oceani: factor out field reference into per-type handler
authorNeilBrown <neil@brown.name>
Sat, 11 Dec 2021 23:33:39 +0000 (10:33 +1100)
committerNeilBrown <neil@brown.name>
Sat, 11 Dec 2021 23:33:39 +0000 (10:33 +1100)
knowledge about how field references for strutures is now in
structure-specific code.  This will allow other types to
behave differently.

Signed-off-by: NeilBrown <neil@brown.name>
csrc/oceani-tests.mdc
csrc/oceani.mdc

index 12116d4cbb5f40325d9fb1976663bb229183fbfa..d672cffc8a97d92b0edb8cc590feb052d5101e8d 100644 (file)
@@ -973,9 +973,9 @@ various places that `type_err()` are called.
        .tmp.code:29:12: error: have number but need string
        .tmp.code:7:8: info: variable 'c' was set as string here.
        .tmp.code:32:8: error: variable used but not declared: foo
-       .tmp.code:32:8: error: field reference attempted on none, not a struct
+       .tmp.code:32:8: error: field reference on none is not supported
        .tmp.code:32:16: error: expected none found number
-       .tmp.code:33:14: error: field reference attempted on string, not a struct
+       .tmp.code:33:14: error: field reference on string is not supported
        .tmp.code:34:14: error: cannot find requested field in foo
        .tmp.code:35:17: error: have string but need number
        .tmp.code:38:29: error: expected number (labels not permitted) found Boolean
index 178532c07a9c1a17d6c2baf788c381fbd533cc9d..e1a2cb076b49c43fc8c5dd95dc2e822929ff875c 100644 (file)
@@ -110,6 +110,7 @@ structures can be used.
        ## macros
        struct parse_context;
        ## ast
+       ## ast late
        struct parse_context {
                struct token_config config;
                char *file_name;
@@ -789,6 +790,7 @@ which might be reported in error messages.
                };
        };
 
+###### ast late
        struct type {
                struct text name;
                struct type *next;
@@ -2620,6 +2622,8 @@ function will be needed.
 
 ###### type functions
        void (*print_type_decl)(struct type *type, FILE *f);
+       struct type *(*fieldref)(struct type *t, struct parse_context *c,
+                                struct fieldref *f, struct value **vp);
 
 ###### value functions
 
@@ -2724,12 +2728,41 @@ function will be needed.
                return 1;
        }
 
+       static int find_struct_index(struct type *type, struct text field)
+       {
+               int i;
+               for (i = 0; i < type->structure.nfields; i++)
+                       if (text_cmp(type->structure.fields[i].name, field) == 0)
+                               return i;
+               return IndexInvalid;
+       }
+
+       static struct type *structure_fieldref(struct type *t, struct parse_context *c,
+                                              struct fieldref *f, struct value **vp)
+       {
+               if (f->index == IndexUnknown) {
+                       f->index = find_struct_index(t, f->name);
+                       if (f->index < 0)
+                               type_err(c, "error: cannot find requested field in %1",
+                                        f->left, t, 0, NULL);
+               }
+               if (f->index < 0)
+                       return NULL;
+               if (vp) {
+                       struct value *v = *vp;
+                       v = (void*)v->ptr + t->structure.fields[f->index].offset;
+                       *vp = v;
+               }
+               return t->structure.fields[f->index].type;
+       }
+
        static struct type structure_prototype = {
                .init = structure_init,
                .free = structure_free,
                .free_type = structure_free_type,
                .print_type_decl = structure_print_type,
                .prepare_type = structure_prepare_type,
+               .fieldref = structure_fieldref,
        };
 
 ###### exec type
@@ -2773,16 +2806,6 @@ function will be needed.
                break;
        }
 
-###### ast functions
-       static int find_struct_index(struct type *type, struct text field)
-       {
-               int i;
-               for (i = 0; i < type->structure.nfields; i++)
-                       if (text_cmp(type->structure.fields[i].name, field) == 0)
-                               return i;
-               return IndexInvalid;
-       }
-
 ###### propagate exec cases
 
        case Xfieldref:
@@ -2790,24 +2813,15 @@ function will be needed.
                struct fieldref *f = cast(fieldref, prog);
                struct type *st = propagate_types(f->left, c, perr, NULL, 0);
 
-               if (!st)
-                       type_err(c, "error: unknown type for field access", f->left,    // UNTESTED
-                                NULL, 0, NULL);
-               else if (st->init != structure_init)
-                       type_err(c, "error: field reference attempted on %1, not a struct",
+               if (!st || !st->fieldref)
+                       type_err(c, "error: field reference on %1 is not supported",
                                 f->left, st, 0, NULL);
-               else if (f->index == IndexUnknown) {
-                       f->index = find_struct_index(st, f->name);
-                       if (f->index < 0)
-                               type_err(c, "error: cannot find requested field in %1",
-                                        f->left, st, 0, NULL);
-               }
-               if (f->index >= 0) {
-                       struct type *ft = st->structure.fields[f->index].type;
-                       if (!type_compat(type, ft, rules))
+               else {
+                       t = st->fieldref(st, c, f, NULL);
+                       if (t && !type_compat(type, t, rules))
                                type_err(c, "error: have %1 but need %2", prog,
-                                        ft, rules, type);
-                       return ft;
+                                        t, rules, type);
+                       return t;
                }
                break;
        }
@@ -2818,8 +2832,8 @@ function will be needed.
                struct fieldref *f = cast(fieldref, e);
                struct type *ltype;
                struct value *lleft = linterp_exec(c, f->left, &ltype);
-               lrv = (void*)lleft->ptr + ltype->structure.fields[f->index].offset;
-               rvtype = ltype->structure.fields[f->index].type;
+               lrv = lleft;
+               rvtype = ltype->fieldref(ltype, c, f, &lrv);
                break;
        }