Add Object helpers (less redundancy). Add new errs

src/object.c

@@ -52,23 +52,87 @@ Object *tail(const Object *listObj)
     return t;
 }
 
+/**
+ * Checks if a given object is empty
+ * BOOL, NUMBER, and ERROR types return true only when 0
+ * LIST, LAMBDA, and FUNC types return true only when NULL
+ * SYMBOL returns true only when it begins with a nullchar
+ * Returns false if obj is NULL
+ */
+inline int isEmpty(const Object *obj)
+{
+    if(obj == NULL)
+        return 0;
+
+    switch(obj->type) {
+        case TYPE_NUMBER:
+        case TYPE_BOOL:
+            return obj->number == 0;
+        case TYPE_LIST:
+            return obj->list == NULL;
+        case TYPE_LAMBDA:
+            return obj->lambda == NULL;
+        case TYPE_SYMBOL:
+            return obj->name[0] == '\0';
+        case TYPE_FUNC:
+            return obj->func == NULL;
+        case TYPE_ERROR:
+            return obj->err == 0;
+        default:
+            return 0;
+    }
+}
+
+void allocObject(Object **spot, const Object src)
+{
+    *spot = malloc(sizeof(struct Object));
+    **spot = src;
+    (*spot)->forward = NULL;
+}
+
+// Insert `src` into list `dest` before index `ind`
+// Adds to the end if the index is too high.
+void insertIntoList(Object *dest, int ind, const Object src)
+{
+    // Only work with non-null list types
+    if(!dest || dest->type != TYPE_LIST || ind < 0)
+        return;
+
+    if(isEmpty(dest)) {
+        allocObject(&dest->list, src);
+        return;
+    }
+
+    // TODO Check for off-by-one errors 
+    //      ensure pointers connect old and new
+    Object *march = dest->list;
+    for(int i = 1; i < ind; i++) {
+        if(march->forward == NULL) {
+            allocObject(&march->forward, src);
+            return;
+        }
+        march = march->forward;
+    }
+
+    // Save and re-apply current march->forward
+    Object *oldForward = march->forward;
+    allocObject(&march->forward, src);
+    march->forward->forward = oldForward;
+}
+
 // Adds an object to the end of a list object
 void addToList(Object *dest, const Object src)
 {
     if(!dest || dest->type != TYPE_LIST)
         return;
 
-    if(dest->list == NULL) {
+    if(isEmpty(dest)) {
-        dest->list = malloc(sizeof(struct Object));
+        allocObject(&dest->list, src);
-        *dest->list = src;
-        dest->list->forward = NULL;
         return;
     }
 
     Object *end = tail(dest);
-    end->forward = malloc(sizeof(struct Object));
+    allocObject(&end->forward, src);
-    *end->forward = src;
-    end->forward->forward = NULL;
 }
 
 void printErr(const Object *obj)
@@ -200,6 +264,11 @@ void deleteList(const Object *dest)
     }
 }
 
+/**
+ * Copies all items from `src` to `dest`
+ * Does nothing if either is NULL, or neither are lists
+ * First deletes all items from `dest`
+ */
 void copyList(Object *dest, const Object *src)
 {
     if(!dest || !src || dest->type != TYPE_LIST || src->type != TYPE_LIST)
@@ -213,6 +282,7 @@ void copyList(Object *dest, const Object *src)
     }
 }
 
+// Returns a basic object with NULL forward and the given `type`
 inline Object newObject(Type type)
 {
     Object no;
@@ -221,6 +291,7 @@ inline Object newObject(Type type)
     return no;
 }
 
+// Returns an empty list object
 inline Object listObject()
 {
     Object list = newObject(TYPE_LIST);
@@ -235,10 +306,16 @@ inline Object numberObject(int num)
     return o;
 }
 
+inline Object boolObject(int b)
+{
+    Object o = newObject(TYPE_BOOL);
+    o.number = b;
+    return o;
+}
+
 inline Object symbolObject()
 {
-    Object o = newObject(TYPE_SYMBOL);
+    return newObject(TYPE_SYMBOL);
-    return o;
 }
 
 inline Object lambdaObject()

src/object.h

@@ -13,7 +13,8 @@ enum errorCode {
     NULL_PARSE,
     NULL_LAMBDA_LIST,
     LAMBDA_ARGS_NOT_LIST,
-    DID_NOT_FIND_SYMBOL
+    DID_NOT_FIND_SYMBOL,
+    UNEXPECTED_FORM
 };
 
 #ifdef STANDALONE
@@ -25,7 +26,8 @@ enum errorCode {
         "NULL_PARSE",
         "NULL_LAMBDA_LIST",
         "LAMBDA_ARGS_NOT_LIST",
-        "DID_NOT_FIND_SYMBOL"
+        "DID_NOT_FIND_SYMBOL",
+        "UNEXPECTED_FORM"
     };
 #endif
 
@@ -50,12 +52,12 @@ struct Object {
         Object *list;
         char name[MAX_TOK_LEN];
         Object (*func)(Object, Object);
-        struct Lambda *lambda; // Maybe better as not a pointer
+        struct Lambda *lambda; // Maybe better as not a pointer?
         enum errorCode err;
     };
 };
 
-// Maybe better as pointers
+// Maybe better as pointers?
 struct Lambda {
     Object params;
     Object body;
@@ -66,6 +68,7 @@ void printList(const Object *list);
 void printObj(const Object *obj);
 void debugObj(const Object *obj);
 
+int isEmpty(const Object *obj);
 Object *tail(const Object *listObj);
 void addToList(Object *dest, Object src);
 void deleteList(const Object *dest);
@@ -74,12 +77,15 @@ Object *itemAt(const Object *listObj, int n);
 void copyList(Object *dest, const Object *src);
 
 void cleanObject(Object *target);
+void allocObject(Object **spot, const Object src);
 
 Object newObject(Type type);
 Object listObject();
-Object numberObject(int num);
 Object lambdaObject();
-Object constructLambda(const Object *params, const Object *body);
+Object symbolObject();
+Object boolObject(int b);
+Object numberObject(int num);
 Object errorObject(enum errorCode err);
+Object constructLambda(const Object *params, const Object *body);
 
 #endif

src/pebblisp.c

@@ -80,26 +80,25 @@ Result readSeq(struct Slice *tokens)
 
 Object parseAtom(struct Slice *s)
 {
-    Object o;
-    o.forward = NULL;
     if(isDigit(s->text[0])) {
-        o.type = TYPE_NUMBER;
+        int num = 0;
-        o.number = 0;
         for(int i = 0; i < s->length; i++) {
-            o.number *= 10;
+            num *= 10;
-            o.number += s->text[i] - '0';
+            num += s->text[i] - '0';
         }
+        return numberObject(num);
+
     } else if (s->text[0] == 'T' && s->text[1] == '\0') {
-        o.type = TYPE_BOOL;
+        return boolObject(1);
-        o.number = 1;
+
     } else if (s->text[0] == 'F' && s->text[1] == '\0') {
-        o.type = TYPE_BOOL;
+        return boolObject(0);
-        o.number = 0;
+
     } else {
-        o.type = TYPE_SYMBOL;
+        Object o = symbolObject();
         copySlice(o.name, s);
+        return o;
     }
-    return o;
 }
 
 Object evalDefArgs(const Object *arg_forms, struct Environment *env)
@@ -242,12 +241,8 @@ Object eval(const Object *obj, struct Environment *env)
             }
         }
         case TYPE_LAMBDA:
-        {
+            return errorObject(UNEXPECTED_FORM);
-            Object o;
+
-            o.type = TYPE_ERROR;
-            printf("UNEXPECTED FORM\n");
-            return o;
-        }
         default:
         ;
     }
@@ -292,50 +287,33 @@ void printEnv(struct Environment *env)
 
 Object basicOp(Object *obj1, Object *obj2, const char op)
 {
-    Object o;
-    o.forward = NULL;
-
-    o.type = TYPE_NUMBER;
     const int n1 = obj1->number;
     const int n2 = obj2->number;
 
     switch(op){
         case '+':
-            o.number = n1 + n2;
+            return numberObject(n1 + n2);
-            return o;
         case '-':
-            o.number = n1 - n2;
+            return numberObject(n1 - n2);
-            return o;
         case '*':
-            o.number = n1 * n2;
+            return numberObject(n1 * n2);
-            return o;
         case '/':
-            o.number = n1 / n2;
+            return numberObject(n1 / n2);
-            return o;
-    }
 
-    o.type = TYPE_BOOL;
-    switch(op) {
         case '=':
-            o.number = n1 == n2;
+            return boolObject(n1 == n2);
-            return o;
         case '>':
-            o.number = n1 > n2;
+            return boolObject(n1 > n2);
-            return o;
         case '<':
-            o.number = n1 < n2;
+            return boolObject(n1 < n2);
-            return o;
     }
 
-    o = *obj1;
+    return *obj1;
-    return o;
 }
 
 #define bopf(_name, _char) \
 Object _name(Object obj1, Object obj2) \
-{ \
+    { return basicOp(&obj1, &obj2, _char); }
-    return basicOp(&obj1, &obj2, _char); \
-}
 
 bopf(add, '+');
 bopf(sub, '-');
@@ -405,9 +383,6 @@ Object parseEval(const char *input, struct Environment *env)
     }
 #endif
     Object parsed = parse(tokens).obj;
-    // printf("PARSEEVAL() PRINTLIST():\n");
-    // debugObject(&parsed);
-    // printf("end PARSEEVAL() PRINTLIST():\n\n");
     free(tokens);
     return eval(&parsed, env);
 }