journalling_symbol_table.h

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#ifndef CPROVER_UTIL_JOURNALLING_SYMBOL_TABLE_H
#define CPROVER_UTIL_JOURNALLING_SYMBOL_TABLE_H
 
#include "irep.h"
#include "symbol_table_base.h"
 
#include <unordered_set>
#include <utility>

class journalling_symbol_tablet : public symbol_table_baset
{
public:
  typedef std::unordered_set<irep_idt> changesett;
 
private:
  symbol_table_baset &base_symbol_table;
  // Symbols originally in the table will never be marked inserted
  changesett inserted;
  // get_writeable marks an existing symbol updated
  // Inserted symbols are marked updated, removed ones aren't
  changesett updated;
  // Symbols not originally in the table will never be marked removed
  changesett removed;
 
private:
  explicit journalling_symbol_tablet(symbol_table_baset &base_symbol_table)
    : symbol_table_baset(
        base_symbol_table.symbols,
        base_symbol_table.symbol_base_map,
        base_symbol_table.symbol_module_map),
      base_symbol_table(base_symbol_table)
  {
  }
 
public:
  journalling_symbol_tablet(const journalling_symbol_tablet &other) = delete;
 
  journalling_symbol_tablet(journalling_symbol_tablet &&other)
    : symbol_table_baset(
        other.symbols,
        other.symbol_base_map,
        other.symbol_module_map),
      base_symbol_table(other.base_symbol_table),
      inserted(std::move(other.inserted)),
      updated(std::move(other.updated)),
      removed(std::move(other.removed))
  {
  }
 
  virtual const symbol_tablet &get_symbol_table() const override
  {
    return base_symbol_table.get_symbol_table();
  }
 
  static journalling_symbol_tablet wrap(symbol_table_baset &base_symbol_table)
  {
    return journalling_symbol_tablet(base_symbol_table);
  }
 
  virtual bool move(symbolt &symbol, symbolt *&new_symbol) override
  {
    bool ret = base_symbol_table.move(symbol, new_symbol);
    if(!ret)
      on_insert(symbol.name);
    else
      on_update(symbol.name);
    return ret;
  }
 
  virtual symbolt *get_writeable(const irep_idt &identifier) override
  {
    symbolt *result = base_symbol_table.get_writeable(identifier);
    if(result)
      on_update(identifier);
    return result;
  }
 
  std::size_t next_unused_suffix(const std::string &prefix) const override
  {
    return base_symbol_table.next_unused_suffix(prefix);
  }
 
  virtual std::pair<symbolt &, bool> insert(symbolt symbol) override
  {
    std::pair<symbolt &, bool> result =
      base_symbol_table.insert(std::move(symbol));
    if(result.second)
      on_insert(result.first.name);
    return result;
  }
 
  virtual void
  erase(const symbol_table_baset::symbolst::const_iterator &entry) override
  {
    const irep_idt entry_name = entry->first;
    base_symbol_table.erase(entry);
    on_remove(entry_name);
  }
 
  virtual void clear() override
  {
    for(const auto &named_symbol : base_symbol_table.symbols)
      on_remove(named_symbol.first);
    base_symbol_table.clear();
  }
 
  virtual iteratort begin() override
  {
    return iteratort(
      base_symbol_table.begin(), [this](const irep_idt &id) { on_update(id); });
  }
  virtual iteratort end() override
  {
    return iteratort(
      base_symbol_table.end(), [this](const irep_idt &id) { on_update(id); });
  }
 
  using symbol_table_baset::begin;
  using symbol_table_baset::end;
 
  void validate(
    const validation_modet vm = validation_modet::INVARIANT) const override
  {
    base_symbol_table.validate(vm);
  }
 
  const changesett &get_inserted() const
  {
    return inserted;
  }
  const changesett &get_updated() const
  {
    return updated;
  }
  const changesett &get_removed() const
  {
    return removed;
  }
 
private:
  void on_insert(const irep_idt &id)
  {
    if(removed.erase(id) == 0)
      inserted.insert(id);
    updated.insert(id);
  }
 
  void on_update(const irep_idt &id)
  {
    updated.insert(id);
  }
 
  void on_remove(const irep_idt &id)
  {
    if(inserted.erase(id) == 0)
      removed.insert(id);
    updated.erase(id);
  }
};
 
#endif // CPROVER_UTIL_JOURNALLING_SYMBOL_TABLE_H