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LibJS: Replace the custom unwind mechanism with completions :^)

This includes:

- Parsing proper LabelledStatements with try_parse_labelled_statement()
- Removing LabelableStatement
- Implementing the LoopEvaluation semantics via loop_evaluation() in
  each IterationStatement subclass; and IterationStatement evaluation
  via {For,ForIn,ForOf,ForAwaitOf,While,DoWhile}Statement::execute()
- Updating ReturnStatement, BreakStatement and ContinueStatement to
  return the appropriate completion types
- Basically reimplementing TryStatement and SwitchStatement according to
  the spec, using completions
- Honoring result completion types in AsyncBlockStart and
  OrdinaryCallEvaluateBody
- Removing any uses of the VM unwind mechanism - most importantly,
  VM::throw_exception() now exclusively sets an exception and no longer
  triggers any unwinding mechanism.
  However, we already did a good job updating all of LibWeb and userland
  applications to not use it, and the few remaining uses elsewhere don't
  rely on unwinding AFAICT.
This commit is contained in:
Linus Groh 2022-01-05 19:11:16 +01:00
parent eed764e1dd
commit 9d0d3affd4
16 changed files with 512 additions and 279 deletions

View file

@ -1,4 +1,4 @@
test("labeled plain scope", () => {
test("labelled plain scope", () => {
notused: test: alsonotused: {
let o = 1;
expect(o).toBe(1);
@ -16,7 +16,7 @@ test("break on plain scope from inner scope", () => {
}
});
test("labeled for loop with break", () => {
test("labelled for loop with break", () => {
let counter = 0;
notused: outer: alsonotused: for (a of [1, 2, 3]) {
for (b of [4, 5, 6]) {
@ -27,7 +27,7 @@ test("labeled for loop with break", () => {
expect(counter).toBe(4);
});
test("labeled for loop with continue", () => {
test("labelled for loop with continue", () => {
let counter = 0;
notused: outer: alsonotused: for (a of [1, 2, 3]) {
for (b of [4, 5, 6]) {
@ -38,6 +38,32 @@ test("labeled for loop with continue", () => {
expect(counter).toBe(6);
});
test("continue label statement is not an iteration statement", () => {
expect(() =>
eval(`
outer: outer2: {
for (;;) {
continue outer;
}
}`)
).toThrowWithMessage(
SyntaxError,
"labelled continue statement cannot use non iterating statement (line: 4, column: 18)"
);
expect(() =>
eval(`
for (;;) {
outer: outer2: {
continue outer;
}
}`)
).toThrowWithMessage(
SyntaxError,
"labelled continue statement cannot use non iterating statement (line: 4, column: 18)"
);
});
test("break on try catch statement", () => {
let entered = false;
label1: label2: label3: try {