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authorDaniel Perez <steew0x8@protonmail.com>2021-12-02 11:39:02 +0100
committerDaniel Perez <steew0x8@protonmail.com>2021-12-02 11:39:02 +0100
commit19dcb7cd30d9bfb690a7dfedf213912173e4d2dd (patch)
treefd368f1e2dc2edbd5a4e090fc26dd0d454aed382
parentfa22526b8477b30fb50e6019fd0248f18964c788 (diff)
downloadrpncalc-master.tar.gz
clean code up, move basic ops to cmds.c HEAD master
-rw-r--r--cmds.c52
-rw-r--r--cmds.h2
-rw-r--r--main.c100
3 files changed, 92 insertions, 62 deletions
diff --git a/cmds.c b/cmds.c
index 30772fb..da5720b 100644
--- a/cmds.c
+++ b/cmds.c
@@ -67,7 +67,42 @@ stack fcos(stack stack) {
   return stack;
 }
 
+stack fadd(stack stack) {
+  PREV = LAST + PREV;
+  REDUCE;
+  return stack;
+}
+
+stack fsub(stack stack) {
+  PREV = PREV - LAST;
+  REDUCE;
+  return stack;
+}
+
+stack fmul(stack stack) {
+  PREV = PREV*LAST;
+  REDUCE;
+  return stack;
+}
+
+stack fdiv(stack stack) {
+  PREV = PREV / LAST;
+  REDUCE;
+  return stack;
+}
+
+stack fpow(stack stack) {
+  PREV = pow(PREV, LAST);
+  REDUCE;
+  return stack;
+}
+
 command CMD_LIST[] = {
+  {"*", &fmul, "multiply last two numbers", 2},
+  {"+", &fadd, "add last two numbers", 2},
+  {"-", &fsub, "substract last two numbers", 2},
+  {"/", &fdiv, "divide last two numbers", 2},
+  {"^", &fpow, "power last two numbers", 2},
   {"ceil", &fceil, "truncate to the next integer", 1},
   {"cos", &fcos, "calculate the cosine", 1},
   {"e", &fe, "return number e", 0},
@@ -100,17 +135,22 @@ void init_state(state *s) {
   s->sorted = CMD_LIST;
 }
 
-void exec(char *buf, state *s) {
+/*
+exec tries to find a function name matching the one provided in buf. If it
+fails to find one, it returns -2. If it finds one, but number of arguments in
+the stack is less than the specified limit, it returns the number of arguments
+needed. If it succeeds, it returns -1, in order not to conflict with the integer
+returned when an incorrect number of arguments have been passed.
+*/
+int exec(char *buf, state *s) {
   command *c = bsearch(&buf, s->sorted, s->numel, sizeof(s->sorted[0]), search);
   if (c == NULL) {
-    fprintf(s->defout, "error: function '%s' not found\n", buf);
-    return;
+    return -2; // not found
   }
   if (c->required_args > s->stk.count) {
-    fprintf(s->defout,"this function requires %d arguments\n", c->required_args);
-    return;
+    return c->required_args; // return number of required arguments
   }
   fprintf(s->defout, "executing function: %s\n", c->name);
   s->stk = c->exec(s->stk);
-
+  return -1; // no error
 }
diff --git a/cmds.h b/cmds.h
index 78a1c13..5951148 100644
--- a/cmds.h
+++ b/cmds.h
@@ -6,6 +6,6 @@
 
 extern command CMD_LIST[];
 void init_state(state *s);
-void exec(char *buf, state *s);
+int exec(char *buf, state *s);
 
 #endif
diff --git a/main.c b/main.c
index 2b79001..09fc6ab 100644
--- a/main.c
+++ b/main.c
@@ -1,12 +1,13 @@
-#include <math.h>
-#include <stdio.h>
+#include "cmds.h"
 #include "state.h"
 #include "util.h"
-#include <stdlib.h>
-#include <string.h>
-#include "cmds.h"
+#include <ctype.h>
 #include <err.h>
 #include <errno.h>
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 
 #define BUF_SIZE 50
 
@@ -27,76 +28,65 @@ int main() {
   s.command_count = 0;
   init_state(&s);
 
+  fprintf(s.defout, "welcome to rpncalc! type 'list' to see a list of "
+	  "commands, or 'quit' to leave.\n");
 
-  fprintf(s.defout,"welcome to rpncalc! type 'list' to see a list of commands, or 'quit' to leave.\n");
-  
-  
   /* start reading from defbuf */
   char buf[BUF_SIZE];
-  while(1){
+  while (1) {
+    int execval = 0;
+    /* prompt the user for input */
     fprintf(s.defout, s.prompt, s.command_count, s.last_op);
     s.last_op = 0;
     char *endptr = NULL;
+    /* get input */
     char *check = fgets(buf, BUF_SIZE, s.defbuf);
-    if (check == NULL) exit(0);
+    if (check == NULL)
+      exit(0);
+    /* strip newline */
     buf[strcspn(buf, "\n")] = 0;
+    /* parse input as a number */
     double interpreted = strtod(buf, &endptr);
     if (errno == ERANGE) {
-      fprintf(s.defout,"sorry, this number is too big\n");
+      fprintf(s.defout, "sorry, this number is too big\n");
       continue;
     }
-    if (interpreted == (double)0 && endptr == buf) { /* strtod returned the char it could not read */
-      TYPE t = discriminate(buf);
-      if (t == OPERATOR ) {
-	if (s.stk.count <= 1) {
-	  fprintf(s.defout, "not enough arguments\n");
-	  continue;
-	}
-	char operator = buf[0];
-	if (operator == '+') {
-	  s.stk.val[s.stk.count-2] = s.stk.val[s.stk.count-1]+s.stk.val[s.stk.count-2];
-	  s.stk.val[s.stk.count--] = 0; /* lower count by 1 */
-	  s.last_op = '+';
-	} else if (operator == '-') {
-	  s.stk.val[s.stk.count-2] = s.stk.val[s.stk.count-2]-s.stk.val[s.stk.count-1];
-	  s.stk.val[s.stk.count--] = 0; /* lower count by 1 */
-	  s.last_op = '-';
-	} else if (operator == '*') {
-	  s.stk.val[s.stk.count-2] = s.stk.val[s.stk.count-2]*s.stk.val[s.stk.count-1];
-	  s.stk.val[s.stk.count--] = 0; /* lower count by 1 */
-	  s.last_op = '*';
-	} else if (operator == '/') {
-	  s.stk.val[s.stk.count-2] = s.stk.val[s.stk.count-2]/s.stk.val[s.stk.count-1];
-	  s.stk.val[s.stk.count--] = 0; /* lower count by 1 */
-	  s.last_op = '/';
-	} else if (operator == '^') {
-	  s.stk.val[s.stk.count-2] = pow(s.stk.val[s.stk.count-2],s.stk.val[s.stk.count-1]);
-	  s.stk.val[s.stk.count--] = 0; /* lower count by 1 */
-	  s.last_op = '^';
-	} else;
-      } else if (t == FUNCTION) {
-	/* check for special commands, else pass to exec() */
-	if (strcmp(buf, "quit") == 0) {
-	  fprintf(s.defout, "quitting, bye!\n");
-	  exit(0);
-	} else if (strcmp(buf, "list") == 0) {
-	  for (int i = 0; i < s.numel; i++) {
-	    fprintf(s.defout, "[%s]\t->\t%s\n", s.sorted[i].name, s.sorted[i].description);
-	  }
-	  continue;
-	} else exec(buf, &s);
+    /* special functions, quit and list, that do not interact with the stack directly */
+    if (strcmp(buf, "quit") == 0) {
+      fprintf(s.defout, "quitting, bye!\n");
+      exit(0);
+    } else if (strcmp(buf, "list") == 0) {
+      for (int i = 0; i < s.numel; i++) {
+        fprintf(s.defout, "[%s]\t->\t%s\n", s.sorted[i].name,
+                s.sorted[i].description);
+      }
+      continue;
+    } else if ((execval = exec(buf, &s)) == -1 || execval > 0) { /* try to execute a known function.
+								    if we fail, we either catch an
+								    incorrect number of arguments
+								    error, or we pass it to the next
+								    else clause.*/
+      if (execval > 0) {
+	fprintf(s.defout, "this function requires %d arguments\n", execval);
+	continue;
       }
     } else { /* we found a number */
-      if (s.stk.count == STACK_SIZE - 1) {
-	fprintf(s.defout, "exceeded stack size %d\n", STACK_SIZE);
+      /* test if provided input could not be parsed by strtod, in this case we are not against
+	 a number, so error out */
+      if (endptr == buf) {
+	fprintf(s.defout, "function %s not found\n", buf);
 	continue;
       }
+      if (s.stk.count == STACK_SIZE - 1) {
+        fprintf(s.defout, "exceeded stack size %d\n", STACK_SIZE);
+        continue;
+      }
       s.stk.val[s.stk.count++] = interpreted;
     }
-    
+    /* add one to the command count, and print the updated stack */
     s.command_count++;
     for (int i = 0; i < s.stk.count; i++) {
-      fprintf(s.defout,"%d → %f\n",i, s.stk.val[i]);
+      fprintf(s.defout, "%d → %f\n", i, s.stk.val[i]);
     }
   }
 }