Reduce exprAllowed usage (#13431)

packages/babel-parser/src/plugins/flow/index.js

@@ -1710,10 +1710,6 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       this.state.inType = true;
       const type = this.flowParseUnionType();
       this.state.inType = oldInType;
-      // Ensure that a brace after a function generic type annotation is a
-      // statement, except in arrow functions (noAnonFunctionType)
-      this.state.exprAllowed =
-        this.state.exprAllowed || this.state.noAnonFunctionType;
       return type;
     }
 
@@ -3706,20 +3702,6 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       return this.finishNode(node, "EnumDeclaration");
     }
 
-    updateContext(prevType: TokenType): void {
-      if (
-        this.match(tt.name) &&
-        this.state.value === "of" &&
-        prevType === tt.name &&
-        this.input.slice(this.state.lastTokStart, this.state.lastTokEnd) ===
-          "interface"
-      ) {
-        this.state.exprAllowed = false;
-      } else {
-        super.updateContext(prevType);
-      }
-    }
-
     // check if the next token is a tt.relation("<")
     isLookaheadToken_lt(): boolean {
       const next = this.nextTokenStart();

packages/babel-parser/src/plugins/jsx/index.js

@@ -45,29 +45,18 @@ const JsxErrors = makeErrorTemplates(
 
 // Be aware that this file is always executed and not only when the plugin is enabled.
 // Therefore this contexts and tokens do always exist.
-tc.j_oTag = new TokContext("<tag", false);
-tc.j_cTag = new TokContext("</tag", false);
-tc.j_expr = new TokContext("<tag>...</tag>", true, true);
+tc.j_oTag = new TokContext("<tag");
+tc.j_cTag = new TokContext("</tag");
+tc.j_expr = new TokContext("<tag>...</tag>", true);
 
 tt.jsxName = new TokenType("jsxName");
 tt.jsxText = new TokenType("jsxText", { beforeExpr: true });
 tt.jsxTagStart = new TokenType("jsxTagStart", { startsExpr: true });
 tt.jsxTagEnd = new TokenType("jsxTagEnd");
 
-tt.jsxTagStart.updateContext = function () {
-  this.state.context.push(tc.j_expr); // treat as beginning of JSX expression
-  this.state.context.push(tc.j_oTag); // start opening tag context
-  this.state.exprAllowed = false;
-};
-
-tt.jsxTagEnd.updateContext = function (prevType) {
-  const out = this.state.context.pop();
-  if ((out === tc.j_oTag && prevType === tt.slash) || out === tc.j_cTag) {
-    this.state.context.pop();
-    this.state.exprAllowed = this.curContext() === tc.j_expr;
-  } else {
-    this.state.exprAllowed = true;
-  }
+tt.jsxTagStart.updateContext = context => {
+  context.push(tc.j_expr); // treat as beginning of JSX expression
+  context.push(tc.j_oTag); // start opening tag context
 };
 
 function isFragment(object: ?N.JSXElement): boolean {
@@ -625,22 +614,35 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     }
 
     updateContext(prevType: TokenType): void {
-      if (this.match(tt.braceL)) {
-        const curContext = this.curContext();
+      super.updateContext(prevType);
+      const { context, type } = this.state;
+      if (type === tt.braceL) {
+        const curContext = context[context.length - 1];
         if (curContext === tc.j_oTag) {
-          this.state.context.push(tc.braceExpression);
+          context.push(tc.brace);
         } else if (curContext === tc.j_expr) {
-          this.state.context.push(tc.templateQuasi);
-        } else {
-          super.updateContext(prevType);
+          context.push(tc.templateQuasi);
         }
         this.state.exprAllowed = true;
-      } else if (this.match(tt.slash) && prevType === tt.jsxTagStart) {
-        this.state.context.length -= 2; // do not consider JSX expr -> JSX open tag -> ... anymore
-        this.state.context.push(tc.j_cTag); // reconsider as closing tag context
+      } else if (type === tt.slash && prevType === tt.jsxTagStart) {
+        context.length -= 2; // do not consider JSX expr -> JSX open tag -> ... anymore
+        context.push(tc.j_cTag); // reconsider as closing tag context
+        this.state.exprAllowed = false;
+      } else if (type === tt.jsxTagEnd) {
+        const out = context.pop();
+        if ((out === tc.j_oTag && prevType === tt.slash) || out === tc.j_cTag) {
+          context.pop();
+          this.state.exprAllowed = context[context.length - 1] === tc.j_expr;
+        } else {
+          this.state.exprAllowed = true;
+        }
+      } else if (
+        type.keyword &&
+        (prevType === tt.dot || prevType === tt.questionDot)
+      ) {
         this.state.exprAllowed = false;
       } else {
-        return super.updateContext(prevType);
+        this.state.exprAllowed = type.beforeExpr;
       }
     }
   };

packages/babel-parser/src/plugins/typescript/index.js

@@ -1887,9 +1887,6 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       if (node.params.length === 0) {
         this.raise(node.start, TSErrors.EmptyTypeArguments);
       }
-      // This reads the next token after the `>` too, so do this in the enclosing context.
-      // But be sure not to parse a regex in the jsx expression `<C<number> />`, so set exprAllowed = false
-      this.state.exprAllowed = false;
       this.expectRelational(">");
       return this.finishNode(node, "TSTypeParameterInstantiation");
     }
@@ -2046,7 +2043,6 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       state: N.ParseSubscriptState,
     ): N.Expression {
       if (!this.hasPrecedingLineBreak() && this.match(tt.bang)) {
-        this.state.exprAllowed = false;
         this.next();
 
         const nonNullExpression: N.TsNonNullExpression = this.startNodeAt(