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-rw-r--r--evaluator.c752
-rw-r--r--evaluator.h90
-rw-r--r--expression.c156
-rw-r--r--expression.h36
4 files changed, 1034 insertions, 0 deletions
diff --git a/evaluator.c b/evaluator.c
new file mode 100644
index 0000000..8c4a740
--- /dev/null
+++ b/evaluator.c
@@ -0,0 +1,752 @@
+/* $Id: evaluator.c,v 1.1 2003/10/06 04:34:06 reinelt Exp $
+ *
+ * expression evaluation
+ *
+ * based on EE (Expression Evaluator) which is
+ * (c) 1992 Mark Morley <morley@Camosun.BC.CA>
+ *
+ * heavily modified 2003 by Michael Reinelt <reinelt@eunet.at>
+ *
+ * FIXME: GPL or not GPL????
+ *
+ * $Log: evaluator.c,v $
+ * Revision 1.1 2003/10/06 04:34:06 reinelt
+ * expression evaluator added
+ *
+ */
+
+
+/***************************************************************************
+ ** **
+ ** EE.C Expression Evaluator **
+ ** **
+ ** AUTHOR: Mark Morley **
+ ** COPYRIGHT: (c) 1992 by Mark Morley **
+ ** DATE: December 1991 **
+ ** HISTORY: Jan 1992 - Made it squash all command line arguments **
+ ** into one big long string. **
+ ** - It now can set/get VMS symbols as if they **
+ ** were variables. **
+ ** - Changed max variable name length from 5 to 15 **
+ ** Jun 1992 - Updated comments and docs **
+ ** **
+ ** You are free to incorporate this code into your own works, even if it **
+ ** is a commercial application. However, you may not charge anyone else **
+ ** for the use of this code! If you intend to distribute your code, **
+ ** I'd appreciate it if you left this message intact. I'd like to **
+ ** receive credit wherever it is appropriate. Thanks! **
+ ** **
+ ** I don't promise that this code does what you think it does... **
+ ** **
+ ** Please mail any bug reports/fixes/enhancments to me at: **
+ ** morley@camosun.bc.ca **
+ ** or **
+ ** Mark Morley **
+ ** 3889 Mildred Street **
+ ** Victoria, BC Canada **
+ ** V8Z 7G1 **
+ ** (604) 479-7861 **
+ ** **
+ ***************************************************************************/
+
+
+/*
+ * exported functions:
+ *
+ * int AddConstant (char *name, double value)
+ * adds a numerical variable to the evaluator
+ *
+ * int AddFunction (char *name, int args, void (*func)())
+ * adds a function to the evaluator
+ *
+ * RESULT* SetResult (RESULT **result, int type, void *value)
+ * initializes a result
+ *
+ * double R2N (RESULT *result)
+ * converts a result into a number
+ *
+ * char* R2S (RESULT *result)
+ * converts a result into a string
+ *
+ * int Eval (char* expression, RESULT *result)
+ * evaluates an expression
+ *
+ */
+
+
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#include <math.h>
+#include <setjmp.h>
+
+#include "debug.h"
+#include "evaluator.h"
+
+
+// Token types
+#define T_DELIMITER 1
+#define T_NUMBER 2
+#define T_STRING 3
+#define T_NAME 4
+
+
+#define is_blank(c) (c==' ' || c=='\t')
+#define is_number(c) (isdigit(c) || c=='.')
+#define is_name(c) (isalnum(c) || c=='_')
+#define is_delim(c) (strchr("+-*/%^().,;=<>&|", c)!=NULL)
+
+
+typedef struct {
+ char *name;
+ RESULT *value;
+} VARIABLE;
+
+static VARIABLE *Variable=NULL;
+static int nVariable=0;
+
+
+typedef struct {
+ char *name;
+ int args;
+ void (*func)();
+} FUNCTION;
+
+static FUNCTION *Function=NULL;
+static int nFunction=0;
+
+
+static char *Expression=NULL;
+static char *Token=NULL;
+static int Type=0;
+
+
+// error handling
+#define ERROR(n) longjmp(jb,n)
+jmp_buf jb;
+
+char* ErrMsg[] = {
+ "",
+ "Syntax error",
+ "Unbalanced parenthesis",
+ "Division by zero",
+ "Unknown variable",
+ "Unrecognized function",
+ "Wrong number of arguments",
+ "Missing an argument",
+ "Empty expression"
+};
+
+
+
+static void FreeResult (RESULT *result)
+{
+ if (result==NULL) return;
+ if (result->string!=NULL) {
+ free (result->string);
+ result->string=NULL;
+ }
+ free (result);
+}
+
+
+static void DelResult (RESULT *result)
+{
+ result->type=0;
+ result->number=0.0;
+ if (result->string) free (result->string);
+ result->string=NULL;
+}
+
+
+RESULT* SetResult (RESULT **result, int type, void *value)
+{
+ if (*result==NULL) {
+ *result=malloc(sizeof(RESULT));
+ if (*result==NULL) {
+ debug ("cannot allocate result: out of memory!");
+ return NULL;
+ }
+ } else if ((*result)->string!=NULL) {
+ free ((*result)->string);
+ (*result)->string=NULL;
+ }
+
+ if (type & R_NUMBER) {
+ (*result)->type=R_NUMBER;
+ (*result)->number=*(double*)value;
+ (*result)->string=NULL;
+ } else if (type & R_STRING) {
+ (*result)->type=R_STRING;
+ (*result)->string=strdup(value);
+ } else {
+ debug ("internal error: invalid result type %d", type);
+ return NULL;
+ }
+
+ return *result;
+}
+
+
+static RESULT* DupResult (RESULT *result)
+{
+ RESULT *result2;
+
+ result2=malloc(sizeof(RESULT));
+ if (result2==NULL) {
+ debug ("cannot allocate result: out of memory!");
+ return NULL;
+ }
+
+ result2->type=result->type;
+ result2->number=result->number;
+ if (result->string!=NULL)
+ result2->string=strdup(result->string);
+ else
+ result2->string=NULL;
+
+ return result2;
+}
+
+
+double R2N (RESULT *result)
+{
+ if (result==NULL) {
+ debug ("internal error: NULL result");
+ return 0.0;
+ }
+
+ if (result->type & R_NUMBER) {
+ return result->number;
+ }
+
+ if (result->type & R_STRING) {
+ result->type |= R_NUMBER;
+ result->number=atof(result->string);
+ return result->number;
+ }
+
+ debug ("internal error: invalid result type %d", result->type);
+ return 0.0;
+}
+
+
+char* R2S (RESULT *result)
+{
+ char buffer[16];
+
+ if (result==NULL) {
+ debug ("internal error: NULL result");
+ return NULL;
+ }
+
+ if (result->type & R_STRING) {
+ return result->string;
+ }
+
+ if (result->type & R_NUMBER) {
+ result->type |= R_STRING;
+ sprintf(buffer, "%g", result->number);
+ result->string=strdup(buffer);
+ return result->string;
+ }
+
+ debug ("internal error: invalid result type %d", result->type);
+ return NULL;
+
+}
+
+
+// bsearch compare function for variables
+static int v_lookup (const void *a, const void *b)
+{
+ char *name=(char*)a;
+ VARIABLE *v=(VARIABLE*)b;
+
+ return strcmp(name, v->name);
+}
+
+
+// qsort compare function for variables
+static int v_sort (const void *a, const void *b)
+{
+ VARIABLE *va=(VARIABLE*)b;
+ VARIABLE *vb=(VARIABLE*)b;
+
+ return strcmp(va->name, vb->name);
+}
+
+
+static int DelVariable (char *name)
+{
+ VARIABLE *V;
+
+ V=bsearch(name, Variable, nVariable, sizeof(VARIABLE), v_lookup);
+ if (V!=NULL) {
+ FreeResult (V->value);
+ memmove (V, V+1, (nVariable-1)*sizeof(VARIABLE)-(V-Variable));
+ nVariable--;
+ Variable=realloc(Variable, nVariable*sizeof(VARIABLE));
+ return 1;
+ }
+ return 0;
+}
+
+
+static int GetVariable (char *name, RESULT *value)
+{
+ VARIABLE *V;
+
+ V=bsearch(name, Variable, nVariable, sizeof(VARIABLE), v_lookup);
+ if (V!=NULL) {
+ value->type=V->value->type;
+ value->number=V->value->number;
+ if (V->value->string!=NULL) value->string=strdup(V->value->string);
+ else value->string=NULL;
+ return 1;
+ }
+
+ DelResult (value);
+ return 0;
+}
+
+
+static int SetVariable (char *name, RESULT *value)
+{
+ VARIABLE *V;
+
+ V=bsearch(name, Variable, nVariable, sizeof(VARIABLE), v_lookup);
+ if (V!=NULL) {
+ FreeResult (V->value);
+ V->value=DupResult(value);
+ return 1;
+ }
+
+ // Fixme: we append the var at the end and re-sort
+ // the whole array! This should be optimized...
+ nVariable++;
+ Variable=realloc(Variable, nVariable*sizeof(VARIABLE));
+ Variable[nVariable-1].name=strdup(name);
+ Variable[nVariable-1].value=DupResult(value);
+ qsort(Variable, nVariable, sizeof(VARIABLE), v_sort);
+
+ return 0;
+}
+
+
+int AddConstant (char *name, double value)
+{
+ RESULT result;
+
+ result.type=R_NUMBER;
+ result.number=value;
+ result.string=NULL;
+
+ return SetVariable (name, &result);
+}
+
+
+// bsearch compare function for functions
+static int f_lookup (const void *a, const void *b)
+{
+ char *name=(char*)a;
+ FUNCTION *f=(FUNCTION*)b;
+ return strcmp(name, f->name);
+}
+
+
+// qsort compare function for functions
+static int f_sort (const void *a, const void *b)
+{
+ FUNCTION *va=(FUNCTION*)a;
+ FUNCTION *vb=(FUNCTION*)b;
+ return strcmp(va->name, vb->name);
+}
+
+
+int AddFunction (char *name, int args, void (*func)())
+{
+ FUNCTION *F;
+
+ F=bsearch(name, Function, nFunction, sizeof(FUNCTION), f_lookup);
+ if (F!=NULL) {
+ if (F->name) free (F->name);
+ F->name=strdup(name);
+ F->args=args;
+ F->func=func;
+ return 1;
+ }
+
+ // Fixme: we append the func at the end and re-sort
+ // the whole array! This should be optimized...
+ nFunction++;
+ Function=realloc(Function, nFunction*sizeof(FUNCTION));
+ Function[nFunction-1].name=strdup(name);
+ Function[nFunction-1].args=args;
+ Function[nFunction-1].func=func;
+ qsort(Function, nFunction, sizeof(FUNCTION), f_sort);
+
+ return 0;
+}
+
+
+
+// Prototypes
+static void Level01 (RESULT *result);
+static void Level02 (RESULT *result);
+static void Level03 (RESULT *result);
+static void Level04 (RESULT *result);
+static void Level05 (RESULT *result);
+static void Level06 (RESULT *result);
+static void Level07 (RESULT *result);
+static void Level08 (RESULT *result);
+static void Level09 (RESULT *result);
+static void Level10 (RESULT *result);
+static void Level11 (RESULT *result);
+
+
+
+static void Parse (void)
+{
+ char *start;
+
+ Type=0;
+ if (Token) {
+ free (Token);
+ Token=NULL;
+ }
+
+ while (is_blank(*Expression)) Expression++;
+
+ if (is_delim(*Expression)) {
+ Type=T_DELIMITER;
+ Token=strndup(Expression++, 1);
+ }
+
+ else if (isdigit(*Expression)) {
+ Type=T_NUMBER;
+ start=Expression;
+ while (is_number(*Expression)) Expression++;
+ Token=strndup(start, Expression-start);
+ }
+
+ else if (is_name(*Expression)) {
+ Type=T_NAME;
+ start=Expression;
+ while (is_name(*Expression)) Expression++;
+ Token=strndup(start, Expression-start);
+ }
+
+ else if (*Expression=='\'') {
+ Type=T_STRING;
+ start=++Expression;
+ while (*Expression && *Expression!='\'') Expression++;
+ Token=strndup(start, Expression-start);
+ if (*Expression=='\'') Expression++;
+ }
+
+ else if (*Expression) {
+ ERROR(E_SYNTAX);
+ }
+
+ while(is_blank(*Expression)) Expression++;
+
+ // empty token
+ if (Token==NULL) Token=strdup("");
+}
+
+
+
+// expression lists
+static void Level01 (RESULT *result)
+{
+ do {
+ while (*Token==';') Parse();
+ Level02(result);
+ } while (*Token==';');
+}
+
+
+// variable assignments
+static void Level02 (RESULT *result)
+{
+ char *name;
+
+ if (Type==T_NAME) {
+ if (*Expression == '=') {
+ name=strdup(Token);
+ Parse();
+ Parse();
+ if (*Token && *Token!=';') {
+ Level03(result);
+ SetVariable(name, result);
+ } else {
+ DelVariable(name);
+ }
+ free (name);
+ return;
+ }
+ }
+ Level03(result);
+}
+
+
+// logical 'or'
+static void Level03 (RESULT *result)
+{
+ RESULT operand;
+ double value;
+
+ Level04(result);
+
+ while(*Token=='|') {
+ Parse();
+ Level04 (&operand);
+ value = (R2N(result)!=0.0) || (R2N(&operand)!=0.0);
+ SetResult(&result, R_NUMBER, &value);
+ }
+}
+
+
+// logical 'and'
+static void Level04 (RESULT *result)
+{
+ RESULT operand;
+ double value;
+
+ Level05(result);
+
+ while(*Token=='&') {
+ Parse();
+ Level06 (&operand);
+ value = (R2N(result)!=0.0) && (R2N(&operand)!=0.0);
+ SetResult(&result, R_NUMBER, &value);
+ }
+}
+
+
+// equal, not equal
+static void Level05 (RESULT *result)
+{
+ char operator;
+ RESULT operand = {0, 0.0, NULL};
+ double value;
+
+ Level06 (result);
+
+ if ((operator=*Token)=='<' || operator=='>') {
+ Parse();
+ Level07 (&operand);
+ if (operator=='<')
+ value = (R2N(result) < R2N(&operand));
+ else
+ value = (R2N(result) > R2N(&operand));
+ SetResult(&result, R_NUMBER, &value);
+ }
+}
+
+
+// relational operators
+static void Level06 (RESULT *result)
+{
+ char operator;
+ RESULT operand = {0, 0.0, NULL};
+ double value;
+
+ Level07 (result);
+
+ if ((operator=*Token)=='<' || operator=='>') {
+ Parse();
+ Level07 (&operand);
+ if (operator=='<')
+ value = (R2N(result) < R2N(&operand));
+ else
+ value = (R2N(result) > R2N(&operand));
+ SetResult(&result, R_NUMBER, &value);
+ }
+}
+
+
+// addition, subtraction, concatenation
+static void Level07 (RESULT *result)
+{
+ char operator;
+ RESULT operand = {0, 0.0, NULL};
+ double value;
+
+ Level08(result);
+
+ while((operator=*Token)=='+' || operator=='-' || operator=='.') {
+ Parse();
+ Level08 (&operand);
+ if (operator=='+') {
+ value = (R2N(result) + R2N(&operand));
+ SetResult(&result, R_NUMBER, &value);
+ } else if (operator=='-') {
+ value = (R2N(result) - R2N(&operand));
+ SetResult(&result, R_NUMBER, &value);
+ } else {
+ char *s1=R2S(result);
+ char *s2=R2S(&operand);
+ char *s3=malloc(strlen(s1)+strlen(s2)+1);
+ strcpy (s3, s1);
+ strcat (s3, s2);
+ SetResult (&result, R_STRING, s3);
+ free (s3);
+ }
+ }
+}
+
+
+// multiplication, division, modulo
+static void Level08 (RESULT *result)
+{
+ char operator;
+ RESULT operand = {0, 0.0, NULL};
+ double value;
+
+ Level09 (result);
+
+ while((operator=*Token)=='*' || operator=='/' || operator=='%') {
+ Parse();
+ Level09(&operand);
+ if (operator == '*') {
+ value = (R2N(result) * R2N(&operand));
+ } else if (operator == '/') {
+ if (R2N(&operand) == 0.0) ERROR (E_DIVZERO);
+ value = (R2N(result) / R2N(&operand));
+ } else {
+ if (R2N(&operand) == 0.0) ERROR (E_DIVZERO);
+ value = fmod(R2N(result), R2N(&operand));
+ }
+ SetResult(&result, R_NUMBER, &value);
+ }
+}
+
+
+// x^y
+static void Level09 (RESULT *result)
+{
+ RESULT exponent = {0, 0.0, NULL};
+ double value;
+
+ Level10 (result);
+
+ if (*Token == '^') {
+ Parse();
+ Level10 (&exponent);
+ value = pow(R2N(result), R2N(&exponent));
+ SetResult(&result, R_NUMBER, &value);
+ }
+}
+
+
+// unary + or - signs or logical 'not'
+static void Level10 (RESULT *result)
+{
+ char sign=0;
+ double value;
+
+ if (*Token=='+' || *Token=='-' || *Token=='!') {
+ sign=*Token;
+ Parse();
+ }
+
+ Level11 (result);
+
+ if (sign == '-') {
+ value = -R2N(result);
+ SetResult(&result, R_NUMBER, &value);
+ }
+ else if (sign == '!') {
+ value = (R2N(result)==0.0);
+ SetResult(&result, R_NUMBER, &value);
+ }
+}
+
+
+// literal numbers, variables, functions
+static void Level11 (RESULT *result)
+{
+ RESULT param[10];
+
+ if (*Token == '(') {
+
+ Parse();
+ if (*Token == ')') ERROR (E_NOARG);
+ Level01(result);
+ if (*Token != ')') ERROR (E_UNBALAN);
+ Parse();
+
+ } else {
+
+ if (Type == T_NUMBER) {
+ double value=atof(Token);
+ SetResult(&result, R_NUMBER, &value);
+ Parse();
+
+ } else if (Type == T_STRING) {
+ SetResult(&result, R_STRING, Token);
+ Parse();
+
+ } else if (Type == T_NAME) {
+
+ if (*Expression == '(') {
+ FUNCTION *F=bsearch(Token, Function, nFunction, sizeof(FUNCTION), f_lookup);
+ if (F!=NULL) {
+ int n=0;
+ Parse();
+ do {
+ Parse();
+ if (*Token == ')' || *Token == ',') ERROR (E_NOARG);
+ param[n].type=0;
+ param[n].string=NULL;
+ Level01(&(param[n]));
+ n++;
+ } while (n < 10 && *Token == ',');
+ Parse();
+ if (n != F->args)
+ ERROR (E_NUMARGS);
+ F->func(result,
+ &param[0], &param[1], &param[2], &param[3], &param[4],
+ &param[5], &param[6], &param[7], &param[8], &param[9]);
+ return;
+
+ } else {
+ ERROR(E_BADFUNC);
+ }
+
+ } else {
+ if (!GetVariable(Token, result))
+ ERROR(E_UNKNOWN);
+ }
+ Parse();
+
+ } else {
+ ERROR(E_SYNTAX);
+ }
+ }
+}
+
+
+int Eval (char* expression, RESULT *result)
+{
+ int err;
+
+ if ((err=setjmp(jb))) {
+ error ("Error: %s in expression <%s>", ErrMsg[err], expression);
+ return -1;
+ }
+
+ Expression=expression;
+ DelResult (result);
+ Parse();
+ if (*Token=='\0') ERROR (E_EMPTY);
+ Level01(result);
+ if (*Token!='\0') ERROR (E_SYNTAX);
+ return 0;
+}
+
+
diff --git a/evaluator.h b/evaluator.h
new file mode 100644
index 0000000..661b967
--- /dev/null
+++ b/evaluator.h
@@ -0,0 +1,90 @@
+/* $Id: evaluator.h,v 1.1 2003/10/06 04:34:06 reinelt Exp $
+ *
+ * expression evaluation
+ *
+ * based on EE (Expression Evaluator) which is
+ * (c) 1992 Mark Morley <morley@Camosun.BC.CA>
+ *
+ * heavily modified 2003 by Michael Reinelt <reinelt@eunet.at>
+ *
+ * FIXME: GPL or not GPL????
+ *
+ * $Log: evaluator.h,v $
+ * Revision 1.1 2003/10/06 04:34:06 reinelt
+ * expression evaluator added
+ *
+ */
+
+
+/***************************************************************************
+ ** **
+ ** EE.C Expression Evaluator **
+ ** **
+ ** AUTHOR: Mark Morley **
+ ** COPYRIGHT: (c) 1992 by Mark Morley **
+ ** DATE: December 1991 **
+ ** HISTORY: Jan 1992 - Made it squash all command line arguments **
+ ** into one big long string. **
+ ** - It now can set/get VMS symbols as if they **
+ ** were variables. **
+ ** - Changed max variable name length from 5 to 15 **
+ ** Jun 1992 - Updated comments and docs **
+ ** **
+ ** You are free to incorporate this code into your own works, even if it **
+ ** is a commercial application. However, you may not charge anyone else **
+ ** for the use of this code! If you intend to distribute your code, **
+ ** I'd appreciate it if you left this message intact. I'd like to **
+ ** receive credit wherever it is appropriate. Thanks! **
+ ** **
+ ** I don't promise that this code does what you think it does... **
+ ** **
+ ** Please mail any bug reports/fixes/enhancments to me at: **
+ ** morley@camosun.bc.ca **
+ ** or **
+ ** Mark Morley **
+ ** 3889 Mildred Street **
+ ** Victoria, BC Canada **
+ ** V8Z 7G1 **
+ ** (604) 479-7861 **
+ ** **
+ ***************************************************************************/
+
+
+#ifndef _EVALUATOR_H_
+#define _EVALUATOR_H_
+
+
+// RESULT bitmask
+#define R_NUMBER 1
+#define R_STRING 2
+
+typedef struct {
+ int type;
+ double number;
+ char *string;
+} RESULT;
+
+
+// error codes
+#define E_OK 0 /* Successful evaluation */
+#define E_SYNTAX 1 /* Syntax error */
+#define E_UNBALAN 2 /* Unbalanced parenthesis */
+#define E_DIVZERO 3 /* Attempted division by zero */
+#define E_UNKNOWN 4 /* Reference to unknown variable */
+#define E_BADFUNC 5 /* Unrecognised function */
+#define E_NUMARGS 6 /* Wrong number of arguments to function */
+#define E_NOARG 7 /* Missing an argument to a function */
+#define E_EMPTY 8 /* Empty expression */
+
+
+int AddConstant (char *name, double value);
+int AddFunction (char *name, int args, void (*func)());
+
+RESULT* SetResult (RESULT **result, int type, void *value);
+
+double R2N (RESULT *result);
+char* R2S (RESULT *result);
+
+int Eval (char* expression, RESULT *result);
+
+#endif
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
diff --git a/expression.h b/expression.h
new file mode 100644
index 0000000..07a53a2
--- /dev/null
+++ b/expression.h
@@ -0,0 +1,36 @@
+/* $Id: expression.h,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.h,v $
+ * Revision 1.1 2003/10/06 04:34:06 reinelt
+ * expression evaluator added
+ *
+ */
+
+
+#ifndef _EXPRESSION_H_
+#define _EXPRESSION_H_
+
+int EX_init (void);
+
+#endif
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