print doc coverage as a table of individual item types

src/librustdoc/passes/calculate_doc_coverage.rs

@@ -1,12 +1,14 @@
 use crate::clean;
 use crate::core::DocContext;
+use crate::html::item_type::ItemType;
 use crate::fold::{self, DocFolder};
 use crate::passes::Pass;
 
 use syntax::attr;
 
-use std::ops::Sub;
+use std::collections::BTreeMap;
 use std::fmt;
+use std::ops;
 
 pub const CALCULATE_DOC_COVERAGE: Pass = Pass {
     name: "calculate-doc-coverage",
@@ -18,17 +20,7 @@ fn calculate_doc_coverage(krate: clean::Crate, _: &DocContext<'_, '_, '_>) -> cl
     let mut calc = CoverageCalculator::default();
     let krate = calc.fold_crate(krate);
 
-    let non_traits = calc.items - calc.trait_impl_items;
-
-    print!("Rustdoc found {} items with documentation", calc.items);
-    println!(" ({} not counting trait impls)", non_traits);
-
-    if let (Some(percentage), Some(percentage_non_traits)) =
-        (calc.items.percentage(), non_traits.percentage())
-    {
-        println!("    Score: {:.1}% ({:.1}% not counting trait impls)",
-                 percentage, percentage_non_traits);
-    }
+    calc.print_results();
 
     krate
 }
@@ -57,7 +49,7 @@ impl ItemCount {
     }
 }
 
-impl Sub for ItemCount {
+impl ops::Sub for ItemCount {
     type Output = Self;
 
     fn sub(self, rhs: Self) -> Self {
@@ -68,6 +60,13 @@ impl Sub for ItemCount {
     }
 }
 
+impl ops::AddAssign for ItemCount {
+    fn add_assign(&mut self, rhs: Self) {
+        self.total += rhs.total;
+        self.with_docs += rhs.with_docs;
+    }
+}
+
 impl fmt::Display for ItemCount {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "{}/{}", self.with_docs, self.total)
@@ -76,58 +75,183 @@ impl fmt::Display for ItemCount {
 
 #[derive(Default)]
 struct CoverageCalculator {
-    items: ItemCount,
-    trait_impl_items: ItemCount,
+    items: BTreeMap<ItemType, ItemCount>,
+}
+
+impl CoverageCalculator {
+    fn print_results(&self) {
+        use crate::html::item_type::ItemType::*;
+
+        let mut total = ItemCount::default();
+
+        let main_types = [
+            Module, Function,
+            Struct, StructField,
+            Enum, Variant,
+            Union,
+            Method,
+            Trait, TyMethod,
+            AssociatedType, AssociatedConst,
+            Macro,
+            Static, Constant,
+            ForeignType, Existential,
+            Typedef, TraitAlias,
+            Primitive, Keyword,
+        ];
+
+        println!("+-{0:->25}-+-{0:->10}-+-{0:->10}-+-{0:->10}-+", "");
+        println!("| {:<25} | {:>10} | {:>10} | {:>10} |",
+                 "Item Type", "Documented", "Total", "Percentage");
+        println!("+-{0:->25}-+-{0:->10}-+-{0:->10}-+-{0:->10}-+", "");
+
+        for item_type in &main_types {
+            let count = self.items.get(item_type).cloned().unwrap_or_default();
+
+            if let Some(percentage) = count.percentage() {
+                println!("| {:<25} | {:>10} | {:>10} | {:>9.1}% |",
+                         table_name(item_type), count.with_docs, count.total, percentage);
+
+                total += count;
+            }
+        }
+
+        println!("+-{0:->25}-+-{0:->10}-+-{0:->10}-+-{0:->10}-+", "");
+
+        if let Some(count) = self.items.get(&Impl) {
+            if let Some(percentage) = count.percentage() {
+                if let Some(percentage) = total.percentage() {
+                    println!("| {:<25} | {:>10} | {:>10} | {:>9.1}% |",
+                             "Total (non trait impls)", total.with_docs, total.total, percentage);
+                }
+
+                println!("+-{0:->25}-+-{0:->10}-+-{0:->10}-+-{0:->10}-+", "");
+
+                println!("| {:<25} | {:>10} | {:>10} | {:>9.1}% |",
+                         table_name(&Impl), count.with_docs, count.total, percentage);
+
+                println!("+-{0:->25}-+-{0:->10}-+-{0:->10}-+-{0:->10}-+", "");
+
+                total += *count;
+            }
+        }
+
+        println!("| {:<25} | {:>10} | {:>10} | {:>9.1}% |",
+                 "Total", total.with_docs, total.total, total.percentage().unwrap_or(0.0));
+        println!("+-{0:->25}-+-{0:->10}-+-{0:->10}-+-{0:->10}-+", "");
+    }
 }
 
 impl fold::DocFolder for CoverageCalculator {
-    fn fold_item(&mut self, i: clean::Item) -> Option<clean::Item> {
+    fn fold_item(&mut self, mut i: clean::Item) -> Option<clean::Item> {
+        let has_docs = !i.attrs.doc_strings.is_empty();
+
         match i.inner {
+            _ if !i.def_id.is_local() => {
+                // non-local items are skipped because they can be out of the users control,
+                // especially in the case of trait impls, which rustdoc eagerly inlines
+                return Some(i);
+            }
             clean::StrippedItem(..) => {
                 // don't count items in stripped modules
                 return Some(i);
             }
-            clean::ImportItem(..) | clean::ExternCrateItem(..) => {}
+            clean::ImportItem(..) | clean::ExternCrateItem(..) => {
+                // docs on `use` and `extern crate` statements are not displayed, so they're not
+                // worth counting
+                return Some(i);
+            }
             clean::ImplItem(ref impl_)
                 if attr::contains_name(&i.attrs.other_attrs, "automatically_derived")
                     || impl_.synthetic || impl_.blanket_impl.is_some() =>
             {
-                // skip counting anything inside these impl blocks
+                // built-in derives get the `#[automatically_derived]` attribute, and
+                // synthetic/blanket impls are made up by rustdoc and can't be documented
                 // FIXME(misdreavus): need to also find items that came out of a derive macro
                 return Some(i);
             }
-            // non-local items are skipped because they can be out of the users control, especially
-            // in the case of trait impls, which rustdoc eagerly inlines
-            _ => if i.def_id.is_local() {
-                let has_docs = !i.attrs.doc_strings.is_empty();
+            clean::ImplItem(ref impl_) => {
+                if let Some(ref tr) = impl_.trait_ {
+                    debug!("counting impl {:#} for {:#}", tr, impl_.for_);
 
-                if let clean::ImplItem(ref i) = i.inner {
-                    if let Some(ref tr) = i.trait_ {
-                        debug!("counting impl {:#} for {:#}", tr, i.for_);
+                    // trait impls inherit their docs from the trait definition, so documenting
+                    // them can be considered optional
+                    self.items.entry(ItemType::Impl).or_default().count_item(has_docs);
 
-                        self.items.count_item(has_docs);
-
-                        // trait impls inherit their docs from the trait definition, so documenting
-                        // them can be considered optional
-
-                        self.trait_impl_items.count_item(has_docs);
-
-                        for it in &i.items {
-                            self.trait_impl_items.count_item(!it.attrs.doc_strings.is_empty());
-                        }
-                    } else {
-                        // inherent impls *can* be documented, and those docs show up, but in most
-                        // cases it doesn't make sense, as all methods on a type are in one single
-                        // impl block
-                        debug!("not counting impl {:#}", i.for_);
+                    for it in &impl_.items {
+                        let has_docs = !it.attrs.doc_strings.is_empty();
+                        self.items.entry(ItemType::Impl).or_default().count_item(has_docs);
                     }
+
+                    // now skip recursing, so that we don't double-count this impl's items
+                    return Some(i);
                 } else {
-                    debug!("counting {} {:?}", i.type_(), i.name);
-                    self.items.count_item(has_docs);
+                    // inherent impls *can* be documented, and those docs show up, but in most
+                    // cases it doesn't make sense, as all methods on a type are in one single
+                    // impl block
+                    debug!("not counting impl {:#}", impl_.for_);
                 }
             }
+            clean::MacroItem(..) | clean::ProcMacroItem(..) => {
+                // combine `macro_rules!` macros and proc-macros in the same count
+                debug!("counting macro {:?}", i.name);
+                self.items.entry(ItemType::Macro).or_default().count_item(has_docs);
+            }
+            clean::TraitItem(ref mut trait_) => {
+                // because both trait methods with a default impl and struct methods are
+                // ItemType::Method, we need to properly tag trait methods as TyMethod instead
+                debug!("counting trait {:?}", i.name);
+                self.items.entry(ItemType::Trait).or_default().count_item(has_docs);
+
+                // since we're not going on to document the crate, it doesn't matter if we discard
+                // the item after counting it
+                trait_.items.retain(|it| {
+                    if it.type_() == ItemType::Method {
+                        let has_docs = !it.attrs.doc_strings.is_empty();
+                        self.items.entry(ItemType::TyMethod).or_default().count_item(has_docs);
+                        false
+                    } else {
+                        true
+                    }
+                });
+            }
+            _ => {
+                debug!("counting {} {:?}", i.type_(), i.name);
+                self.items.entry(i.type_()).or_default().count_item(has_docs);
+            }
         }
 
         self.fold_item_recur(i)
     }
 }
+
+fn table_name(type_: &ItemType) -> &'static str {
+        match *type_ {
+            ItemType::Module          => "Modules",
+            ItemType::Struct          => "Structs",
+            ItemType::Union           => "Unions",
+            ItemType::Enum            => "Enums",
+            ItemType::Function        => "Functions",
+            ItemType::Typedef         => "Type Aliases",
+            ItemType::Static          => "Statics",
+            ItemType::Trait           => "Traits",
+            // inherent impls aren't counted, and trait impls get all their items thrown into this
+            // counter
+            ItemType::Impl            => "Trait Impl Items",
+            // even though trait methods with a default impl get cleaned as Method, we convert them
+            // to TyMethod when counting
+            ItemType::TyMethod        => "Trait Methods",
+            ItemType::Method          => "Methods",
+            ItemType::StructField     => "Struct Fields",
+            ItemType::Variant         => "Enum Variants",
+            ItemType::Macro           => "Macros",
+            ItemType::Primitive       => "Primitives",
+            ItemType::AssociatedType  => "Associated Types",
+            ItemType::Constant        => "Constants",
+            ItemType::AssociatedConst => "Associated Constants",
+            ItemType::ForeignType     => "Foreign Types",
+            ItemType::Keyword         => "Keywords",
+            ItemType::Existential     => "Existential Types",
+            ItemType::TraitAlias      => "Trait Aliases",
+            _                         => panic!("unanticipated ItemType: {}", type_),
+        }
+}