feat: implement format strings

src/vm/fzl_vm.c

@@ -13,6 +13,7 @@
 #include <vm/fzl_vm_env.h>
 #include <vm/fzl_vm_object.h>
 
+char build_result[512];
 char last_err[256];
 size_t last_jmp_ip       = 0;
 size_t total_jmp_on_same = 0;
@@ -297,6 +298,139 @@ int fzl_vm_run(fzl_vm_t *vm, bool allow_infinite, uint64_t max_iter)
 
     switch (opcode)
     {
+      case FZL_OPCODE_BUILD_STR:
+      {
+        uint64_t n = vm->ops[++vm->ip];
+        if (vm->dtop < n)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - expected %zu value(s) in dstack", n);
+          print_err_data(vm);
+          return -1;
+        }
+
+        char temp[64];
+        size_t gi = 0;
+        memset(build_result, 0, sizeof(build_result));
+        for (size_t i = 0; i < n; i++)
+        {
+          if (gi >= 512)
+          {
+            for (size_t i = 511; i > 508; i--)
+              build_result[i] = '.';
+            break;
+          }
+
+          memset(temp, 0, sizeof(temp));
+          fzl_value_t val = vm->dstack[i];
+
+          switch (val.type)
+          {
+            case FZL_TYPE_UINT:
+              snprintf(temp, sizeof(temp), "%zu", val.as.u);
+              strcpy(build_result + gi, temp);
+              gi += strlen(temp);
+              break;
+
+            case FZL_TYPE_UINT64:
+              snprintf(temp, sizeof(temp), "%lu", val.as.u64);
+              strcpy(build_result + gi, temp);
+              gi += strlen(temp);
+              break;
+
+            case FZL_TYPE_UINT32:
+              snprintf(temp, sizeof(temp), "%u", val.as.u32);
+              strcpy(build_result + gi, temp);
+              gi += strlen(temp);
+              break;
+
+            case FZL_TYPE_UINT16:
+              snprintf(temp, sizeof(temp), "%u", val.as.u16);
+              strcpy(build_result + gi, temp);
+              gi += strlen(temp);
+              break;
+
+            case FZL_TYPE_UINT8:
+              snprintf(temp, sizeof(temp), "%u", val.as.u8);
+              strcpy(build_result + gi, temp);
+              gi += strlen(temp);
+              break;
+
+            case FZL_TYPE_INT:
+              snprintf(temp, sizeof(temp), "%zd", val.as.i);
+              strcpy(build_result + gi, temp);
+              gi += strlen(temp);
+              break;
+
+            case FZL_TYPE_INT64:
+              snprintf(temp, sizeof(temp), "%ld", val.as.i64);
+              strcpy(build_result + gi, temp);
+              gi += strlen(temp);
+              break;
+
+            case FZL_TYPE_INT32:
+              snprintf(temp, sizeof(temp), "%d", val.as.i32);
+              strcpy(build_result + gi, temp);
+              gi += strlen(temp);
+              break;
+
+            case FZL_TYPE_INT16:
+              snprintf(temp, sizeof(temp), "%d", val.as.i16);
+              strcpy(build_result + gi, temp);
+              gi += strlen(temp);
+              break;
+
+            case FZL_TYPE_INT8:
+              snprintf(temp, sizeof(temp), "%d", val.as.i8);
+              strcpy(build_result + gi, temp);
+              gi += strlen(temp);
+              break;
+
+            case FZL_TYPE_BOOL:
+              snprintf(build_result + gi, sizeof(build_result) - gi, "%s",
+                       val.as.b ? "true" : "false");
+              gi += val.as.b ? 4 : 5;
+              break;
+
+            case FZL_TYPE_CHAR:
+              snprintf(build_result + gi, sizeof(build_result) - gi, "%d",
+                       val.as.c);
+              gi += 1;
+              break;
+
+            case FZL_TYPE_STRING:
+              snprintf(build_result + gi, sizeof(build_result) - gi, "%s",
+                       val.as.s.value);
+              gi += val.as.s.length;
+              break;
+
+            case FZL_TYPE_EXTERN_FN:
+              snprintf(temp, sizeof(temp), "<extern:%zu>", val.as.u);
+              strcpy(build_result + gi, temp);
+              gi += strlen(temp);
+              break;
+
+            case FZL_TYPE_OBJECT:
+              snprintf(temp, sizeof(temp), "<ref:%p>", val.as.obj);
+              strcpy(build_result + gi, temp);
+              gi += strlen(temp);
+              break;
+
+            case FZL_TYPE_NULL:
+              snprintf(build_result + gi, sizeof(build_result) - gi, "<null>");
+              gi += 6;
+              break;
+          }
+        }
+
+        vm->dtop -= n;
+        vm->dstack[vm->dtop++] =
+            (fzl_value_t){.type        = FZL_TYPE_STRING,
+                          .as.s.length = strlen(build_result),
+                          .as.s.value  = build_result};
+        break;
+      }
+
       case FZL_OPCODE_DEREFERENCE:
       {
         if (vm->dtop < 1)

src/vm/fzl_vm_debug.c

@@ -20,6 +20,10 @@ void fzl_vm_print_ops(fzl_vm_t *vm)
 
     switch (vm->ops[i])
     {
+      case FZL_OPCODE_BUILD_STR:
+        printf("BUILD_STR %zu\n", vm->ops[++i]);
+        break;
+
       case FZL_OPCODE_DEREFERENCE:
         printf("DEREFERENCE\n");
         break;
@@ -163,9 +167,6 @@ void fzl_vm_print_ops(fzl_vm_t *vm)
       case FZL_OPCODE_JMP:
         printf("JMP IP: %ld\n", vm->ops[++i]);
         break;
-
-      default:
-        printf("<UNKNOWN>\n");
     }
   }
 }