Add a way to construct a parsetype form existing types and a basetype.

src/parsetype.c

@@ -1,6 +1,54 @@
 #include "parsetype.h"
 #include <stdlib.h>
 
+libab_result libab_parsetpe_init(libab_parsetype* type, libab_basetype* from,
+        size_t n, ...) {
+    libab_result result;
+    va_list params;
+    va_start(params, n);
+    result = libab_parsetype_init_va(type, from, n, params);
+    va_end(params);
+    return result;
+}
+
+libab_result libab_parsetype_init_va(libab_parsetype* type, libab_basetype* from,
+        size_t n, va_list args) {
+    libab_result result = LIBAB_SUCCESS;
+    size_t base_index = 0, param_index = 0;
+    int free_vec = 0;
+
+    if(from->count > n) result = LIBAB_BAD_TYPE;
+    while(base_index < from->count && param_index < n) {
+        if(from->params[base_index].variant == BT_NAME) {
+            base_index++;
+        }
+        param_index++;
+    }
+
+    if(param_index < n) {
+        result = LIBAB_BAD_TYPE;
+    }
+
+    type->data_u.base = from;
+    type->variant = LIBABACUS_TYPE_F_RESOLVED; 
+    if(result == LIBAB_SUCCESS && n) {
+        type->variant |= LIBABACUS_TYPE_F_PARENT;
+        result = libab_ref_vec_init(&type->children);
+        if(result == LIBAB_SUCCESS) free_vec = 1;
+    }
+
+    while(n-- && result == LIBAB_SUCCESS) {
+        libab_ref* ref = va_arg(args, libab_ref*);
+        result = libab_ref_vec_insert(&type->children, ref);
+    }
+
+    if(free_vec) {
+        libab_ref_vec_free(&type->children);
+    }
+
+    return result;
+}
+
 void libab_parsetype_free(libab_parsetype* type) {
     if (!(type->variant & LIBABACUS_TYPE_F_RESOLVED)) {
         free(type->data_u.name);