Reformat main entry

lib/parser/prism.rb

@@ -28,10 +28,10 @@ def parse(source_buffer)
       @source_buffer = source_buffer
       source = source_buffer.source
 
-      offset_cache = build_offset_cache(source)
-      result = ::Prism.parse(source, filepath: source_buffer.name).value
-
-      build_ast(result, offset_cache)
+      build_ast(
+        ::Prism.parse(source, filepath: source_buffer.name).value,
+        build_offset_cache(source)
+      )
     ensure
       @source_buffer = nil
     end
@@ -47,10 +47,12 @@ def parse_with_comments(source_buffer)
       @source_buffer = source_buffer
       source = source_buffer.source
 
-      offset_cache = build_offset_cache(source)
       result = ::Prism.parse(source, filepath: source_buffer.name)
 
-      [build_ast(result.value, offset_cache), build_comments(result.comments)]
+      [
+        build_ast(result.value, build_offset_cache(source)),
+        build_comments(result.comments)
+      ]
     ensure
       @source_buffer = nil
     end
@@ -64,13 +66,17 @@ def parse_with_comments(source_buffer)
     #
     def tokenize(source_buffer, _recover = false)
       @source_buffer = source_buffer
-      souce = source_buffer.source
+      source = source_buffer.source
 
       offset_cache = build_offset_cache(source)
       result = ::Prism.parse_lex(source, filepath: source_buffer.name)
-
       program, tokens = result.value
-      [build_ast(program, offset_cache), build_comments(result.comments), build_tokens(tokens, offset_cache)]
+
+      [
+        build_ast(program, offset_cache),
+        build_comments(result.comments),
+        build_tokens(tokens, offset_cache)
+      ]
     ensure
       @source_buffer = nil
     end
@@ -83,6 +89,13 @@ def try_declare_numparam(node)
 
     private
 
+    # Prism deals with offsets in bytes, while the parser gem deals with offsets
+    # in characters. We need to handle this conversion in order to build the
+    # parser gem AST.
+    #
+    # If the bytesize of the source is the same as the length, then we can just
+    # use the offset directly. Otherwise, we build a hash that functions as a
+    # cache for the conversion.
     def build_offset_cache(source)
       if source.bytesize == source.length
         -> (offset) { offset }
@@ -91,17 +104,20 @@ def build_offset_cache(source)
       end
     end
 
+    # Build the parser gem AST from the prism AST.
     def build_ast(program, offset_cache)
       program.accept(Compiler.new(self, offset_cache))
     end
 
+    # Build the parser gem comments from the prism comments.
     def build_comments(comments)
       comments.map do |comment|
         location = comment.location
         Source::Comment.new(Source::Range.new(source_buffer, location.start_offset, location.end_offset))
       end
     end
 
+    # Build the parser gem tokens from the prism tokens.
     def build_tokens(tokens, offset_cache)
       Lexer.new(source_buffer, tokens.map(&:first), offset_cache).to_a
     end