Raise when meta-file cannot be unambiguously associated with content …

…file

nanoc/lib/nanoc/base/errors.rb

@@ -236,6 +236,12 @@ def initialize(filter_name)
       end
     end
 
+    class AmbiguousMetadataAssociation < Generic
+      def initialize(content_filenames, meta_filename)
+        super("There are multiple content files (#{content_filenames.join(', ')}) that could match the file containing metadata (#{meta_filename}).")
+      end
+    end
+
     class InternalInconsistency < Generic
     end
   end

nanoc/lib/nanoc/data_sources/filesystem.rb

@@ -176,30 +176,49 @@ def load_objects(dir_name, klass)
 
       return [] if dir_name.nil?
 
-      all_split_files_in(dir_name).each do |base_filename, (meta_ext, content_exts)|
-        content_exts.each do |content_ext|
-          meta_filename    = filename_for(base_filename, meta_ext)
-          content_filename = filename_for(base_filename, content_ext)
-
-          proto_doc = read_proto_document(content_filename, meta_filename, klass)
-
-          content = content_for(proto_doc, content_filename)
-          attributes = attributes_for(proto_doc, content_filename, meta_filename)
-          identifier = identifier_for(content_filename, meta_filename, dir_name)
-
-          res << klass.new(
-            content,
-            attributes,
-            identifier,
-            content_checksum_data: content_checksum_data_for(proto_doc),
-            attributes_checksum_data: attributes_checksum_data_for(proto_doc, content_filename, meta_filename),
-          )
-        end
+      each_content_meta_pair_in(dir_name) do |content_filename, meta_filename|
+        proto_doc = read_proto_document(content_filename, meta_filename, klass)
+
+        content = content_for(proto_doc, content_filename)
+        attributes = attributes_for(proto_doc, content_filename, meta_filename)
+        identifier = identifier_for(content_filename, meta_filename, dir_name)
+
+        res << klass.new(
+          content,
+          attributes,
+          identifier,
+          content_checksum_data: content_checksum_data_for(proto_doc),
+          attributes_checksum_data: attributes_checksum_data_for(proto_doc, content_filename, meta_filename),
+        )
       end
 
       res
     end
 
+    # Enumerates each pair of content file and meta file. If there is ambiguity, it will raise an error.
+    def each_content_meta_pair_in(dir_name)
+      all_split_files_in(dir_name).each do |base_filename, (meta_ext, content_exts)|
+        meta_filename = filename_for(base_filename, meta_ext)
+        content_filenames = content_exts.map { |e| filename_for(base_filename, e) }
+
+        have_possible_ambiguity = meta_filename && content_filenames.size > 1
+        if have_possible_ambiguity && content_filenames.count { |fn| !parser.has_frontmatter?(fn) } != 1
+          raise Nanoc::Int::Errors::AmbiguousMetadataAssociation.new(content_filenames, meta_filename)
+        end
+
+        content_filenames.each do |content_filename|
+          real_meta_filename =
+            if have_possible_ambiguity && parser.has_frontmatter?(content_filename)
+              nil
+            else
+              meta_filename
+            end
+
+          yield(content_filename, real_meta_filename)
+        end
+      end
+    end
+
     def content_checksum_data_for(proto_doc)
       data = proto_doc.content_checksum_data
       data ? Digest::SHA1.digest(data) : nil
@@ -379,8 +398,11 @@ def allow_periods_in_identifiers?
       end
     end
 
+    def parser
+      @parser ||= Parser.new(config: @config)
+    end
+
     def parse(content_filename, meta_filename)
-      parser = Parser.new(config: @config)
       parser.call(content_filename, meta_filename)
     end
   end

nanoc/lib/nanoc/data_sources/filesystem/parser.rb

@@ -70,6 +70,11 @@ def parse_metadata(data, filename)
       meta
     end
 
+    def has_frontmatter?(filename)
+      data = Tools.read_file(filename, config: @config)
+      /\A#{SEPARATOR}\s*$/.match?(data)
+    end
+
     def verify_meta(meta, filename)
       return if meta.is_a?(Hash)
 

nanoc/spec/nanoc/data_sources/filesystem_spec.rb

@@ -110,6 +110,117 @@
           expect(subject[0].content_checksum_data).to be_nil
         end
       end
+
+      context 'two content files (no inline metadata) with one meta file' do
+        let(:params) { { identifier_type: 'full' } }
+
+        before do
+          FileUtils.mkdir_p('foo')
+          File.write('foo/a.txt', 'hi')
+          File.write('foo/a.md', 'ho')
+          File.write('foo/a.yaml', 'title: Aaah')
+        end
+
+        it 'errors' do
+          expect { subject }
+            .to raise_error(
+              Nanoc::Int::Errors::AmbiguousMetadataAssociation,
+              'There are multiple content files (foo/a.txt, foo/a.md) that could match the file containing metadata (foo/a.yaml).',
+            )
+        end
+      end
+
+      context 'two content files (one has inline metadata) with one meta file' do
+        let(:params) { { identifier_type: 'full' } }
+
+        before do
+          FileUtils.mkdir_p('foo')
+          File.write('foo/a.txt', "---\ntitle: Hi\n---\n\nhi")
+          File.write('foo/a.md', 'ho')
+          File.write('foo/a.yaml', 'title: Aaah')
+        end
+
+        it 'assigns metadata to the file that doesn’t have any yet' do
+          expect(subject.size).to eq(2)
+
+          items = subject.sort_by { |i| i.identifier.to_s }
+
+          expect(items[0].content).to be_a(Nanoc::Int::TextualContent)
+          expect(items[0].identifier).to eq(Nanoc::Identifier.new('/a.md', type: :full))
+          expect(items[0].attributes[:title]).to eq('Aaah')
+
+          expect(items[1].content).to be_a(Nanoc::Int::TextualContent)
+          expect(items[1].identifier).to eq(Nanoc::Identifier.new('/a.txt', type: :full))
+          expect(items[1].attributes[:title]).to eq('Hi')
+        end
+      end
+
+      context 'two content files (both have inline metadata) with one meta file' do
+        let(:params) { { identifier_type: 'full' } }
+
+        before do
+          FileUtils.mkdir_p('foo')
+          File.write('foo/a.txt', "---\ntitle: Hi\n---\n\nhi")
+          File.write('foo/a.md', "---\ntitle: Ho\n---\n\nho")
+          File.write('foo/a.yaml', 'title: Aaah')
+        end
+
+        it 'errors' do
+          expect { subject }
+            .to raise_error(
+              Nanoc::Int::Errors::AmbiguousMetadataAssociation,
+              'There are multiple content files (foo/a.txt, foo/a.md) that could match the file containing metadata (foo/a.yaml).',
+            )
+        end
+      end
+
+      context 'two content files (both have inline metadata) with no meta file' do
+        let(:params) { { identifier_type: 'full' } }
+
+        before do
+          FileUtils.mkdir_p('foo')
+          File.write('foo/a.txt', "---\ntitle: Hi\n---\n\nhi")
+          File.write('foo/a.md', "---\ntitle: Ho\n---\n\nho")
+        end
+
+        it 'uses inline metadata' do
+          expect(subject.size).to eq(2)
+
+          items = subject.sort_by { |i| i.identifier.to_s }
+
+          expect(items[0].content).to be_a(Nanoc::Int::TextualContent)
+          expect(items[0].identifier).to eq(Nanoc::Identifier.new('/a.md', type: :full))
+          expect(items[0].attributes[:title]).to eq('Ho')
+
+          expect(items[1].content).to be_a(Nanoc::Int::TextualContent)
+          expect(items[1].identifier).to eq(Nanoc::Identifier.new('/a.txt', type: :full))
+          expect(items[1].attributes[:title]).to eq('Hi')
+        end
+      end
+
+      context 'two content files (neither have inline metadata) with no meta file' do
+        let(:params) { { identifier_type: 'full' } }
+
+        before do
+          FileUtils.mkdir_p('foo')
+          File.write('foo/a.txt', "hi")
+          File.write('foo/a.md', "ho")
+        end
+
+        it 'uses no metadata' do
+          expect(subject.size).to eq(2)
+
+          items = subject.sort_by { |i| i.identifier.to_s }
+
+          expect(items[0].content).to be_a(Nanoc::Int::TextualContent)
+          expect(items[0].identifier).to eq(Nanoc::Identifier.new('/a.md', type: :full))
+          expect(items[0].attributes[:title]).to be_nil
+
+          expect(items[1].content).to be_a(Nanoc::Int::TextualContent)
+          expect(items[1].identifier).to eq(Nanoc::Identifier.new('/a.txt', type: :full))
+          expect(items[1].attributes[:title]).to be_nil
+        end
+      end
     end
   end