ContactBook/CExpr/Cexpr.cpp

/*
 * File:	cexpr.cpp
 * Purpose:	Prolog-like file I/O
 * Author:	Julian Smart
 * Created:	1993
 * Updated:	
 * Copyright:	(c) 1993
 */

static const char sccsid[] = "%W% %G%";

#include "stdafx.h"
#include <fstream.h>
#include <stdarg.h>
#include <ctype.h>

#include "expr.h"
#include "cexpr.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

extern "C" void add_expr(char *);
extern "C" void LexFromFile(FILE *fd);
extern "C" void LexFromString(char *buf);

CExprDatabase *theCExprDatabase = NULL;
CExprErrorHandler currentCExprErrorHandler;

IMPLEMENT_DYNAMIC(CExprDatabase, wxList)

CExpr::CExpr(const CString& functor)
{
  type = CExprList;
  next = NULL;
  last = NULL;
  value.first = NULL;

  CExpr *pfunctor = new CExpr(CExprWord, functor);
  Append(pfunctor);
  client_data = NULL;
}

CExpr::CExpr(CExprType the_type, const CString& word_or_string)
{
  type = the_type;

  switch (the_type)
  {
   case CExprWord:
    value.word = copystring((const char *)word_or_string);
    break;
   case CExprString:
    value.string = copystring((const char *)word_or_string);
    break;
   case CExprList:
    last = NULL;
    value.first = NULL;
    break;
   case CExprReal:
   case CExprInteger:
   case CExprNull: 
    break;
  }
  client_data = NULL;
  next = NULL;
}

CExpr::CExpr(CExprType the_type, char *word_or_string, BOOL allocate)
{
  type = the_type;

  switch (the_type)
  {
   case CExprWord:
    value.word = allocate ? copystring(word_or_string) : word_or_string;
    break;
   case CExprString:
    value.string = allocate ? copystring(word_or_string) : word_or_string;
    break;
   case CExprList:
    last = NULL;
    value.first = NULL;
    break;
   case CExprReal:
   case CExprInteger:
   case CExprNull: 
    break;
  }
  client_data = NULL;
  next = NULL;
}

CExpr::CExpr(long the_integer)
{
  type = CExprInteger;
  value.integer = the_integer;
  client_data = NULL;
  next = NULL;
}

CExpr::CExpr(float the_real)
{
  type = CExprReal;
  value.real = the_real;
  client_data = NULL;
  next = NULL;
}

CExpr::CExpr(wxList *the_list)
{
  type = CExprList;
  client_data = NULL;
  last = NULL;
  value.first = NULL;

  CExpr *listExpr = new CExpr(CExprList);

  wxNode *node = the_list->First();
  while (node)
  {
    CExpr *expr = (CExpr *)node->Data();
    listExpr->Append(expr);
    node = node->Next();
  }
  Append(listExpr);

  delete the_list;
}

CExpr::~CExpr(void)
{
  switch (type)
  {
    case CExprInteger:
    case CExprReal:
    {
     break;
    }
   case CExprString:
   {
     delete[] value.string;
     break;
   }
   case CExprWord:
   {
     delete[] value.word;
     break;
   }
   case CExprList:
   {
     CExpr *expr = value.first;
     while (expr)
     {
       CExpr *expr1 = expr->next;

       delete expr;
       expr = expr1;
     }
     break;
   }
   case CExprNull: break;
  }
}

void CExpr::Append(CExpr *expr)
{
  if (!value.first)
    value.first = expr;

  if (last)
    last->next = expr;
  last = expr;
}

void CExpr::Insert(CExpr *expr)
{
  expr->next = value.first;
  value.first = expr;

  if (!last)
    last = expr;
}

CExpr *CExpr::Copy(void)
{
  // This seems to get round an optimizer bug when
  // using Watcom C++ 10a in WIN32 compilation mode.
  // If these lines not present, the type seems to be
  // interpreted wrongly as an integer.
  // I don't want to turn optimization off since it's needed
  // for reading in files quickly.
#if defined(__WATCOMC__)
  char buf[2];
  sprintf(buf, "");
#endif

  switch (type)
  {
    case CExprInteger:
      return new CExpr(value.integer);
    case CExprReal:
      return new CExpr(value.real);
    case CExprString:
      return new CExpr(CExprString, CString(value.string));
    case CExprWord:
      return new CExpr(CExprWord, CString(value.word));
    case CExprList:
    {
      CExpr *expr = value.first;
      CExpr *new_list = new CExpr(CExprList);
      while (expr)
      {
        CExpr *expr2 = expr->Copy();
        new_list->Append(expr2);
        expr = expr->next;
      }
      return new_list;
    }
   case CExprNull: 
    break;
  }
  return NULL;
}


// Get the CExpr (containing (= CExpr Value) form) for the given word
//  or string, assuming that we have Attribute=Value, ...
CExpr *CExpr::GetAttributeValueNode(const CString& word)  // Use only for a clause or list
{
  if (type != CExprList)
    return NULL;

  CExpr *expr = value.first;
  while (expr)
  {
    if (expr->type == CExprList)
    {
      CExpr *firstNode = expr->value.first;
      if ((firstNode->type == CExprWord) && (firstNode->value.word[0] == '='))
      {
        CExpr *secondNode = firstNode->next;
        if ((secondNode->type == CExprWord) && 
            (strcmp((const char *)word, secondNode->value.word) == 0))
        {
          return expr;
        }
      }
    }
    expr = expr->next;
  }
  return NULL;
}

// Get the value (in CExpr form) for the given word or string, assuming
// that we have Attribute=Value, ...
CExpr *CExpr::AttributeValue(const CString& word)  // Use only for a clause or list
{
  if (type != CExprList)
    return NULL;

  CExpr *attExpr = GetAttributeValueNode(word);
  if (attExpr && attExpr->value.first && attExpr->value.first->next)
    return attExpr->value.first->next->next;
  else return NULL;
}

CString CExpr::Functor(void)  // Use only for a clause
{
  if ((type != CExprList) || !value.first)
    return CString("");

  if (value.first->type == CExprWord)
    return CString(value.first->value.word);
  else
    return CString("");
}

BOOL CExpr::IsFunctor(const CString& f)  // Use only for a clause
{
  if ((type != CExprList) || !value.first)
    return FALSE;

  return (value.first->type == CExprWord && 
          (strcmp((const char *)f, value.first->value.word) == 0));
}

// Return nth argument of a clause (starting from 1)
CExpr *CExpr::Arg(CExprType theType, int arg)
{
  CExpr *expr = value.first;
  int i;
  for (i = 1; i < arg; i++)
    if (expr)
      expr = expr->next;

  if (expr && (expr->type == theType))
    return expr;
  else
    return NULL;
}

// Return nth argument of a list expression (starting from zero)
CExpr *CExpr::Nth(int arg)
{
  if (type != CExprList)
    return NULL;

  CExpr *expr = value.first;
  int i;
  for (i = 0; i < arg; i++)
    if (expr)
      expr = expr->next;
    else return NULL;

  if (expr)
    return expr;
  else
    return NULL;
}

  // Returns the number of elements in a list expression
int CExpr::Number(void)
{
  if (type != CExprList)
    return 0;

  int i = 0;
  CExpr *expr = value.first;
  while (expr)
  {
    expr = expr->next;
    i ++;
  }
  return i;
}

void CExpr::DeleteAttributeValue(const CString& attribute)
{
  if (type != CExprList)
    return;

  CExpr *expr = value.first;
  CExpr *lastExpr = this;
  while (expr)
  {
    if (expr->type == CExprList)
    {
      CExpr *firstNode = expr->value.first;
      if ((firstNode->type == CExprWord) && (firstNode->value.word[0] == '='))
      {
        CExpr *secondNode = firstNode->next;
        if ((secondNode->type == CExprWord) && 
            (strcmp((const char *)attribute, secondNode->value.word) == 0))
        {
          CExpr *nextExpr = expr->next;
          delete expr;

          lastExpr->next = nextExpr;

          if (last == expr)
            last = lastExpr;

          return;
        }
      }
    }
    lastExpr = expr;
    expr = expr->next;
  }
  return;
}

void CExpr::AddAttributeValue(const CString& attribute, CExpr *val)
{
  if (type != CExprList)
  {
//    cout << "Error! tried to add an attribute-value pair to a nonlist CExpr expression\n";
    return;
  }
  // Warning - existing code may assume that any existing value
  // is deleted first. For efficiency, we leave this to the application.
//  DeleteAttributeValue(attribute);

  CExpr *patt = new CExpr(CExprWord, attribute);
  CExpr *pequals = new CExpr(CExprWord, "=");

  CExpr *listExpr = new CExpr(CExprList);

  listExpr->Append(pequals);
  listExpr->Append(patt);
  listExpr->Append(val);

  Append(listExpr);
}

void CExpr::AddAttributeValue(const CString& attribute, long val)
{
  if (type != CExprList)
  {
//    cout << "Error! tried to add an attribute-value pair to a nonlist CExpr expression\n";
    return;
  }
  // Warning - existing code may assume that any existing value
  // is deleted first. For efficiency, we leave this to the application.
//  DeleteAttributeValue(attribute);

  CExpr *patt = new CExpr(CExprWord, attribute);
  CExpr *pval = new CExpr(val);
  CExpr *pequals = new CExpr(CExprWord, "=");

  CExpr *listExpr = new CExpr(CExprList);

  listExpr->Append(pequals);
  listExpr->Append(patt);
  listExpr->Append(pval);

  Append(listExpr);
}

void CExpr::AddAttributeValue(const CString& attribute, float val)
{
  if (type != CExprList)
  {
//    cout << "Error! tried to add an attribute-value pair to a nonlist CExpr expression\n";
    return;
  }

//  DeleteAttributeValue(attribute);
  CExpr *patt = new CExpr(CExprWord, attribute);
  CExpr *pval = new CExpr(val);
  CExpr *pequals = new CExpr(CExprWord, "=");

  CExpr *listExpr = new CExpr(CExprList);

  listExpr->Append(pequals);
  listExpr->Append(patt);
  listExpr->Append(pval);

  Append(listExpr);
}

void CExpr::AddAttributeValueString(const CString& attribute, const CString& val)
{
  if (type != CExprList)
  {
//    cout << "Error! tried to add an attribute-value pair to a nonlist CExpr expression\n";
    return;
  }

//  DeleteAttributeValue(attribute);

  CExpr *patt = new CExpr(CExprWord, attribute);
  CExpr *pval = new CExpr(CExprString, val);
  CExpr *pequals = new CExpr(CExprWord, "=");

  CExpr *listExpr = new CExpr(CExprList);

  listExpr->Append(pequals);
  listExpr->Append(patt);
  listExpr->Append(pval);

  Append(listExpr);
}

void CExpr::AddAttributeValueWord(const CString& attribute, const CString& val)
{
  if (type != CExprList)
  {
//    cout << "Error! tried to add an attribute-value pair to a nonlist CExpr expression\n";
    return;
  }

//  DeleteAttributeValue(attribute);

  CExpr *patt = new CExpr(CExprWord, attribute);
  CExpr *pval = new CExpr(CExprWord, val);
  CExpr *pequals = new CExpr(CExprWord, "=");

  CExpr *listExpr = new CExpr(CExprList);

  listExpr->Append(pequals);
  listExpr->Append(patt);
  listExpr->Append(pval);

  Append(listExpr);
}

void CExpr::AddAttributeValue(const CString& attribute, wxList *val)
{
  if (type != CExprList)
  {
//    cout << "Error! tried to add an attribute-value pair to a nonlist CExpr expression\n";
    return;
  }
  if (!val)
    return;

//  DeleteAttributeValue(attribute);

  CExpr *patt = new CExpr(CExprWord, attribute);
  CExpr *pval = new CExpr(val);
  CExpr *pequals = new CExpr(CExprWord, "=");

  CExpr *listExpr = new CExpr(CExprList);

  listExpr->Append(pequals);
  listExpr->Append(patt);
  listExpr->Append(pval);

  Append(listExpr);
}

void CExpr::AddAttributeValueStringList(const CString& attribute, wxList *string_list)
{
  if (type != CExprList)
  {
//    cout << "Error! tried to add an attribute-value pair to a nonlist CExpr expression\n";
    return;
  }
  if (!string_list)
    return;

//  DeleteAttributeValue(attribute);

  // First make a list of CExpr strings
  CExpr *listExpr = new CExpr(CExprList);
  wxNode *node = string_list->First();
  while (node)
  {
    char *string = (char *)node->Data();
    CExpr *expr = new CExpr(CExprString, CString(string));
    listExpr->Append(expr);
    node = node->Next();
  }

  // Now make an (=, Att, Value) triple
  CExpr *patt = new CExpr(CExprWord, attribute);
  CExpr *pequals = new CExpr(CExprWord, "=");

  CExpr *listExpr2 = new CExpr(CExprList);

  listExpr2->Append(pequals);
  listExpr2->Append(patt);
  listExpr2->Append(listExpr);

  Append(listExpr2);
}

BOOL CExpr::GetAttributeValue(const CString& att, int& var)
{
  CExpr *expr = AttributeValue(att);

  if (expr && (expr->Type() == CExprInteger || expr->Type() == CExprReal))
  {
    var = (int)(expr->IntegerValue());
    return TRUE;
  }
  else
    return FALSE;
}

BOOL CExpr::GetAttributeValue(const CString& att, long& var)
{
  CExpr *expr = AttributeValue(att);

  if (expr && (expr->Type() == CExprInteger || expr->Type() == CExprReal))
  {
    var = expr->IntegerValue();
    return TRUE;
  }
  else
    return FALSE;
}

BOOL CExpr::GetAttributeValue(const CString& att, float& var)
{
  CExpr *expr = AttributeValue(att);
  if (expr && (expr->Type() == CExprInteger || expr->Type() == CExprReal))
  {
    var = expr->RealValue();
    return TRUE;
  }
  else
    return FALSE;
}

BOOL CExpr::GetAttributeValue(const CString& att, CString& var)  // Word OR string -> string
{
  CExpr *expr = AttributeValue(att);
  if (expr && expr->Type() == CExprWord)
  {
    var = expr->WordValue();
    return TRUE;
  }
  else if (expr && expr->Type() == CExprString)
  {
    var = expr->StringValue();
    return TRUE;
  }
  else
    return FALSE;
}

BOOL CExpr::GetAttributeValue(const CString& att, CExpr **var)
{
  CExpr *expr = AttributeValue(att);
  if (expr)
  {
    *var = expr;
    return TRUE;
  }
  else
    return FALSE;
}

BOOL CExpr::GetAttributeValueStringList(const CString& att, wxList *var)
{
  CExpr *expr = AttributeValue(att);
  if (expr && expr->Type() == CExprList)
  {
    CExpr *string_expr = expr->value.first;
    while (string_expr)
    {
      if (string_expr->Type() == CExprString)
        var->Append((CObject *)copystring(string_expr->StringValue()));

      string_expr = string_expr->next;
    }
	return TRUE;
  }
  else
    return FALSE;
}

void CExpr::WriteClause(ostream& stream)  // Write this expression as a top-level clause
{
  if (type != CExprList)
    return;

  CExpr *node = value.first;
  if (node)
  {
    node->WriteExpr(stream);
    stream << "(";
    node = node->next;
    BOOL first = TRUE;
    while (node)
    {
      if (!first)
        stream << "  ";
      node->WriteExpr(stream);
      node = node->next;
      if (node) stream << ",\n";
      first = FALSE;
    }
    stream << ").\n\n";
  }
}

void CExpr::WriteExpr(ostream& stream)    // Write as any other subexpression
{
  // This seems to get round an optimizer bug when
  // using Watcom C++ 10a in WIN32 compilation mode.
  // If these lines not present, the type seems to be
  // interpreted wrongly as an integer.
  // I don't want to turn optimization off since it's needed
  // for reading in files quickly.
#if defined(__WATCOMC__)
  char buf[2];
  sprintf(buf, "");
#endif

  switch (type)
  {
    case CExprInteger:
    {
      stream << value.integer;
      break;
    }
    case CExprReal:
    {
      float f = value.real;
/* Now the parser can cope with this.
      // Prevent printing in 'e' notation. Any better way?
      if (fabs(f) < 0.00001)
        f = 0.0;
*/
      char buf[40];
      sprintf(buf, "%.6g", f);
      stream << buf;
      break;
    }
    case CExprString:
    {
      stream << "\"";
      int i;
      int len = strlen(value.string);
      for (i = 0; i < len; i++)
      {
        char ch = value.string[i];
        if (ch == '"' || ch == '\\')
          stream << "\\";
        stream << ch;
      }

      stream << "\"";
      break;
    }
    case CExprWord:
    {
      BOOL quote_it = FALSE;
      int len = strlen(value.word);
      if ((len == 0) || (len > 0 && (value.word[0] > 64 && value.word[0] < 91)))
        quote_it = TRUE;
      else
      {
        int i;
        for (i = 0; i < len; i++)
          if ((!isalpha(value.word[i])) && (!isdigit(value.word[i])) &&
              (value.word[i] != '_'))
            { quote_it = TRUE; i = len; }
      }

      if (quote_it)
        stream << "'";

      stream << value.word;

      if (quote_it)
        stream << "'";

      break;
    }
    case CExprList:
    {
      if (!value.first)
        stream << "[]";
      else
      {
        CExpr *expr = value.first;

        if ((expr->Type() == CExprWord) && (strcmp(expr->WordValue(), "=") == 0))
        {
          CExpr *arg1 = expr->next;
          CExpr *arg2 = arg1->next;
          arg1->WriteExpr(stream);
          stream << " = ";
          arg2->WriteExpr(stream);
        }
        else
        {
          stream << "[";
          while (expr)
          {
            expr->WriteExpr(stream);
            expr = expr->next;
            if (expr) stream << ", ";
          }
          stream << "]";
        }
      }
      break;
    }
   case CExprNull: break;
  }
}

void CExpr::WriteLispExpr(ostream& stream)
{
  switch (type)
  {
    case CExprInteger:
    {
      stream << value.integer;
      break;
    }
    case CExprReal:
    {
      stream << value.real;
      break;
    }
    case CExprString:
    {
      stream << "\"" << value.string << "\"";
      break;
    }
    case CExprWord:
    {
      stream << value.word;
      break;
    }
    case CExprList:
    {
      CExpr *expr = value.first;

      stream << "(";
      while (expr)
      {
        expr->WriteLispExpr(stream);
        expr = expr->next;
        if (expr) stream << " ";
      }

      stream << ")";
      break;
    }
   case CExprNull: break;
  }
}

// CExpr 'database' (list of expressions)
CExprDatabase::CExprDatabase(CExprErrorHandler handler)
{
  position = NULL;
  hash_table = NULL;
  currentCExprErrorHandler = handler;
  noErrors = 0;
}

CExprDatabase::CExprDatabase(CExprType type, const CString& attribute, int size,
                               CExprErrorHandler handler)
{
  position = NULL;
  attribute_to_hash = attribute;
  if (type == CExprString)
    hash_table = new wxHashTable(wxKEY_STRING, size);
  else if (type == CExprInteger)
    hash_table = new wxHashTable(wxKEY_INTEGER, size);
  else hash_table = NULL;

  currentCExprErrorHandler = handler;
  noErrors = 0;
}

CExprDatabase::~CExprDatabase(void)
{
  ClearDatabase();
  if (hash_table)
    delete hash_table;
}

int CExprDatabase::GetItemCount(void)	// get count of possible items
{
	int z = 0;
	wxNode *node = First();
	while (node)
	{
		z++;
		node = node->Next();
	}
	return z;
}

void CExprDatabase::BeginFind(void)          // Initialise a search
{
  position = First();
}

CExpr *CExprDatabase::FindClause(long id)  // Find a term based on an integer id attribute
                                 // e.g. node(id=23, type=rectangle, ....).
{
  CExpr *found = NULL;
  while (position && !found)
  {
    CExpr *term = (CExpr *)position->Data();
    
    if (term->Type() == CExprList)
    {
      CExpr *value = term->AttributeValue("id");
      if (value->Type() == CExprInteger && value->IntegerValue() == id)
        found = term;
    }
    position = position->Next();
  }
  return found;
}

// Find on basis of attribute/value pairs, e.g. type=rectangle
CExpr *CExprDatabase::FindClause(const CString& word, const CString& val)
{
  CExpr *found = NULL;
  while (position && !found)
  {
    CExpr *term = (CExpr *)position->Data();
    
    if (term->Type() == CExprList)
    {
      CExpr *value = term->AttributeValue(word);
      if ((value->Type() == CExprWord && value->WordValue() == val) ||
          (value->Type() == CExprString && value->StringValue() == val))
        found = term;
    }
    position = position->Next();
  }
  return found;
}

CExpr *CExprDatabase::FindClause(const CString& word, long val)
{
  CExpr *found = NULL;
  while (position && !found)
  {
    CExpr *term = (CExpr *)position->Data();
    
    if (term->Type() == CExprList)
    {
      CExpr *value = term->AttributeValue(word);
      if ((value->Type() == CExprInteger) && (value->IntegerValue() == val))
        found = term;
    }
    position = position->Next();
  }
  return found;
}

CExpr *CExprDatabase::FindClause(const CString& word, float val)
{
  CExpr *found = NULL;
  while (position && !found)
  {
    CExpr *term = (CExpr *)position->Data();
    
    if (term->Type() == CExprList)
    {
      CExpr *value = term->AttributeValue(word);
      if ((value->Type() == CExprReal) && (value->RealValue() == val))
        found = term;
    }
    position = position->Next();
  }
  return found;
}

CExpr *CExprDatabase::FindClauseByFunctor(const CString& functor)
{
  CExpr *found = NULL;
  while (position && !found)
  {
    CExpr *term = (CExpr *)position->Data();
    
    if (term->Type() == CExprList)
    {
      if (term->Functor() == functor)
        found = term;
    }
    position = position->Next();
  }
  return found;
}

// If hashing is on, must store in hash table too
void CExprDatabase::Append(CExpr *clause)
{
  wxList::Append((CObject *)clause);
  if (hash_table)
  {
    CString functor(clause->Functor());
    CExpr *expr = clause->AttributeValue(attribute_to_hash);
    if (expr)
    {
      long functor_key = hash_table->MakeKey((char *)(const char *)functor);
      long value_key = 0;
      if (expr && expr->Type() == CExprString)
      {
        value_key = hash_table->MakeKey((char *)(const char *)expr->StringValue());
        hash_table->Put(functor_key + value_key, (char *)(const char *)expr->StringValue(), (CObject *)clause);
      }
      else if (expr && expr->Type() == CExprInteger)
      {
        value_key = expr->IntegerValue();
        hash_table->Put(functor_key + value_key, expr->IntegerValue(), (CObject *)clause);
      }

    }
  }
}

CExpr *CExprDatabase::HashFind(const CString& functor, long value)
{
  long key = hash_table->MakeKey((char *)(const char *)functor) + value;

  // The key alone isn't guaranteed to be unique:
  // must supply value too. Let's assume the value of the
  // id is going to be reasonably unique.
  return (CExpr *)hash_table->Get(key, value);
}

CExpr *CExprDatabase::HashFind(const CString& functor, const CString& value)
{
  long key = hash_table->MakeKey((char *)(const char *)functor) + hash_table->MakeKey((char *)(const char *)value);
  return (CExpr *)hash_table->Get(key, (char *)(const char *)value);
}

void CExprDatabase::ClearDatabase(void)
{
  noErrors = 0;
  wxNode *node = First();
  while (node)
  {
    CExpr *expr = (CExpr *)node->Data();
    delete expr;
    delete node;
    node = First();
  }

  if (hash_table)
    hash_table->Clear();
}

BOOL CExprDatabase::Read(const CString& filename)
{
  noErrors = 0;

  FILE *f = fopen((const char *)filename, "r");
  if (f)
  {
    theCExprDatabase = this;

    LexFromFile(f);
    yyparse();
    fclose(f);

    CExprCleanUp();
    return (noErrors == 0);
  }
  else
  {
    return FALSE;
  }
}

BOOL CExprDatabase::ReadFromString(const CString& buffer)
{
  noErrors = 0;
  theCExprDatabase = this;

  LexFromString((char *)(const char *)buffer);
  yyparse();
  CExprCleanUp();
  return (noErrors == 0);
}

BOOL CExprDatabase::Write(const CString& fileName)
{
  ofstream str((char *)(const char *)fileName);
  if (str.bad())
    return FALSE;
  return Write(str);
}

BOOL CExprDatabase::Write(ostream& stream)
{
  noErrors = 0;
  wxNode *node = First();
  while (node)
  {
    CExpr *expr = (CExpr *)node->Data();
    expr->WriteClause(stream);
    node = node->Next();
  }
  return (noErrors == 0);
}

void CExprDatabase::WriteLisp(ostream& stream)
{
  noErrors = 0;
  wxNode *node = First();
  while (node)
  {
    CExpr *expr = (CExpr *)node->Data();
    expr->WriteLispExpr(stream);
    stream << "\n\n";
    node = node->Next();
  }
}

void add_expr(CExpr * expr)
{
  theCExprDatabase->Append(expr);
}

// Checks functor
BOOL CExprIsFunctor(CExpr *expr, const CString& functor)
{
  if (expr && (expr->Type() == CExprList))
  {
    CExpr *first_expr = expr->value.first;

    if (first_expr && (first_expr->Type() == CExprWord) &&
       (first_expr->WordValue() == functor))
      return TRUE;
    else 
      return FALSE;
  } 
  else 
    return FALSE;
}

/*
 * Called from parser
 *
 */

char *make_integer(char *str)
{
  CExpr *x = new CExpr(atol(str));

  return (char *)x;
}

char *make_real(char *str1, char *str2)
{
  char buf[50];

  sprintf(buf, "%s.%s", str1, str2);
  float f = (float)atof(buf);
  CExpr *x = new CExpr(f);

  return (char *)x;
}

// extern "C" double exp10(double);

char *make_exp(char *str1, char *str2)
{
  double mantissa = (double)atoi(str1);
  double exponent = (double)atoi(str2);

  double d = mantissa * pow(10.0, exponent);

  CExpr *x = new CExpr((float)d);

  return (char *)x;
}

char *make_exp2(char *str1, char *str2, char *str3)
{
  char buf[50];

  sprintf(buf, "%s.%s", str1, str2);
  double mantissa = (double)atof(buf);
  double exponent = (double)atoi(str3);

  double d = mantissa * pow(10.0, exponent);

  CExpr *x = new CExpr((float)d);

  return (char *)x;
}

char *make_word(char *str)
{
  CExpr *x = new CExpr(CExprWord, str);
  return (char *)x;
}

char *make_string(char *str)
{
  char *s, *t;
  int len, i;

  str++;			/* skip leading quote */
  len = strlen(str) - 1;	/* ignore trailing quote */
    
  s = new char[len + 1];
    
  t = s;
  for(i=0; i<len; i++)
  {
    if (str[i] == '\\' && str[i+1] == '"')
    {
      *t++ = '"';
      i ++;
    }
    else if (str[i] == '\\' && str[i+1] == '\\')
    {
      *t++ = '\\';
      i ++;
    }
    else
      *t++ = str[i];
  }

  *t = '\0';

  CExpr *x = new CExpr(CExprString, s, FALSE);
  return (char *)x;
}

char *cexpr_cons(char * ccar, char * ccdr)
{
  CExpr *car = (CExpr *)ccar;
  CExpr *cdr = (CExpr *)ccdr;

  if (cdr == NULL)
  {
    cdr = new CExpr(CExprList);
  }
  if (car)
    cdr->Insert(car);
  return (char *)cdr;
}

void process_command(char * cexpr)
{
  CExpr *expr = (CExpr *)cexpr;
  add_expr(expr);
}

void syntax_error(char *s)
{
  if (currentCExprErrorHandler)
    (void)(*(currentCExprErrorHandler))(CEXPR_ERROR_SYNTAX, "syntax error");
  if (theCExprDatabase) theCExprDatabase->noErrors += 1;
}

#ifdef _WINDLL
char *__cdecl strdup(const char *s)
{
  int len = strlen(s);
  char *new_s = (char *)malloc(sizeof(char)*(len+1));
  strcpy(new_s, s);
  return new_s;
}
#endif