path: root/cpp/032array.cc

//: Arrays contain a variable number of elements of the same type. Their value
//: starts with the length of the array.
//:
//: You can create arrays of containers, but containers can only contain
//: elements of a fixed size, so you can't create containers containing arrays.
//: Create containers containing addresses to arrays instead.

:(scenario copy_array)
# Arrays can be copied around with a single instruction just like integers,
# no matter how large they are.
recipe main [
  1:integer <- copy 3:literal
  2:integer <- copy 14:literal
  3:integer <- copy 15:literal
  4:integer <- copy 16:literal
  5:array:integer <- copy 1:array:integer
]
+run: instruction main/4
+run: ingredient 0 is 1
+mem: location 1 is 3
+mem: location 2 is 14
+mem: location 3 is 15
+mem: location 4 is 16
+mem: storing 3 in location 5
+mem: storing 14 in location 6
+mem: storing 15 in location 7
+mem: storing 16 in location 8

:(scenario copy_array_indirect)
recipe main [
  1:integer <- copy 3:literal
  2:integer <- copy 14:literal
  3:integer <- copy 15:literal
  4:integer <- copy 16:literal
  5:address:array:integer <- copy 1:literal
  6:array:integer <- copy 5:address:array:integer/deref
]
+run: instruction main/5
+run: ingredient 0 is 5
+mem: location 1 is 3
+mem: location 2 is 14
+mem: location 3 is 15
+mem: location 4 is 16
+mem: storing 3 in location 6
+mem: storing 14 in location 7
+mem: storing 15 in location 8
+mem: storing 16 in location 9

//: disable the size mismatch check since the destination array need not be initialized
:(replace "if (size_of(x) != data.size())" following "void write_memory(reagent x, vector<long long int> data)")
if (x.types[0] != Type_number["array"] && size_of(x) != data.size())
:(after "size_t size_of(const reagent& r)")
  static const type_number ARRAY = Type_number["array"];
  if (r.types[0] == ARRAY) {
    assert(r.types.size() > 1);
    // skip the 'array' type to get at the element type
    return 1 + Memory[r.value]*size_of(array_element(r.types));
  }

//:: To access elements of an array, use 'index'

:(scenario index)
recipe main [
  1:integer <- copy 3:literal
  2:integer <- copy 14:literal
  3:integer <- copy 15:literal
  4:integer <- copy 16:literal
  5:integer <- index 1:array:integer, 0:literal
]
+run: instruction main/4
+run: address to copy is 2
+run: its type is 1
+mem: location 2 is 14
+run: product 0 is 14
+mem: storing 14 in location 5

:(scenario index_direct_offset)
recipe main [
  1:integer <- copy 3:literal
  2:integer <- copy 14:literal
  3:integer <- copy 15:literal
  4:integer <- copy 16:literal
  5:integer <- copy 0:literal
  6:integer <- index 1:array:integer, 5:integer
]
+run: instruction main/5
+run: address to copy is 2
+run: its type is 1
+mem: location 2 is 14
+run: product 0 is 14
+mem: storing 14 in location 6

:(before "End Primitive Recipe Declarations")
INDEX,
:(before "End Primitive Recipe Numbers")
Recipe_number["index"] = INDEX;
:(before "End Primitive Recipe Implementations")
case INDEX: {
  static const type_number ARRAY = Type_number["array"];
//?   if (Trace_stream) Trace_stream->dump_layer = "run"; //? 1
  trace("run") << "ingredient 0 is " << current_instruction().ingredients[0].to_string();
  reagent base = canonize(current_instruction().ingredients[0]);
//?   trace("run") << "ingredient 0 after canonize: " << base.to_string(); //? 1
  index_t base_address = base.value;
  assert(base.types[0] == ARRAY);
  trace("run") << "ingredient 1 is " << current_instruction().ingredients[1].to_string();
  reagent offset = canonize(current_instruction().ingredients[1]);
//?   trace("run") << "ingredient 1 after canonize: " << offset.to_string(); //? 1
  vector<long long int> offset_val(read_memory(offset));
  vector<type_number> element_type = array_element(base.types);
//?   trace("run") << "offset: " << offset_val[0]; //? 1
//?   trace("run") << "size of elements: " << size_of(element_type); //? 1
  index_t src = base_address + 1 + offset_val[0]*size_of(element_type);
  trace("run") << "address to copy is " << src;
  trace("run") << "its type is " << element_type[0];
  reagent tmp;
  tmp.set_value(src);
  copy(element_type.begin(), element_type.end(), inserter(tmp.types, tmp.types.begin()));
//?   trace("run") << "AAA: " << tmp.to_string() << '\n'; //? 3
  vector<long long int> result(read_memory(tmp));
  trace("run") << "product 0 is " << result[0];
  write_memory(current_instruction().products[0], result);
//?   if (Trace_stream) Trace_stream->dump_layer = ""; //? 1
  break;
}

:(code)
vector<type_number> array_element(const vector<type_number>& types) {
  return vector<type_number>(++types.begin(), types.end());
}

:(scenario index_address)
recipe main [
  1:integer <- copy 3:literal
  2:integer <- copy 14:literal
  3:integer <- copy 15:literal
  4:integer <- copy 16:literal
  5:integer <- index-address 1:array:integer, 0:literal
]
+run: instruction main/4
+run: address to copy is 2
+mem: storing 2 in location 5

//:: To write to elements of containers, you need their address.

:(scenario index_indirect)
recipe main [
  1:integer <- copy 3:literal
  2:integer <- copy 14:literal
  3:integer <- copy 15:literal
  4:integer <- copy 16:literal
  5:address:array:integer <- copy 1:literal
  6:integer <- index 5:address:array:integer/deref, 1:literal
]
+run: instruction main/5
+mem: storing 15 in location 6

:(before "End Primitive Recipe Declarations")
INDEX_ADDRESS,
:(before "End Primitive Recipe Numbers")
Recipe_number["index-address"] = INDEX_ADDRESS;
:(before "End Primitive Recipe Implementations")
case INDEX_ADDRESS: {
  static const type_number ARRAY = Type_number["array"];
  trace("run") << "ingredient 0 is " << current_instruction().ingredients[0].name;
  reagent base = canonize(current_instruction().ingredients[0]);
  index_t base_address = base.value;
  assert(base.types[0] == ARRAY);
  trace("run") << "ingredient 1 is " << current_instruction().ingredients[1].to_string();
  reagent offset = canonize(current_instruction().ingredients[1]);
  vector<long long int> offset_val(read_memory(offset));
  vector<type_number> element_type = array_element(base.types);
  index_t src = base_address + 1 + offset_val[0]*size_of(element_type);
  trace("run") << "address to copy is " << src;
  vector<long long int> result;
  result.push_back(src);
  trace("run") << "product 0 is " << result[0];
  write_memory(current_instruction().products[0], result);
  break;
}