Convert ERB code into Ruby before type-checking

lib/steep.rb

@@ -84,6 +84,7 @@
 require "steep/module_helper"
 require "steep/source"
 require "steep/source/ignore_ranges"
+require "steep/source/erb_to_ruby_code"
 require "steep/annotation_parser"
 require "steep/typing"
 require "steep/type_construction"

lib/steep/source.rb

@@ -38,6 +38,8 @@ def self.new_parser
     end
 
     def self.parse(source_code, path:, factory:)
+      source_code = ErbToRubyCode.convert(source_code) if path.to_s.end_with?(".erb")
+
       buffer = ::Parser::Source::Buffer.new(path.to_s, 1, source: source_code)
       node, comments = new_parser().parse_with_comments(buffer)
 

lib/steep/source/erb_to_ruby_code.rb

@@ -0,0 +1,112 @@
+# frozen_string_literal: true
+
+module Steep
+  class Source
+    # Converts ERB template code to Ruby code by replacing ERB tags with Ruby statements
+    # and HTML content with spaces, preserving line numbers and basic spacing.
+    #
+    # Supports all ERB tag variations:
+    # - `<% ruby_code %>` - execution tags
+    # - `<%= ruby_code %>` - output tags
+    # - `<%- ruby_code %>` - execution tags with leading whitespace control
+    # - `<% ruby_code -%>` - execution tags with trailing whitespace control
+    # - `<%- ruby_code -%>` - execution tags with both leading and trailing whitespace control
+    #
+    # Adds semicolons after each ERB tag to separate multiple statements on the same line,
+    # except for comments (lines starting with #).
+    module ErbToRubyCode
+      ERB_TAG_PREFIX_POSITION_REGEX = /<%[-=]?/
+      ERB_TAG_SUFIX_POSITION_REGEX = /%>/
+      ERB_TAG_PREFIX_REGEX = /^<%[-=]?\s*/
+      ERB_TAG_SUFFIX_REGEX = /\s*-?%>$/
+      NON_NEWLINE_REGEX = /[^\n]/
+
+      private_constant :ERB_TAG_PREFIX_POSITION_REGEX,
+                       :ERB_TAG_SUFIX_POSITION_REGEX,
+                       :ERB_TAG_SUFFIX_REGEX,
+                       :NON_NEWLINE_REGEX
+
+      class << self
+        def convert(source_code)
+          idx = 0
+
+          while idx < source_code.length
+            erb_tag_prefix_position = source_code.index(ERB_TAG_PREFIX_POSITION_REGEX, idx)
+            break unless erb_tag_prefix_position
+
+            replace_everything_before_erb_tag_with_whitespace(erb_tag_prefix_position:, idx:, source_code:)
+
+            erb_tag_sufix_position = source_code.index(ERB_TAG_SUFIX_POSITION_REGEX, erb_tag_prefix_position)
+            if erb_tag_sufix_position.nil?
+              # Incomplete ERB tag, replace rest with spaces, preserving newlines
+              remaining = source_code[erb_tag_prefix_position..]
+              source_code[erb_tag_prefix_position..-1] = remaining&.gsub(NON_NEWLINE_REGEX, ' ') || ''
+              break
+            end
+
+            erb_tag_full_content = source_code[erb_tag_prefix_position..(erb_tag_sufix_position + 1)]
+            unless erb_tag_full_content
+              raise 'Internal error: erb_tag_full_content should not be nil after finding start and end tags'
+            end
+
+            erb_tag_prefix_length = erb_tag_prefix_length(erb_tag_full_content:)
+            erb_tag_sufix_length = erb_tag_sufix_length(erb_tag_full_content:)
+
+            replacement_erb_tag = generate_replacement(erb_tag_full_content:, erb_tag_prefix_length:,
+                                                       erb_tag_sufix_length:)
+
+            source_code[erb_tag_prefix_position..(erb_tag_sufix_position + 1)] = replacement_erb_tag
+            idx = erb_tag_prefix_position + replacement_erb_tag.length
+          end
+
+          replace_everything_after_erb_tag_with_whitespace(idx:, source_code:)
+        end
+
+        private
+
+        def replace_everything_before_erb_tag_with_whitespace(erb_tag_prefix_position:, idx:, source_code:)
+          before_erb = source_code[idx...erb_tag_prefix_position] || ''
+          source_code[idx...erb_tag_prefix_position] = before_erb.gsub(NON_NEWLINE_REGEX, ' ')
+        end
+
+        def erb_tag_prefix_length(erb_tag_full_content:)
+          tag_prefix_match = erb_tag_full_content.match(ERB_TAG_PREFIX_REGEX) or raise
+          tag_prefix_string = tag_prefix_match[0] or raise
+
+          tag_prefix_string.length
+        end
+
+        def erb_tag_sufix_length(erb_tag_full_content:)
+          tag_suffix_match = erb_tag_full_content.match(ERB_TAG_SUFFIX_REGEX) or raise
+          tag_suffix_string = tag_suffix_match[0] or raise
+
+          tag_suffix_string.length
+        end
+
+        def generate_replacement(erb_tag_full_content:, erb_tag_prefix_length:, erb_tag_sufix_length:)
+          inner_with_tags_removed = inner_with_tags_removed(erb_tag_full_content:, erb_tag_prefix_length:,
+                                                            erb_tag_sufix_length:)
+
+          if inner_with_tags_removed.start_with?('#')
+            (' ' * erb_tag_prefix_length) + inner_with_tags_removed + (' ' * erb_tag_sufix_length)
+          else
+            "#{' ' * erb_tag_prefix_length}#{inner_with_tags_removed}#{' ' * (erb_tag_sufix_length - 1)};"
+          end
+        end
+
+        def inner_with_tags_removed(erb_tag_full_content:, erb_tag_prefix_length:, erb_tag_sufix_length:)
+          erb_tag_full_content[erb_tag_prefix_length...-erb_tag_sufix_length] or raise
+        end
+
+        def replace_everything_after_erb_tag_with_whitespace(idx:, source_code:)
+          return source_code if idx >= source_code.length
+
+          remaining = source_code[idx..]
+          source_code[idx..-1] = remaining&.gsub(NON_NEWLINE_REGEX, ' ') || ''
+
+          source_code
+        end
+      end
+    end
+  end
+end

sig/steep/source/erb_to_ruby_code.rbs

@@ -0,0 +1,27 @@
+module Steep
+  class Source
+    module ErbToRubyCode
+      def self.convert: (String erb_code) -> String
+
+      private
+
+      ERB_TAG_PREFIX_POSITION_REGEX: Regexp
+      ERB_TAG_SUFIX_POSITION_REGEX: Regexp
+      ERB_TAG_PREFIX_REGEX: Regexp
+      ERB_TAG_SUFFIX_REGEX: Regexp
+      NON_NEWLINE_REGEX: Regexp
+
+      def self.replace_everything_before_erb_tag_with_whitespace: (idx: Integer, erb_tag_prefix_position: Integer, source_code: String) -> String
+
+      def self.erb_tag_prefix_length: (erb_tag_full_content: String) -> Integer
+
+      def self.erb_tag_sufix_length: (erb_tag_full_content: String) -> Integer
+
+      def self.inner_with_tags_removed: (erb_tag_full_content: String, erb_tag_prefix_length: Integer, erb_tag_sufix_length: Integer) -> String
+
+      def self.generate_replacement: (erb_tag_full_content: String, erb_tag_prefix_length: Integer, erb_tag_sufix_length: Integer) -> String
+
+      def self.replace_everything_after_erb_tag_with_whitespace: (idx: Integer, source_code: String) -> String
+    end
+  end
+end

sig/test/cli_test.rbs

@@ -21,6 +21,10 @@ class CLITest < Minitest::Test
 
   def test_check_failure: () -> untyped
 
+  def test_erb_check_failure: () -> untyped
+
+  def test_erb_check_success: () -> untyped
+
   def test_check_failure_with_formatter: () -> untyped
 
   def test_check_group__target: () -> untyped

sig/test/source/erb_to_ruby_code_test.rbs

@@ -0,0 +1,19 @@
+class Steep::Source::ErbToRubyCodeTest < Minitest::Test
+  include TestHelper
+
+  def test_erb_output_tag_to_ruby_code: () -> untyped
+
+  def test_erb_output_tag_without_begin_space_to_ruby_code: () -> untyped
+
+  def test_erb_output_tag_without_end_space_to_ruby_code: () -> untyped
+
+  def test_erb_execution_tag_to_ruby_code: () -> untyped
+
+  def test_erb_with_dash_to_ruby_code: () -> untyped
+
+  def test_erb_to_ruby_code_handles_comments_html_and_multiple_tags: () -> untyped
+
+  def test_erb_multiline_tag_with_closing_on_separate_line: () -> untyped
+
+  def test_erb_multiple_tags_same_line_conversion: () -> untyped
+end

test/cli_test.rb

@@ -125,6 +125,52 @@ def test_check_failure
     end
   end
 
+  def test_erb_check_failure
+    in_tmpdir do
+      (current_dir + "Steepfile").write(<<-EOF)
+target :app do
+  check "app/views/**/*.erb"
+end
+      EOF
+
+      (current_dir + "app").mkdir
+      (current_dir + "app/views").mkdir
+      (current_dir + "app/views/companies").mkdir
+
+      (current_dir + "app/views/companies/_form.html.erb").write(<<-EOF)
+<div> Count: <%= 1 + "2" %> </div>
+      EOF
+
+      stdout, status = sh(*steep, "check")
+
+      refute_predicate status, :success?, stdout
+      assert_match(/Detected 1 problem from 1 file/, stdout)
+    end
+  end
+
+  def test_erb_check_success
+    in_tmpdir do
+      (current_dir + "Steepfile").write(<<-EOF)
+target :app do
+  check "app/views/**/*.erb"
+end
+      EOF
+
+      (current_dir + "app").mkdir
+      (current_dir + "app/views").mkdir
+      (current_dir + "app/views/companies").mkdir
+
+      (current_dir + "app/views/companies/_form.html.erb").write(<<-EOF)
+<div> Count: <%= 1 + 2 %> </div>
+      EOF
+
+      stdout, status = sh(*steep, "check")
+
+      assert_predicate status, :success?, stdout
+      assert_match(/No type error detected\./, stdout)
+    end
+  end
+
   def test_check_failure_with_formatter
     in_tmpdir do
       (current_dir + "Steepfile").write(<<-EOF)

test/source/erb_to_ruby_code_test.rb

@@ -0,0 +1,115 @@
+require_relative "../test_helper"
+
+class Steep::Source::ErbToRubyCodeTest < Minitest::Test
+  include TestHelper
+
+  def test_erb_output_tag_to_ruby_code
+    erb_source_code    = "<%= if order.with_error? %>"
+    expected_ruby_code = "    if order.with_error?  ;"
+
+    ruby_code = Steep::Source::ErbToRubyCode.convert(erb_source_code)
+
+    assert_equal expected_ruby_code, ruby_code
+  end
+
+  def test_erb_output_tag_without_begin_space_to_ruby_code
+    erb_source_code    = "<%=if order.with_error? %>"
+    expected_ruby_code = "   if order.with_error?  ;"
+
+    ruby_code = Steep::Source::ErbToRubyCode.convert(erb_source_code)
+
+    assert_equal expected_ruby_code, ruby_code
+  end
+
+  def test_erb_output_tag_without_end_space_to_ruby_code
+    erb_source_code    = "<%=if order.with_error?%>"
+    expected_ruby_code = "   if order.with_error? ;"
+
+    ruby_code = Steep::Source::ErbToRubyCode.convert(erb_source_code)
+
+    assert_equal expected_ruby_code, ruby_code
+  end
+
+  def test_erb_execution_tag_to_ruby_code
+    erb_source_code    = "<div> Count <% 1 + '2' %> </div>"
+    expected_ruby_code = "               1 + '2'  ;       "
+
+    ruby_code = Steep::Source::ErbToRubyCode.convert(erb_source_code)
+
+    assert_equal expected_ruby_code, ruby_code
+  end
+
+  def test_erb_to_ruby_code_handles_comments_html_and_multiple_tags
+    form_erb = <<ERB
+<% # This is a comment %>
+<div class="container">
+  <%= user.name %>
+  <% if user.admin? %>
+    <%= link_to "Admin Panel", admin_path %>
+  <% end %>
+  <p>Welcome!</p>
+</div>
+ERB
+
+    ruby_result = Steep::Source::ErbToRubyCode.convert(form_erb)
+
+    expected_ruby_result = <<RUBY
+   # This is a comment   
+
+      user.name  ;
+     if user.admin?  ;
+        link_to "Admin Panel", admin_path  ;
+     end  ;
+
+
+RUBY
+
+    assert_equal expected_ruby_result, ruby_result
+  end
+
+  def test_erb_multiline_tag_with_closing_on_separate_line
+    erb_source_code = <<ERB
+<%= form_with model: @user,
+              url: users_path,
+              local: true
+            %>
+ERB
+
+    expected_ruby_code = <<RUBY
+    form_with model: @user,
+              url: users_path,
+              local: true              ;
+RUBY
+
+    ruby_code = Steep::Source::ErbToRubyCode.convert(erb_source_code)
+
+    assert_equal expected_ruby_code, ruby_code
+  end
+
+  def test_erb_multiple_tags_same_line_conversion 
+    erb_with_two_tags_ruby = <<ERB
+<div class="alert">
+  <strong><%= t("messages.welcome") %></strong> <%= current_user.name %>
+</div>
+<%= link_to "Home", root_path %>
+ERB
+
+    expected_ruby_with_two_tags = <<RUBY
+
+              t("messages.welcome")  ;              current_user.name  ;
+
+    link_to "Home", root_path  ;
+RUBY
+
+    assert_equal expected_ruby_with_two_tags, Steep::Source::ErbToRubyCode.convert(erb_with_two_tags_ruby)
+  end
+
+  def test_erb_with_dash_to_ruby_code
+    erb_source_code    = "<%- if foo -%>"
+    expected_ruby_code = "    if foo   ;"
+
+    ruby_code = Steep::Source::ErbToRubyCode.convert(erb_source_code)
+
+    assert_equal expected_ruby_code, ruby_code
+  end
+end