1 files changed, 260 insertions, 0 deletions
diff --git a/archive/2.vm/021check_instruction.cc b/archive/2.vm/021check_instruction.cc
new file mode 100644
index 00000000..5a8e1324
--- /dev/null
+++ b/archive/2.vm/021check_instruction.cc
@@ -0,0 +1,260 @@
+//: Introduce a new transform to perform various checks in instructions before
+//: we start running them. It'll be extensible, so that we can add checks for
+//: new recipes as we extend 'run' to support them.
+//:
+//: Doing checking in a separate part complicates things, because the values
+//: of variables in memory and the processor (current_recipe_name,
+//: current_instruction) aren't available at checking time. If I had a more
+//: sophisticated layer system I'd introduce the simpler version first and
+//: transform it in a separate layer or set of layers.
+
+:(before "End Checks")
+Transform.push_back(check_instruction);  // idempotent
+
+:(code)
+void check_instruction(const recipe_ordinal r) {
+  trace(101, "transform") << "--- perform checks for recipe " << get(Recipe, r).name << end();
+  map<string, vector<type_ordinal> > metadata;
+  for (int i = 0;  i < SIZE(get(Recipe, r).steps);  ++i) {
+    instruction& inst = get(Recipe, r).steps.at(i);
+    if (inst.is_label) continue;
+    switch (inst.operation) {
+      // Primitive Recipe Checks
+      case COPY: {
+        if (SIZE(inst.products) > SIZE(inst.ingredients)) {
+          raise << maybe(get(Recipe, r).name) << "too many products in '" << to_original_string(inst) << "'\n" << end();
+          break;
+        }
+        for (int i = 0;  i < SIZE(inst.products);  ++i) {
+          if (!types_coercible(inst.products.at(i), inst.ingredients.at(i))) {
+            raise << maybe(get(Recipe, r).name) << "can't copy '" << inst.ingredients.at(i).original_string << "' to '" << inst.products.at(i).original_string << "'; types don't match\n" << end();
+            goto finish_checking_instruction;
+          }
+        }
+        break;
+      }
+      // End Primitive Recipe Checks
+      default: {
+        // Defined Recipe Checks
+        // End Defined Recipe Checks
+      }
+    }
+    finish_checking_instruction:;
+  }
+}
+
+void test_copy_checks_reagent_count() {
+  Hide_errors = true;
+  run(
+      "def main [\n"
+      "  1:num, 2:num <- copy 34\n"
+      "]\n"
+  );
+  CHECK_TRACE_CONTENTS(
+      "error: main: too many products in '1:num, 2:num <- copy 34'\n"
+  );
+}
+
+void test_write_scalar_to_array_disallowed() {
+  Hide_errors = true;
+  run(
+      "def main [\n"
+      "  1:array:num <- copy 34\n"
+      "]\n"
+  );
+  CHECK_TRACE_CONTENTS(
+      "error: main: can't copy '34' to '1:array:num'; types don't match\n"
+  );
+}
+
+void test_write_scalar_to_array_disallowed_2() {
+  Hide_errors = true;
+  run(
+      "def main [\n"
+      "  1:num, 2:array:num <- copy 34, 35\n"
+      "]\n"
+  );
+  CHECK_TRACE_CONTENTS(
+      "error: main: can't copy '35' to '2:array:num'; types don't match\n"
+  );
+}
+
+void test_write_scalar_to_address_disallowed() {
+  Hide_errors = true;
+  run(
+      "def main [\n"
+      "  1:&:num <- copy 34\n"
+      "]\n"
+  );
+  CHECK_TRACE_CONTENTS(
+      "error: main: can't copy '34' to '1:&:num'; types don't match\n"
+  );
+}
+
+void test_write_address_to_character_disallowed() {
+  Hide_errors = true;
+  run(
+      "def main [\n"
+      "  1:&:num <- copy 12/unsafe\n"
+      "  2:char <- copy 1:&:num\n"
+      "]\n"
+  );
+  CHECK_TRACE_CONTENTS(
+      "error: main: can't copy '1:&:num' to '2:char'; types don't match\n"
+  );
+}
+
+void test_write_number_to_character_allowed() {
+  run(
+      "def main [\n"
+      "  1:num <- copy 97\n"
+      "  2:char <- copy 1:num\n"
+      "]\n"
+  );
+  CHECK_TRACE_COUNT("error", 0);
+}
+
+:(code)
+// types_match with some leniency
+bool types_coercible(reagent/*copy*/ to, reagent/*copy*/ from) {
+  // Begin types_coercible(reagent to, reagent from)
+  if (types_match_sub(to, from)) return true;
+  if (is_real_mu_number(from) && is_mu_character(to)) return true;
+  // End types_coercible Special-cases
+  return false;
+}
+
+bool types_match_sub(const reagent& to, const reagent& from) {
+  // to sidestep type-checking, use /unsafe in the source.
+  // this will be highlighted in red inside vim. just for setting up some tests.
+  if (is_unsafe(from)) return true;
+  if (is_literal(from)) {
+    if (is_mu_array(to)) return false;
+    // End Matching Types For Literal(to)
+    if (!to.type) return false;
+    // allow writing null to any address
+    if (is_mu_address(to)) return from.name == "null";
+    return size_of(to) == 1;  // literals are always scalars
+  }
+  return types_strictly_match_sub(to, from);
+}
+// variant for others to call
+bool types_match(reagent/*copy*/ to, reagent/*copy*/ from) {
+  // Begin types_match(reagent to, reagent from)
+  return types_match_sub(to, from);
+}
+
+//: copy arguments for later layers
+bool types_strictly_match_sub(const reagent& to, const reagent& from) {
+  if (to.type == NULL) return false;  // error
+  if (is_literal(from) && to.type->value == Number_type_ordinal) return true;
+  // to sidestep type-checking, use /unsafe in the source.
+  // this will be highlighted in red inside vim. just for setting up some tests.
+  if (is_unsafe(from)) return true;
+  // '_' never raises type error
+  if (is_dummy(to)) return true;
+  if (!to.type) return !from.type;
+  return types_strictly_match(to.type, from.type);
+}
+// variant for others to call
+bool types_strictly_match(reagent/*copy*/ to, reagent/*copy*/ from) {
+  // Begin types_strictly_match(reagent to, reagent from)
+  return types_strictly_match_sub(to, from);
+}
+
+bool types_strictly_match(const type_tree* to, const type_tree* from) {
+  if (from == to) return true;
+  if (!to) return false;
+  if (!from) return to->atom && to->value == 0;
+  if (from->atom != to->atom) return false;
+  if (from->atom) {
+    if (from->value == -1) return from->name == to->name;
+    return from->value == to->value;
+  }
+  if (types_strictly_match(to->left, from->left) && types_strictly_match(to->right, from->right))
+    return true;
+  // fallback: (x) == x
+  if (to->right == NULL && types_strictly_match(to->left, from)) return true;
+  if (from->right == NULL && types_strictly_match(to, from->left)) return true;
+  return false;
+}
+
+void test_unknown_type_does_not_match_unknown_type() {
+  reagent a("a:foo");
+  reagent b("b:bar");
+  CHECK(!types_strictly_match(a, b));
+}
+
+void test_unknown_type_matches_itself() {
+  reagent a("a:foo");
+  reagent b("b:foo");
+  CHECK(types_strictly_match(a, b));
+}
+
+void test_type_abbreviations_match_raw_types() {
+  put(Type_abbreviations, "text", new_type_tree("address:array:character"));
+  // a has type (address buffer (address array character))
+  reagent a("a:address:buffer:text");
+  expand_type_abbreviations(a.type);
+  // b has type (address buffer address array character)
+  reagent b("b:address:buffer:address:array:character");
+  CHECK(types_strictly_match(a, b));
+  delete Type_abbreviations["text"];
+  put(Type_abbreviations, "text", NULL);
+}
+
+//: helpers
+
+bool is_unsafe(const reagent& r) {
+  return has_property(r, "unsafe");
+}
+
+bool is_mu_array(reagent/*copy*/ r) {
+  // End Preprocess is_mu_array(reagent r)
+  return is_mu_array(r.type);
+}
+bool is_mu_array(const type_tree* type) {
+  if (!type) return false;
+  if (is_literal(type)) return false;
+  if (type->atom) return false;
+  if (!type->left->atom) {
+    raise << "invalid type " << to_string(type) << '\n' << end();
+    return false;
+  }
+  return type->left->value == Array_type_ordinal;
+}
+
+bool is_mu_boolean(reagent/*copy*/ r) {
+  // End Preprocess is_mu_boolean(reagent r)
+  if (!r.type) return false;
+  if (is_literal(r)) return false;
+  if (!r.type->atom) return false;
+  return r.type->value == Boolean_type_ordinal;
+}
+
+bool is_mu_number(reagent/*copy*/ r) {
+  if (is_mu_character(r.type)) return true;  // permit arithmetic on unicode code points
+  return is_real_mu_number(r);
+}
+
+bool is_real_mu_number(reagent/*copy*/ r) {
+  // End Preprocess is_mu_number(reagent r)
+  if (!r.type) return false;
+  if (!r.type->atom) return false;
+  if (is_literal(r)) {
+    return r.type->name == "literal-fractional-number"
+        || r.type->name == "literal";
+  }
+  return r.type->value == Number_type_ordinal;
+}
+
+bool is_mu_character(reagent/*copy*/ r) {
+  // End Preprocess is_mu_character(reagent r)
+  return is_mu_character(r.type);
+}
+bool is_mu_character(const type_tree* type) {
+  if (!type) return false;
+  if (!type->atom) return false;
+  if (is_literal(type)) return false;
+  return type->value == Character_type_ordinal;
+}