Add proto field to tables to allow prototypal inheritance.

src/compiler/boot.dst

@@ -114,14 +114,17 @@
         ret)
  })
 
-(defn onerr [t e]
- (print (string t " error: " e)))
+# Compile time
 
 (var *read* nil)
 (var *onvalue* identity)
+(var *env* _env)
 
 (def require-loading @{})
 
+(defn onerr [t e]
+ (print (string t " error: " e)))
+
 (defn char-stream [getchunk ondone]
  (fiber (fn [parent]
    (def buf @"")
@@ -197,7 +200,7 @@
   (def wrapper (fiber (fn []
     (while *read*
       (def source (*read*))
-      (def res (compile source _env))
+      (def res (compile source *env*))
       (if (= (type res) :function)
         (*onvalue* (res))
         (onerr "compile" (get res :error)))))))

src/compiler/stl.c

@@ -47,6 +47,9 @@ static const DstReg cfuns[] = {
     {"buffer", dst_core_buffer},
     {"gensym", dst_core_gensym},
     {"get", dst_core_get},
+    {"rawget", dst_core_rawget},
+    {"getproto", dst_core_getproto},
+    {"setproto", dst_core_setproto},
     {"put", dst_core_put},
     {"length", dst_core_length},
     {"gccollect", dst_core_gccollect},

src/core/corelib.c

@@ -172,6 +172,33 @@ int dst_core_get(DstArgs args) {
     return dst_return(args, ds);
 }
 
+int dst_core_rawget(DstArgs args) {
+    if (args.n != 2) return dst_throw(args, "expected 2 arguments");
+    if (!dst_checktype(args.v[0], DST_TABLE)) return dst_throw(args, "expected table");
+    return dst_return(args, dst_table_rawget(dst_unwrap_table(args.v[0]), args.v[1]));
+}
+
+int dst_core_getproto(DstArgs args) {
+    DstTable *t;
+    if (args.n != 1) return dst_throw(args, "expected 1 argument");
+    if (!dst_checktype(args.v[0], DST_TABLE)) return dst_throw(args, "expected table");
+    t = dst_unwrap_table(args.v[0]);
+    return dst_return(args, t->proto
+            ? dst_wrap_table(t->proto)
+            : dst_wrap_nil());
+}
+
+int dst_core_setproto(DstArgs args) {
+    if (args.n != 2) return dst_throw(args, "expected 2 arguments");
+    if (!dst_checktype(args.v[0], DST_TABLE)) return dst_throw(args, "expected table");
+    if (!dst_checktype(args.v[1], DST_TABLE) && !dst_checktype(args.v[1], DST_NIL))
+        return dst_throw(args, "expected table");
+    dst_unwrap_table(args.v[0])->proto = dst_checktype(args.v[1], DST_TABLE)
+        ? dst_unwrap_table(args.v[1])
+        : NULL;
+    return dst_return(args, args.v[0]);
+}
+
 int dst_core_fiber_status(DstArgs args) {
     const char *status = "";
     if (args.n != 1) return dst_throw(args, "expected 1 argument");

src/core/gc.c

@@ -109,10 +109,15 @@ static void dst_mark_array(DstArray *array) {
 }
 
 static void dst_mark_table(DstTable *table) {
+    recur: /* Manual tail recursion */
     if (dst_gc_reachable(table))
         return;
     dst_gc_mark(table);
     dst_mark_kvs(table->data, table->capacity);
+    if (table->proto) {
+        table = table->proto;
+        goto recur;
+    }
 }
 
 static void dst_mark_struct(const DstKV *st) {

src/core/table.c

@@ -43,6 +43,7 @@ DstTable *dst_table_init(DstTable *table, int32_t capacity) {
     }
     table->count = 0;
     table->deleted = 0;
+    table->proto = NULL;
     return table;
 }
 
@@ -114,8 +115,25 @@ static void dst_table_rehash(DstTable *t, int32_t size) {
     free(olddata);
 }
 
-/* Get a value out of the object */
+/* Get a value out of the table */
 Dst dst_table_get(DstTable *t, Dst key) {
+    DstKV *bucket = dst_table_find(t, key);
+    if (NULL != bucket && !dst_checktype(bucket->key, DST_NIL))
+        return bucket->value;
+    /* Check prototypes */
+    {
+        int i;
+        for (i = DST_MAX_PROTO_DEPTH, t = t->proto; t && i; t = t->proto, --i) {
+            bucket = dst_table_find(t, key);
+            if (NULL != bucket && !dst_checktype(bucket->key, DST_NIL))
+                return bucket->value;
+        }
+    }
+    return dst_wrap_nil();
+}
+
+/* Get a value out of the table. Don't check prototype tables. */
+Dst dst_table_rawget(DstTable *t, Dst key) {
     DstKV *bucket = dst_table_find(t, key);
     if (NULL != bucket && !dst_checktype(bucket->key, DST_NIL))
         return bucket->value;

src/include/dst/dst.h

@@ -120,6 +120,7 @@ DstTable *dst_table(int32_t capacity);
 DstTable *dst_table_init(DstTable *table, int32_t capacity);
 void dst_table_deinit(DstTable *table);
 Dst dst_table_get(DstTable *t, Dst key);
+Dst dst_table_rawget(DstTable *t, Dst key);
 Dst dst_table_remove(DstTable *t, Dst key);
 void dst_table_put(DstTable *t, Dst key, Dst value);
 const DstKV *dst_table_next(DstTable *t, const DstKV *kv);

src/include/dst/dstconfig.h

@@ -120,6 +120,9 @@ extern "C" {
  * ands crashing (the parser). Instead, error out. */
 #define DST_RECURSION_GUARD 1024
 
+/* Maximum depth to follow table prototypes before giving up and returning nil. */
+#define DST_MAX_PROTO_DEPTH 200
+
 /* Define max stack size for stacks before raising a stack overflow error.
  * If this is not defined, fiber stacks can grow without limit (until memory
  * runs out) */

src/include/dst/dstcorelib.h

@@ -90,6 +90,9 @@ int dst_core_buffer(DstArgs args);
 int dst_core_gensym(DstArgs args);
 int dst_core_length(DstArgs args);
 int dst_core_get(DstArgs args);
+int dst_core_rawget(DstArgs args);
+int dst_core_getproto(DstArgs args);
+int dst_core_setproto(DstArgs args);
 int dst_core_fiber_status(DstArgs args);
 int dst_core_fiber_current(DstArgs args);
 int dst_core_put(DstArgs args);

src/include/dst/dsttypes.h

@@ -359,6 +359,7 @@ struct DstBuffer {
 /* A mutable associative data type. Backed by a hashtable. */
 struct DstTable {
     DstKV *data;
+    DstTable *proto;
     int32_t count;
     int32_t capacity;
     int32_t deleted;

thoughts.md

@@ -2,38 +2,6 @@
 
 A collection of thoughts and todo tasks for the project.
 
-- Allow entrances into the VM to track the size of the stack when they entered, and return
-  when the stack is less that. This would make calling dst functions from C feasible (
-  The programmer would still have to ensure no GC violations).
-
-  Instead, we can just keep allocating new Fibers when we call a dst function from C. A pool
-  of fibers would mostly mitigate the overhead of allocation. (going with this).
-
-  We can now call into dst from C without suspending the entire garbage collector. A separate
-  function does exactly that.
-
-- Make unknown instruction in vm trap and put current fiber in a new state, 'debug'.
-  This could allow implementation of a debugger. Since opcodes are encoded in one byte,
-  we can use the most significant bit (0x80) to set breakpoints in code, assuming all valid
-  opcodes are in the range [0, 127]. The debugger could simply set the MSB of the opcode for each
-  instruction that was marked. This would allow debugging with 0 overhead.
- 
-  We could also add a debugger instruction, much like JavaScripts debugger; statement very easily.
-
-  Lastly, to make continuation after a breakpoint easier, stopping on the first instruction
-  could be optional. This could be as simple as selecting the first 7 bits of the instructions
-  instead of the usual 8 for the very instruction executed after entering the vm loop.
-
-  What exactly should happen on a trapped instruction is another issue. It would be preferable
-  for the runtime to be able to handle a trap in dst, but allow nested fibers to not capture
-  debugging signals unless needed.
-
-  Fiber's currently propagate all states to their direct parent, but perhaps each fiber
-  could have a mask for different signals - error, debug, return. So a single fiber could
-  say capture returns, error, but not debug. Possibly like try - catch in other languages, where
-  we only catch certain kinds of errors. The default fiber would be to only mask debug, so a single fiber
-  could wrap an entire running application for debugging.
-
 - Remove the concept of 'Ast node'. While providing fine-grained source mapping is
   is reasonably useful, it complicates the implementation of macros and other source
   transforming operations. Instead, we can key collection types (which have the unique
@@ -53,7 +21,7 @@ A collection of thoughts and todo tasks for the project.
   definitions generated with this one form.
 
 - Serialization and deserialization of all datatypes. This would allow loading of bytecode
-  without needing the compiler present. However, loading C functions is currently problamatic.
+  without needing the compiler present. However, loading C functions is currently problematic.
   C functions could perhaps be wrapped in data structures that contain some meta information
   about them, say home module and types. This could also allow some automated type checking for
   C functions rather than writing it manually. Some slight overhead could perhaps be compensated
@@ -65,7 +33,7 @@ A collection of thoughts and todo tasks for the project.
   values and data structure style values. For example, simply adding special keys as fields
   would make plain a table or struct possibly become object-like if the write keys are added.
 
-  A Lua like solution would be a metatables. It would perhaps make sense to only allow
+  A Lua like solution would be metatables. It would perhaps make sense to only allow
   metatables on tables, as object like behavior seems to makes most sense on mutable data (?).
   For example, metatables on a struct could allow non-pure behavior unless they were extremely
   limited, or purity was enforced somehow. This could break expectations of a struct to behave
@@ -73,7 +41,7 @@ A collection of thoughts and todo tasks for the project.
 
   Also, it might make sense that the metatable of a value would actually be a struct, so
   a metastruct. Implementations of Lua (LuaJIT) do not allow (or do not acknowledge) 
-  changing certain values of a metatables after it is set, such as __gc, for performance
+  changing certain values of a metatables after it is set, such as gc, for performance
   reasons.
 
 - Actually make a debugger. While the VM changes to enable debugging are relatively