2323 - static dispatch!

3 files changed, 186 insertions, 1 deletions

diff --git a/011load.cc b/011load.cc
index d848fd55..36b45214 100644
--- a/011load.cc
+++ b/011load.cc
@@ -53,7 +53,7 @@ long long int slurp_recipe(istream& in) {
   if (Recipe.find(Recipe_ordinal[result.name]) != Recipe.end()) {
     trace(9991, "parse") << "already exists" << end();
     if (warn_on_redefine(result.name))
-      raise << "redefining recipe " << Recipe[Recipe_ordinal[result.name]].name << "\n" << end();
+      raise << "redefining recipe " << result.name << "\n" << end();
     Recipe.erase(Recipe_ordinal[result.name]);
   }
   slurp_body(in, result);
diff --git a/057static_dispatch.cc b/057static_dispatch.cc
new file mode 100644
index 00000000..fa77cbde
--- /dev/null
+++ b/057static_dispatch.cc
@@ -0,0 +1,164 @@
+//: Transform to maintain multiple variants of a recipe depending on the
+//: number and types of the ingredients and products. Allows us to use nice
+//: names like 'print' or 'length' in many mutually extensible ways.
+
+:(scenario static_dispatch)
+recipe main [
+  7:number/raw <- test 3
+]
+recipe test a:number -> z:number [
+  z <- copy 1
+]
+recipe test a:number, b:number -> z:number [
+  z <- copy 2
+]
++mem: storing 1 in location 7
+
+//: When loading recipes, accumulate variants if headers don't collide, and
+//: raise a warning if headers collide.
+
+:(before "End Globals")
+map<string, vector<recipe_ordinal> > Recipe_variants;
+
+:(before "End Load Recipe Header(result)")
+if (Recipe_ordinal.find(result.name) != Recipe_ordinal.end()
+    && (Recipe.find(Recipe_ordinal[result.name]) == Recipe.end()
+        || Recipe[Recipe_ordinal[result.name]].has_header)
+    && !header_already_exists(result)) {
+  string new_name = next_unused_recipe_name(result.name);
+  Recipe_ordinal[new_name] = Next_recipe_ordinal++;
+  Recipe_variants[result.name].push_back(Recipe_ordinal[new_name]);
+  result.name = new_name;
+}
+
+:(code)
+bool header_already_exists(const recipe& rr) {
+  const vector<recipe_ordinal>& variants = Recipe_variants[rr.name];
+  for (long long int i = 0; i < SIZE(variants); ++i) {
+    if (Recipe.find(variants.at(i)) != Recipe.end()
+        && all_reagents_match(rr, Recipe[variants.at(i)])) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool all_reagents_match(const recipe& r1, const recipe& r2) {
+  if (SIZE(r1.ingredients) != SIZE(r2.ingredients)) return false;
+  if (SIZE(r1.products) != SIZE(r2.products)) return false;
+  for (long long int i = 0; i < SIZE(r1.ingredients); ++i) {
+    if (!exact_match(r1.ingredients.at(i).type, r2.ingredients.at(i).type))
+      return false;
+  }
+  for (long long int i = 0; i < SIZE(r1.products); ++i) {
+    if (!exact_match(r1.products.at(i).type, r2.products.at(i).type))
+      return false;
+  }
+  return true;
+}
+
+bool exact_match(type_tree* a, type_tree* b) {
+  if (a == b) return true;
+  return a->value == b->value
+      && exact_match(a->left, b->left)
+      && exact_match(a->right, b->right);
+}
+
+string next_unused_recipe_name(const string& recipe_name) {
+  for (long long int i = 2; ; ++i) {
+    ostringstream out;
+    out << recipe_name << '_' << i;
+    if (Recipe_ordinal.find(out.str()) == Recipe_ordinal.end()) {
+      return out.str();
+    }
+  }
+}
+
+//: Once all the recipes are loaded, transform their bodies to replace each
+//: call with the most suitable variant.
+
+:(scenario static_dispatch_picks_most_similar_variant)
+recipe main [
+  7:number/raw <- test 3, 4, 5
+]
+recipe test a:number -> z:number [
+  z <- copy 1
+]
+recipe test a:number, b:number -> z:number [
+  z <- copy 2
+]
++mem: storing 2 in location 7
+
+:(after "int main")
+  Transform.push_back(resolve_ambiguous_calls);
+
+:(code)
+void resolve_ambiguous_calls(recipe_ordinal r) {
+  trace(9991, "transform") << "--- resolve ambiguous calls for recipe " << Recipe[r].name << end();
+  for (long long int index = 0; index < SIZE(Recipe[r].steps); ++index) {
+    instruction& inst = Recipe[r].steps.at(index);
+    if (inst.is_label) continue;
+    if (Recipe_variants.find(inst.name) == Recipe_variants.end()) continue;
+    replace_best_variant(inst);
+  }
+}
+
+void replace_best_variant(instruction& inst) {
+  vector<recipe_ordinal>& variants = Recipe_variants[inst.name];
+  long long int best_score = variant_score(inst, Recipe_ordinal[inst.name]);
+  for (long long int i = 0; i < SIZE(variants); ++i) {
+    long long int current_score = variant_score(inst, variants.at(i));
+    trace(9992, "transform") << "checking variant " << i << ": " << current_score << end();
+    if (current_score > best_score) {
+      inst.name = Recipe[variants.at(i)].name;
+      best_score = current_score;
+    }
+  }
+}
+
+long long int variant_score(const instruction& inst, recipe_ordinal variant) {
+  const vector<reagent>& header_ingredients = Recipe[variant].ingredients;
+  if (SIZE(inst.ingredients) < SIZE(header_ingredients)) {
+    trace(9993, "transform") << "too few ingredients" << end();
+    return -1;
+  }
+  for (long long int i = 0; i < SIZE(header_ingredients); ++i) {
+    if (!types_match(header_ingredients.at(i), inst.ingredients.at(i))) {
+      trace(9993, "transform") << "mismatch: ingredient " << i << end();
+      return -1;
+    }
+  }
+  if (SIZE(inst.products) > SIZE(Recipe[variant].products)) {
+    trace(9993, "transform") << "too few products" << end();
+    return -1;
+  }
+  const vector<reagent>& header_products = Recipe[variant].products;
+  for (long long int i = 0; i < SIZE(inst.products); ++i) {
+    if (!types_match(header_products.at(i), inst.products.at(i))) {
+      trace(9993, "transform") << "mismatch: product " << i << end();
+      return -1;
+    }
+  }
+  return 100 - (SIZE(Recipe[variant].products)-SIZE(inst.products))
+             - (SIZE(inst.ingredients)-SIZE(Recipe[variant].ingredients));  // ok to go negative
+}
+
+:(scenario static_dispatch_disabled_on_headerless_definition)
+% Hide_warnings = true;
+recipe test a:number -> z:number [
+  z <- copy 1
+]
+recipe test [
+  z:number <- copy 1
+]
++warn: redefining recipe test
+
+:(scenario static_dispatch_disabled_on_headerless_definition_2)
+% Hide_warnings = true;
+recipe test [
+  z:number <- copy 1
+]
+recipe test a:number -> z:number [
+  z <- copy 1
+]
++warn: redefining recipe test
diff --git a/static_dispatch.mu b/static_dispatch.mu
new file mode 100644
index 00000000..00160a2a
--- /dev/null
+++ b/static_dispatch.mu
@@ -0,0 +1,21 @@
+recipe test a:number -> b:number [
+  local-scope
+  load-ingredients
+  b <- add a, 1
+]
+
+recipe test a:number, b:number -> c:number [
+  local-scope
+  load-ingredients
+  c <- add a, b
+]
+
+recipe main [
+  local-scope
+  a:number <- test 3  # selects single-ingredient version
+  $print a, 10/newline
+  b:number <- test 3, 4  # selects double-ingredient version
+  $print b, 10/newline
+  c:number <- test 3, 4, 5  # prefers double- to single-ingredient version
+  $print c, 10/newline
+]