Introduce RuboCop Performance

.rubocop.yml

@@ -1,4 +1,5 @@
 plugins:
+  - rubocop-performance
   - rubocop-rake
   - rubocop-rspec
 
@@ -21,7 +22,18 @@ Metrics/MethodLength:
   Enabled: false
 Metrics/ModuleLength:
   Enabled: false
+Performance/CollectionLiteralInLoop:
+  Exclude:
+    - spec/**/*
+Performance/RedundantBlockCall:
+  Enabled: false # TODO: temporarily disabled to avoid potential breaking change
+Performance/StringInclude:
+  Exclude:
+    - lib/ruby_llm/providers/**/capabilities.rb
+Performance/UnfreezeString:
+  Exclude:
+    - spec/**/*
 RSpec/ExampleLength:
   Enabled: false
 RSpec/MultipleExpectations:
-  Enabled: false
+  Enabled: false

Gemfile

@@ -22,6 +22,7 @@ group :development do # rubocop:disable Metrics/BlockLength
   gem 'reline'
   gem 'rspec', '~> 3.12'
   gem 'rubocop', '>= 1.0'
+  gem 'rubocop-performance'
   gem 'rubocop-rake', '>= 0.6'
   gem 'rubocop-rspec'
   gem 'ruby_llm-schema', '~> 0.1.0'

lib/ruby_llm/active_record/acts_as.rb

@@ -234,7 +234,7 @@ def setup_persistence_callbacks
       end
 
       def persist_new_message
-        @message = messages.create!(role: :assistant, content: String.new)
+        @message = messages.create!(role: :assistant, content: '')
       end
 
       def persist_message_completion(message)

lib/ruby_llm/content.rb

@@ -43,7 +43,7 @@ def process_attachments_array_or_string(attachments)
     def process_attachments(attachments)
       if attachments.is_a?(Hash)
         # Ignores types (like :image, :audio, :text, :pdf) since we have robust MIME type detection
-        attachments.each_value(&method(:process_attachments_array_or_string))
+        attachments.each_value { |attachment| process_attachments_array_or_string(attachment) }
       else
         process_attachments_array_or_string attachments
       end

lib/ruby_llm/models.rb

@@ -64,7 +64,7 @@ def resolve(model_id, provider: nil, assume_exists: false, config: nil) # ruboco
 
           model = Model::Info.new(
             id: model_id,
-            name: model_id.gsub('-', ' ').capitalize,
+            name: model_id.tr('-', ' ').capitalize,
             provider: provider_instance.slug,
             capabilities: %w[function_calling streaming],
             modalities: { input: %w[text image], output: %w[text] },

lib/ruby_llm/providers/bedrock/streaming/base.rb

@@ -47,7 +47,7 @@ def stream_response(connection, payload, additional_headers = {}, &block)
           end
 
           def handle_stream(&block)
-            buffer = String.new
+            buffer = +''
             proc do |chunk, _bytes, env|
               if env && env.status != 200
                 handle_failed_response(chunk, buffer, env)

lib/ruby_llm/providers/openai/capabilities.rb

@@ -198,11 +198,11 @@ def apply_special_formatting(name)
             .gsub(/(\d{4}) (\d{2}) (\d{2})/, '\1\2\3')
             .gsub(/^(?:Gpt|Chatgpt|Tts|Dall E) /) { |m| special_prefix_format(m.strip) }
             .gsub(/^O([13]) /, 'O\1-')
-            .gsub(/^O[13] Mini/, '\0'.gsub(' ', '-'))
+            .gsub(/^O[13] Mini/, '\0'.tr(' ', '-'))
             .gsub(/\d\.\d /, '\0'.sub(' ', '-'))
             .gsub(/4o (?=Mini|Preview|Turbo|Audio|Realtime|Transcribe|Tts)/, '4o-')
             .gsub(/\bHd\b/, 'HD')
-            .gsub(/(?:Omni|Text) Moderation/, '\0'.gsub(' ', '-'))
+            .gsub(/(?:Omni|Text) Moderation/, '\0'.tr(' ', '-'))
             .gsub('Text Embedding', 'text-embedding-')
         end
 

lib/ruby_llm/stream_accumulator.rb

@@ -8,7 +8,7 @@ class StreamAccumulator
     attr_reader :content, :model_id, :tool_calls
 
     def initialize
-      @content = String.new
+      @content = +''
       @tool_calls = {}
       @input_tokens = 0
       @output_tokens = 0
@@ -66,7 +66,7 @@ def accumulate_tool_calls(new_tool_calls)
       new_tool_calls.each_value do |tool_call|
         if tool_call.id
           tool_call_id = tool_call.id.empty? ? SecureRandom.uuid : tool_call.id
-          tool_call_arguments = tool_call.arguments.empty? ? String.new : tool_call.arguments
+          tool_call_arguments = tool_call.arguments.empty? ? +'' : tool_call.arguments
           @tool_calls[tool_call.id] = ToolCall.new(
             id: tool_call_id,
             name: tool_call.name,

lib/ruby_llm/streaming.rb

@@ -43,7 +43,7 @@ def handle_stream(&block)
     private
 
     def to_json_stream(&)
-      buffer = String.new
+      buffer = +''
       parser = EventStreamParser::Parser.new
 
       create_stream_processor(parser, buffer, &)

lib/tasks/aliases.rake

@@ -65,7 +65,7 @@ namespace :aliases do # rubocop:disable Metrics/BlockLength
 
       base_name = Regexp.last_match(1)
       # Normalize to Anthropic naming convention
-      anthropic_name = base_name.gsub('.', '-')
+      anthropic_name = base_name.tr('.', '-')
 
       # Skip if we already have an alias for this
       next if aliases[anthropic_name]
@@ -91,7 +91,7 @@ namespace :aliases do # rubocop:disable Metrics/BlockLength
       # OpenRouter uses "google/" prefix and sometimes different naming
       openrouter_variants = [
         "google/#{model}",
-        "google/#{model.gsub('gemini-', 'gemini-').gsub('.', '-')}",
+        "google/#{model.gsub('gemini-', 'gemini-').tr('.', '-')}",
         "google/#{model.gsub('gemini-', 'gemini-')}"
       ]
 

lib/tasks/models_docs.rake

@@ -86,7 +86,7 @@ def generate_models_markdown
 end
 
 def generate_provider_sections
-  RubyLLM::Provider.providers.map do |provider, provider_class|
+  RubyLLM::Provider.providers.filter_map do |provider, provider_class|
     models = RubyLLM.models.by_provider(provider)
     next if models.none?
 
@@ -95,7 +95,7 @@ def generate_provider_sections
 
       #{models_table(models)}
     PROVIDER
-  end.compact.join("\n\n")
+  end.join("\n\n")
 end
 
 def generate_capability_sections
@@ -107,15 +107,15 @@ def generate_capability_sections
     'Batch Processing' => RubyLLM.models.select { |m| m.capabilities.include?('batch') }
   }
 
-  capabilities.map do |capability, models|
+  capabilities.filter_map do |capability, models|
     next if models.none?
 
     <<~CAPABILITY
       ### #{capability} (#{models.count})
 
       #{models_table(models)}
     CAPABILITY
-  end.compact.join("\n\n")
+  end.join("\n\n")
 end
 
 def generate_modality_sections # rubocop:disable Metrics/PerceivedComplexity

spec/ruby_llm/chat_error_spec.rb

@@ -14,7 +14,7 @@
 
 RSpec::Matchers.define :look_like_json do
   match do |actual|
-    actual.strip.start_with?('{') || actual.strip.start_with?('[')
+    actual.strip.start_with?('{', '[')
   end
 
   failure_message do |actual|

spec/ruby_llm/chat_tools_spec.rb

@@ -300,7 +300,7 @@ def execute(query:)
       # Monkey-patch to count complete calls
       described_class.define_method(:complete) do |&block|
         call_count += 1
-        original_complete.bind(self).call(&block)
+        original_complete.bind_call(self, &block)
       end
 
       chat = RubyLLM.chat.with_tool(HaltingTool)