include/stp/Parser/LetMgr.h

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 *
 * BEGIN DATE: November, 2005
 *
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#ifndef LETMGR_H
#define LETMGR_H

#include "stp/AST/AST.h"

namespace stp
{
using std::string;

// LET Management
class LETMgr
{
private:
  const ASTNode ASTUndefined;

  typedef std::unordered_map<string, ASTNode> MapType;

  // MAP: This map is from bound IDs that occur in LETs to
  // expression. The map is useful in checking replacing the IDs
  // with the corresponding expressions. As soon as the brackets
  // that close a let expression is reached, it is emptied by
  // a call to CleanupLetIDMap().
  MapType* _letid_expr_map;

  // Need to pop/push the let nodes, they can be nested.
  std::stack<vector<string>> stack;

  // Allocate LetID map
  void InitializeLetIDMap(void);

public:
  // I think this keeps a reference to symbols so they don't get garbage
  // collected. Used only by the CVC parser.
  ASTNodeSet _parser_symbol_table;

  // A let with this name has already been declared.
  bool isLetDeclared(string s)
  {
    return _letid_expr_map->find(s) != _letid_expr_map->end();
  }

  void cleanupParserSymbolTable() { _parser_symbol_table.clear(); }

  LETMgr(ASTNode undefined) : ASTUndefined(undefined)
  {
    assert(!undefined.IsNull());
    InitializeLetIDMap();
  }

  ~LETMgr() { delete _letid_expr_map; }

  // We know for sure that it's a let.
  ASTNode resolveLet(const string s)
  {
    assert(isLetDeclared(s));
    return _letid_expr_map->find(s)->second;
  }

  ASTNode ResolveID(const ASTNode& var);

  // Functions that are used to manage LET expressions
  void LetExprMgr(const ASTNode& var, const ASTNode& letExpr);
  void LetExprMgr(string name, const ASTNode& letExpr);

  // Delete Letid Map. Called when we move onto the expression after (let ... )
  void CleanupLetIDMap(void);

  void push()
  {
    // new frame.
    stack.push(vector<string>());
  }

  void pop()
  {
    vector<string> v = stack.top();
    for (string s : v)
    {
      _letid_expr_map->erase(s);
    }
    stack.pop();
  }
};
} // end of namespace

#endif