Refactoring accoring to tsc implementation

babel · May 1, 2022 · 1509f4e · 1509f4e
1 parent 926581e
commit 1509f4e
Show file tree

Hide file tree

Showing 4 changed files with 63 additions and 21 deletions.
diff --git a/packages/babel-parser/src/plugins/typescript/index.js b/packages/babel-parser/src/plugins/typescript/index.js
@@ -1260,19 +1260,37 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       this.expectContextual(tt._infer);
       const typeParameter = this.startNode();
       typeParameter.name = this.tsParseTypeParameterName();
-      typeParameter.constraint = this.tsEatThenParseType(tt._extends);
+      typeParameter.constraint = this.tsTryParse(() =>
+        this.tsParseConstraintForInferType(),
+      );
       node.typeParameter = this.finishNode(typeParameter, "TSTypeParameter");
       return this.finishNode(node, "TSInferType");
     }
 
+    tsParseConstraintForInferType() {
+      if (this.eat(tt._extends)) {
+        const constraint = this.tsInDisallowConditionalTypesContext(() =>
+          this.tsParseType(),
+        );
+        if (
+          this.state.inDisallowConditionalTypesContext ||
+          !this.match(tt.question)
+        ) {
+          return constraint;
+        }
+      }
+    }
+
     tsParseTypeOperatorOrHigher(): N.TsType {
       const isTypeOperator =
         tokenIsTSTypeOperator(this.state.type) && !this.state.containsEsc;
       return isTypeOperator
         ? this.tsParseTypeOperator()
         : this.isContextual(tt._infer)
         ? this.tsParseInferType()
-        : this.tsParseArrayTypeOrHigher();
+        : this.tsInAllowConditionalTypesContext(() =>
+            this.tsParseArrayTypeOrHigher(),
+          );
     }
 
     tsParseUnionOrIntersectionType(
@@ -1507,31 +1525,30 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       assert(this.state.inType);
       const type = this.tsParseNonConditionalType();
 
-      const constraintForInfer =
-        type.type === "TSInferType" && type.typeParameter.constraint;
-      const inParsingConditionalType =
-        constraintForInfer && this.state.type === tt.question;
-
       if (
-        !inParsingConditionalType &&
-        (this.hasPrecedingLineBreak() || !this.eat(tt._extends))
+        this.state.inDisallowConditionalTypesContext ||
+        this.hasPrecedingLineBreak() ||
+        !this.eat(tt._extends)
       ) {
         return type;
       }
       const node: N.TsConditionalType = this.startNodeAtNode(type);
       node.checkType = type;
 
-      node.extendsType = inParsingConditionalType
-        ? ((constraintForInfer: any): N.TsType)
-        : this.tsParseNonConditionalType();
-      if (inParsingConditionalType) {
-        ((type: any): N.TsInferType).typeParameter.constraint = undefined;
-      }
+      node.extendsType = this.tsInDisallowConditionalTypesContext(() =>
+        this.tsParseNonConditionalType(),
+      );
 
       this.expect(tt.question);
-      node.trueType = this.tsParseType();
+      node.trueType = this.tsInAllowConditionalTypesContext(() =>
+        this.tsParseType(),
+      );
+
       this.expect(tt.colon);
-      node.falseType = this.tsParseType();
+      node.falseType = this.tsInAllowConditionalTypesContext(() =>
+        this.tsParseType(),
+      );
+
       return this.finishNode(node, "TSConditionalType");
     }
 
@@ -1676,6 +1693,30 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       }
     }
 
+    tsInDisallowConditionalTypesContext<T>(cb: () => T): T {
+      const oldInDisallowConditionalTypesContext =
+        this.state.inDisallowConditionalTypesContext;
+      this.state.inDisallowConditionalTypesContext = true;
+      try {
+        return cb();
+      } finally {
+        this.state.inDisallowConditionalTypesContext =
+          oldInDisallowConditionalTypesContext;
+      }
+    }
+
+    tsInAllowConditionalTypesContext<T>(cb: () => T): T {
+      const oldInDisallowConditionalTypesContext =
+        this.state.inDisallowConditionalTypesContext;
+      this.state.inDisallowConditionalTypesContext = false;
+      try {
+        return cb();
+      } finally {
+        this.state.inDisallowConditionalTypesContext =
+          oldInDisallowConditionalTypesContext;
+      }
+    }
+
     tsEatThenParseType(token: TokenType): N.TsType | typeof undefined {
       return !this.match(token) ? undefined : this.tsNextThenParseType();
     }

diff --git a/packages/babel-parser/src/tokenizer/state.js b/packages/babel-parser/src/tokenizer/state.js
@@ -75,6 +75,7 @@ export default class State {
   hasFlowComment: boolean = false;
   isAmbientContext: boolean = false;
   inAbstractClass: boolean = false;
+  inDisallowConditionalTypesContext: boolean = false;
 
   // For the Hack-style pipelines plugin
   topicContext: TopicContextState = {

diff --git a/...ixtures/typescript/types/infer-with-constraints-and-conditional-types-babel-7/output.json b/...ixtures/typescript/types/infer-with-constraints-and-conditional-types-babel-7/output.json
@@ -52,10 +52,10 @@
                 "start":26,"end":51,"loc":{"start":{"line":1,"column":26,"index":26},"end":{"line":1,"column":51,"index":51}},
                 "checkType": {
                   "type": "TSInferType",
-                  "start":26,"end":43,"loc":{"start":{"line":1,"column":26,"index":26},"end":{"line":1,"column":43,"index":43}},
+                  "start":26,"end":33,"loc":{"start":{"line":1,"column":26,"index":26},"end":{"line":1,"column":33,"index":33}},
                   "typeParameter": {
                     "type": "TSTypeParameter",
-                    "start":32,"end":43,"loc":{"start":{"line":1,"column":32,"index":32},"end":{"line":1,"column":43,"index":43}},
+                    "start":32,"end":33,"loc":{"start":{"line":1,"column":32,"index":32},"end":{"line":1,"column":33,"index":33}},
                     "name": "U"
                   }
                 },

diff --git a/...r/test/fixtures/typescript/types/infer-with-constraints-and-conditional-types/output.json b/...r/test/fixtures/typescript/types/infer-with-constraints-and-conditional-types/output.json
@@ -60,10 +60,10 @@
                 "start":26,"end":51,"loc":{"start":{"line":1,"column":26,"index":26},"end":{"line":1,"column":51,"index":51}},
                 "checkType": {
                   "type": "TSInferType",
-                  "start":26,"end":43,"loc":{"start":{"line":1,"column":26,"index":26},"end":{"line":1,"column":43,"index":43}},
+                  "start":26,"end":33,"loc":{"start":{"line":1,"column":26,"index":26},"end":{"line":1,"column":33,"index":33}},
                   "typeParameter": {
                     "type": "TSTypeParameter",
-                    "start":32,"end":43,"loc":{"start":{"line":1,"column":32,"index":32},"end":{"line":1,"column":43,"index":43}},
+                    "start":32,"end":33,"loc":{"start":{"line":1,"column":32,"index":32},"end":{"line":1,"column":33,"index":33}},
                     "name": {
                       "type": "Identifier",
                       "start":32,"end":33,"loc":{"start":{"line":1,"column":32,"index":32},"end":{"line":1,"column":33,"index":33},"identifierName":"U"},