[lcd4linux @ 2003-10-06 04:34:06 by reinelt]

expression evaluator added

1 files changed, 156 insertions, 0 deletions

diff --git a/expression.c b/expression.c
new file mode 100644
index 0000000..bae6ab8
--- /dev/null
+++ b/expression.c
@@ -0,0 +1,156 @@
+/* $Id: expression.c,v 1.1 2003/10/06 04:34:06 reinelt Exp $
+ *
+ * expression handling
+ *
+ * Copyright 2003 Michael Reinelt <reinelt@eunet.at>
+ *
+ * This file is part of LCD4Linux.
+ *
+ * LCD4Linux 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.
+ *
+ * LCD4Linux 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ *
+ * $Log: expression.c,v $
+ * Revision 1.1  2003/10/06 04:34:06  reinelt
+ * expression evaluator added
+ *
+ */
+
+/* 
+ * exported functions:
+ *
+ * int EX_init (void)
+ *  initializes the expression evaluator
+ *  adds some handy constants and functions
+ *
+ */
+
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <math.h>
+#include <string.h>
+
+#include "debug.h"
+#include "cfg.h"
+#include "evaluator.h"
+#include "expression.h"
+
+
+
+static void my_sqrt (RESULT *result, RESULT *arg1)
+{
+  double value=sqrt(R2N(arg1));
+  SetResult(&result, R_NUMBER, &value); 
+}
+
+static void my_exp (RESULT *result, RESULT *arg1)
+{
+  double value=exp(R2N(arg1));
+  SetResult(&result, R_NUMBER, &value); 
+}
+
+static void my_ln (RESULT *result, RESULT *arg1)
+{
+  double value=log(R2N(arg1));
+  SetResult(&result, R_NUMBER, &value); 
+}
+
+static void my_log (RESULT *result, RESULT *arg1)
+{
+  double value=log10(R2N(arg1));
+  SetResult(&result, R_NUMBER, &value); 
+}
+
+static void my_sin (RESULT *result, RESULT *arg1)
+{
+  double value=sin(R2N(arg1));
+  SetResult(&result, R_NUMBER, &value); 
+}
+
+static void my_cos (RESULT *result, RESULT *arg1)
+{
+  double value=cos(R2N(arg1));
+  SetResult(&result, R_NUMBER, &value); 
+}
+
+static void my_tan (RESULT *result, RESULT *arg1)
+{
+  double value=tan(R2N(arg1));
+  SetResult(&result, R_NUMBER, &value); 
+}
+
+
+static void my_strlen (RESULT *result, RESULT *arg1)
+{
+  double value=strlen(R2S(arg1));
+  SetResult(&result, R_NUMBER, &value); 
+}
+
+
+static void my_cfg (RESULT *result, RESULT *arg1)
+{
+  char *value=cfg_get(R2S(arg1), "");
+  SetResult(&result, R_STRING, value); 
+}
+
+
+int EX_init (void)
+{
+  // set some handy constants
+  AddConstant ("Pi", M_PI);
+  AddConstant ("e",  M_E);
+  
+  // register some basic math functions
+  AddFunction ("sqrt", 1, my_sqrt);
+  AddFunction ("exp",  1, my_exp);
+  AddFunction ("ln",   1, my_ln);
+  AddFunction ("log",  1, my_log);
+  AddFunction ("sin",  1, my_sin);
+  AddFunction ("cos",  1, my_cos);
+  AddFunction ("tan",  1, my_tan);
+  
+  // register some basic string functions
+  AddFunction ("strlen", 1, my_strlen);
+
+  // config file access
+  AddFunction ("cfg", 1, my_cfg);
+
+  
+  return 0;
+}
+
+
+#if 1
+
+int EX_test(int argc, char* argv[])
+{
+  int ec;
+  char line[1024];
+  RESULT result = {0, 0.0, NULL};
+  
+  printf("\nEE> ");
+  for(gets(line); !feof(stdin); gets(line)) {
+    ec=Eval(line, &result);
+    if (result.type==R_NUMBER) {
+      printf ("%g\n", R2N(&result));
+    } else if (result.type==R_STRING) {
+      printf ("<%s>\n", R2S(&result));
+    }
+    printf("EE> ");
+  }
+
+  return 0;
+}
+#endif