From 8eae0678a50aa91d6473251b59286f2026ad81bc Mon Sep 17 00:00:00 2001
From: "Eric S. Raymond" <esr@thyrsus.com>
Date: Fri, 4 Nov 1994 17:31:13 +0000
Subject: [PATCH] Recursion seems to work OK.

---
 Makefile  |  2 +-
 cupl.h    | 11 +++++++++
 execute.c | 68 +++++++++++++++++++++++++++++++++++++++++++++----------
 3 files changed, 68 insertions(+), 13 deletions(-)

diff --git a/Makefile b/Makefile
index 29f5a8d..559c1a9 100644
--- a/Makefile
+++ b/Makefile
@@ -10,7 +10,7 @@ SOURCES = cupl.[ylh] tokdump.c main.c interpret.c execute.c monitor.c nodetype.h
 
 MODULES = main.o grammar.o lexer.o interpret.o tokdump.o execute.o monitor.o
 cupl: $(MODULES)
-	$(CC) $(MODULES) -o cupl
+	$(CC) $(MODULES) -lm -o cupl
 
 lexer.c: cupl.l
 	lex $(LFLAGS) cupl.l
diff --git a/cupl.h b/cupl.h
index 22a352d..ce67466 100644
--- a/cupl.h
+++ b/cupl.h
@@ -67,6 +67,7 @@ typedef struct
     int		rank;			/* 0, 1, or 2 */
     int		width, depth;		/* dimensions */
     scalar	*elements;		/* elements */
+    int		refcount;		/* how many copies are there? */
 }
 value;
 
@@ -106,6 +107,16 @@ extern void execute(node *tree);
 /* monitor.c */
 extern void die(char *msg, ...);
 extern void warn(char *msg, ...);
+extern void make_scalar(value *v, scalar n);
+extern value copy_value(value);
+extern void deallocate_value(value *);
+extern value cupl_add(value, value);
+extern value cupl_multiply(value, value);
+extern value cupl_subtract(value, value);
+extern value cupl_divide(value, value);
+extern value cupl_power(value, value);
+extern value cupl_uminus(value);
+extern value cupl_sqrt(value);
 
 #define DEBUG_PARSEDUMP	1
 #define DEBUG_CHECKDUMP	2
diff --git a/execute.c b/execute.c
index 4e8f29b..dbd4f80 100644
--- a/execute.c
+++ b/execute.c
@@ -19,6 +19,7 @@ handed off to execute().
 
 #define car	u.n.left
 #define cdr	u.n.right
+#define EVAL_WRAP
 
 static node *pc;	/* the statement node to evaluate next */
 static node *data;	/* pointer to *DATA item to be grabbed next */
@@ -114,20 +115,15 @@ static void cupl_write(node *tp)
     }
 }
 
-static void make_scalar(value *v, scalar i)
-/* initialize a scalar value element */
-{
-    v->width = v->depth = 1;
-    v->elements = (scalar *)malloc(sizeof(scalar));
-    v->elements[0] = i;
-}
-
 static value cupl_eval(node *tree)
 /* recursively evaluate a CUPL parse tree */
 {
     value	leftside, rightside, result;
     node	*np;
 
+    if (verbose >= DEBUG_ALLOCATE)
+	(void) printf("Evaluating %9x (%s)\n", tree, tokdump(tree->type));
+
     switch(tree->type)
     {
     case NUMBER:
@@ -135,22 +131,70 @@ static value cupl_eval(node *tree)
 	return(result);
 
     case IDENTIFIER:
-	return(tree->syminf->value);
+	result = EVAL_WRAP(tree->syminf->value);
+	return(result);
 
     case READ:
 	for_cdr(np, tree)
 	    cupl_read(np->car);
-	break;
+	return(result);		/* garbage value */
 
     case WRITE:
 	needspace(0);
 	for_cdr(np, tree)
 	    cupl_write(np->car);
 	needspace(-1);
-	break;
+	return(result);		/* garbage value */
+
+    case LET:
+	deallocate_value(&(tree->car->syminf->value));
+	tree->car->syminf->value = EVAL_WRAP(cupl_eval(tree->cdr));
+	return(result);		/* garbage value */
+
+    case PLUS:
+	leftside = EVAL_WRAP(cupl_eval(tree->car));
+	rightside = EVAL_WRAP(cupl_eval(tree->cdr));
+	result = cupl_add(leftside, rightside);
+	return(result);
+
+    case MULTIPLY:
+	leftside = EVAL_WRAP(cupl_eval(tree->car));
+	rightside = EVAL_WRAP(cupl_eval(tree->cdr));
+	result = cupl_multiply(leftside, rightside);
+	return(result);
+
+    case MINUS:
+	leftside = EVAL_WRAP(cupl_eval(tree->car));
+	rightside = EVAL_WRAP(cupl_eval(tree->cdr));
+	result = cupl_subtract(leftside, rightside);
+	return(result);
+
+    case DIVIDE:
+	leftside = EVAL_WRAP(cupl_eval(tree->car));
+	rightside = EVAL_WRAP(cupl_eval(tree->cdr));
+	result = cupl_add(leftside, rightside);
+	return(result);
+
+    case POWER:
+	leftside = EVAL_WRAP(cupl_eval(tree->car));
+	rightside = EVAL_WRAP(cupl_eval(tree->cdr));
+	result = cupl_power(leftside, rightside);
+	return(result);
+
+    case UMINUS:
+	rightside = EVAL_WRAP(cupl_eval(tree->cdr));
+	result = cupl_uminus(rightside);
+	return(result);
+
+    case SQRT:
+	rightside = EVAL_WRAP(cupl_eval(tree->cdr));
+	result = cupl_sqrt(rightside);
+	return(result);
 
     default:
-	die("unknown node type %d (%s), cannot execute\n",tokdump(tree->type));
+	die("unknown node type %d (%s), cannot execute\n",
+	    tree->type,
+	    tokdump(tree->type));
 	break;
     }
 }
-- 
2.43.0