From: NeilBrown <neil@brown.name>
Date: Sat, 4 Dec 2021 23:34:58 +0000 (+1100)
Subject: oceani: allow types to be used before declaration
X-Git-Url: https://ocean-lang.org/code/?p=ocean;a=commitdiff_plain;h=a0ff449bc7dff46460913fc7b1a379fb71db866b

oceani: allow types to be used before declaration

As we prepare all types after parsing, we can now use a type before it
is declared.
We need to be careful of mutually recursive structures, and
we need to retry prepare_type if it fails because a needed
member hasn't been prepared yet.

Signed-off-by: NeilBrown <neil@brown.name>
---

diff --git a/csrc/oceani-tests.mdc b/csrc/oceani-tests.mdc
index c13a9d1..d155701 100644
--- a/csrc/oceani-tests.mdc
+++ b/csrc/oceani-tests.mdc
@@ -585,6 +585,7 @@ Time to test if structure declarations and accesses work correctly.
 	struct foo
 		size:[three]number
 		name:string
+		thing:baz
 		active:Boolean = True
 
 	struct baz { a:number; b:Boolean; }
@@ -607,6 +608,7 @@ Time to test if structure declarations and accesses work correctly.
 
 		for i:=0; then i=i+1; while i < 4:
 			print info[i].name, info[i].active, info[i].size[0]
+		info[0].thing.b = True
 
 ###### output: structs
 
@@ -776,10 +778,10 @@ separate file first, then run from there.
 		This is a multiline string
 		With an unsupportable suffix
 		"""Aa
-	.tmp.code:14:11: error: undefined type: unknown
 	.tmp.code:15:12: error: name undeclared: unknowable
 	.tmp.code:17:12: error: array size must be a constant: zzsize
 	.tmp.code:20:12: error: unrecognised number: 00123
+	.tmp.code:14:11: error: type used but not declared: unknown
 
 ## Tests for type errors
 
@@ -792,7 +794,7 @@ These programs were generated by looking for the
 various places that `type_err()` are called.
 
 ###### test list
-	oceani_failing_tests += type_err1 type_err2 type_err3 type_err4
+	oceani_failing_tests += type_err1 type_err2 type_err3 type_err4 type_err5
 
 ###### test: type_err1
 
@@ -921,6 +923,22 @@ various places that `type_err()` are called.
 	.tmp.code:3:14: info: variable 'b' was set as none here.
 	oceani: type error in program - not running.
 
+###### test: type_err5
+	struct foo
+		bar:baz
+		a:number
+	struct baz
+		bat:foo
+		b:string
+	struct foo
+		c:number
+
+###### output: type_err5
+	.tmp.code:8:7: error: type already declared: foo
+	.tmp.code:2:7: info: this is location of declartion: foo
+	.tmp.code:2:7: error: type has recursive definition: foo
+	.tmp.code:5:7: error: type has recursive definition: baz
+
 ###### test list
 	oceani_failing_tests += type_err_const type_err_const1 type_err_const2 missing_program bad_main
 
diff --git a/csrc/oceani.mdc b/csrc/oceani.mdc
index 9720d22..e09fe07 100644
--- a/csrc/oceani.mdc
+++ b/csrc/oceani.mdc
@@ -367,6 +367,7 @@ context so indicate that parsing failed.
 	static void type_err(struct parse_context *c,
 	                     char *fmt, struct exec *loc,
 	                     struct type *t1, int rules, struct type *t2);
+	static void tok_err(struct parse_context *c, char *fmt, struct token *t);
 
 ###### core functions
 
@@ -789,10 +790,11 @@ which might be reported in error messages.
 	struct type {
 		struct text name;
 		struct type *next;
+		struct token first_use;
 		int size, align;
 		int anon;
 		void (*init)(struct type *type, struct value *val);
-		void (*prepare_type)(struct parse_context *c, struct type *type, int parse_time);
+		int (*prepare_type)(struct parse_context *c, struct type *type, int parse_time);
 		void (*print)(struct type *type, struct value *val, FILE *f);
 		void (*print_type)(struct type *type, FILE *f);
 		int (*cmp_order)(struct type *t1, struct type *t2,
@@ -836,7 +838,10 @@ which might be reported in error messages.
 		struct type *n;
 
 		n = calloc(1, sizeof(*n));
-		*n = *proto;
+		if (proto)
+			*n = *proto;
+		else
+			n->size = -1;
 		n->name = s;
 		n->anon = anon;
 		n->next = c->typelist;
@@ -924,10 +929,35 @@ which might be reported in error messages.
 	static void prepare_types(struct parse_context *c)
 	{
 		struct type *t;
+		int retry = 1;
+		enum { none, some, cannot } progress = none;
 
-		for (t = c->typelist; t; t = t->next)
-			if (t->prepare_type)
-				t->prepare_type(c, t, 1);
+		while (retry) {
+			retry = 0;
+
+			for (t = c->typelist; t; t = t->next) {
+				if (t->size < 0)
+					tok_err(c, "error: type used but not declared",
+						 &t->first_use);
+				if (t->size == 0 && t->prepare_type) {
+					if (t->prepare_type(c, t, 1))
+						progress = some;
+					else if (progress == cannot)
+						tok_err(c, "error: type has recursive definition",
+							&t->first_use);
+					else
+						retry = 1;
+				}
+			}
+			switch (progress) {
+			case cannot:
+				retry = 0; break;
+			case none:
+				progress = cannot; break;
+			case some:
+				progress = none; break;
+			}
+		}
 	}
 
 ###### forward decls
@@ -966,12 +996,10 @@ symbol for those.
 
 	$*type
 	Type -> IDENTIFIER ${
-		$0 = find_type(c, $1.txt);
+		$0 = find_type(c, $ID.txt);
 		if (!$0) {
-			tok_err(c,
-				"error: undefined type", &$1);
-
-			$0 = Tnone;
+			$0 = add_type(c, $ID.txt, NULL);
+			$0->first_use = $ID;
 		}
 	}$
 	## type grammar
@@ -2251,33 +2279,37 @@ with a const size by whether they are prepared at parse time or not.
 
 ###### value functions
 
-	static void array_prepare_type(struct parse_context *c, struct type *type,
+	static int array_prepare_type(struct parse_context *c, struct type *type,
 				       int parse_time)
 	{
 		struct value *vsize;
 		mpz_t q;
 		if (type->array.static_size)
-			return;
+			return 1;	// UNTESTED
 		if (type->array.unspec && parse_time)
-			return;
+			return 1;	// UNTESTED
 		if (parse_time && type->array.vsize && !type->array.vsize->global)
-			return;
+			return 1;	// UNTESTED
 
 		if (type->array.vsize) {
 			vsize = var_value(c, type->array.vsize);
 			if (!vsize)
-				return;	// UNTESTED
+				return 1;	// UNTESTED
 			mpz_init(q);
 			mpz_tdiv_q(q, mpq_numref(vsize->num), mpq_denref(vsize->num));
 			type->array.size = mpz_get_si(q);
 			mpz_clear(q);
 		}
+		if (!parse_time)
+			return 1;
+		if (type->array.member->size <= 0)
+			return 0;
 
-		if (parse_time && type->array.member->size) {
-			type->array.static_size = 1;
-			type->size = type->array.size * type->array.member->size;
-			type->align = type->array.member->align;
-		}
+		type->array.static_size = 1;
+		type->size = type->array.size * type->array.member->size;
+		type->align = type->array.member->align;
+
+		return 1;
 	}
 
 	static void array_init(struct type *type, struct value *val)
@@ -2606,21 +2638,24 @@ function will be needed.
 		free_fieldlist(t->structure.field_list);
 	}
 
-	static void structure_prepare_type(struct parse_context *c,
-					   struct type *t, int parse_time)
+	static int structure_prepare_type(struct parse_context *c,
+					  struct type *t, int parse_time)
 	{
 		int cnt = 0;
 		struct fieldlist *f;
 
 		if (!parse_time || t->structure.fields)
-			return;
+			return 1;
 
 		for (f = t->structure.field_list; f; f=f->prev) {
 			enum prop_err perr;
 			cnt += 1;
 
+			if (f->f.type->size <= 0)
+				return 0;
 			if (f->f.type->prepare_type)
-				f->f.type->prepare_type(c, f->f.type, 1);
+				f->f.type->prepare_type(c, f->f.type, parse_time);
+
 			if (f->init == NULL)
 				continue;
 			do {
@@ -2653,6 +2688,7 @@ function will be needed.
 
 			f = f->prev;
 		}
+		return 1;
 	}
 
 	static struct type structure_prototype = {
@@ -2755,9 +2791,23 @@ function will be needed.
 
 ###### top level grammar
 	DeclareStruct -> struct IDENTIFIER FieldBlock Newlines ${ {
-		struct type *t =
-			add_type(c, $2.txt, &structure_prototype);
+		struct type *t;
+		t = find_type(c, $ID.txt);
+		if (!t)
+			t = add_type(c, $ID.txt, &structure_prototype);
+		else if (t->size >= 0) {
+			tok_err(c, "error: type already declared", &$ID);
+			tok_err(c, "info: this is location of declartion", &t->first_use);
+			/* Create a new one - duplicate */
+			t = add_type(c, $ID.txt, &structure_prototype);
+		} else {
+			struct type tmp = *t;
+			*t = structure_prototype;
+			t->name = tmp.name;
+			t->next = tmp.next;
+		}
 		t->structure.field_list = $<FB;
+		t->first_use = $ID;
 	} }$
 
 	$*fieldlist