Adds handling for column index in error reporting (#85)

Author: davidwessman

CHANGELOG.md

@@ -7,6 +7,8 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 ## [Unreleased]
 
 - Support Ruby 3.3 by handling yield in ERB specifically
+- Use SyntaxTree own class for ParseError to get better error feedback
+- Adds handling for keeping track of column index, to support better error messages
 
 ## [0.11.0] - 2024-04-23
 

README.md

@@ -30,18 +30,26 @@ Currently handles
 Add this line to your application's Gemfile:
 
 ```ruby
-gem "w_syntax_tree-erb", "~> 0.10", require: false
+gem "w_syntax_tree-erb", "~> 0.11", require: false
 ```
 
 > I added the `w_` prefix to avoid conflicts if there will ever be an official `syntax_tree-erb` gem.
 
 ## Usage
 
+### Parsing
+
+```sh
+bundle exec stree ast --plugins=erb "./**/*.html.erb"
+```
+
+### Format
+
 ```sh
-bundle exec stree --plugins=erb "./**/*.html.erb"
+bundle exec stree write --plugins=erb "./**/*.html.erb"
 ```
 
-From code:
+### In code
 
 ```ruby
 require "syntax_tree/erb"

lib/syntax_tree/erb/format.rb

@@ -20,7 +20,8 @@ def visit_token(node)
 
       # Visit a Document node.
       def visit_document(node)
-        child_nodes = node.child_nodes.sort_by(&:location)
+        child_nodes =
+          node.child_nodes.sort_by { |node| node.location.start_char }
 
         handle_child_nodes(child_nodes)
 

lib/syntax_tree/erb/nodes.rb

@@ -2,48 +2,6 @@
 
 module SyntaxTree
   module ERB
-    # A Location represents a position for a node in the source file.
-    class Location
-      attr_reader :start_char, :end_char, :start_line, :end_line
-
-      def initialize(start_char:, end_char:, start_line:, end_line:)
-        @start_char = start_char
-        @end_char = end_char
-        @start_line = start_line
-        @end_line = end_line
-      end
-
-      def deconstruct_keys(keys)
-        {
-          start_char: start_char,
-          end_char: end_char,
-          start_line: start_line,
-          end_line: end_line
-        }
-      end
-
-      def to(other)
-        Location.new(
-          start_char: start_char,
-          start_line: start_line,
-          end_char: other.end_char,
-          end_line: other.end_line
-        )
-      end
-
-      def <=>(other)
-        start_char <=> other.start_char
-      end
-
-      def to_s
-        if start_line == end_line
-          "line #{start_line}, char #{start_char}..#{end_char}"
-        else
-          "line #{start_line},char #{start_char} to line #{end_line}, char #{end_char}"
-        end
-      end
-    end
-
     # A parent node that contains a bit of shared functionality.
     class Node
       def format(q)
@@ -322,6 +280,7 @@ def initialize(
             )
           end
 
+        @content = content
         @content = prepare_content(content)
         @closing_tag = closing_tag
       end
@@ -376,11 +335,19 @@ def prepare_content(content)
 
           result
         rescue SyntaxTree::Parser::ParseError => error
+          opening_location = opening_tag.location
+          content_location = content.first&.location || opening_location
           raise(
             SyntaxTree::Parser::ParseError.new(
               "Could not parse ERB-tag: #{error.message}",
               @opening_tag.location.start_line + error.lineno - 1,
-              error.column
+              (
+                if opening_location.start_line == error.lineno
+                  opening_location.start_column + error.column - 1
+                else
+                  content_location.start_column + error.column - 1
+                end
+              )
             )
           )
         end