Improve symbol table style

Author: smowton

src/util/recording_symbol_table.h

@@ -56,18 +56,11 @@ class recording_symbol_tablet:public symbol_tablet
   virtual symbolt *get_writeable(const irep_idt &identifier) override
   {
     symbolt *result=base_symbol_table.get_writeable(identifier);
-    if(result)
+    if(result!=nullptr)
       on_update(identifier);
     return result;
   }
 
-  virtual symbolt &get_writeable_ref(const irep_idt &identifier) override
-  {
-    symbolt &result=base_symbol_table.get_writeable_ref(identifier);
-    on_update(identifier);
-    return result;
-  }
-
   virtual std::pair<symbolt &, bool> insert(symbolt symbol) override
   {
     std::pair<symbolt &, bool> result=

src/util/symbol_table.cpp

@@ -7,19 +7,6 @@
 #include <util/invariant.h>
 
 
-/// Find a symbol in the symbol table.
-/// \param identifier: The name of the symbol to look for
-/// \return Returns an optional reference to the found symbol, without a value
-///   if a symbol with the given name does not exist in the symbol table
-const symbolt *symbol_tablet::lookup(
-  const irep_idt &identifier) const
-{
-  symbolst::const_iterator it=symbols.find(identifier);
-  if(it==symbols.end())
-    return nullptr;
-  return &it->second;
-}
-
 /// Add a new symbol to the symbol table
 /// \param symbol: The symbol to be added to the symbol table
 /// \return Returns true if the process failed, which should only happen if
@@ -106,12 +93,7 @@ std::ostream &operator<<(std::ostream &out, const symbol_tablet &symbol_table)
 }
 
 
-/// Find a symbol in the symbol table.
-/// \param identifier: The name of the symbol to look for
-/// \return Returns an optional reference to the found symbol, without a value
-///   if a symbol with the given name does not exist in the symbol table
-symbolt *concrete_symbol_tablet::get_writeable(
-  const irep_idt &identifier)
+symbolt *concrete_symbol_tablet::get_writeable(const irep_idt &identifier)
 {
   symbolst::iterator it=internal_symbols.find(identifier);
   if(it==symbols.end())

src/util/symbol_table.h

@@ -68,27 +68,39 @@ class symbol_tablet
   }
 
   /// Find a symbol in the symbol table for read-only access.
-  /// \param id: The name of the symbol to look for
-  /// \return an optional reference, set if found, nullptr otherwise.
-  const symbolt *lookup(const irep_idt &identifier) const;
+  /// \param identifier: The name of the symbol to look for
+  /// \return an optional pointer, set if found, nullptr otherwise.
+  const symbolt *lookup(const irep_idt &identifier) const
+  {
+    symbolst::const_iterator it=symbols.find(identifier);
+    if(it==symbols.end())
+      return nullptr;
+    return &it->second;
+  }
 
   /// Find a symbol in the symbol table for read-write access.
-  /// \param id: The name of the symbol to look for
-  /// \return an optional reference, set if found, unset otherwise.
+  /// \param identifier: The name of the symbol to look for
+  /// \return an optional pointer, set if found, nullptr otherwise.
   virtual symbolt *get_writeable(const irep_idt &identifier)=0;
 
   /// Find a symbol in the symbol table for read-only access.
-  /// \param id: The name of the symbol to look for
+  /// \param identifier: The name of the symbol to look for
   /// \return A reference to the symbol
   /// \throw `std::out_of_range` if no such symbol exists
-  const symbolt &lookup_ref(const irep_idt &id) const
-    { return symbols.at(id); }
+  const symbolt &lookup_ref(const irep_idt &identifier) const
+  { return symbols.at(identifier); }
 
   /// Find a symbol in the symbol table for read-write access.
-  /// \param id: The name of the symbol to look for
+  /// \param identifier: The name of the symbol to look for
   /// \return A reference to the symbol
   /// \throw `std::out_of_range` if no such symbol exists
-  virtual symbolt &get_writeable_ref(const irep_idt &id)=0;
+  symbolt &get_writeable_ref(const irep_idt &identifier)
+  {
+    symbolt *symbol=get_writeable(identifier);
+    if(symbol==nullptr)
+      throw std::out_of_range("identifier not found in symbol_table");
+    return *symbol;
+  }
 
   bool add(const symbolt &symbol);
   /// Move or copy a new symbol to the symbol table
@@ -103,6 +115,8 @@ class symbol_tablet
   bool move(symbolt &symbol, symbolt *&new_symbol);
 
   bool remove(const irep_idt &name);
+  /// Remove a symbol from the symbol table
+  /// \param entry: an iterator pointing at the symbol to remove
   virtual void erase(const symbolst::const_iterator &entry)=0;
   virtual void clear()=0;
 
@@ -187,8 +201,6 @@ class concrete_symbol_tablet:public symbol_tablet
   }
 
   virtual symbolt *get_writeable(const irep_idt &identifier) override;
-  virtual symbolt &get_writeable_ref(const irep_idt &identifier) override
-    { return internal_symbols.at(identifier); }
 
   virtual std::pair<symbolt &, bool> insert(symbolt symbol) override;