Module: Metz::ErbRubyExtractor

Defined in:
lib/metz/erb_ruby_extractor.rb

Overview

Ruby extractor for ERB / HAML / SLIM view templates. Registered with RuboCop::Runner.ruby_extractors so that view-aware Metz cops (currently Metz/ViewsDeepNavigation) can run against ERB content. RuboCop's parser would otherwise emit Lint/Syntax for any .erb file because the raw template is not a valid Ruby program.

The extractor scans for ERB tags, hands each <% ... %> / <%= ... %> body to RuboCop as its own ProcessedSource, and records the byte offset of the body inside the original template. RuboCop adds that offset back to every offense location, so reported line / column numbers point at the original .erb file -- not the synthetic snippet.

Control-flow openers such as <% if ... %> are reduced to the condition expression. Other invalid fragments are skipped to avoid Lint/Syntax noise. ERB comments (<%# ... %>) are skipped as well.

Constant Summary collapse

ERB_TAG = 
/<%(?<kind>[-=#]?)(?<body>.*?)-?%>/m
CONTROL_CONDITION = 
/\A(?<prefix>\s*(?:if|unless|while|until|elsif|case)\b\s*)(?<expr>.*?)(?:\s+then)?\s*\z/m
TRAILING_DO_BLOCK = 
/\A(?<expr>.*?)(?<suffix>\s+do\b(?:\s*\|[^|]*\|)?\s*)\z/m
MAGIC_COMMENT = 
"# frozen_string_literal: true\n\n"

Class Method Summary collapse

Class Method Details

.call(processed_source) ⇒ Object 



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# File 'lib/metz/erb_ruby_extractor.rb', line 29

def call(processed_source)
  path = processed_source.path
  return nil unless path && handles?(path)

  snippets = extract_snippets(processed_source)
  snippets << empty_snippet(processed_source) if snippets.empty?
  snippets
end

.code_tag?(kind) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/metz/erb_ruby_extractor.rb', line 81

def code_tag?(kind)
  kind.empty? || kind == "-"
end

.control_expression(expr) ⇒ Object 



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# File 'lib/metz/erb_ruby_extractor.rb', line 93

def control_expression(expr)
  "#{MAGIC_COMMENT}#{expr}\n"
end

.empty_snippet(processed_source) ⇒ Object 



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# File 'lib/metz/erb_ruby_extractor.rb', line 101

def empty_snippet(processed_source)
  ruby_version = processed_source.ruby_version || RUBY_VERSION.to_f
  ps = RuboCop::ProcessedSource.new("", ruby_version, processed_source.path)
  { offset: 0, processed_source: ps }
end

.enumerate_matches(raw, pos: 0, matches: []) ⇒ Object 



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# File 'lib/metz/erb_ruby_extractor.rb', line 54

def enumerate_matches(raw, pos: 0, matches: [])
  while (match = raw.match(ERB_TAG, pos))
    matches << match
    pos = match.end(0)
  end
  matches
end

.expression_offset(body_offset, match) ⇒ Object 



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# File 'lib/metz/erb_ruby_extractor.rb', line 97

def expression_offset(body_offset, match)
  body_offset + match.begin(:expr) - MAGIC_COMMENT.bytesize
end

.expression_source(body, ruby_version, path, body_offset) ⇒ Object 



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# File 'lib/metz/erb_ruby_extractor.rb', line 85

def expression_source(body, ruby_version, path, body_offset)
  match = body.match(CONTROL_CONDITION) || body.match(TRAILING_DO_BLOCK)
  return unless match

  ps = RuboCop::ProcessedSource.new(control_expression(match[:expr]), ruby_version, path)
  [ps, expression_offset(body_offset, match)] if ps.valid_syntax?
end

.extract_snippets(processed_source) ⇒ Object 



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# File 'lib/metz/erb_ruby_extractor.rb', line 48

def extract_snippets(processed_source)
  enumerate_matches(processed_source.raw_source).filter_map do |match|
    snippet_for(match, processed_source)
  end
end

.handles?(path) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/metz/erb_ruby_extractor.rb', line 38

def handles?(path)
  File.extname(path.to_s) == ".erb" && ::Metz::FileClassifier.view?(path)
end

.install! ⇒ Object 



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# File 'lib/metz/erb_ruby_extractor.rb', line 42

def install!
  extractors = RuboCop::Runner.ruby_extractors
  extractor = method(:call)
  extractors.unshift(extractor) unless extractors.include?(extractor)
end

.snippet_for(match, processed_source) ⇒ Object 



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# File 'lib/metz/erb_ruby_extractor.rb', line 62

def snippet_for(match, processed_source)
  return if match[:kind] == "#"

  ruby_version = processed_source.ruby_version || RUBY_VERSION.to_f
  ps, offset = source_and_offset(match, ruby_version, processed_source.path)
  return unless ps

  { offset: offset, processed_source: ps }
end

.source_and_offset(match, ruby_version, path) ⇒ Object 



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# File 'lib/metz/erb_ruby_extractor.rb', line 72

def source_and_offset(match, ruby_version, path)
  body = match[:body]
  ps = RuboCop::ProcessedSource.new(body, ruby_version, path)
  return [ps, match.begin(:body)] if ps.valid_syntax?
  return unless code_tag?(match[:kind])

  expression_source(body, ruby_version, path, match.begin(:body))
end