text: // Copyright 2015 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef CHROME_BROWSER_EXTENSIONS_API_DECLARATIVE_CONTENT_CONTENT_PREDICATE_H_
  #define CHROME_BROWSER_EXTENSIONS_API_DECLARATIVE_CONTENT_CONTENT_PREDICATE_H_
  
  #include <string>
  
  #include "base/macros.h"
  #include "base/memory/scoped_ptr.h"
  
  namespace base {
  class Value;
  }
  
  namespace extensions {
  
  class ContentPredicateEvaluator;
  class Extension;
  
  // Represents a predicate that is part of a declarative rule condition in the
  // Declarative Content API. This is created and can be evaluated by its
  // associated ContentPredicateEvaluator subclass.
  //
  // For example, given the sample code at
  // https://developer.chrome.com/extensions/declarativeContent#rules, the
  // entities { hostEquals: 'www.google.com', schemes: ['https'] } and
  // ["input[type='password']"] are both represented by ContentPredicate
  // subclasses.
  class ContentPredicate {
   public:
    virtual ~ContentPredicate();
  
    // Returns true if this predicate should be ignored during evaluation. By
    // default predicates are not ignored.
    virtual bool IsIgnored() const;
  
    // Returns the evaluator associated with this predicate.
    virtual ContentPredicateEvaluator* GetEvaluator() const = 0;
  
   protected:
    ContentPredicate();
  
   private:
    DISALLOW_COPY_AND_ASSIGN(ContentPredicate);
  };
  
  // Defines the interface for objects that create predicates.
  //
  // Given the sample code at
  // https://developer.chrome.com/extensions/declarativeContent#rules,
  // ContentPredicateFactories are directly responsible for creating individual
  // predicates from the { hostEquals: 'www.google.com', schemes: ['https'] } and
  // ["input[type='password']"] JSON entities encoded in |value|.
  class ContentPredicateFactory {
   public:
    virtual ~ContentPredicateFactory();
  
    // Creates a new predicate from |value|, as specified in the declarative
    // API. Sets *|error| and returns null if creation failed for any reason.
    virtual scoped_ptr<const ContentPredicate> CreatePredicate(
        const Extension* extension,
        const base::Value& value,
        std::string* error) = 0;
  
   protected:
    ContentPredicateFactory();
  
   private:
    DISALLOW_COPY_AND_ASSIGN(ContentPredicateFactory);
  };
  
  }  // namespace extensions
  
  #endif  // CHROME_BROWSER_EXTENSIONS_API_DECLARATIVE_CONTENT_CONTENT_PREDICATE_H_
  