[dartdevc] Add helper methods to emit `For` and `ForOf` loops
Creates a single code path for the each of the "for loops" regardless if you are
running with one of the experiment flags to prevent regressions in existing
behavior.
The helpers will also be used in by implementation of control flow collections.
Issue: #36005
Change-Id: Ieb62dd76488386db2214b2b6d935fcfd6e7c56b9
Reviewed-on: https://dart-review.googlesource.com/c/93930
Commit-Queue: Nicholas Shahan <nshahan@google.com>
Reviewed-by: Jenny Messerly <jmesserly@google.com>
diff --git a/pkg/dev_compiler/lib/src/analyzer/code_generator.dart b/pkg/dev_compiler/lib/src/analyzer/code_generator.dart
index 0ca0351..b9defaa 100644
--- a/pkg/dev_compiler/lib/src/analyzer/code_generator.dart
+++ b/pkg/dev_compiler/lib/src/analyzer/code_generator.dart
@@ -5420,17 +5420,8 @@
@override
JS.For visitForStatement(ForStatement node) {
- var init = _visitExpression(node.initialization) ??
- visitVariableDeclarationList(node.variables);
- var updaters = node.updaters;
- JS.Expression update;
- if (updaters != null && updaters.isNotEmpty) {
- update =
- JS.Expression.binary(updaters.map(_visitExpression).toList(), ',')
- .toVoidExpression();
- }
- var condition = _visitTest(node.condition);
- return JS.For(init, condition, update, _visitScope(node.body));
+ return _emitFor(node.initialization, node.variables, node.condition,
+ node.updaters, node.body);
}
@override
@@ -5446,29 +5437,16 @@
@override
JS.Statement visitForEachStatement(ForEachStatement node) {
if (node.awaitKeyword != null) {
- return _emitAwaitFor(node);
+ return _emitAwaitFor(
+ node.identifier, node.loopVariable, node.iterable, node.body);
}
- var init = _visitExpression(node.identifier);
- var iterable = _visitExpression(node.iterable);
-
- var body = _visitScope(node.body);
- if (init == null) {
- var id = _emitVariableDef(node.loopVariable.identifier);
- init = js.call('let #', id);
- if (_annotatedNullCheck(node.loopVariable.declaredElement)) {
- body = JS.Block([_nullParameterCheck(JS.Identifier(id.name)), body]);
- }
- if (variableIsReferenced(id.name, iterable)) {
- var temp = JS.TemporaryId('iter');
- return JS.Block(
- [iterable.toVariableDeclaration(temp), JS.ForOf(init, temp, body)]);
- }
- }
- return JS.ForOf(init, iterable, body);
+ return _emitForEach(
+ node.identifier, node.loopVariable, node.iterable, node.body);
}
- JS.Statement _emitAwaitFor(ForEachStatement node) {
+ JS.Statement _emitAwaitFor(SimpleIdentifier identifier,
+ DeclaredIdentifier loopVariable, Expression iterable, Statement body) {
// Emits `await for (var value in stream) ...`, which desugars as:
//
// let iter = new StreamIterator(stream);
@@ -5491,10 +5469,10 @@
var createStreamIter = _emitInstanceCreationExpression(
streamIterator.element.unnamedConstructor,
streamIterator,
- () => [_visitExpression(node.iterable)]);
+ () => [_visitExpression(iterable)]);
var iter = JS.TemporaryId('iter');
- var variable = node.identifier ?? node.loopVariable.identifier;
- var init = _visitExpression(node.identifier);
+ var variable = identifier ?? loopVariable.identifier;
+ var init = _visitExpression(identifier);
if (init == null) {
init = js.call('let # = #.current', [_emitVariableDef(variable), iter]);
} else {
@@ -5513,7 +5491,7 @@
JS.Yield(js.call('#.moveNext()', iter))
..sourceInformation = _nodeStart(variable),
init,
- _visitStatement(node.body),
+ _visitStatement(body),
JS.Yield(js.call('#.cancel()', iter))
..sourceInformation = _nodeStart(variable)
]);
@@ -6469,6 +6447,48 @@
@override
visitWithClause(node) => _unreachable(node);
+ // TODO(nshahan) Simplify when control-flow-collections experiments are removed.
+ // Should just accept a ForParts as an arg with fewer casts.
+ JS.For _emitFor(Expression initialization, VariableDeclarationList variables,
+ Expression condition, Iterable<Expression> updaters, Statement body) {
+ var init = _visitExpression(initialization) ??
+ visitVariableDeclarationList(variables);
+ JS.Expression update;
+ if (updaters != null && updaters.isNotEmpty) {
+ update =
+ JS.Expression.binary(updaters.map(_visitExpression).toList(), ',')
+ .toVoidExpression();
+ }
+
+ return JS.For(init, _visitTest(condition), update, _visitScope(body));
+ }
+
+ // TODO(nshahan) Simplify when control-flow-collections experiments are removed.
+ // Should just accept a ForEachParts as an arg with fewer casts.
+ JS.Statement _emitForEach(SimpleIdentifier identifier,
+ DeclaredIdentifier loopVariable, Expression iterable, Statement body) {
+ var jsLeftExpression = _visitExpression(identifier);
+ var jsIterable = _visitExpression(iterable);
+
+ var jsBody = _visitScope(body);
+ if (jsLeftExpression == null) {
+ var id = _emitVariableDef(loopVariable.identifier);
+ jsLeftExpression = js.call('let #', id);
+ if (_annotatedNullCheck(loopVariable.declaredElement)) {
+ jsBody =
+ JS.Block([_nullParameterCheck(JS.Identifier(id.name)), jsBody]);
+ }
+ if (variableIsReferenced(id.name, jsIterable)) {
+ var temp = JS.TemporaryId('iter');
+ return JS.Block([
+ jsIterable.toVariableDeclaration(temp),
+ JS.ForOf(jsLeftExpression, temp, jsBody)
+ ]);
+ }
+ }
+ return JS.ForOf(jsLeftExpression, jsIterable, jsBody);
+ }
+
@override
visitForElement(ForElement node) => _unreachable(node);
@@ -6484,7 +6504,32 @@
_unreachable(node);
@override
- visitForStatement2(ForStatement2 node) => _unreachable(node);
+ JS.Statement visitForStatement2(ForStatement2 node) {
+ // TODO(nshahan) Simplify when control-flow-collections experiments are removed.
+ var forParts = node.forLoopParts;
+ if (forParts is ForPartsWithExpression) {
+ return _emitFor(forParts.initialization, null, forParts.condition,
+ forParts.updaters, node.body);
+ } else if (forParts is ForPartsWithDeclarations) {
+ return _emitFor(null, forParts.variables, forParts.condition,
+ forParts.updaters, node.body);
+ } else if (node.awaitKeyword == null) {
+ if (forParts is ForEachPartsWithIdentifier) {
+ return _emitForEach(
+ forParts.identifier, null, forParts.iterable, node.body);
+ } else if (forParts is ForEachPartsWithDeclaration) {
+ return _emitForEach(
+ null, forParts.loopVariable, forParts.iterable, node.body);
+ }
+ } else if (forParts is ForEachPartsWithIdentifier) {
+ return _emitAwaitFor(
+ forParts.identifier, null, forParts.iterable, node.body);
+ } else if (forParts is ForEachPartsWithDeclaration) {
+ return _emitAwaitFor(
+ null, forParts.loopVariable, forParts.iterable, node.body);
+ }
+ return _unreachable(node);
+ }
@deprecated
@override
