mu/archive/1.vm/040brace.cc

567 lines
14 KiB
C++

//: Structured programming
//:
//: Our jump recipes are quite inconvenient to use, so Mu provides a
//: lightweight tool called 'transform_braces' to work in a slightly more
//: convenient format with nested braces:
//:
//: {
//: some instructions
//: {
//: more instructions
//: }
//: }
//:
//: Braces are just labels, they require no special parsing. The pseudo
//: instructions 'loop' and 'break' jump to just after the enclosing '{' and
//: '}' respectively.
//:
//: Conditional and unconditional 'loop' and 'break' should give us 80% of the
//: benefits of the control-flow primitives we're used to in other languages,
//: like 'if', 'while', 'for', etc.
void test_brace_conversion() {
transform(
"def main [\n"
" {\n"
" break\n"
" 1:num <- copy 0\n"
" }\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"transform: --- transform braces for recipe main\n"
"transform: jump 1:offset\n"
"transform: copy ...\n"
);
}
:(before "End Instruction Modifying Transforms")
Transform.push_back(transform_braces); // idempotent
:(code)
void transform_braces(const recipe_ordinal r) {
const bool OPEN = false, CLOSE = true;
// use signed integer for step index because we'll be doing arithmetic on it
list<pair<bool/*OPEN/CLOSE*/, /*step*/int> > braces;
trace(101, "transform") << "--- transform braces for recipe " << get(Recipe, r).name << end();
for (int index = 0; index < SIZE(get(Recipe, r).steps); ++index) {
const instruction& inst = get(Recipe, r).steps.at(index);
if (inst.label == "{") {
trace(103, "transform") << maybe(get(Recipe, r).name) << "push (open, " << index << ")" << end();
braces.push_back(pair<bool,int>(OPEN, index));
}
if (inst.label == "}") {
trace(103, "transform") << "push (close, " << index << ")" << end();
braces.push_back(pair<bool,int>(CLOSE, index));
}
}
stack</*step*/int> open_braces;
for (int index = 0; index < SIZE(get(Recipe, r).steps); ++index) {
instruction& inst = get(Recipe, r).steps.at(index);
if (inst.label == "{") {
open_braces.push(index);
continue;
}
if (inst.label == "}") {
if (open_braces.empty()) {
raise << maybe(get(Recipe, r).name) << "unbalanced '}'\n" << end();
return;
}
open_braces.pop();
continue;
}
if (inst.is_label) continue;
if (inst.name != "loop"
&& inst.name != "loop-if"
&& inst.name != "loop-unless"
&& inst.name != "break"
&& inst.name != "break-if"
&& inst.name != "break-unless") {
trace(102, "transform") << inst.name << " ..." << end();
continue;
}
// check for errors
if (inst.name.find("-if") != string::npos || inst.name.find("-unless") != string::npos) {
if (inst.ingredients.empty()) {
raise << maybe(get(Recipe, r).name) << "'" << inst.name << "' expects 1 or 2 ingredients, but got none\n" << end();
continue;
}
}
// update instruction operation
string old_name = inst.name; // save a copy
if (inst.name.find("-if") != string::npos) {
inst.name = "jump-if";
inst.operation = JUMP_IF;
}
else if (inst.name.find("-unless") != string::npos) {
inst.name = "jump-unless";
inst.operation = JUMP_UNLESS;
}
else {
inst.name = "jump";
inst.operation = JUMP;
}
// check for explicitly provided targets
if (inst.name.find("-if") != string::npos || inst.name.find("-unless") != string::npos) {
// conditional branches check arg 1
if (SIZE(inst.ingredients) > 1 && is_literal(inst.ingredients.at(1))) {
trace(102, "transform") << inst.name << ' ' << inst.ingredients.at(1).name << ":offset" << end();
continue;
}
}
else {
// unconditional branches check arg 0
if (!inst.ingredients.empty() && is_literal(inst.ingredients.at(0))) {
trace(102, "transform") << "jump " << inst.ingredients.at(0).name << ":offset" << end();
continue;
}
}
// if implicit, compute target
reagent target(new type_tree("offset"));
target.set_value(0);
if (open_braces.empty())
raise << maybe(get(Recipe, r).name) << "'" << old_name << "' needs a '{' before\n" << end();
else if (old_name.find("loop") != string::npos)
target.set_value(open_braces.top()-index);
else // break instruction
target.set_value(matching_brace(open_braces.top(), braces, r) - index - 1);
inst.ingredients.push_back(target);
// log computed target
if (inst.name == "jump")
trace(102, "transform") << "jump " << no_scientific(target.value) << ":offset" << end();
else
trace(102, "transform") << inst.name << ' ' << inst.ingredients.at(0).name << ", " << no_scientific(target.value) << ":offset" << end();
}
}
// returns a signed integer not just so that we can return -1 but also to
// enable future signed arithmetic
int matching_brace(int index, const list<pair<bool, int> >& braces, recipe_ordinal r) {
int stacksize = 0;
for (list<pair<bool, int> >::const_iterator p = braces.begin(); p != braces.end(); ++p) {
if (p->second < index) continue;
stacksize += (p->first ? 1 : -1);
if (stacksize == 0) return p->second;
}
raise << maybe(get(Recipe, r).name) << "unbalanced '{'\n" << end();
return SIZE(get(Recipe, r).steps); // exit current routine
}
void test_loop() {
transform(
"def main [\n"
" 1:num <- copy 0\n"
" 2:num <- copy 0\n"
" {\n"
" 3:num <- copy 0\n"
" loop\n"
" }\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"transform: --- transform braces for recipe main\n"
"transform: copy ...\n"
"transform: copy ...\n"
"transform: copy ...\n"
"transform: jump -2:offset\n"
);
}
void test_break_empty_block() {
transform(
"def main [\n"
" 1:num <- copy 0\n"
" {\n"
" break\n"
" }\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"transform: --- transform braces for recipe main\n"
"transform: copy ...\n"
"transform: jump 0:offset\n"
);
}
void test_break_cascading() {
transform(
"def main [\n"
" 1:num <- copy 0\n"
" {\n"
" break\n"
" }\n"
" {\n"
" break\n"
" }\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"transform: --- transform braces for recipe main\n"
"transform: copy ...\n"
"transform: jump 0:offset\n"
"transform: jump 0:offset\n"
);
}
void test_break_cascading_2() {
transform(
"def main [\n"
" 1:num <- copy 0\n"
" 2:num <- copy 0\n"
" {\n"
" break\n"
" 3:num <- copy 0\n"
" }\n"
" {\n"
" break\n"
" }\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"transform: --- transform braces for recipe main\n"
"transform: copy ...\n"
"transform: copy ...\n"
"transform: jump 1:offset\n"
"transform: copy ...\n"
"transform: jump 0:offset\n"
);
}
void test_break_if() {
transform(
"def main [\n"
" 1:num <- copy 0\n"
" 2:num <- copy 0\n"
" {\n"
" break-if 2:num\n"
" 3:num <- copy 0\n"
" }\n"
" {\n"
" break\n"
" }\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"transform: --- transform braces for recipe main\n"
"transform: copy ...\n"
"transform: copy ...\n"
"transform: jump-if 2, 1:offset\n"
"transform: copy ...\n"
"transform: jump 0:offset\n"
);
}
void test_break_nested() {
transform(
"def main [\n"
" 1:num <- copy 0\n"
" {\n"
" 2:num <- copy 0\n"
" break\n"
" {\n"
" 3:num <- copy 0\n"
" }\n"
" 4:num <- copy 0\n"
" }\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"transform: jump 4:offset\n"
);
}
void test_break_nested_degenerate() {
transform(
"def main [\n"
" 1:num <- copy 0\n"
" {\n"
" 2:num <- copy 0\n"
" break\n"
" {\n"
" }\n"
" 4:num <- copy 0\n"
" }\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"transform: jump 3:offset\n"
);
}
void test_break_nested_degenerate_2() {
transform(
"def main [\n"
" 1:num <- copy 0\n"
" {\n"
" 2:num <- copy 0\n"
" break\n"
" {\n"
" }\n"
" }\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"transform: jump 2:offset\n"
);
}
void test_break_label() {
Hide_errors = true;
transform(
"def main [\n"
" 1:num <- copy 0\n"
" {\n"
" break +foo:offset\n"
" }\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"transform: jump +foo:offset\n"
);
}
void test_break_unless() {
transform(
"def main [\n"
" 1:num <- copy 0\n"
" 2:num <- copy 0\n"
" {\n"
" break-unless 2:num\n"
" 3:num <- copy 0\n"
" }\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"transform: --- transform braces for recipe main\n"
"transform: copy ...\n"
"transform: copy ...\n"
"transform: jump-unless 2, 1:offset\n"
"transform: copy ...\n"
);
}
void test_loop_unless() {
transform(
"def main [\n"
" 1:num <- copy 0\n"
" 2:num <- copy 0\n"
" {\n"
" loop-unless 2:num\n"
" 3:num <- copy 0\n"
" }\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"transform: --- transform braces for recipe main\n"
"transform: copy ...\n"
"transform: copy ...\n"
"transform: jump-unless 2, -1:offset\n"
"transform: copy ...\n"
);
}
void test_loop_nested() {
transform(
"def main [\n"
" 1:num <- copy 0\n"
" {\n"
" 2:num <- copy 0\n"
" {\n"
" 3:num <- copy 0\n"
" }\n"
" loop-if 4:bool\n"
" 5:num <- copy 0\n"
" }\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"transform: --- transform braces for recipe main\n"
"transform: jump-if 4, -5:offset\n"
);
}
void test_loop_label() {
transform(
"def main [\n"
" 1:num <- copy 0\n"
" +foo\n"
" 2:num <- copy 0\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"transform: --- transform braces for recipe main\n"
"transform: copy ...\n"
"transform: copy ...\n"
);
}
//: test how things actually run
void test_brace_conversion_and_run() {
run(
"def test-factorial [\n"
" 1:num <- copy 5\n"
" 2:num <- copy 1\n"
" {\n"
" 3:bool <- equal 1:num, 1\n"
" break-if 3:bool\n"
" 2:num <- multiply 2:num, 1:num\n"
" 1:num <- subtract 1:num, 1\n"
" loop\n"
" }\n"
" 4:num <- copy 2:num\n" // trigger a read
"]\n"
);
CHECK_TRACE_CONTENTS(
"mem: location 2 is 120\n"
);
}
void test_break_outside_braces_fails() {
Hide_errors = true;
run(
"def main [\n"
" break\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"error: main: 'break' needs a '{' before\n"
);
}
void test_break_conditional_without_ingredient_fails() {
Hide_errors = true;
run(
"def main [\n"
" {\n"
" break-if\n"
" }\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"error: main: 'break-if' expects 1 or 2 ingredients, but got none\n"
);
}
//: Using break we can now implement conditional returns.
void test_return_if() {
run(
"def main [\n"
" 1:num <- test1\n"
"]\n"
"def test1 [\n"
" return-if 0, 34\n"
" return 35\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"mem: storing 35 in location 1\n"
);
}
void test_return_if_2() {
run(
"def main [\n"
" 1:num <- test1\n"
"]\n"
"def test1 [\n"
" return-if 1, 34\n"
" return 35\n"
"]\n"
);
CHECK_TRACE_CONTENTS(
"mem: storing 34 in location 1\n"
);
}
:(before "End Rewrite Instruction(curr, recipe result)")
// rewrite 'return-if a, b, c, ...' to
// ```
// {
// break-unless a
// return b, c, ...
// }
// ```
if (curr.name == "return-if" || curr.name == "reply-if") {
if (curr.products.empty()) {
emit_return_block(result, "break-unless", curr);
curr.clear();
}
else {
raise << "'" << curr.name << "' never yields any products\n" << end();
}
}
// rewrite 'return-unless a, b, c, ...' to
// ```
// {
// break-if a
// return b, c, ...
// }
// ```
if (curr.name == "return-unless" || curr.name == "reply-unless") {
if (curr.products.empty()) {
emit_return_block(result, "break-if", curr);
curr.clear();
}
else {
raise << "'" << curr.name << "' never yields any products\n" << end();
}
}
:(code)
void emit_return_block(recipe& out, const string& break_command, const instruction& inst) {
const vector<reagent>& ingredients = inst.ingredients;
reagent/*copy*/ condition = ingredients.at(0);
vector<reagent> return_ingredients;
copy(++ingredients.begin(), ingredients.end(), inserter(return_ingredients, return_ingredients.end()));
// {
instruction open_label; open_label.is_label=true; open_label.label = "{";
out.steps.push_back(open_label);
// <break command> <condition>
instruction break_inst;
break_inst.operation = get(Recipe_ordinal, break_command);
break_inst.name = break_command;
break_inst.ingredients.push_back(condition);
out.steps.push_back(break_inst);
// return <return ingredients>
instruction return_inst;
return_inst.operation = get(Recipe_ordinal, "return");
return_inst.name = "return";
return_inst.ingredients.swap(return_ingredients);
return_inst.original_string = inst.original_string;
out.steps.push_back(return_inst);
// }
instruction close_label; close_label.is_label=true; close_label.label = "}";
out.steps.push_back(close_label);
}
//: Make sure these pseudo recipes get consistent numbers in all tests, even
//: though they aren't implemented. Allows greater flexibility in ordering
//: transforms.
:(before "End Primitive Recipe Declarations")
BREAK,
BREAK_IF,
BREAK_UNLESS,
LOOP,
LOOP_IF,
LOOP_UNLESS,
:(before "End Primitive Recipe Numbers")
put(Recipe_ordinal, "break", BREAK);
put(Recipe_ordinal, "break-if", BREAK_IF);
put(Recipe_ordinal, "break-unless", BREAK_UNLESS);
put(Recipe_ordinal, "loop", LOOP);
put(Recipe_ordinal, "loop-if", LOOP_IF);
put(Recipe_ordinal, "loop-unless", LOOP_UNLESS);
:(before "End Primitive Recipe Checks")
case BREAK: break;
case BREAK_IF: break;
case BREAK_UNLESS: break;
case LOOP: break;
case LOOP_IF: break;
case LOOP_UNLESS: break;