perf(Builder): render templates directly to ostream

Author: alandefreitas

src/lib/Gen/hbs/Builder.cpp

@@ -10,11 +10,9 @@
 //
 
 #include "Builder.hpp"
-#include "lib/Support/Radix.hpp"
 #include <lib/Lib/ConfigImpl.hpp>
 #include <mrdocs/Metadata/DomCorpus.hpp>
 #include <mrdocs/Support/Path.hpp>
-#include <llvm/Support/FileSystem.h>
 #include <llvm/Support/Path.h>
 #include <fmt/format.h>
 #include <filesystem>
@@ -149,23 +147,25 @@ Builder(
 
 //------------------------------------------------
 
-Expected<std::string>
+Expected<void>
 Builder::
 callTemplate(
+    std::ostream& os,
     std::string_view name,
     dom::Value const& context)
 {
     auto pathName = files::appendPath(layoutDir(), name);
     MRDOCS_TRY(auto fileText, files::getFileText(pathName));
     HandlebarsOptions options;
     options.escapeFunction = escapeFn_;
-    Expected<std::string, HandlebarsError> exp =
-        hbs_.try_render(fileText, context, options);
+    OutputRef out(os);
+    Expected<void, HandlebarsError> exp =
+        hbs_.try_render_to(out, fileText, context, options);
     if (!exp)
     {
         return Unexpected(Error(exp.error().what()));
     }
-    return *exp;
+    return {};
 }
 
 //------------------------------------------------
@@ -215,56 +215,35 @@ createContext(
 }
 
 template<class T>
-Expected<std::string>
+requires std::derived_from<T, Info> || std::same_as<T, OverloadSet>
+Expected<void>
 Builder::
-operator()(T const& I)
+operator()(std::ostream& os, T const& I)
 {
-    auto const templateFile = fmt::format("index.{}.hbs", domCorpus.fileExtension);
+    std::string const templateFile =
+        std::derived_from<T, Info> ?
+            fmt::format("index.{}.hbs", domCorpus.fileExtension) :
+            fmt::format("index-overload-set.{}.hbs", domCorpus.fileExtension);
     dom::Object ctx = createContext(I);
 
     auto& config = domCorpus->config;
     bool isSinglePage = !config->multipage;
     if (config->embedded ||
         isSinglePage)
     {
-        return callTemplate(templateFile, ctx);
+        return callTemplate(os, templateFile, ctx);
     }
 
     auto const wrapperFile = fmt::format("wrapper.{}.hbs", domCorpus.fileExtension);
     dom::Object wrapperCtx = createFrame(ctx);
-    wrapperCtx.set("contents", dom::makeInvocable([this, &I, templateFile](
+    wrapperCtx.set("contents", dom::makeInvocable([this, &I, templateFile, &os](
         dom::Value const& options) -> Expected<dom::Value>
         {
             // Helper to write contents directly to stream
-            return callTemplate(templateFile, createContext(I));
-        }));
-    return callTemplate(wrapperFile, wrapperCtx);
-}
-
-Expected<std::string>
-Builder::
-operator()(OverloadSet const& OS)
-{
-    auto const templateFile = fmt::format("index-overload-set.{}.hbs", domCorpus.fileExtension);
-    dom::Object ctx = createContext(OS);
-
-    auto& config = domCorpus->config;
-    bool isSinglePage = !config->multipage;
-    if (config->embedded ||
-        isSinglePage)
-    {
-        return callTemplate(templateFile, ctx);
-    }
-
-    auto const wrapperFile = fmt::format("wrapper.{}.hbs", domCorpus.fileExtension);
-    dom::Object wrapperCtx = createFrame(ctx);
-    wrapperCtx.set("contents", dom::makeInvocable([this, &OS, templateFile](
-        dom::Value const& options) -> Expected<dom::Value>
-        {
-            // Helper to write contents directly to stream
-            return callTemplate(templateFile, createContext(OS));
+            MRDOCS_TRY(callTemplate(os, templateFile, createContext(I)));
+            return {};
         }));
-    return callTemplate(wrapperFile, wrapperCtx);
+    return callTemplate(os, wrapperFile, wrapperCtx);
 }
 
 Expected<void>
@@ -352,14 +331,12 @@ commonTemplatesDir(std::string_view subdir) const
         subdir);
 }
 
-
 // Define Builder::operator() for each Info type
-#define DEFINE(T) template Expected<std::string> \
-    Builder::operator()<T>(T const&)
-
-#define INFO(Type) DEFINE(Type##Info);
+#define INFO(T) template Expected<void> Builder::operator()<T##Info>(std::ostream&, T##Info const&);
 #include <mrdocs/Metadata/InfoNodesPascal.inc>
 
+template Expected<void> Builder::operator()<OverloadSet>(std::ostream&, OverloadSet const&);
+
 } // hbs
 } // mrdocs
 } // clang

src/lib/Gen/hbs/Builder.hpp

@@ -57,12 +57,9 @@ class Builder
         with the index template as the contents.
      */
     template<class T>
-    Expected<std::string>
-    operator()(T const&);
-
-    /// @copydoc operator()(T const&)
-    Expected<std::string>
-    operator()(OverloadSet const&);
+    requires std::derived_from<T, Info> || std::same_as<T, OverloadSet>
+    Expected<void>
+    operator()(std::ostream& os, T const&);
 
     /** Render the contents in the wrapper layout.
 
@@ -123,8 +120,9 @@ class Builder
 
     /** Render a Handlebars template from the templates directory.
      */
-    Expected<std::string>
+    Expected<void>
     callTemplate(
+        std::ostream& os,
         std::string_view name,
         dom::Value const& context);
 

src/lib/Gen/hbs/MultiPageVisitor.cpp

@@ -17,77 +17,90 @@ namespace clang {
 namespace mrdocs {
 namespace hbs {
 
+template <class T>
+requires std::derived_from<T, Info> || std::same_as<T, OverloadSet>
 void
 MultiPageVisitor::
-writePage(
-    std::string_view text,
-    std::string_view filename)
+operator()(T const& I0)
 {
-    std::string path = files::appendPath(outputPath_, filename);
-    std::string dir = files::getParentDir(path);
-    auto exp = files::createDirectory(dir);
-    if (!exp)
-    {
-        exp.error().Throw();
-    }
-    std::ofstream os;
-    try
+    // If T is an OverloadSet, we make a copy for the lambda because
+    // these are temporary objects that don't live in the corpus.
+    // Otherwise, the lambda will capture a reference to the corpus Info.
+    auto Ref = [&I0] {
+        if constexpr (std::derived_from<T, Info>)
+        {
+            return std::ref(I0);
+        }
+        else if constexpr (std::same_as<T, OverloadSet>)
+        {
+            return OverloadSet(I0);
+        }
+    }();
+    ex_.async([this, Ref](Builder& builder)
     {
-        os.open(path,
-            std::ios_base::binary |
-                std::ios_base::out |
-                std::ios_base::trunc // | std::ios_base::noreplace
+        T const& I = Ref;
+
+        // ===================================
+        // Open the output file
+        // ===================================
+        std::string path = files::appendPath(outputPath_, builder.domCorpus.getXref(I));
+        std::string dir = files::getParentDir(path);
+        if (auto exp = files::createDirectory(dir); !exp)
+        {
+            exp.error().Throw();
+        }
+        std::ofstream os;
+        try
+        {
+            os.open(path,
+                    std::ios_base::binary |
+                        std::ios_base::out |
+                        std::ios_base::trunc // | std::ios_base::noreplace
             );
-        os.write(text.data(), static_cast<std::streamsize>(text.size()));
-    }
-    catch(std::exception const& ex)
-    {
-        formatError(R"(std::ofstream("{}") threw "{}")", path, ex.what()).Throw();
-    }
-}
+            if (!os.is_open()) {
+                formatError(R"(std::ofstream("{}") failed)", path)
+                    .Throw();
+            }
+        }
+        catch (std::exception const& ex)
+        {
+            formatError(R"(std::ofstream("{}") threw "{}")", path, ex.what())
+                .Throw();
+        }
 
-template<std::derived_from<Info> T>
-void
-MultiPageVisitor::
-operator()(T const& I)
-{
-    ex_.async([this, &I](Builder& builder)
-    {
-        if(const auto r = builder(I))
-            writePage(*r, builder.domCorpus.getXref(I));
-        else
-            r.error().Throw();
-        if constexpr(
+        // ===================================
+        // Generate the output
+        // ===================================
+        if (auto exp = builder(os, I); !exp)
+        {
+            exp.error().Throw();
+        }
+
+        // ===================================
+        // Traverse the symbol members
+        // ===================================
+        if constexpr (std::derived_from<T, Info>)
+        {
+            if constexpr(
                 T::isNamespace() ||
                 T::isRecord() ||
                 T::isEnum())
+            {
+                corpus_.traverseOverloads(I, *this);
+            }
+        }
+        else if constexpr (std::same_as<T, OverloadSet>)
         {
-            // corpus_.traverse(I, *this);
-            corpus_.traverseOverloads(I, *this);
+            corpus_.traverse(I, *this);
         }
     });
 }
 
-void
-MultiPageVisitor::
-operator()(OverloadSet const& OS)
-{
-    ex_.async([this, OS](Builder& builder)
-    {
-        if(const auto r = builder(OS))
-            writePage(*r, builder.domCorpus.getXref(OS));
-        else
-            r.error().Throw();
-        corpus_.traverse(OS, *this);
-    });
-}
-
-#define DEFINE(T) template void \
-    MultiPageVisitor::operator()<T>(T const&)
-
-#define INFO(Type) DEFINE(Type##Info);
+#define INFO(T) template void MultiPageVisitor::operator()<T##Info>(T##Info const&);
 #include <mrdocs/Metadata/InfoNodesPascal.inc>
 
+template void MultiPageVisitor::operator()<OverloadSet>(OverloadSet const&);
+
 } // hbs
 } // mrdocs
 } // clang

src/lib/Gen/hbs/MultiPageVisitor.hpp

@@ -32,11 +32,6 @@ class MultiPageVisitor
     std::string_view outputPath_;
     Corpus const& corpus_;
 
-    void
-    writePage(
-        std::string_view text,
-        std::string_view filename);
-
 public:
     MultiPageVisitor(
         ExecutorGroup<Builder>& ex,
@@ -54,16 +49,9 @@ class MultiPageVisitor
         respective tasks are also pushed to the executor group.
 
     */
-    template <std::derived_from<Info> T>
+    template <class T>
+    requires std::derived_from<T, Info> || std::same_as<T, OverloadSet>
     void operator()(T const& I);
-
-    /** Push a task for the specified OverloadSet to the executor group.
-
-        If the OverloadSet object refers to other Info objects, their
-        respective tasks are also pushed to the executor group.
-
-    */
-    void operator()(OverloadSet const& OS);
 };
 
 } // hbs