2
+            (0, true)
         } else {
             let prefix = prefix + &format!("{:#}", Method(d, indent));
-            prefix.lines().last().unwrap().len() + 1
+            (prefix.lines().last().unwrap().len() + 1, true)
         };
         write!(w, "{}{}{}fn <a href='{href}' class='fnname'>{name}</a>\
                    {generics}{decl}{where_clause}",
@@ -2345,7 +2351,11 @@ fn render_assoc_item(w: &mut fmt::Formatter,
                name = name,
                generics = *g,
                decl = Method(d, indent),
-               where_clause = WhereClause(g, where_indent))
+               where_clause = WhereClause {
+                   gens: g,
+                   indent: where_indent,
+                   end_newline: end_newline,
+               })
     }
     match item.inner {
         clean::StrippedItem(..) => Ok(()),
@@ -2458,15 +2468,11 @@ fn item_enum(w: &mut fmt::Formatter, cx: &Context, it: &clean::Item,
              e: &clean::Enum) -> fmt::Result {
     write!(w, "<pre class='rust enum'>")?;
     render_attributes(w, it)?;
-    let padding = format!("{}enum {}{:#} ",
-                          VisSpace(&it.visibility),
-                          it.name.as_ref().unwrap(),
-                          e.generics).len();
     write!(w, "{}enum {}{}{}",
            VisSpace(&it.visibility),
            it.name.as_ref().unwrap(),
            e.generics,
-           WhereClause(&e.generics, padding))?;
+           WhereClause { gens: &e.generics, indent: 0, end_newline: true })?;
     if e.variants.is_empty() && !e.variants_stripped {
         write!(w, " {{}}")?;
     } else {
@@ -2640,23 +2646,17 @@ fn render_struct(w: &mut fmt::Formatter, it: &clean::Item,
                  fields: &[clean::Item],
                  tab: &str,
                  structhead: bool) -> fmt::Result {
-    let mut plain = String::new();
     write!(w, "{}{}{}",
            VisSpace(&it.visibility),
            if structhead {"struct "} else {""},
            it.name.as_ref().unwrap())?;
-    plain.push_str(&format!("{}{}{}",
-                            VisSpace(&it.visibility),
-                            if structhead {"struct "} else {""},
-                            it.name.as_ref().unwrap()));
     if let Some(g) = g {
-        plain.push_str(&format!("{:#}", g));
         write!(w, "{}", g)?
     }
     match ty {
         doctree::Plain => {
             if let Some(g) = g {
-                write!(w, "{}", WhereClause(g, plain.len() + 1))?
+                write!(w, "{}", WhereClause { gens: g, indent: 0, end_newline: true })?
             }
             let mut has_visible_fields = false;
             write!(w, " {{")?;
@@ -2685,35 +2685,30 @@ fn render_struct(w: &mut fmt::Formatter, it: &clean::Item,
         }
         doctree::Tuple => {
             write!(w, "(")?;
-            plain.push_str("(");
             for (i, field) in fields.iter().enumerate() {
                 if i > 0 {
                     write!(w, ", ")?;
-                    plain.push_str(", ");
                 }
                 match field.inner {
                     clean::StrippedItem(box clean::StructFieldItem(..)) => {
-                        plain.push_str("_");
                         write!(w, "_")?
                     }
                     clean::StructFieldItem(ref ty) => {
-                        plain.push_str(&format!("{}{:#}", VisSpace(&field.visibility), *ty));
                         write!(w, "{}{}", VisSpace(&field.visibility), *ty)?
                     }
                     _ => unreachable!()
                 }
             }
             write!(w, ")")?;
-            plain.push_str(")");
             if let Some(g) = g {
-                write!(w, "{}", WhereClause(g, plain.len() + 1))?
+                write!(w, "{}", WhereClause { gens: g, indent: 0, end_newline: true })?
             }
             write!(w, ";")?;
         }
         doctree::Unit => {
             // Needed for PhantomData.
             if let Some(g) = g {
-                write!(w, "{}", WhereClause(g, plain.len() + 1))?
+                write!(w, "{}", WhereClause { gens: g, indent: 0, end_newline: true })?
             }
             write!(w, ";")?;
         }
@@ -2726,19 +2721,13 @@ fn render_union(w: &mut fmt::Formatter, it: &clean::Item,
                 fields: &[clean::Item],
                 tab: &str,
                 structhead: bool) -> fmt::Result {
-    let mut plain = String::new();
     write!(w, "{}{}{}",
            VisSpace(&it.visibility),
            if structhead {"union "} else {""},
            it.name.as_ref().unwrap())?;
-    plain.push_str(&format!("{}{}{}",
-                            VisSpace(&it.visibility),
-                            if structhead {"union "} else {""},
-                            it.name.as_ref().unwrap()));
     if let Some(g) = g {
         write!(w, "{}", g)?;
-        plain.push_str(&format!("{:#}", g));
-        write!(w, "{}", WhereClause(g, plain.len() + 1))?;
+        write!(w, "{}", WhereClause { gens: g, indent: 0, end_newline: true })?;
     }
 
     write!(w, " {{\n{}", tab)?;
@@ -3037,13 +3026,12 @@ fn render_impl(w: &mut fmt::Formatter, cx: &Context, i: &Impl, link: AssocItemLi
 
 fn item_typedef(w: &mut fmt::Formatter, cx: &Context, it: &clean::Item,
                 t: &clean::Typedef) -> fmt::Result {
-    let indent = format!("type {}{:#} ", it.name.as_ref().unwrap(), t.generics).len();
     write!(w, "<pre class='rust typedef'>")?;
     render_attributes(w, it)?;
     write!(w, "type {}{}{where_clause} = {type_};</pre>",
            it.name.as_ref().unwrap(),
            t.generics,
-           where_clause = WhereClause(&t.generics, indent),
+           where_clause = WhereClause { gens: &t.generics, indent: 0, end_newline: true },
            type_ = t.type_)?;
 
     document(w, cx, it)
diff --git a/src/librustdoc/html/static/rustdoc.css b/src/librustdoc/html/static/rustdoc.css
index 4047f6045bc..77ae2b58704 100644
--- a/src/librustdoc/html/static/rustdoc.css
+++ b/src/librustdoc/html/static/rustdoc.css
@@ -379,12 +379,6 @@ h4 > code, h3 > code, .invisible > code {
 .content .where.fmt-newline {
 	display: block;
 }
-/* Bit of whitespace to indent it */
-.content .method .where::before,
-.content .fn .where::before,
-.content .where.fmt-newline::before {
-	content: '  ';
-}
 
 .content .methods > div { margin-left: 40px; }
 
@@ -399,11 +393,6 @@ h4 > code, h3 > code, .invisible > code {
 	font-size: 90%;
 }
 
-/* Shift where in trait listing down a line */
-pre.trait .where::before {
-	content: '\a         ';
-}
-
 nav {
 	border-bottom: 1px solid;
 	padding-bottom: 10px;
@@ -772,4 +761,4 @@ span.since {
 	nav.sub, .content .out-of-band, .collapse-toggle {
 		display: none;
 	}
-}
\ No newline at end of file
+}