added mix_eval_t, a w-expression evaluator

9 files changed, 675 insertions, 14 deletions

diff --git a/mixlib/.cvsignore b/mixlib/.cvsignore
index d2486ce..71b540f 100644
--- a/mixlib/.cvsignore
+++ b/mixlib/.cvsignore
@@ -1,5 +1,7 @@
+
 .deps
 Makefile
 Makefile.in
+lex.yy.c
+mix_eval_scanner.c
 mix_scanner.c
-
diff --git a/mixlib/Makefile.am b/mixlib/Makefile.am
index 26355cf..a81403c 100644
--- a/mixlib/Makefile.am
+++ b/mixlib/Makefile.am
@@ -1,6 +1,6 @@
 ## Process this file with automake to produce Makefile.in
 
-# Copyright (C) 2000 jose antonio ortega ruiz <jaortega@retemail.es>
+# Copyright (C) 2000 jose antonio ortega ruiz <jaortega@acm.org>
 #  
 # This file is free software; as a special exception the author gives
 # unlimited permission to copy and/or distribute it, with or without 
@@ -24,14 +24,5 @@ libmix_a_SOURCES = mix.h mix.c \
 		   mix_file.h mix_file.c \
                    mix_code_file.h mix_code_file.c \
 		   mix_parser.h xmix_parser.h mix_parser.c mix_scanner.l \
-                   mix_device.h mix_device.c
-
-
-
-
-
-
-
-
-
-
+                   mix_device.h mix_device.c \
+                   mix_eval.h mix_eval.c xmix_eval.h mix_eval_scanner.l
diff --git a/mixlib/mix_eval.c b/mixlib/mix_eval.c
new file mode 100644
index 0000000..683b8ac
--- /dev/null
+++ b/mixlib/mix_eval.c
@@ -0,0 +1,154 @@
+/* -*-c-*- -------------- mix_eval.c :
+ * Implementation of the functions declared in mix_eval.h
+ * ------------------------------------------------------------------
+ *  Last change: Time-stamp: "00/12/02 23:13:47 jose"
+ * ------------------------------------------------------------------
+ * Copyright (C) 2000 jose antonio ortega ruiz <jaortega@acm.org>
+ *  
+ * This program 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 of the License, or
+ * (at your option) any later version.
+ *  
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *  
+ */
+
+
+#include "xmix_eval.h"
+
+
+static const gchar *errors_[] = {
+  N_("Successful evaluation"),
+  N_("Syntax error in expression"),
+  N_("Out of range F-specification"),
+  N_("Mismatched parenthesis"),
+  N_("Undefined symbol"),
+  N_("Internal error")
+};
+
+
+/* create a new evaluator */
+mix_eval_t *
+mix_eval_new (void) 
+{
+  mix_eval_t *result = g_new (mix_eval_t, 1);
+  result->table = mix_symbol_table_new ();
+  if (result->table == NULL) {
+    g_free (result);
+    return NULL;
+  }
+  result->towner = TRUE;
+  result->value = MIX_WORD_ZERO;
+  result->errpos = 0;
+  return result;
+}
+
+/* create a new evaluator with an external symbol table */
+mix_eval_t *
+mix_eval_new_with_table (mix_symbol_table_t *table)
+{
+  mix_eval_t *result = g_new (mix_eval_t, 1);
+  result->table = table;
+  result->towner = FALSE;
+  result->value = MIX_WORD_ZERO;
+  result->errpos = 0;
+  return result;
+}
+
+/* delete */
+void
+mix_eval_delete (mix_eval_t *eval)
+{
+  g_return_if_fail (eval);
+  if (eval->table && eval->towner) {
+    mix_symbol_table_delete (eval->table);
+  }
+  g_free (eval);
+}
+
+/* eval an expression */
+mix_eval_result_t
+mix_eval_expression_with_loc (mix_eval_t *eval, const gchar *expr,
+			      mix_short_t loc)
+{
+  mix_eval_data_ data;
+  
+  if (expr == NULL || eval == NULL)
+    return MIX_EVAL_INTERN;
+  data.expr = g_strdup_printf ("%s\n", expr);
+  data.table = eval->table;
+  data.errpos = eval->errpos;
+  data.value = eval->value;
+  data.loc = loc;
+  eval->result = mix_eval_expr (&data);
+  if (eval->result == MIX_EVAL_OK) {
+    eval->value = data.value;
+    eval->errpos = -1;
+  } else {
+    eval->errpos = data.errpos;
+  }
+  g_free (data.expr);
+    
+  return eval->result;
+}
+
+/* get the result of the last evaluation */
+mix_word_t
+mix_eval_value (mix_eval_t *eval) 
+{
+  g_return_val_if_fail (eval != NULL, MIX_WORD_ZERO);
+  return eval->value;
+}
+
+/* get the last eval result code */
+mix_eval_result_t 
+mix_eval_last_error (mix_eval_t *eval) 
+{
+  g_return_val_if_fail (eval != NULL, MIX_EVAL_INTERN);
+  return eval->result;
+}
+
+/* get the last error string */
+const gchar*
+mix_eval_last_error_string (mix_eval_t *eval) 
+{
+  g_return_val_if_fail (eval != NULL, errors_[MIX_EVAL_INTERN]);
+  return errors_[eval->result];
+}
+
+/* get the position of last error */
+guint
+mix_eval_last_error_pos (mix_eval_t *eval)
+{
+  g_return_val_if_fail (eval != NULL, 0);
+  return eval->errpos;
+}
+
+/* add, or redefine, a symbol. see mix_symbol_table.h for
+   possible outcomes. */
+gint
+mix_eval_set_symbol (mix_eval_t *eval, const gchar *symbol,
+		     mix_word_t value)
+{
+  g_return_val_if_fail (eval != NULL && eval->table != NULL,
+			MIX_SYM_FAIL);
+  return mix_symbol_table_insert (eval->table, symbol, value);
+}
+
+void
+mix_eval_remove_symbol (mix_eval_t *eval, const gchar *symbol)
+{
+  g_return_if_fail (eval != NULL && eval->table != NULL);
+  mix_symbol_table_remove (eval->table, symbol);
+}
+
+  
+  
diff --git a/mixlib/mix_eval.h b/mixlib/mix_eval.h
new file mode 100644
index 0000000..94995fb
--- /dev/null
+++ b/mixlib/mix_eval.h
@@ -0,0 +1,95 @@
+/* -*-c-*- ---------------- mix_eval.h :
+ * mix_eval_t is an evaluator of MIX W-expressions
+ * ------------------------------------------------------------------
+ *  Last change: Time-stamp: <00/12/02 23:11:44 jose>
+ * ------------------------------------------------------------------
+ * Copyright (C) 2000 jose antonio ortega ruiz <jaortega@acm.org>
+ *  
+ * This program 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 of the License, or
+ * (at your option) any later version.
+ *  
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *  
+ */
+
+
+#ifndef MIX_EVAL_H
+#define MIX_EVAL_H
+
+#include "mix.h"
+#include "mix_types.h"
+#include "mix_symbol_table.h"
+
+/* the evaluator type */
+typedef struct mix_eval_t mix_eval_t;
+
+/* possible evaluation outcomes*/
+typedef enum {
+  MIX_EVAL_OK, /* sucess*/
+  MIX_EVAL_SYNTAX, /* syntax error */
+  MIX_EVAL_INV_FSPEC, /* out of range fspec */
+  MIX_EVAL_MIS_PAREN, /* mismatched parenthesis */
+  MIX_EVAL_UNDEF_SYM, /* undefined symbol */
+  MIX_EVAL_INTERN /* internal error */
+} mix_eval_result_t;
+
+/* create a new evaluator */
+extern mix_eval_t *
+mix_eval_new (void);
+
+/* create a new evaluator with an external symbol table */
+extern mix_eval_t *
+mix_eval_new_with_table (mix_symbol_table_t *table);
+
+/* delete */
+extern void
+mix_eval_delete (mix_eval_t *eval);
+
+/* eval an expression providing a value for loc counter */
+extern mix_eval_result_t
+mix_eval_expression_with_loc (mix_eval_t *eval, const gchar *expr,
+			      mix_short_t loc);
+/* eval an expression with null loc*/
+#define mix_eval_expression (eval,expr) \
+  mix_eval_expression_with_loc (eval, expr, MIX_SHORT_ZERO)
+
+
+/* get the result of the last evaluation */
+extern mix_word_t
+mix_eval_value (mix_eval_t *eval);
+
+/* get the last eval result code */
+extern mix_eval_result_t 
+mix_eval_last_error (mix_eval_t *eval);
+
+/* get the last error string */
+extern const gchar*
+mix_eval_last_error_string (mix_eval_t *eval);
+
+/* get the position of last error */
+extern guint
+mix_eval_last_error_pos (mix_eval_t *eval);
+
+/* add, or redefine, a symbol. see mix_symbol_table.h for
+   possible outcomes. */
+extern gint
+mix_eval_set_symbol (mix_eval_t *eval, const gchar *symbol,
+		     mix_word_t value);
+
+extern void
+mix_eval_remove_symbol (mix_eval_t *eval, const gchar *symbol);
+
+
+
+
+#endif /* MIX_EVAL_H */
+
diff --git a/mixlib/mix_eval_scanner.l b/mixlib/mix_eval_scanner.l
new file mode 100644
index 0000000..443654d
--- /dev/null
+++ b/mixlib/mix_eval_scanner.l
@@ -0,0 +1,246 @@
+/* -*-c-*- ------------------ mix_eval_scanner.l :
+ * scanner used by mix_eval_t
+ * ------------------------------------------------------------------
+ *  Last change: Time-stamp: <00/12/02 22:48:00 jose>
+ * ------------------------------------------------------------------
+ * Copyright (C) 2000 jose antonio ortega ruiz <jaortega@acm.org>
+ *  
+ * This program 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 of the License, or
+ * (at your option) any later version.
+ *  
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *  
+ */
+
+%{
+#include "mix.h"
+#include "xmix_eval.h"
+
+#define YY_DECL							\
+  mix_eval_result_t  mix_eval_expr (mix_eval_data_ *data)
+
+#define RETURN_STATE(err)			\
+  do {						\
+    done = TRUE;                                \
+    state = err;				\
+    BEGIN (INITIAL);				\
+  } while (FALSE)
+
+#define CLEAN_UP()				\
+  do {						\
+    yy_delete_buffer (buffer);			\
+    g_free (expr_cp);				\
+ } while (FALSE)
+
+static mix_word_t
+  eval_binop_ (const gchar *op, mix_word_t x, mix_word_t y);
+ 
+static void
+  unput_word_ (mix_word_t word);
+ 
+%}
+
+%option nomain
+%option caseless
+%option pointer
+%option stack
+%option noyywrap
+%option noyy_top_state
+%option noreject
+%option outfile="lex.yy.c"
+
+%s  EVAL
+%s  WEVAL
+
+ws	[ \t]+
+digit	[0-9]
+letter	[A-Z]
+number	[+-]?{digit}+
+mixchar [0-9A-Z .,'')(+*/=$<>@;:\-]
+locsymbol   {digit}H
+flocsymbol  {digit}F
+blocsymbol  {digit}B
+symbol	{digit}*{letter}+[A-Z0-9]*
+binop	"+"|"-"|"*"|"/"|"//"|":"
+atexpr	{digit}+|{symbol}|\*
+expr	[+-]?{atexpr}({binop}{1}{atexpr})*
+fpart   \({expr}\)
+wexpr   {expr}({fpart})?(,{expr}({fpart})?)*
+  
+
+%%
+
+%{
+  YY_BUFFER_STATE buffer;
+  mix_word_t expr_val = MIX_WORD_ZERO, wexpr_val = MIX_WORD_ZERO;
+  mix_word_t wexpr_val_tmp = MIX_WORD_ZERO;
+  mix_eval_result_t state = MIX_EVAL_OK;
+  gchar *expr_cp;
+  gboolean is_fp = FALSE, done = FALSE;
+  g_assert (data != NULL && data->expr != NULL);
+  /* make room enough to unput computed values */
+  expr_cp = g_strdup_printf ("                              %s", data->expr);
+  buffer = yy_scan_string (expr_cp);
+%}
+  
+
+<*><<EOF>> {
+  CLEAN_UP ();
+  return MIX_EVAL_INTERN;
+}
+
+<INITIAL>{
+  {ws} /* eat whitespace */
+  . {
+    if (!done && state == MIX_EVAL_OK) {
+      yyless (0);
+      yy_push_state (WEVAL);
+    } else {
+      CLEAN_UP ();
+      if (state == MIX_EVAL_OK) return (MIX_EVAL_SYNTAX);
+      return state;
+    }
+  }
+  "\n" {
+    CLEAN_UP();
+    if (state == MIX_EVAL_OK)
+      data->value = wexpr_val;
+    return state;
+  }
+}			
+
+<WEVAL>{
+  {number}"(" {
+    is_fp = TRUE;
+    wexpr_val_tmp = mix_word_new (atol (yytext));
+  }
+  {number}")"  {
+    glong val  = atol (yytext);
+    if ( !is_fp ) { 
+      RETURN_STATE (MIX_EVAL_MIS_PAREN);
+    }  else if ( val < 0 || val > MIX_BYTE_MAX 
+         || !mix_fspec_is_valid (mix_byte_new (val)) ) {
+      RETURN_STATE (MIX_EVAL_INV_FSPEC);
+    } else {
+      is_fp = FALSE;
+      wexpr_val = mix_word_store_field (mix_byte_new (val),
+					wexpr_val_tmp, 
+					wexpr_val);
+    }
+  }
+  {number} {
+    wexpr_val = mix_word_new (atol (yytext));
+  }
+  {expr}  yyless (0); yy_push_state (EVAL);
+  ,/{expr} /* eat comma if followed by expression */
+  [\t\n ] { /* ok if not inside an f-part */
+    if ( is_fp ) {
+      RETURN_STATE (MIX_EVAL_MIS_PAREN);
+    }
+    unput (yytext[yyleng-1]);
+    done = TRUE;
+    yy_pop_state ();
+  }
+  .  RETURN_STATE (MIX_EVAL_SYNTAX);
+}
+
+<EVAL>{
+  {binop}{digit}+ {
+    const gchar *s = ( yytext[1] == '/' ) ? yytext+2 : yytext+1;
+    mix_word_t value = mix_word_new (atol (s));
+    expr_val = eval_binop_ (yytext, expr_val, value);
+  }
+  {binop}{symbol} {
+    const gchar *s = ( yytext[1] == '/' ) ? yytext+2 : yytext+1;
+    if ( !mix_symbol_table_is_defined (data->table, s) ) {
+      RETURN_STATE (MIX_EVAL_UNDEF_SYM);
+    }
+    expr_val = eval_binop_ (yytext, expr_val, 
+			    mix_symbol_table_value (data->table, s));
+  }
+  "***" {
+    mix_word_t loc = mix_short_to_word_fast (data->loc);
+    (void)mix_word_mul (loc, loc, NULL, &loc);
+    unput_word_ (loc);
+  }
+  {binop}"*" {
+    expr_val = eval_binop_ (yytext, expr_val, 
+			    mix_short_to_word_fast (data->loc));
+  }
+  "*"         unput_word_ (mix_short_to_word_fast (data->loc));
+  {number}    expr_val = mix_word_new (atol (yytext));
+  {symbol} {
+    if ( !mix_symbol_table_is_defined (data->table, yytext) ) {
+      RETURN_STATE (MIX_EVAL_UNDEF_SYM);
+    }
+    expr_val = mix_symbol_table_value (data->table, yytext);
+  }
+  [,)(\n\t ]   {
+    unput (yytext[0]);
+    unput_word_ (expr_val);
+    yy_pop_state ();
+  }
+  
+  .   RETURN_STATE (MIX_EVAL_SYNTAX);
+}
+
+
+%%
+
+static mix_word_t
+eval_binop_ (const gchar *op, mix_word_t x, mix_word_t y)
+{
+  mix_word_t result = MIX_WORD_ZERO;
+  switch (op[0])
+    {
+    case '+': 
+      result = mix_word_add (x,y); 
+      break;
+    case '-':
+      result = mix_word_sub (x,y);
+      break;
+    case '*':
+      mix_word_mul (x, y, NULL, &result);
+      break;
+    case ':':
+      {
+	mix_word_t a;
+	mix_word_mul (x, 8, NULL, &a);
+	result = mix_word_add (a, y);
+	break;
+      }
+    case '/':
+      if ( strlen (op) > 1 && op[1] == '/' ) {
+	mix_word_div (x,MIX_WORD_ZERO,y, &result, NULL);
+      } else {
+	mix_word_div (MIX_WORD_ZERO, x, y, &result, NULL);
+      }
+      break;
+    default:
+      g_assert_not_reached ();
+    }
+  return result;
+}
+
+
+static void
+unput_word_ (mix_word_t word)					
+{								
+  gchar *value;						
+  gint k;							
+  value = g_strdup_printf ("%s%ld",				
+			   mix_word_is_negative (word)? "-":"+",
+			   mix_word_magnitude (word));		
+  for (k = strlen (value) - 1; k >= 0; --k)			
+    unput (value[k]);						
+  g_free (value);						
+}
diff --git a/mixlib/testsuite/.cvsignore b/mixlib/testsuite/.cvsignore
index fa47ca5..c936d6c 100644
--- a/mixlib/testsuite/.cvsignore
+++ b/mixlib/testsuite/.cvsignore
@@ -11,6 +11,7 @@ disk5.dev
 disk6.dev
 disk7.dev
 mixdevtest
+mixevaltest
 mixinstest
 mixparsertest
 mixtypest
diff --git a/mixlib/testsuite/Makefile.am b/mixlib/testsuite/Makefile.am
index 62d5db6..81ef11d 100644
--- a/mixlib/testsuite/Makefile.am
+++ b/mixlib/testsuite/Makefile.am
@@ -11,7 +11,7 @@
 INCLUDES = -I.. 
 LDADD = $(top_builddir)/mixlib/libmix.a 
 
-check_PROGRAMS = mixtypest mixinstest mixvminstest mixparsertest mixdevtest
+check_PROGRAMS = mixtypest mixinstest mixvminstest mixparsertest mixdevtest mixevaltest
 TESTS = $(check_PROGRAMS)
 
 mixtypest_SOURCES = test.h mix_types_t.c
@@ -19,6 +19,8 @@ mixinstest_SOURCES = test.h mix_ins_t.c
 mixvminstest_SOURCES = test.h mix_vm_ins_t.c
 mixparsertest_SOURCES = test.h mix_parser_t.c
 mixdevtest_SOURCES = test.h mix_device_t.c
+mixevaltest_SOURCES = test.h mix_eval_t.c
+
 
 
 
diff --git a/mixlib/testsuite/mix_eval_t.c b/mixlib/testsuite/mix_eval_t.c
new file mode 100644
index 0000000..e9b53c8
--- /dev/null
+++ b/mixlib/testsuite/mix_eval_t.c
@@ -0,0 +1,115 @@
+/* -*-c-*- -------------- mix_eval_t.c :
+ * Test of mix_eval_t
+ * ------------------------------------------------------------------
+ *  Last change: Time-stamp: "00/12/02 23:18:39 jose"
+ * ------------------------------------------------------------------
+ * Copyright (C) 2000 jose antonio ortega ruiz <jaortega@acm.org>
+ *  
+ * This program 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 of the License, or
+ * (at your option) any later version.
+ *  
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *  
+ */
+
+
+#include <stdlib.h>
+#include <mix_eval.h>
+/* Define VERBOSE_TEST if you want to get prints of the test */
+/* #define VERBOSE_TEST */
+#include "test.h"
+
+typedef struct test_case_t
+{
+  const gchar *expr;
+  gint value;
+  mix_eval_result_t result;
+} test_case_t;
+
+#define ok_case(exp,val) {exp, val, MIX_EVAL_OK}
+#define err_case(exp,err) {exp, 0, err}
+
+typedef struct sym_val_t
+{
+  const gchar *sym;
+  mix_word_t value;
+} sym_val_t;
+
+#define new_symbol(sym,val) {sym, mix_word_new (val)}
+
+int 
+main(int argc, char **argv)
+{
+  size_t k;
+  mix_eval_t *eval;
+  mix_short_t loc = mix_short_new (30);
+  sym_val_t symbols[] = {
+    new_symbol ("s0", 43),
+    new_symbol ("s1", -1234),
+    new_symbol ("s2", 0),
+    new_symbol ("s3", -20),
+    new_symbol (NULL, 0)
+  };
+  
+  test_case_t cases[] = {
+    ok_case ("2343", 2343),
+    ok_case ("-890", -890),
+    ok_case ("15+1015", 1030),
+    ok_case ("1-481", -480),
+    ok_case ("2300/10", 230),
+    ok_case ("24*3", 72),
+    ok_case ("2:5", 21),
+    ok_case ("1//3", 357913941),
+    ok_case ("12+*", 42),
+    ok_case ("***", 900),
+    ok_case ("1:3*2-4", 18),
+    ok_case ("-1+5*20/6", 13),
+    ok_case ("-1000(0,2),1", 1),
+    ok_case ("s0-s2*3", 129),
+    ok_case ("s3**", -600),
+    ok_case ("s3(3:5)", 20),
+    ok_case ("-s1", 1234),
+    ok_case ("s1/10+s0", 166),
+    err_case ("foo", MIX_EVAL_UNDEF_SYM),
+    err_case ("11--2", MIX_EVAL_SYNTAX),
+    err_case ("foo*3", MIX_EVAL_UNDEF_SYM),
+    err_case ("32),1", MIX_EVAL_MIS_PAREN),
+    err_case ("2000(88)", MIX_EVAL_INV_FSPEC),
+    ok_case (NULL, 0)
+  };
+  
+  INIT_TEST;
+  g_print ("Entering mix_eval test...");
+  eval = mix_eval_new ();
+
+  for (k = 0; symbols[k].sym; ++k)
+    mix_eval_set_symbol (eval, symbols[k].sym, symbols[k].value);
+  
+  for (k = 0; cases[k].expr; ++k) {
+    mix_eval_result_t r = cases[k].result, s;
+    g_print ("Evaluating \"%s\" = %d ...",
+	       cases[k].expr, cases[k].value);
+    
+    s = mix_eval_expression_with_loc (eval, cases[k].expr, loc);
+    g_assert (s == r);
+    if ( s == MIX_EVAL_OK ) {
+      mix_word_print (mix_eval_value (eval), "... ");
+      g_print ("\n");
+      g_assert (mix_eval_value (eval) == mix_word_new(cases[k].value));
+    }
+  }
+  mix_eval_delete (eval);
+
+  return EXIT_SUCCESS;
+}
+
+
diff --git a/mixlib/xmix_eval.h b/mixlib/xmix_eval.h
new file mode 100644
index 0000000..5382d73
--- /dev/null
+++ b/mixlib/xmix_eval.h
@@ -0,0 +1,55 @@
+/* -*-c-*- ---------------- xmix_eval.h :
+ * Definition of opaque types in mix_eval.h
+ * ------------------------------------------------------------------
+ *  Last change: Time-stamp: <00/12/02 03:53:09 jose>
+ * ------------------------------------------------------------------
+ * Copyright (C) 2000 jose antonio ortega ruiz <jaortega@acm.org>
+ *  
+ * This program 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 of the License, or
+ * (at your option) any later version.
+ *  
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *  
+ */
+
+
+#ifndef XMIX_EVAL_H
+#define XMIX_EVAL_H
+
+#include "mix_eval.h"
+
+/* the evaluator type */
+struct mix_eval_t 
+{
+  mix_symbol_table_t *table;	/* symbol table */
+  gboolean towner;		/* true if owns the table */
+  mix_eval_result_t result;	/* last evaluation result */
+  gint errpos;			/* location of last error */
+  mix_word_t value;		/* last computed value */
+};
+
+/* flex scanner data/result struct */
+typedef struct mix_eval_data_ 
+{
+  gchar *expr;
+  const mix_symbol_table_t *table;
+  mix_word_t value;
+  mix_short_t loc;
+  gint errpos;
+} mix_eval_data_;
+
+/* flex scanner prototype */
+extern
+mix_eval_result_t mix_eval_expr (mix_eval_data_ *data);
+
+#endif /* XMIX_EVAL_H */
+