71 lines
2.7 KiB
C++
71 lines
2.7 KiB
C++
//: So far you can have global variables by not setting default-space, and
|
|
//: local variables by setting default-space. You can isolate variables
|
|
//: between those extremes by creating 'surrounding' spaces.
|
|
//:
|
|
//: (Surrounding spaces are like lexical scopes in other languages.)
|
|
|
|
:(scenario surrounding_space)
|
|
# location 2 in space 1 (remember that locations 0 and 1 are reserved in all
|
|
# spaces) refers to the space surrounding the default space, here 20.
|
|
def main [
|
|
# prepare default-space address
|
|
10:num/alloc-id, 11:num <- copy 0, 1000
|
|
# prepare default-space payload
|
|
1000:num <- copy 0 # alloc id of payload
|
|
1001:num <- copy 5 # length
|
|
# prepare address of chained space
|
|
20:num/alloc-id, 21:num <- copy 0, 2000
|
|
# prepare payload of chained space
|
|
2000:num <- copy 0 # alloc id of payload
|
|
2001:num <- copy 5 # length
|
|
# actual start of this recipe
|
|
default-space:space <- copy 10:space
|
|
#: later layers will explain the /names: property
|
|
0:space/names:dummy <- copy 20:space/raw
|
|
2:num <- copy 94
|
|
2:num/space:1 <- copy 95
|
|
]
|
|
def dummy [ # just for the /names: property above
|
|
]
|
|
# chain space: 1000 + (alloc id) 1 + (length) 1
|
|
+mem: storing 0 in location 1002
|
|
+mem: storing 2000 in location 1003
|
|
# store to default space: 1000 + (alloc id) 1 + (length) 1 + (index) 2
|
|
+mem: storing 94 in location 1004
|
|
# store to chained space: (contents of location 1003) 2000 + (alloc id) 1 + (length) 1 + (index) 2
|
|
+mem: storing 95 in location 2004
|
|
|
|
//: If you think of a space as a collection of variables with a common
|
|
//: lifetime, surrounding allows managing shorter lifetimes inside a longer
|
|
//: one.
|
|
|
|
:(replace{} "int space_base(const reagent& x)")
|
|
int space_base(const reagent& x) {
|
|
int base = current_call().default_space ? (current_call().default_space+/*skip alloc id*/1) : 0;
|
|
return space_base(x, space_index(x), base);
|
|
}
|
|
|
|
int space_base(const reagent& x, int space_index, int base) {
|
|
if (space_index == 0)
|
|
return base;
|
|
double chained_space_address = base+/*skip length*/1+/*skip alloc id of chaining slot*/1;
|
|
double chained_space_base = get_or_insert(Memory, chained_space_address) + /*skip alloc id of chained space*/1;
|
|
return space_base(x, space_index-1, chained_space_base);
|
|
}
|
|
|
|
int space_index(const reagent& x) {
|
|
for (int i = 0; i < SIZE(x.properties); ++i) {
|
|
if (x.properties.at(i).first == "space") {
|
|
if (!x.properties.at(i).second || x.properties.at(i).second->right)
|
|
raise << maybe(current_recipe_name()) << "/space metadata should take exactly one value in '" << x.original_string << "'\n" << end();
|
|
return to_integer(x.properties.at(i).second->value);
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
:(scenario permit_space_as_variable_name)
|
|
def main [
|
|
space:num <- copy 0
|
|
]
|