'better' LazyString

mongodb · Feb 20, 2009 · 6f25a72 · 6f25a72
1 parent 406442d
commit 6f25a72
Show file tree

Hide file tree

Showing 5 changed files with 29 additions and 43 deletions.
diff --git a/client/dbclient.h b/client/dbclient.h
@@ -111,9 +111,7 @@ namespace mongo {
         Query& where(const char *jscode) { return where(jscode, BSONObj()); }
 
         string toString() const;
-        static string toString( void *o ) {
-            return ( (Query*) o )->toString();
-        }
+        operator string() const { return toString(); }
     };
 
 /** Typically one uses the QUERY(...) macro to construct a Query object.

diff --git a/db/jsobj.h b/db/jsobj.h
@@ -502,9 +502,7 @@ namespace mongo {
             This is an abbreviated representation which might be used for logging.
         */
         string toString() const;
-        static string toString( void *o ) {
-            return ( (BSONObj*) o )->toString();
-        }
+        operator string() const { return toString(); }
 
         /** Properly formatted JSON string. */
         string jsonString( JsonStringFormat format = Strict ) const;

diff --git a/s/shard.h b/s/shard.h
@@ -53,9 +53,7 @@ namespace mongo {
         void split( const BSONObj& middle );
 
         string toString() const;
-        static string toString( void *o ) {
-            return ( (Shard*) o )->toString();
-        }
+        operator string() const { return toString(); }
 
         bool operator==(const Shard& s);
 
@@ -104,9 +102,7 @@ namespace mongo {
         bool loadByName( const string& ns );
 
         string toString() const;
-        static string toString( void *o ) {
-            return ( (ShardInfo*) o )->toString();
-        }
+        operator string() const { return toString(); }
 
     private:
         DBConfig * _config;

diff --git a/stdafx.h b/stdafx.h
@@ -70,12 +70,6 @@ using namespace std;
 
 namespace mongo {
 
-    class Stringable {
-    public:
-        virtual ~Stringable() throw() {}
-        virtual string toString() const = 0;
-    };
-
     /* these are manipulated outside of mutexes, so be careful */
     struct Assertion {
         Assertion() {
@@ -113,12 +107,13 @@ namespace mongo {
     /* last assert of diff types: regular, wassert, msgassert, uassert: */
     extern Assertion lastAssert[4];
 
-    class DBException : public exception, public Stringable {
+    class DBException : public exception {
     public:
         virtual const char* what() const throw() = 0;
         virtual string toString() const {
             return what();
         }
+        operator string() const { return toString(); }
     };
 
     class AssertionException : public DBException {

diff --git a/util/log.h b/util/log.h
@@ -20,22 +20,33 @@
 
 namespace mongo {
 
-    // If you don't want your class to inherit from Stringable (for example, if
-    // you don't want a virtual destructor) then add a function like the
-    // following to your class, which takes a pointer to an object of your class
-    // type:
-    // static string toString( void * );
     class LazyString {
     public:
-        // LazyString is designed to be used in situations where the lifespan of
-        // a temporary object used to construct a LazyString completely includes
-        // the lifespan of the LazyString object itself.
         template< class T >
-        LazyString( const T &t ) : obj_( (void*)&t ), fun_( &T::toString ) {}
-        string val() const { return (*fun_)(obj_); }
+        LazyString( const T& t ) {
+            if ( sizeof( Stringifier< T > ) > ( sizeof( Stringifier< unsigned > ) * 2 ) ) {
+                stringifier_ = &stringifierError_;
+            } else {
+                stringifier_ = new ( stringifierBuf_ ) Stringifier< T >( t );
+            }
+        }
+        string val() const { return stringifier_->val(); }
     private:
-        void *obj_;
-        string (*fun_) (void *);
+        struct StringifierBase {
+            virtual ~StringifierBase() {}
+            virtual string val() const = 0;
+        };
+        template< class T >
+        struct Stringifier : public StringifierBase {
+            Stringifier( const T& t ) : t_( t ) {}
+            virtual string val() const { return string( t_ ); }
+            const T& t_;
+        };
+        static struct StringifierError : public StringifierBase {
+            virtual string val() const { return "Error converting to string"; }
+        } stringifierError_;
+        StringifierBase *stringifier_;
+        char stringifierBuf_[ sizeof( Stringifier< unsigned > ) * 2 ];
     };
 
     class Nullstream {
@@ -72,15 +83,9 @@ namespace mongo {
         virtual Nullstream& operator<<(unsigned long long) {
             return *this;
         }
-        virtual Nullstream& operator<<(const string&) {
-            return *this;
-        }
         virtual Nullstream& operator<<(const LazyString&) {
             return *this;
         }
-        virtual Nullstream& operator<<(const Stringable&) {
-            return *this;
-        }
         virtual Nullstream& operator<< (ostream& ( *endl )(ostream&)) {
             return *this;
         }
@@ -109,17 +114,11 @@ namespace mongo {
         Logstream& operator<<(void *x) LOGIT
         Logstream& operator<<(long long x) LOGIT
         Logstream& operator<<(unsigned long long x) LOGIT
-        Logstream& operator<<(const string& x) LOGIT
         Logstream& operator<<(const LazyString& x) {
             boostlock lk(mutex);
             cout << x.val();
             return *this;
         }
-        Logstream& operator<<(const Stringable& x) {
-            boostlock lk(mutex);
-            cout << x.toString();
-            return *this;
-        }
         Logstream& operator<< (ostream& ( *_endl )(ostream&)) {
             boostlock lk(mutex);
             cout << _endl;