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-rw-r--r--activestorage/lib/active_storage/analyzer.rb33
1 files changed, 33 insertions, 0 deletions
diff --git a/activestorage/lib/active_storage/analyzer.rb b/activestorage/lib/active_storage/analyzer.rb
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+# frozen_string_literal: true
+
+require "active_storage/downloading"
+
+module ActiveStorage
+ # This is an abstract base class for analyzers, which extract metadata from blobs. See
+ # ActiveStorage::Analyzer::ImageAnalyzer for an example of a concrete subclass.
+ class Analyzer
+ include Downloading
+
+ attr_reader :blob
+
+ # Implement this method in a concrete subclass. Have it return true when given a blob from which
+ # the analyzer can extract metadata.
+ def self.accept?(blob)
+ false
+ end
+
+ def initialize(blob)
+ @blob = blob
+ end
+
+ # Override this method in a concrete subclass. Have it return a Hash of metadata.
+ def metadata
+ raise NotImplementedError
+ end
+
+ private
+ def logger #:doc:
+ ActiveStorage.logger
+ end
+ end
+end