refactor(compiler): move handling of translations to the ConstantPool (#22942)

PR Close #22942

packages/compiler/src/constant_pool.ts

@@ -11,8 +11,16 @@ import {OutputContext, error} from './util';
 
 const CONSTANT_PREFIX = '_c';
 
+// Closure variables holding messages must be named `MSG_[A-Z0-9]+`
+const TRANSLATION_PREFIX = 'MSG_';
+
 export const enum DefinitionKind {Injector, Directive, Component, Pipe}
 
+/**
+ * Closure uses `goog.getMsg(message)` to lookup translations
+ */
+const GOOG_GET_MSG = 'goog.getMsg';
+
 /**
  * Context to use when producing a key.
  *
@@ -68,6 +76,7 @@ class FixupExpression extends o.Expression {
  */
 export class ConstantPool {
   statements: o.Statement[] = [];
+  private translations = new Map<string, o.Expression>();
   private literals = new Map<string, FixupExpression>();
   private literalFactories = new Map<string, o.Expression>();
   private injectorDefinitions = new Map<any, FixupExpression>();
@@ -103,6 +112,40 @@ export class ConstantPool {
     return fixup;
   }
 
+  // Generates closure specific code for translation.
+  //
+  // ```
+  // /**
+  //  * @desc description?
+  //  * @meaning meaning?
+  //  */
+  // const MSG_XYZ = goog.getMsg('message');
+  // ```
+  getTranslation(message: string, meta: {description?: string, meaning?: string}): o.Expression {
+    // The identity of an i18n message depends on the message and its meaning
+    const key = meta.meaning ? `${message}\u0000\u0000${meta.meaning}` : message;
+
+    const exp = this.translations.get(key);
+
+    if (exp) {
+      return exp;
+    }
+
+    const docStmt = i18nMetaToDocStmt(meta);
+    if (docStmt) {
+      this.statements.push(docStmt);
+    }
+
+    // Call closure to get the translation
+    const variable = o.variable(this.freshTranslationName());
+    const fnCall = o.variable(GOOG_GET_MSG).callFn([o.literal(message)]);
+    const msgStmt = variable.set(fnCall).toDeclStmt(o.INFERRED_TYPE, [o.StmtModifier.Final]);
+    this.statements.push(msgStmt);
+
+    this.translations.set(key, variable);
+    return variable;
+  }
+
   getDefinition(type: any, kind: DefinitionKind, ctx: OutputContext, forceShared: boolean = false):
       o.Expression {
     const definitions = this.definitionsOf(kind);
@@ -213,25 +256,36 @@ export class ConstantPool {
 
   private freshName(): string { return this.uniqueName(CONSTANT_PREFIX); }
 
+  private freshTranslationName(): string {
+    return this.uniqueName(TRANSLATION_PREFIX).toUpperCase();
+  }
+
   private keyOf(expression: o.Expression) {
     return expression.visitExpression(new KeyVisitor(), KEY_CONTEXT);
   }
 }
 
+/**
+ * Visitor used to determine if 2 expressions are equivalent and can be shared in the
+ * `ConstantPool`.
+ *
+ * When the id (string) generated by the visitor is equal, expressions are considered equivalent.
+ */
 class KeyVisitor implements o.ExpressionVisitor {
   visitLiteralExpr(ast: o.LiteralExpr): string {
     return `${typeof ast.value === 'string' ? '"' + ast.value + '"' : ast.value}`;
   }
+
   visitLiteralArrayExpr(ast: o.LiteralArrayExpr, context: object): string {
     return `[${ast.entries.map(entry => entry.visitExpression(this, context)).join(',')}]`;
   }
 
   visitLiteralMapExpr(ast: o.LiteralMapExpr, context: object): string {
-    const mapKey =
+    const mapKey = (entry: o.LiteralMapEntry) => {
-        (entry: o.LiteralMapEntry) => {
       const quote = entry.quoted ? '"' : '';
       return `${quote}${entry.key}${quote}`;
-        } const mapEntry = (entry: o.LiteralMapEntry) =>
+    };
+    const mapEntry = (entry: o.LiteralMapEntry) =>
         `${mapKey(entry)}:${entry.value.visitExpression(this, context)}`;
     return `{${ast.entries.map(mapEntry).join(',')}`;
   }
@@ -241,13 +295,7 @@ class KeyVisitor implements o.ExpressionVisitor {
                                   `EX:${ast.value.runtime.name}`;
   }
 
-  visitReadVarExpr(ast: o.ReadVarExpr): string {
+  visitReadVarExpr = invalid;
-    if (!ast.name) {
-      invalid(ast);
-    }
-    return ast.name as string;
-  }
-
   visitWriteVarExpr = invalid;
   visitWriteKeyExpr = invalid;
   visitWritePropExpr = invalid;
@@ -273,3 +321,20 @@ function invalid<T>(arg: o.Expression | o.Statement): never {
 function isVariable(e: o.Expression): e is o.ReadVarExpr {
   return e instanceof o.ReadVarExpr;
 }
+
+// Converts i18n meta informations for a message (description, meaning) to a JsDoc statement
+// formatted as expected by the Closure compiler.
+function i18nMetaToDocStmt(meta: {description?: string, id?: string, meaning?: string}):
+    o.JSDocCommentStmt|null {
+  const tags: o.JSDocTag[] = [];
+
+  if (meta.description) {
+    tags.push({tagName: o.JSDocTagName.Desc, text: meta.description});
+  }
+
+  if (meta.meaning) {
+    tags.push({tagName: o.JSDocTagName.Meaning, text: meta.meaning});
+  }
+
+  return tags.length == 0 ? null : new o.JSDocCommentStmt(tags);
+}

packages/compiler/src/render3/r3_view_compiler.ts

@@ -46,9 +46,6 @@ const I18N_ATTR_PREFIX = 'i18n-';
 const MEANING_SEPARATOR = '|';
 const ID_SEPARATOR = '@@';
 
-/** Closure functions **/
-const GOOG_GET_MSG = 'goog.getMsg';
-
 export function compileDirective(
     outputCtx: OutputContext, directive: CompileDirectiveMetadata, reflector: CompileReflector,
     bindingParser: BindingParser, mode: OutputMode) {
@@ -317,12 +314,6 @@ class BindingScope {
     const ref = `${REFERENCE_PREFIX}${current.referenceNameIndex++}`;
     return ref;
   }
-
-  // closure variables holding i18n messages are name `MSG_[A-Z0-9]+`
-  freshI18nName(): string {
-    const name = this.freshReferenceName();
-    return `MSG_${name}`.toUpperCase();
-  }
 }
 
 const ROOT_SCOPE = new BindingScope(null).set('$event', o.variable('$event'));
@@ -573,8 +564,8 @@ class TemplateDefinitionBuilder implements TemplateAstVisitor, LocalResolver {
       attributes.push(o.literal(name));
       if (attrI18nMetas.hasOwnProperty(name)) {
         hasI18nAttr = true;
-        const {statements, variable} = this.genI18nMessageStmts(value, attrI18nMetas[name]);
+        const meta = parseI18nMeta(attrI18nMetas[name]);
-        i18nMessages.push(...statements);
+        const variable = this.constantPool.getTranslation(value, meta);
         attributes.push(variable);
       } else {
         attributes.push(o.literal(value));
@@ -790,8 +781,8 @@ class TemplateDefinitionBuilder implements TemplateAstVisitor, LocalResolver {
   // i0.ɵT(1, MSG_XYZ);
   // ```
   visitSingleI18nTextChild(text: TextAst, i18nMeta: string) {
-    const {statements, variable} = this.genI18nMessageStmts(text.value, i18nMeta);
+    const meta = parseI18nMeta(i18nMeta);
-    this._creationMode.push(...statements);
+    const variable = this.constantPool.getTranslation(text.value, meta);
     this.instruction(
         this._creationMode, text.sourceSpan, R3.text, o.literal(this.allocateDataSlot()), variable);
   }
@@ -835,35 +826,6 @@ class TemplateDefinitionBuilder implements TemplateAstVisitor, LocalResolver {
   private bind(implicit: o.Expression, value: AST, sourceSpan: ParseSourceSpan): o.Expression {
     return this.convertPropertyBinding(implicit, value);
   }
-
-  // Transforms an i18n message into a const declaration.
-  //
-  // `message`
-  // becomes
-  // ```
-  // /**
-  //  * @desc description?
-  //  * @meaning meaning?
-  //  */
-  // const MSG_XYZ = goog.getMsg('message');
-  // ```
-  private genI18nMessageStmts(msg: string, meta: string):
-      {statements: o.Statement[], variable: o.ReadVarExpr} {
-    const statements: o.Statement[] = [];
-    const m = parseI18nMeta(meta);
-    const docStmt = i18nMetaToDocStmt(m);
-    if (docStmt) {
-      statements.push(docStmt);
-    }
-
-    // Call closure to get the translation
-    const variable = o.variable(this.bindingScope.freshI18nName());
-    const fnCall = o.variable(GOOG_GET_MSG).callFn([o.literal(msg)]);
-    const msgStmt = variable.set(fnCall).toDeclStmt(o.INFERRED_TYPE, [o.StmtModifier.Final]);
-    statements.push(msgStmt);
-
-    return {statements, variable};
-  }
 }
 
 function getQueryPredicate(query: CompileQueryMetadata, outputCtx: OutputContext): o.Expression {
@@ -1221,20 +1183,3 @@ function parseI18nMeta(i18n?: string): {description?: string, id?: string, meani
 
   return {description, id, meaning};
 }
-
-// Converts i18n meta informations for a message (description, meaning) to a JsDoc statement
-// formatted as expected by the Closure compiler.
-function i18nMetaToDocStmt(meta: {description?: string, id?: string, meaning?: string}):
-    o.JSDocCommentStmt|null {
-  const tags: o.JSDocTag[] = [];
-
-  if (meta.description) {
-    tags.push({tagName: o.JSDocTagName.Desc, text: meta.description});
-  }
-
-  if (meta.meaning) {
-    tags.push({tagName: o.JSDocTagName.Meaning, text: meta.meaning});
-  }
-
-  return tags.length == 0 ? null : new o.JSDocCommentStmt(tags);
-}

packages/compiler/test/render3/r3_view_compiler_i18n_spec.ts

@@ -29,6 +29,7 @@ describe('i18n support in the view compiler', () => {
                 <div i18n>Hello world</div>
                 <div>&</div>
                 <div i18n>farewell</div>
+                <div i18n>farewell</div>
               \`
             })
             export class MyComponent {}
@@ -40,16 +41,19 @@ describe('i18n support in the view compiler', () => {
       };
 
       const template = `
+      const $msg_1$ = goog.getMsg('Hello world');
+      const $msg_2$ = goog.getMsg('farewell');
+      …
       template: function MyComponent_Template(ctx: IDENT, cm: IDENT) {
         if (cm) {
           …
-          const $g2$ = goog.getMsg('Hello world');
+          $r3$.ɵT(1, $msg_1$);
-          $r3$.ɵT(1, $g2$);
           …
           $r3$.ɵT(3,'&');
           …
-          const $g3$ = goog.getMsg('farewell');
+          $r3$.ɵT(5, $msg_2$);
-          $r3$.ɵT(5, $g3$);
+          …
+          $r3$.ɵT(7, $msg_2$);
           …
         }
       }
@@ -80,23 +84,25 @@ describe('i18n support in the view compiler', () => {
       };
 
       const template = `
+      /**
+       * @desc desc
+       */
+      const $msg_1$ = goog.getMsg('introduction');
+      …
       const $c1$ = ($a1$:any) => {
         return ['title', $a1$];
       };
       …
-      template: function MyComponent_Template(ctx: IDENT, cm: IDENT) {
-        if (cm) {
-          /**
-           * @desc desc
-           */
-          const $g1$ = goog.getMsg('introduction');
-          $r3$.ɵE(0, 'div', $r3$.ɵf1($c1$, $g1$));
       /**
        * @desc desc
        * @meaning meaning
        */
-          const $g2$ = goog.getMsg('Hello world');
+      const $msg_2$ = goog.getMsg('Hello world');
-          $r3$.ɵT(1, $g2$);
+      …
+      template: function MyComponent_Template(ctx: IDENT, cm: IDENT) {
+        if (cm) {
+          $r3$.ɵE(0, 'div', $r3$.ɵf1($c1$, $msg_1$));
+          $r3$.ɵT(1, $msg_2$);
           $r3$.ɵe();
         }
       }
@@ -129,18 +135,19 @@ describe('i18n support in the view compiler', () => {
       };
 
       const template = `
+      /**
+       * @desc d
+       * @meaning m
+       */
+      const $msg_1$ = goog.getMsg('introduction');
+      …
       const $c1$ = ($a1$:any) => {
         return ['id', 'static', 'title', $a1$];
       };
       …
       template: function MyComponent_Template(ctx: IDENT, cm: IDENT) {
         if (cm) {
-          /**
+          $r3$.ɵE(0, 'div', $r3$.ɵf1($c1$, $msg_1$));
-           * @desc d
-           * @meaning m
-           */
-          const $g1$ = goog.getMsg('introduction');
-          $r3$.ɵE(0, 'div', $r3$.ɵf1($c1$, $g1$));
           $r3$.ɵe();
         }
       }