path: root/036call_reply.cc

//: Calls can also generate products, using 'reply'.

:(scenario reply)
recipe main [
  1:number, 2:number <- f 34
]
recipe f [
  12:number <- next-ingredient
  13:number <- add 1, 12:number
  reply 12:number, 13:number
]
+mem: storing 34 in location 1
+mem: storing 35 in location 2

:(before "End Primitive Recipe Declarations")
REPLY,
:(before "End Primitive Recipe Numbers")
Recipe_ordinal["reply"] = REPLY;
:(before "End Primitive Recipe Implementations")
case REPLY: {
  // Starting Reply
  const instruction& reply_inst = current_instruction();  // save pointer into recipe before pop
  const string& callee = current_recipe_name();
  --Callstack_depth;
  Current_routine->calls.pop_front();
  // just in case 'main' returns a value, drop it for now
  if (Current_routine->calls.empty()) goto stop_running_current_routine;
  const instruction& caller_instruction = current_instruction();
  // make reply products available to caller
  copy(ingredients.begin(), ingredients.end(), inserter(products, products.begin()));
  // check that any reply ingredients with /same-as-ingredient connect up
  // the corresponding ingredient and product in the caller.
  if (SIZE(caller_instruction.products) > SIZE(ingredients))
    raise << "too few values replied from " << callee << '\n' << end();
  for (long long int i = 0; i < SIZE(caller_instruction.products); ++i) {
    trace(Primitive_recipe_depth, "run") << "result " << i << " is " << to_string(ingredients.at(i)) << end();
    if (has_property(reply_inst.ingredients.at(i), "same-as-ingredient")) {
      vector<string> tmp = property(reply_inst.ingredients.at(i), "same-as-ingredient");
      if (SIZE(tmp) != 1) {
        raise << current_recipe_name() << ": 'same-as-ingredient' metadata should take exactly one value in " << reply_inst.to_string() << '\n' << end();
        goto finish_reply;
      }
      long long int ingredient_index = to_integer(tmp.at(0));
      if (ingredient_index >= SIZE(caller_instruction.ingredients))
        raise << current_recipe_name() << ": 'same-as-ingredient' metadata overflows ingredients in: " << caller_instruction.to_string() << '\n' << end();
      if (!is_dummy(caller_instruction.products.at(i)) && caller_instruction.products.at(i).value != caller_instruction.ingredients.at(ingredient_index).value)
        raise << current_recipe_name() << ": 'same-as-ingredient' product from call to " << callee << " must be " << caller_instruction.ingredients.at(ingredient_index).original_string << " rather than " << caller_instruction.products.at(i).original_string << '\n' << end();
    }
  }
  // End Reply
  finish_reply:
  break;  // continue to process rest of *caller* instruction
}

//: Products can include containers and exclusive containers, addresses and arrays.
:(scenario reply_container)
recipe main [
  3:point <- f 2
]
recipe f [
  12:number <- next-ingredient
  13:number <- copy 35
  reply 12:point/raw  # unsafe
]
+run: result 0 is [2, 35]
+mem: storing 2 in location 3
+mem: storing 35 in location 4

//: In mu we'd like to assume that any instruction doesn't modify its
//: ingredients unless they're also products. The /same-as-ingredient inside
//: the recipe's 'reply' will help catch accidental misuse of such
//: 'ingredient-products' (sometimes called in-out parameters in other languages).

:(scenario reply_same_as_ingredient)
% Hide_warnings = true;
recipe main [
  1:number <- copy 0
  2:number <- test1 1:number  # call with different ingredient and product
]
recipe test1 [
  10:address:number <- next-ingredient
  reply 10:address:number/same-as-ingredient:0
]
+warn: main: 'same-as-ingredient' product from call to test1 must be 1:number rather than 2:number

:(scenario reply_same_as_ingredient_dummy)
% Hide_warnings = true;
recipe main [
  1:number <- copy 0
  _ <- test1 1:number  # call with different ingredient and product
]
recipe test1 [
  10:address:number <- next-ingredient
  reply 10:address:number/same-as-ingredient:0
]
$warn: 0

:(code)
string to_string(const vector<double>& in) {
  if (in.empty()) return "[]";
  ostringstream out;
  if (SIZE(in) == 1) {
    out << in.at(0);
    return out.str();
  }
  out << "[";
  for (long long int i = 0; i < SIZE(in); ++i) {
    if (i > 0) out << ", ";
    out << in.at(i);
  }
  out << "]";
  return out.str();
}

//: Conditional reply.

:(scenario reply_if)
recipe main [
  1:number <- test1
]
recipe test1 [
  reply-if 0, 34
  reply 35
]
+mem: storing 35 in location 1

:(scenario reply_if_2)
recipe main [
  1:number <- test1
]
recipe test1 [
  reply-if 1, 34
  reply 35
]
+mem: storing 34 in location 1

:(before "End Rewrite Instruction(curr)")
// rewrite `reply-if a, b, c, ...` to
//   ```
//   jump-unless a, 1:offset
//   reply b, c, ...
//   ```
if (curr.name == "reply-if") {
  if (curr.products.empty()) {
    curr.operation = Recipe_ordinal["jump-unless"];
    curr.name = "jump-unless";
    vector<reagent> results;
    copy(++curr.ingredients.begin(), curr.ingredients.end(), inserter(results, results.end()));
    curr.ingredients.resize(1);
    curr.ingredients.push_back(reagent("1:offset"));
    result.steps.push_back(curr);
    curr.clear();
    curr.operation = Recipe_ordinal["reply"];
    curr.name = "reply";
    curr.ingredients.swap(results);
  }
  else {
    raise << "'reply-if' never yields any products\n" << end();
  }
}
// rewrite `reply-unless a, b, c, ...` to
//   ```
//   jump-if a, 1:offset
//   reply b, c, ...
//   ```
if (curr.name == "reply-unless") {
  if (curr.products.empty()) {
    curr.operation = Recipe_ordinal["jump-if"];
    curr.name = "jump-if";
    vector<reagent> results;
    copy(++curr.ingredients.begin(), curr.ingredients.end(), inserter(results, results.end()));
    curr.ingredients.resize(1);
    curr.ingredients.push_back(reagent("1:offset"));
    result.steps.push_back(curr);
    curr.clear();
    curr.operation = Recipe_ordinal["reply"];
    curr.name = "reply";
    curr.ingredients.swap(results);
  }
  else {
    raise << "'reply-unless' never yields any products\n" << end();
  }
}