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Change Match clauses from pairs to classes (#858)

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Updates style of the Match class at the same time.
This commit is contained in:
Jon Meow
2021-09-29 13:36:54 -07:00
committed by GitHub
parent bf49f2efed
commit 25dce9fbcf
6 changed files with 57 additions and 43 deletions
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executable_semantics/interpreter/interpreter.cpp
+6 -6
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@@ -737,7 +737,7 @@ auto Interpreter::StepStmt() -> Transition {
// { { (match (e) ...) :: C, E, F} :: S, H}
// -> { { e :: (match ([]) ...) :: C, E, F} :: S, H}
frame->scopes.Push(arena->New<Scope>(CurrentEnv()));
return Spawn{arena->New<ExpressionAction>(match_stmt.Exp())};
return Spawn{arena->New<ExpressionAction>(&match_stmt.expression())};
} else {
// Regarding act->Pos():
// * odd: start interpreting the pattern of a clause
@@ -749,31 +749,31 @@ auto Interpreter::StepStmt() -> Transition {
// * 2: the pattern for clause 1
// * ...
auto clause_num = (act->Pos() - 1) / 2;
if (clause_num >= static_cast<int>(match_stmt.Clauses().size())) {
if (clause_num >= static_cast<int>(match_stmt.clauses().size())) {
DeallocateScope(frame->scopes.Top());
frame->scopes.Pop();
return Done{};
}
auto c = match_stmt.Clauses()[clause_num];
auto c = match_stmt.clauses()[clause_num];
if (act->Pos() % 2 == 1) {
// start interpreting the pattern of the clause
// { {v :: (match ([]) ...) :: C, E, F} :: S, H}
// -> { {pi :: (match ([]) ...) :: C, E, F} :: S, H}
return Spawn{arena->New<PatternAction>(c.first)};
return Spawn{arena->New<PatternAction>(&c.pattern())};
} else { // try to match
auto v = act->Results()[0];
auto pat = act->Results()[clause_num + 1];
std::optional<Env> matches = PatternMatch(pat, v, stmt->SourceLoc());
if (matches) { // we have a match, start the body
// Ensure we don't process any more clauses.
act->SetPos(2 * match_stmt.Clauses().size() + 1);
act->SetPos(2 * match_stmt.clauses().size() + 1);
for (const auto& [name, value] : *matches) {
frame->scopes.Top()->values.Set(name, value);
frame->scopes.Top()->locals.push_back(name);
}
return Spawn{arena->New<StatementAction>(c.second)};
return Spawn{arena->New<StatementAction>(&c.statement())};
} else {
return RunAgain{};
}