feat: javascript helpers extension

fix #881

Author: alandefreitas

src/lib/Gen/hbs/Builder.cpp

@@ -53,6 +53,51 @@ templateDirs(Config const& config, std::string_view generator, std::string_view
     return dirs;
 }
 
+} // (anon)
+
+namespace paths {
+
+std::string selectExistingTemplateDir(std::vector<std::string> const& candidates)
+{
+    for (auto const& dir : candidates)
+    {
+        if (files::exists(dir))
+            return dir;
+    }
+    return {};
+}
+
+} // namespace paths
+
+
+static std::string pickTemplateDir(
+    Config const& config,
+    std::string_view generator,
+    std::string_view subdir,
+    std::string_view purpose)
+{
+    auto dirs = templateDirs(config, generator, subdir);
+    auto selected = paths::selectExistingTemplateDir(dirs);
+    if (!selected.empty())
+        return selected;
+
+    std::string searched;
+    for (auto it = dirs.begin(); it != dirs.end(); ++it)
+    {
+        if (it != dirs.begin())
+            searched.append(", ");
+        searched.append(*it);
+    }
+
+    formatError(
+        "No {} templates found for generator '{}' (subdir '{}'); searched: {}",
+        purpose,
+        generator,
+        subdir,
+        searched.empty() ? std::string{"<none>"} : searched).Throw();
+    return {};
+}
+
 void
 loadPartials(
     Handlebars& hbs,
@@ -181,11 +226,6 @@ relativize_fn(dom::Value to0, dom::Value from0, dom::Value options)
     relativePath += hash;
     return relativePath;
 }
-
-} // (anon)
-
-
-
 Builder::
 Builder(
     HandlebarsCorpus const& corpus,
@@ -454,40 +494,35 @@ std::string
 Builder::
 layoutDir() const
 {
-    auto dirs = templateDirs(domCorpus->config, domCorpus.fileExtension, "layouts");
-    return dirs.empty() ? std::string{} : dirs.back();
+    return pickTemplateDir(domCorpus->config, domCorpus.fileExtension, "layouts", "layout");
 }
 
 std::string
 Builder::
 templatesDir() const
 {
-    auto dirs = templateDirs(domCorpus->config, domCorpus.fileExtension, {});
-    return dirs.empty() ? std::string{} : dirs.back();
+    return pickTemplateDir(domCorpus->config, domCorpus.fileExtension, {}, "template");
 }
 
 std::string
 Builder::
 templatesDir(std::string_view subdir) const
 {
-    auto dirs = templateDirs(domCorpus->config, domCorpus.fileExtension, subdir);
-    return dirs.empty() ? std::string{} : dirs.back();
+    return pickTemplateDir(domCorpus->config, domCorpus.fileExtension, subdir, "template");
 }
 
 std::string
 Builder::
 commonTemplatesDir() const
 {
-    auto dirs = templateDirs(domCorpus->config, "common", {});
-    return dirs.empty() ? std::string{} : dirs.back();
+    return pickTemplateDir(domCorpus->config, "common", {}, "common template");
 }
 
 std::string
 Builder::
 commonTemplatesDir(std::string_view const subdir) const
 {
-    auto dirs = templateDirs(domCorpus->config, "common", subdir);
-    return dirs.empty() ? std::string{} : dirs.back();
+    return pickTemplateDir(domCorpus->config, "common", subdir, "common template");
 }
 
 

src/lib/Gen/hbs/Builder.hpp

@@ -19,11 +19,16 @@
 #include <mrdocs/Support/Handlebars.hpp>
 #include <mrdocs/Support/JavaScript.hpp>
 #include <ostream>
+#include <vector>
 
 
 namespace mrdocs {
 namespace hbs {
 
+namespace paths {
+std::string selectExistingTemplateDir(std::vector<std::string> const& candidates);
+}
+
 /** Builds reference output as a string for any Info type
 
     This contains all the state information