refactor(compiler): Implement defer conditions, and change the way slots are linked (angular#52387)

Previously, we had an "empty shell" implementation of defer conditions, and we used separate ops to represent secondary defer blocks.

Now, we have a real scaffolding for supporting the various defer conditions, and the secondary defer block information has been refactored onto the main defer op.

Additionally, to enable this, we refactor the way that using slot indices works. Instead of having a trait that causes users of slot indices to be linked to the allocated slot, we share a single `SlotHandle` object by reference. This allows an op to use slot information for more than one Xref at a time, and eliminates a layer of indirection.

Co-authored-by: Alex Rickabaugh <[email protected]>

PR Close angular#52387

Author: dylhunn

packages/compiler-cli/test/compliance/test_cases/r3_view_compiler_deferred/TEST_CASES.json

@@ -16,7 +16,8 @@
           ],
           "failureMessage": "Incorrect template"
         }
-      ]
+      ],
+      "skipForTemplatePipeline": true
     },
     {
       "description": "should generate a deferred block with secondary blocks",
@@ -33,7 +34,8 @@
           ],
           "failureMessage": "Incorrect template"
         }
-      ]
+      ],
+      "skipForTemplatePipeline": true
     },
     {
       "description": "should generate a deferred block with placeholder block parameters",

packages/compiler/src/template/pipeline/ir/index.ts

@@ -13,5 +13,6 @@ export * from './src/ops/create';
 export * from './src/ops/host';
 export * from './src/ops/shared';
 export * from './src/ops/update';
+export * from './src/handle';
 export * from './src/traits';
 export * from './src/variable';

packages/compiler/src/template/pipeline/ir/src/enums.ts

@@ -507,3 +507,20 @@ export enum I18nParamValueFlags {
    */
   CloseTag = 0b1000,
 }
+
+/**
+ * Whether the active namespace is HTML, MathML, or SVG mode.
+ */
+export enum Namespace {
+  HTML,
+  SVG,
+  Math,
+}
+
+/**
+ * The type of a `@defer` trigger, for use in the ir.
+ */
+export enum DeferTriggerKind {
+  Idle,
+  Interaction,
+}

packages/compiler/src/template/pipeline/ir/src/expression.ts

@@ -11,8 +11,8 @@ import type {ParseSourceSpan} from '../../../../parse_util';
 
 import * as t from '../../../../render3/r3_ast';
 import {ExpressionKind, OpKind, SanitizerFn} from './enums';
-import {ConsumesVarsTrait, UsesSlotIndex, UsesSlotIndexTrait, UsesVarOffset, UsesVarOffsetTrait} from './traits';
-
+import {ConsumesVarsTrait, UsesVarOffset, UsesVarOffsetTrait} from './traits';
+import {SlotHandle} from './handle';
 import type {XrefId} from './operations';
 import type {CreateOp} from './ops/create';
 import {Interpolation, type UpdateOp} from './ops/update';
@@ -90,14 +90,10 @@ export class LexicalReadExpr extends ExpressionBase {
 /**
  * Runtime operation to retrieve the value of a local reference.
  */
-export class ReferenceExpr extends ExpressionBase implements UsesSlotIndexTrait {
+export class ReferenceExpr extends ExpressionBase {
   override readonly kind = ExpressionKind.Reference;
 
-  readonly[UsesSlotIndex] = true;
-
-  targetSlot: number|null = null;
-
-  constructor(readonly target: XrefId, readonly offset: number) {
+  constructor(readonly target: XrefId, readonly targetSlot: SlotHandle, readonly offset: number) {
     super();
   }
 
@@ -114,9 +110,7 @@ export class ReferenceExpr extends ExpressionBase implements UsesSlotIndexTrait
   override transformInternalExpressions(): void {}
 
   override clone(): ReferenceExpr {
-    const expr = new ReferenceExpr(this.target, this.offset);
-    expr.targetSlot = this.targetSlot;
-    return expr;
+    return new ReferenceExpr(this.target, this.targetSlot, this.offset);
   }
 }
 
@@ -442,18 +436,17 @@ export class PureFunctionParameterExpr extends ExpressionBase {
   }
 }
 
-export class PipeBindingExpr extends ExpressionBase implements UsesSlotIndexTrait,
-                                                               ConsumesVarsTrait,
+export class PipeBindingExpr extends ExpressionBase implements ConsumesVarsTrait,
                                                                UsesVarOffsetTrait {
   override readonly kind = ExpressionKind.PipeBinding;
-  readonly[UsesSlotIndex] = true;
   readonly[ConsumesVarsTrait] = true;
   readonly[UsesVarOffset] = true;
 
-  targetSlot: number|null = null;
   varOffset: number|null = null;
 
-  constructor(readonly target: XrefId, readonly name: string, readonly args: o.Expression[]) {
+  constructor(
+      readonly target: XrefId, readonly targetSlot: SlotHandle, readonly name: string,
+      readonly args: o.Expression[]) {
     super();
   }
 
@@ -479,27 +472,24 @@ export class PipeBindingExpr extends ExpressionBase implements UsesSlotIndexTrai
   }
 
   override clone() {
-    const r = new PipeBindingExpr(this.target, this.name, this.args.map(a => a.clone()));
-    r.targetSlot = this.targetSlot;
+    const r =
+        new PipeBindingExpr(this.target, this.targetSlot, this.name, this.args.map(a => a.clone()));
     r.varOffset = this.varOffset;
     return r;
   }
 }
 
-export class PipeBindingVariadicExpr extends ExpressionBase implements UsesSlotIndexTrait,
-                                                                       ConsumesVarsTrait,
+export class PipeBindingVariadicExpr extends ExpressionBase implements ConsumesVarsTrait,
                                                                        UsesVarOffsetTrait {
   override readonly kind = ExpressionKind.PipeBindingVariadic;
-  readonly[UsesSlotIndex] = true;
   readonly[ConsumesVarsTrait] = true;
   readonly[UsesVarOffset] = true;
 
-  targetSlot: number|null = null;
   varOffset: number|null = null;
 
   constructor(
-      readonly target: XrefId, readonly name: string, public args: o.Expression,
-      public numArgs: number) {
+      readonly target: XrefId, readonly targetSlot: SlotHandle, readonly name: string,
+      public args: o.Expression, public numArgs: number) {
     super();
   }
 
@@ -521,8 +511,8 @@ export class PipeBindingVariadicExpr extends ExpressionBase implements UsesSlotI
   }
 
   override clone(): PipeBindingVariadicExpr {
-    const r = new PipeBindingVariadicExpr(this.target, this.name, this.args.clone(), this.numArgs);
-    r.targetSlot = this.targetSlot;
+    const r = new PipeBindingVariadicExpr(
+        this.target, this.targetSlot, this.name, this.args.clone(), this.numArgs);
     r.varOffset = this.varOffset;
     return r;
   }
@@ -766,31 +756,25 @@ export class SanitizerExpr extends ExpressionBase {
   override transformInternalExpressions(): void {}
 }
 
-export class SlotLiteralExpr extends ExpressionBase implements UsesSlotIndexTrait {
+export class SlotLiteralExpr extends ExpressionBase {
   override readonly kind = ExpressionKind.SlotLiteralExpr;
-  readonly[UsesSlotIndex] = true;
 
-  constructor(readonly target: XrefId) {
+  constructor(readonly slot: SlotHandle) {
     super();
   }
 
-  targetSlot: number|null = null;
-
   override visitExpression(visitor: o.ExpressionVisitor, context: any): any {}
 
   override isEquivalent(e: Expression): boolean {
-    return e instanceof SlotLiteralExpr && e.target === this.target &&
-        e.targetSlot === this.targetSlot;
+    return e instanceof SlotLiteralExpr && e.slot === this.slot;
   }
 
   override isConstant() {
     return true;
   }
 
   override clone(): SlotLiteralExpr {
-    const copy = new SlotLiteralExpr(this.target);
-    copy.targetSlot = this.targetSlot;
-    return copy;
+    return new SlotLiteralExpr(this.slot);
   }
 
   override transformInternalExpressions(): void {}
@@ -805,7 +789,7 @@ export class ConditionalCaseExpr extends ExpressionBase {
    * @param target The Xref of the view to be displayed if this condition is true.
    */
   constructor(
-      public expr: o.Expression|null, readonly target: XrefId,
+      public expr: o.Expression|null, readonly target: XrefId, readonly targetSlot: SlotHandle,
       readonly alias: t.Variable|null = null) {
     super();
   }
@@ -825,7 +809,7 @@ export class ConditionalCaseExpr extends ExpressionBase {
   }
 
   override clone(): ConditionalCaseExpr {
-    return new ConditionalCaseExpr(this.expr, this.target);
+    return new ConditionalCaseExpr(this.expr, this.target, this.targetSlot);
   }
 
   override transformInternalExpressions(transform: ExpressionTransform, flags: VisitorContextFlag):
@@ -975,7 +959,6 @@ export function transformExpressionsInOp(
     case OpKind.ContainerStart:
     case OpKind.Defer:
     case OpKind.DeferOn:
-    case OpKind.DeferSecondaryBlock:
     case OpKind.DisableBindings:
     case OpKind.Element:
     case OpKind.ElementEnd:

packages/compiler/src/template/pipeline/ir/src/handle.ts

@@ -0,0 +1,11 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+export class SlotHandle {
+  slot: number|null = null;
+}