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Diffstat (limited to 'archive/2.vm/044space_surround.cc')
-rw-r--r-- | archive/2.vm/044space_surround.cc | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/archive/2.vm/044space_surround.cc b/archive/2.vm/044space_surround.cc new file mode 100644 index 00000000..5a4afb5e --- /dev/null +++ b/archive/2.vm/044space_surround.cc @@ -0,0 +1,79 @@ +//: 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.) + +void test_surrounding_space() { + run( + // 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 [\n" + // prepare default-space address + " 10:num/alloc-id, 11:num <- copy 0, 1000\n" + // prepare default-space payload + " 1000:num <- copy 0\n" // alloc id of payload + " 1001:num <- copy 5\n" // length + // prepare address of chained space + " 20:num/alloc-id, 21:num <- copy 0, 2000\n" + // prepare payload of chained space + " 2000:num <- copy 0\n" // alloc id of payload + " 2001:num <- copy 5\n" // length + // actual start of this recipe + " default-space:space <- copy 10:space\n" + // later layers will explain the /names: property + " 0:space/names:dummy <- copy 20:space/raw\n" + " 2:num <- copy 94\n" + " 2:num/space:1 <- copy 95\n" + "]\n" + "def dummy [\n" // just for the /names: property above + "]\n" + ); + CHECK_TRACE_CONTENTS( + // chain space: 1000 + (alloc id) 1 + (length) 1 + "mem: storing 0 in location 1002\n" + "mem: storing 2000 in location 1003\n" + // store to default space: 1000 + (alloc id) 1 + (length) 1 + (index) 2 + "mem: storing 94 in location 1004\n" + // store to chained space: (contents of location 1003) 2000 + (alloc id) 1 + (length) 1 + (index) 2 + "mem: storing 95 in location 2004\n" + ); +} + +//: 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; +} + +:(code) +void test_permit_space_as_variable_name() { + run( + "def main [\n" + " space:num <- copy 0\n" + "]\n" + ); +} |