new file mode 100644
--- /dev/null
+++ b/src/pt-cmd.cc
@@ -0,0 +1,827 @@
+// Tree class.                                          -*- C++ -*-
+/*
+
+Copyright (C) 1992, 1993, 1994 John W. Eaton
+
+This file is part of Octave.
+
+Octave is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the
+Free Software Foundation; either version 2, or (at your option) any
+later version.
+
+Octave is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with Octave; see the file COPYING.  If not, write to the Free
+Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#if defined (__GNUG__)
+#pragma implementation
+#endif
+
+#include <iostream.h>
+
+// For NULL.
+#include <stdio.h>
+
+#include "user-prefs.h"
+#include "variables.h"
+#include "symtab.h"
+#include "error.h"
+#include "gripes.h"
+#include "tree.h"
+#include "tree-cmd.h"
+#include "tree-const.h"
+
+// Nonzero means we're breaking out of a loop.
+static int breaking = 0;
+
+// Nonzero means we're jumping to the end of a loop.
+static int continuing = 0;
+
+// Nonzero means we're returning from a function.  Global because it
+// is also needed in tree-expr.cc.
+int returning = 0;
+
+// Decide if it's time to quit a for or while loop.
+static int
+quit_loop_now (void)
+{
+// Maybe handle `continue N' someday...
+
+  if (continuing)
+    continuing--;
+
+  int quit = (returning || breaking || continuing);
+
+  if (breaking)
+    breaking--;
+
+  return quit;
+}
+
+// But first, some extra functions used by the tree classes.
+
+// We seem to have no use for this now.  Maybe it will be needed at
+// some future date, so here it is.
+#if 0
+/*
+ * Convert a linked list of trees to a vector of pointers to trees.
+ */
+static tree **
+list_to_vector (tree *list, int& len)
+{
+  len = list->length () + 1;
+
+  tree **args = new tree * [len];
+
+// args[0] may eventually hold something useful, like the function
+// name.
+  tree *tmp_list = list;
+  for (int k = 1; k < len; k++)
+    {
+      args[k] = tmp_list;
+      tmp_list = tmp_list->next_elem ();
+    }
+  return args;
+}
+#endif
+
+/*
+ * A command or two to be executed.
+ */
+tree_command_list::tree_command_list (void)
+{
+  command = NULL_TREE;
+  print_flag = 1;
+  next = (tree_command_list *) NULL;
+}
+
+tree_command_list::tree_command_list (tree *t)
+{
+  command = t;
+  print_flag = 1;
+  next = (tree_command_list *) NULL;
+}
+
+tree_command_list::~tree_command_list (void)
+{
+  delete command;
+  delete next;
+}
+
+void
+tree_command_list::set_print_flag (int flag)
+{
+  print_flag = flag;
+}
+
+tree_command_list *
+tree_command_list::chain (tree *t)
+{
+  tree_command_list *tmp = new tree_command_list (t);
+  tmp->next = this;
+  return tmp;
+}
+
+tree_command_list *
+tree_command_list::reverse (void)
+{
+  tree_command_list *list = this;
+  tree_command_list *next;
+  tree_command_list *prev = (tree_command_list *) NULL;
+
+  while (list != (tree_command_list *) NULL)
+    {
+      next = list->next;
+      list->next = prev;
+      prev = list;
+      list = next;
+    }
+  return prev;
+}
+
+tree_constant
+tree_command_list::eval (int print)
+{
+  int pf;
+  tree_constant retval;
+
+  if (error_state)
+    return retval;
+
+  tree_command_list *list;
+  for (list = this; list != (tree_command_list *) NULL; list = list->next)
+    {
+      if (print == 0)
+	pf = 0;
+      else
+	pf = list->print_flag;
+
+      tree *cmd = list->command;
+      if (cmd == NULL_TREE)
+	retval = tree_constant ();
+      else
+	{
+	  retval = cmd->eval (pf);
+
+	  if (error_state)
+	    return tree_constant ();
+
+	  if (breaking || continuing)
+	    break;
+
+	  if (returning)
+	    break;
+	}
+    }
+  return retval;
+}
+
+/*
+ * Global.
+ */
+tree_global_command::tree_global_command (int l = -1, int c = -1)
+{
+  line_num = l;
+  column_num = c;
+  sr = (symbol_record *) NULL;
+  rhs = (tree_expression *) NULL;
+  next = (tree_global_command *) NULL;
+}
+
+tree_global_command::tree_global_command (symbol_record *s,
+					  int l = -1, int c = -1)
+{
+  line_num = l;
+  column_num = c;
+  sr = s;
+  rhs = (tree_expression *) NULL;
+  next = (tree_global_command *) NULL;
+}
+
+tree_global_command::tree_global_command (symbol_record *s,
+					  tree_expression *e,
+					  int l = -1, int c = -1) 
+{
+  line_num = l;
+  column_num = c;
+  sr = s;
+  rhs = e;
+  next = (tree_global_command *) NULL;
+}
+
+tree_global_command::~tree_global_command (void)
+{
+  delete next;
+}
+
+tree_global_command *
+tree_global_command::chain (symbol_record *s, int l = -1, int c = -1)
+{
+  tree_global_command *tmp = new tree_global_command (s, l, c);
+  tmp->next = this;
+  return tmp;
+}
+
+tree_global_command *
+tree_global_command::chain (symbol_record *s, tree_expression *e,
+			    int l = -1, int c = -1)
+{
+  tree_global_command *tmp = new tree_global_command (s, e, l, c);
+  tmp->next = this;
+  return tmp;
+}
+
+tree_global_command *
+tree_global_command::reverse (void)
+{
+  tree_global_command *list = this;
+  tree_global_command *next;
+  tree_global_command *prev = (tree_global_command *) NULL;
+
+  while (list != (tree_global_command *) NULL)
+    {
+      next = list->next;
+      list->next = prev;
+      prev = list;
+      list = next;
+    }
+  return prev;
+}
+
+tree_constant
+tree_global_command::eval (int print)
+{
+  tree_constant retval;
+
+  link_to_global_variable (sr);
+
+  if (rhs != NULL_TREE)
+    {
+      tree_identifier *id = new tree_identifier (sr);
+      tree_constant tmp_rhs = rhs->eval (0);
+      if (error_state)
+	{
+	  delete id;
+	  eval_error ();
+	  return retval;
+	}
+      else
+	{
+	  tree_constant *tmp_val = new tree_constant (tmp_rhs);
+
+	  tree_simple_assignment_expression tmp_ass (id, tmp_val);
+
+	  tmp_ass.eval (0);
+
+	  delete id; // XXX FIXME XXX
+
+	  if (error_state)
+	    {
+	      eval_error ();
+	      return retval;
+	    }
+	}
+    }
+
+  if (next != (tree_global_command *) NULL)
+    next->eval (print);
+
+  return retval;
+}
+
+void
+tree_global_command::eval_error (void)
+{
+  if (error_state > 0)
+    ::error ("evaluating global command near line %d, column %d",
+	     line (), column ());
+}
+
+/*
+ * While.
+ */
+tree_while_command::tree_while_command (int l = -1, int c = -1)
+{
+  line_num = l;
+  column_num = c;
+  expr = (tree_expression *) NULL;
+  list = NULL_TREE;
+}
+
+tree_while_command::tree_while_command (tree_expression *e,
+					int l = -1, int c = -1) 
+{
+  line_num = l;
+  column_num = c;
+  expr = e;
+  list = NULL_TREE;
+}
+
+tree_while_command::tree_while_command (tree_expression *e, tree *lst,
+					int l = -1, int c = -1)
+{
+  line_num = l;
+  column_num = c;
+  expr = e;
+  list = lst;
+}
+
+tree_while_command::~tree_while_command (void)
+{
+  delete expr;
+  delete list;
+}
+
+tree_constant
+tree_while_command::eval (int print)
+{
+  tree_constant retval;
+
+  if (error_state)
+    return retval;
+
+  for (;;)
+    {
+      int expr_value = 0;
+      if (expr == (tree_expression *) NULL)
+	return tree_constant ();
+      tree_constant t1 = expr->eval (0);
+
+      if (error_state)
+	{
+	  eval_error ();
+	  return tree_constant ();
+	}
+
+      if (t1.rows () == 0 || t1.columns () == 0)
+	{
+	  int flag = user_pref.propagate_empty_matrices;
+	  if (flag < 0)
+	    warning ("while: empty matrix used in conditional");
+	  else if (flag == 0)
+	    {
+	      ::error ("while: empty matrix used in conditional");
+	      return tree_constant ();
+	    }
+	  t1 = tree_constant (0.0);
+	}
+      else if (! t1.is_scalar_type ())
+	{
+	  tree_constant t2 = t1.all ();
+	  t1 = t2.all ();
+	}
+
+      tree_constant_rep::constant_type t = t1.const_type ();
+      if (t == tree_constant_rep::scalar_constant)
+	expr_value = (int) t1.double_value ();
+      else if (t == tree_constant_rep::complex_scalar_constant)
+	expr_value = t1.complex_value () != 0.0;
+      else
+	panic_impossible ();
+
+      if (expr_value)
+	{
+	  if (list != NULL_TREE)
+	    {
+	      retval = list->eval (1);
+	      if (error_state)
+		{
+		  eval_error ();
+		  return tree_constant ();
+		}
+	    }
+
+	  if (quit_loop_now ())
+	    break;
+	}
+      else
+	break;
+    }
+  return retval;
+}
+
+void
+tree_while_command::eval_error (void)
+{
+  if (error_state > 0)
+    ::error ("evaluating while command near line %d, column %d",
+	     line (), column ());
+}
+
+/*
+ * For.
+ */
+tree_for_command::tree_for_command (int l = -1, int c = -1)
+{
+  line_num = l;
+  column_num = c;
+  id = (tree_index_expression *) NULL;
+  expr = (tree_expression *) NULL;
+  list = NULL_TREE;
+}
+
+tree_for_command::tree_for_command (tree_index_expression *ident,
+				    tree_expression *e, tree *lst,
+				    int l = -1, int c = -1)
+{
+  line_num = l;
+  column_num = c;
+  id = ident;
+  expr = e;
+  list = lst;
+}
+
+tree_for_command::~tree_for_command (void)
+{
+  delete id;
+  delete expr;
+  delete list;
+}
+
+tree_constant
+tree_for_command::eval (int print)
+{
+  tree_constant retval;
+
+  if (error_state || expr == (tree_expression *) NULL)
+    return retval;
+
+  tree_constant tmp_expr = expr->eval (0);
+
+  if (error_state || tmp_expr.is_undefined ())
+    {
+      eval_error ();
+      return retval;
+    }
+
+  tree_constant_rep::constant_type expr_type = tmp_expr.const_type ();
+  switch (expr_type)
+    {
+    case tree_constant_rep::complex_scalar_constant:
+    case tree_constant_rep::scalar_constant:
+      {
+	tree_constant *rhs = new tree_constant (tmp_expr);
+	int quit = 0;
+	retval = do_for_loop_once (rhs, quit);
+      }
+      break;
+    case tree_constant_rep::complex_matrix_constant:
+    case tree_constant_rep::matrix_constant:
+      {
+	Matrix m_tmp;
+	ComplexMatrix cm_tmp;
+	int nr;
+	int steps;
+	if (expr_type == tree_constant_rep::matrix_constant)
+	  {
+	    m_tmp = tmp_expr.matrix_value ();
+	    nr = m_tmp.rows ();
+	    steps = m_tmp.columns ();
+	  }
+	else
+	  {
+	    cm_tmp = tmp_expr.complex_matrix_value ();
+	    nr = cm_tmp.rows ();
+	    steps = cm_tmp.columns ();
+	  }
+
+	for (int i = 0; i < steps; i++)
+	  {
+	    tree_constant *rhs;
+
+	    if (nr == 1)
+	      {
+		if (expr_type == tree_constant_rep::matrix_constant)
+		  rhs = new tree_constant (m_tmp (0, i));
+		else
+		  rhs = new tree_constant (cm_tmp (0, i));
+	      }
+	    else
+	      {
+		if (expr_type == tree_constant_rep::matrix_constant)
+		  rhs = new tree_constant (m_tmp.extract (0, i, nr-1, i));
+		else
+		  rhs = new tree_constant (cm_tmp.extract (0, i, nr-1, i));
+	      }
+
+	    int quit = 0;
+	    retval = do_for_loop_once (rhs, quit);
+	    if (quit)
+	      break;
+	  }
+      }
+      break;
+    case tree_constant_rep::string_constant:
+      gripe_string_invalid ();
+      break;
+    case tree_constant_rep::range_constant:
+      {
+	Range rng = tmp_expr.range_value ();
+
+	int steps = rng.nelem ();
+	double b = rng.base ();
+	double increment = rng.inc ();
+
+	for (int i = 0; i < steps; i++)
+	  {
+	    double tmp_val = b + i * increment;
+
+	    tree_constant *rhs = new tree_constant (tmp_val);
+
+	    int quit = 0;
+	    retval = do_for_loop_once (rhs, quit);
+	    if (quit)
+	      break;
+	  }
+      }
+      break;
+    default:
+      panic_impossible ();
+      break;
+    }
+  
+  return retval;
+}
+
+void
+tree_for_command::eval_error (void)
+{
+  if (error_state > 0)
+    ::error ("evaluating for command near line %d, column %d",
+	     line (), column ());
+}
+
+tree_constant
+tree_for_command::do_for_loop_once (tree_constant *rhs, int& quit)
+{
+  tree_constant retval;
+
+  quit = 0;
+
+  tree_simple_assignment_expression tmp_ass (id, rhs);
+
+  tmp_ass.eval (0);
+
+  if (error_state)
+    {
+      eval_error ();
+      return tree_constant ();
+    }
+
+  if (list != NULL_TREE)
+    {
+      retval = list->eval (1);
+      if (error_state)
+	{
+	  eval_error ();
+	  quit = 1;
+	  return tree_constant ();
+	}
+    }
+
+  quit = quit_loop_now ();
+
+  return retval;
+}
+
+/*
+ * If.
+ */
+tree_if_command::tree_if_command (int l = -1, int c = -1)
+{
+  line_num = l;
+  column_num = c;
+  expr = (tree_expression *) NULL;
+  list = NULL_TREE;
+  next = (tree_if_command *) NULL;
+}
+
+tree_if_command::tree_if_command (tree *lst, int l = -1, int c = -1)
+{
+  line_num = l;
+  column_num = c;
+  expr = (tree_expression *) NULL;
+  list = lst;
+  next = (tree_if_command *) NULL;
+}
+
+tree_if_command::tree_if_command (tree_expression *e, tree *lst,
+				  int l = -1, int c = -1)
+{
+  line_num = l;
+  column_num = c;
+  expr = e;
+  list = lst;
+  next = (tree_if_command *) NULL;
+}
+
+tree_if_command::~tree_if_command (void)
+{
+  delete expr;
+  delete list;
+  delete next;
+}
+
+tree_if_command *
+tree_if_command::chain (tree *lst, int l = -1, int c = -1)
+{
+  tree_if_command *tmp = new tree_if_command (lst, l, c);
+  tmp->next = this;
+  return tmp;
+}
+
+tree_if_command *
+tree_if_command::chain (tree_expression *e, tree *lst, int l = -1, int c = -1)
+{
+  tree_if_command *tmp = new tree_if_command (e, lst, l, c);
+  tmp->next = this;
+  return tmp;
+}
+
+tree_if_command *
+tree_if_command::reverse (void)
+{
+  tree_if_command *list = this;
+  tree_if_command *next;
+  tree_if_command *prev = (tree_if_command *) NULL;
+
+  while (list != (tree_if_command *) NULL)
+    {
+      next = list->next;
+      list->next = prev;
+      prev = list;
+      list = next;
+    }
+  return prev;
+}
+
+tree_constant
+tree_if_command::eval (int print)
+{
+  int expr_value = 0;
+  tree_constant retval;
+
+  if (error_state)
+    return retval;
+
+  tree_if_command *lst;
+  for (lst = this; lst != (tree_if_command *) NULL; lst = lst->next)
+    {
+      if (lst->expr != (tree_expression *) NULL)
+	{
+	  tree_expression *tmp = lst->expr;
+	  if (tmp == (tree_expression *) NULL)
+	    return tree_constant ();
+	  tree_constant t1 = tmp->eval (0);
+	  if (error_state || t1.is_undefined ())
+	    {
+	      lst->eval_error ();
+	      break;
+	    }
+
+	  if (t1.rows () == 0 || t1.columns () == 0)
+	    {
+	      int flag = user_pref.propagate_empty_matrices;
+	      if (flag < 0)
+		warning ("if: empty matrix used in conditional");
+	      else if (flag == 0)
+		{
+		  ::error ("if: empty matrix used in conditional");
+		  lst->eval_error ();
+		  return tree_constant ();
+		}
+	      t1 = tree_constant (0.0);
+	    }
+	  else if (! t1.is_scalar_type ())
+	    {
+	      tree_constant t2 = t1.all ();
+	      t1 = t2.all ();
+	    }
+
+	  tree_constant_rep::constant_type t = t1.const_type ();
+	  if (t == tree_constant_rep::scalar_constant)
+	    expr_value = (int) t1.double_value ();
+	  else if (t == tree_constant_rep::complex_scalar_constant)
+	    expr_value = t1.complex_value () != 0.0;
+	  else
+	    panic_impossible ();
+
+	  if (expr_value)
+	    {
+	      if (lst->list != NULL_TREE)
+		retval = lst->list->eval (1);
+	      else
+		::error ("if: empty command list");
+
+	      if (error_state)
+		lst->eval_error ();
+
+	      break;
+	    }
+	}
+      else
+	{
+	  if (lst->list != NULL_TREE)
+	    retval = lst->list->eval (1);
+	  else
+	    ::error ("if: empty command list");
+
+	  if (error_state)
+	    lst->eval_error ();
+
+	  break;
+	}
+    }
+
+  return retval;
+}
+
+void
+tree_if_command::eval_error (void)
+{
+  if (error_state > 0)
+    ::error ("evaluating if command near line %d, column %d",
+	     line (), column ());
+}
+
+/*
+ * Break.  Is this overkill, or what?
+ */
+tree_break_command::tree_break_command (int l = -1, int c = -1)
+{
+  line_num = l;
+  column_num = c;
+}
+
+tree_break_command::~tree_break_command (void)
+{
+}
+
+tree_constant
+tree_break_command::eval (int print)
+{
+  if (! error_state)
+    breaking = 1;
+  return tree_constant ();
+}
+
+/*
+ * Continue.
+ */
+tree_continue_command::tree_continue_command (int l = -1, int c = -1)
+{
+  line_num = l;
+  column_num = c;
+}
+
+tree_continue_command::~tree_continue_command (void)
+{
+}
+
+tree_constant
+tree_continue_command::eval (int print)
+{
+  if (! error_state)
+    continuing = 1;
+  return tree_constant ();
+}
+
+/*
+ * Return.
+ */
+tree_return_command::tree_return_command (int l = -1, int c = -1)
+{
+  line_num = l;
+  column_num = c;
+}
+
+tree_return_command::~tree_return_command (void)
+{
+}
+
+tree_constant
+tree_return_command::eval (int print)
+{
+  if (! error_state)
+    returning = 1;
+  return tree_constant ();
+}
+
+/*
+;;; Local Variables: ***
+;;; mode: C++ ***
+;;; page-delimiter: "^/\\*" ***
+;;; End: ***
+*/