[close #64] WIP

Author: schneems

lib/dead_end/around_block_scan.rb

@@ -9,10 +9,10 @@ module DeadEnd
   #
   # Example:
   #
-  #   def dog
-  #     puts "bark"
-  #     puts "bark"
-  #   end
+  #   def dog         # 1
+  #     puts "bark"   # 2
+  #     puts "bark"   # 3
+  #   end             # 4
   #
   #   scan = AroundBlockScan.new(
   #     code_lines: code_lines
@@ -22,7 +22,7 @@ module DeadEnd
   #   scan.scan_while { true }
   #
   #   puts scan.before_index # => 0
-  #   puts scan.after_index # => 3
+  #   puts scan.after_index  # => 3
   #
   # Contents can also be filtered using AroundBlockScan#skip
   #
@@ -109,8 +109,6 @@ def capture_neighbor_context
       kw_count = 0
       end_count = 0
       after_lines.each do |line|
-        # puts "line: #{line.number} #{line.original_line}, indent: #{line.indent}, #{line.empty?} #{line.indent == @orig_indent}"
-
         next if line.empty?
         break if line.indent < @orig_indent
         next if line.indent != @orig_indent
@@ -124,7 +122,6 @@ def capture_neighbor_context
 
         lines << line
       end
-      lines.select! { |line| !line.is_comment? }
 
       lines
     end

lib/dead_end/capture_code_context.rb

@@ -1,13 +1,27 @@
 # frozen_string_literal: true
 
 module DeadEnd
-  # Given a block, this method will capture surrounding
-  # code to give the user more context for the location of
-  # the problem.
+  # Turns a "invalid block(s)" into useful context
   #
-  # Return is an array of CodeLines to be rendered.
+  # There are three main phases in the algorithm:
   #
-  # Surrounding code is captured regardless of visible state
+  # 1. Sanitize/format input source
+  # 2. Search for invalid blocks
+  # 3. Format invalid blocks into something meaninful
+  #
+  # This class handles the third part.
+  #
+  # The algorithm is very good at capturing all of a syntax
+  # error in a single block in number 2, however the results
+  # can contain ambiguities. Humans are good at pattern matching
+  # and filtering and can mentally remove extraneous data, but
+  # they can't add extra data that's not present.
+  #
+  # In the case of known ambiguious cases, this class adds context
+  # back to the ambiguitiy so the programmer has full information.
+  #
+  # Beyond handling these ambiguities, it also captures surrounding
+  # code context information:
   #
   #   puts block.to_s # => "def bark"
   #
@@ -16,7 +30,8 @@ module DeadEnd
   #     code_lines: code_lines
   #   )
   #
-  #   puts context.call.join
+  #   lines = context.call.map(&:original)
+  #   puts lines.join
   #   # =>
   #     class Dog
   #       def bark
@@ -34,19 +49,34 @@ def initialize(blocks:, code_lines:)
 
     def call
       @blocks.each do |block|
+        capture_first_kw_end_same_indent(block)
         capture_last_end_same_indent(block)
         capture_before_after_kws(block)
         capture_falling_indent(block)
       end
 
       @lines_to_output.select!(&:not_empty?)
-      @lines_to_output.select!(&:not_comment?)
       @lines_to_output.uniq!
       @lines_to_output.sort!
 
       @lines_to_output
     end
 
+    # Shows the context around code provided by "falling" indentation
+    #
+    # Converts:
+    #
+    #       it "foo" do
+    #
+    # into:
+    #
+    #   class OH
+    #     def hello
+    #       it "foo" do
+    #     end
+    #   end
+    #
+    #
     def capture_falling_indent(block)
       AroundBlockScan.new(
         block: block,
@@ -56,7 +86,36 @@ def capture_falling_indent(block)
       end
     end
 
+    # Shows surrounding kw/end pairs
+    #
+    # The purpose of showing these extra pairs is due to cases
+    # of ambiguity when only one visible line is matched.
+    #
+    # For example:
+    #
+    #     1  class Dog
+    #     2    def bark
+    #     4    def eat
+    #     5    end
+    #     6  end
+    #
+    # In this case either line 2 could be missing an `end` or
+    # line 4 was an extra line added by mistake (it happens).
+    #
+    # When we detect the above problem it shows the issue
+    # as only being on line 2
+    #
+    #     2    def bark
+    #
+    # Showing "neighbor" keyword pairs gives extra context:
+    #
+    #     2    def bark
+    #     4    def eat
+    #     5    end
+    #
     def capture_before_after_kws(block)
+      return unless block.visible_lines.count == 1
+
       around_lines = AroundBlockScan.new(code_lines: @code_lines, block: block)
         .start_at_next_line
         .capture_neighbor_context
@@ -66,9 +125,10 @@ def capture_before_after_kws(block)
       @lines_to_output.concat(around_lines)
     end
 
-    # When there is an invalid with a keyword
-    # right before an end, it's unclear where
-    # the correct code should be.
+    # When there is an invalid block with a keyword
+    # missing an end right before another end,
+    # it is unclear where which keyword is missing the
+    # end
     #
     # Take this example:
     #
@@ -87,20 +147,21 @@ def capture_before_after_kws(block)
     # line 4. Also work backwards and if there's a mis-matched keyword, show it
     # too
     def capture_last_end_same_indent(block)
-      start_index = block.visible_lines.first.index
-      lines = @code_lines[start_index..block.lines.last.index]
+      return if block.visible_lines.length != 1
+      return unless block.visible_lines.first.is_kw?
+
+      visible_line = block.visible_lines.first
+      lines = @code_lines[visible_line.index..block.lines.last.index]
 
       # Find first end with same indent
       # (this would return line 4)
       #
       #   end             # 4
-      matching_end = lines.find { |line| line.indent == block.current_indent && line.is_end? }
+      matching_end = lines.detect { |line| line.indent == block.current_indent && line.is_end? }
       return unless matching_end
 
       @lines_to_output << matching_end
 
-      lines = @code_lines[start_index..matching_end.index]
-
       # Work backwards from the end to
       # see if there are mis-matched
       # keyword/end pairs
@@ -113,7 +174,7 @@ def capture_last_end_same_indent(block)
       #   end             # 4
       end_count = 0
       kw_count = 0
-      kw_line = lines.reverse.detect do |line|
+      kw_line = @code_lines[visible_line.index..matching_end.index].reverse.detect do |line|
         end_count += 1 if line.is_end?
         kw_count += 1 if line.is_kw?
 
@@ -122,5 +183,51 @@ def capture_last_end_same_indent(block)
       return unless kw_line
       @lines_to_output << kw_line
     end
+
+    # The logical inverse of `capture_last_end_same_indent`
+    #
+    # When there is an invalid block with an `end`
+    # missing a keyword right after another `end`,
+    # it is unclear where which end is missing the
+    # keyword.
+    #
+    # Take this example:
+    #
+    #   class Dog       # 1
+    #       puts "woof" # 2
+    #     end           # 3
+    #   end             # 4
+    #
+    # the problem line will be identified as:
+    #
+    #  ❯ end            # 4
+    #
+    # This happens because lines 1, 2, and 3 are technically valid code and are expanded
+    # first, deemed valid, and hidden. We need to un-hide the matching keyword on
+    # line 1. Also work backwards and if there's a mis-matched end, show it
+    # too
+    def capture_first_kw_end_same_indent(block)
+      return if block.visible_lines.length != 1
+      return unless block.visible_lines.first.is_end?
+
+      visible_line = block.visible_lines.first
+      lines = @code_lines[block.lines.first.index..visible_line.index]
+      matching_kw = lines.reverse.detect { |line| line.indent == block.current_indent && line.is_kw? }
+      return unless matching_kw
+
+      @lines_to_output << matching_kw
+
+      kw_count = 0
+      end_count = 0
+      orphan_end = @code_lines[matching_kw.index..visible_line.index].detect do |line|
+        kw_count += 1 if line.is_kw?
+        end_count += 1 if line.is_end?
+
+        end_count >= kw_count
+      end
+
+      return unless orphan_end
+      @lines_to_output << orphan_end
+    end
   end
 end