Improve @babel/generator typings

packages/babel-generator/src/buffer.ts

@@ -1,12 +1,11 @@
 import type SourceMap from "./source-map";
-import type * as t from "@babel/types";
 import * as charcodes from "charcodes";
 
-type Pos = {
+export type Pos = {
   line: number;
   column: number;
 };
-type Loc = {
+export type Loc = {
   start?: Pos;
   end?: Pos;
   identifierName?: string;
@@ -63,14 +62,18 @@ export default class Buffer {
 
       // Encoding the sourcemap is moderately CPU expensive.
       get map() {
-        return (result.map = map ? map.get() : null);
+        const resultMap = map ? map.get() : null;
+        result.map = resultMap;
+        return resultMap;
       },
       set map(value) {
         Object.defineProperty(result, "map", { value, writable: true });
       },
       // Retrieving the raw mappings is very memory intensive.
       get rawMappings() {
-        return (result.rawMappings = map?.getRawMappings());
+        const mappings = map?.getRawMappings();
+        result.rawMappings = mappings;
+        return mappings;
       },
       set rawMappings(value) {
         Object.defineProperty(result, "rawMappings", { value, writable: true });
@@ -241,7 +244,7 @@ export default class Buffer {
    * With this line, there will be one mapping range over "mod" and another
    * over "();", where previously it would have been a single mapping.
    */
-  exactSource(loc: any, cb: () => void) {
+  exactSource(loc: Loc | undefined, cb: () => void) {
     this.source("start", loc);
 
     cb();
@@ -262,7 +265,7 @@ export default class Buffer {
    * will be given this position in the sourcemap.
    */
 
-  source(prop: string, loc: t.SourceLocation): void {
+  source(prop: "start" | "end", loc: Loc | undefined): void {
     if (prop && !loc) return;
 
     // Since this is called extremely often, we re-use the same _sourcePosition
@@ -274,7 +277,7 @@ export default class Buffer {
    * Call a callback with a specific source location and restore on completion.
    */
 
-  withSource(prop: string, loc: t.SourceLocation, cb: () => void): void {
+  withSource(prop: "start" | "end", loc: Loc, cb: () => void): void {
     if (!this._map) return cb();
 
     // Use the call stack to manage a stack of "source location" data because
@@ -309,14 +312,14 @@ export default class Buffer {
    * sourcemap output, so that certain printers can be sure that the
    * "end" location that they set is actually treated as the end position.
    */
-  _disallowPop(prop: string, loc: t.SourceLocation) {
+  _disallowPop(prop: "start" | "end", loc: Loc) {
     if (prop && !loc) return;
 
     this._disallowedPop = this._normalizePosition(prop, loc, SourcePos());
   }
 
   _normalizePosition(
-    prop: string,
+    prop: "start" | "end",
     loc: Loc | undefined | null,
     targetObj: SourcePos,
   ) {

packages/babel-generator/src/generators/base.ts

@@ -58,7 +58,7 @@ const unescapedDoubleQuoteRE = /(?:^|[^\\])(?:\\\\)*"/;
 
 export function DirectiveLiteral(this: Printer, node: t.DirectiveLiteral) {
   const raw = this.getPossibleRaw(node);
-  if (!this.format.minified && raw != null) {
+  if (!this.format.minified && raw !== undefined) {
     this.token(raw);
     return;
   }

packages/babel-generator/src/generators/classes.ts

@@ -9,7 +9,7 @@ import * as charCodes from "charcodes";
 export function ClassDeclaration(
   this: Printer,
   node: t.ClassDeclaration,
-  parent: any,
+  parent: t.Node,
 ) {
   if (
     !this.format.decoratorsBeforeExport ||
@@ -86,7 +86,7 @@ export function ClassProperty(this: Printer, node: t.ClassProperty) {
   // between member modifiers and the property key.
   this.source("end", node.key.loc);
 
-  this.tsPrintClassMemberModifiers(node, /* isField */ true);
+  this.tsPrintClassMemberModifiers(node);
 
   if (node.computed) {
     this.token("[");
@@ -125,7 +125,8 @@ export function ClassAccessorProperty(
   // between member modifiers and the property key.
   this.source("end", node.key.loc);
 
-  this.tsPrintClassMemberModifiers(node, /* isField */ true);
+  // TS does not support class accessor property yet
+  this.tsPrintClassMemberModifiers(node);
 
   this.word("accessor");
   this.printInnerComments(node);
@@ -136,6 +137,7 @@ export function ClassAccessorProperty(
     this.print(node.key, node);
     this.token("]");
   } else {
+    // Todo: Flow does not support class accessor property yet.
     this._variance(node);
     this.print(node.key, node);
   }
@@ -190,12 +192,15 @@ export function ClassPrivateMethod(this: Printer, node: t.ClassPrivateMethod) {
   this.print(node.body, node);
 }
 
-export function _classMethodHead(this: Printer, node) {
+export function _classMethodHead(
+  this: Printer,
+  node: t.ClassMethod | t.ClassPrivateMethod | t.TSDeclareMethod,
+) {
   this.printJoin(node.decorators, node);
   // catch up to method key, avoid line break
   // between member modifiers/method heads and the method key.
   this.source("end", node.key.loc);
-  this.tsPrintClassMemberModifiers(node, /* isField */ false);
+  this.tsPrintClassMemberModifiers(node);
   this._methodHead(node);
 }
 

packages/babel-generator/src/generators/expressions.ts

@@ -49,9 +49,7 @@ export function UpdateExpression(this: Printer, node: t.UpdateExpression) {
     this.token(node.operator);
     this.print(node.argument, node);
   } else {
-    this.startTerminatorless(true);
-    this.print(node.argument, node);
-    this.endTerminatorless();
+    this.printTerminatorless(node.argument, node, true);
     this.token(node.operator);
   }
 }
@@ -74,7 +72,7 @@ export function ConditionalExpression(
 export function NewExpression(
   this: Printer,
   node: t.NewExpression,
-  parent: any,
+  parent: t.Node,
 ) {
   this.word("new");
   this.space();
@@ -116,7 +114,7 @@ export function Super(this: Printer) {
 
 function isDecoratorMemberExpression(
   node: t.Expression | t.V8IntrinsicIdentifier,
-) {
+): boolean {
   switch (node.type) {
     case "Identifier":
       return true;
@@ -218,25 +216,27 @@ export function Import(this: Printer) {
   this.word("import");
 }
 
-function buildYieldAwait(keyword: string) {
-  return function (this: Printer, node: any) {
-    this.word(keyword);
-
-    if (node.delegate) {
-      this.token("*");
-    }
+export function AwaitExpression(this: Printer, node: t.AwaitExpression) {
+  this.word("await");
 
-    if (node.argument) {
-      this.space();
-      const terminatorState = this.startTerminatorless();
-      this.print(node.argument, node);
-      this.endTerminatorless(terminatorState);
-    }
-  };
+  if (node.argument) {
+    this.space();
+    this.printTerminatorless(node.argument, node, false);
+  }
 }
 
-export const YieldExpression = buildYieldAwait("yield");
-export const AwaitExpression = buildYieldAwait("await");
+export function YieldExpression(this: Printer, node: t.YieldExpression) {
+  this.word("yield");
+
+  if (node.delegate) {
+    this.token("*");
+  }
+
+  if (node.argument) {
+    this.space();
+    this.printTerminatorless(node.argument, node, false);
+  }
+}
 
 export function EmptyStatement(this: Printer) {
   this.semicolon(true /* force */);
@@ -265,7 +265,7 @@ export function AssignmentPattern(this: Printer, node: t.AssignmentPattern) {
 export function AssignmentExpression(
   this: Printer,
   node: t.AssignmentExpression,
-  parent: any,
+  parent: t.Node,
 ) {
   // Somewhere inside a for statement `init` node but doesn't usually
   // needs a paren except for `in` expressions: `for (a in b ? a : b;;)`

packages/babel-generator/src/generators/flow.ts

@@ -48,7 +48,7 @@ export function DeclareClass(
 export function DeclareFunction(
   this: Printer,
   node: t.DeclareFunction,
-  parent: any,
+  parent: t.Node,
 ) {
   if (!isDeclareExportDeclaration(parent)) {
     this.word("declare");
@@ -118,7 +118,7 @@ export function DeclareTypeAlias(this: Printer, node: t.DeclareTypeAlias) {
 export function DeclareOpaqueType(
   this: Printer,
   node: t.DeclareOpaqueType,
-  parent: any,
+  parent: t.Node,
 ) {
   if (!isDeclareExportDeclaration(parent)) {
     this.word("declare");
@@ -130,7 +130,7 @@ export function DeclareOpaqueType(
 export function DeclareVariable(
   this: Printer,
   node: t.DeclareVariable,
-  parent: any,
+  parent: t.Node,
 ) {
   if (!isDeclareExportDeclaration(parent)) {
     this.word("declare");
@@ -174,7 +174,7 @@ export function EnumDeclaration(this: Printer, node: t.EnumDeclaration) {
 }
 
 function enumExplicitType(
-  context: any,
+  context: Printer,
   name: string,
   hasExplicitType: boolean,
 ) {
@@ -187,7 +187,7 @@ function enumExplicitType(
   context.space();
 }
 
-function enumBody(context: any, node: any) {
+function enumBody(context: Printer, node: t.EnumBody) {
   const { members } = node;
   context.token("{");
   context.indent();
@@ -236,7 +236,10 @@ export function EnumDefaultedMember(
   this.token(",");
 }
 
-function enumInitializedMember(context: any, node: any) {
+function enumInitializedMember(
+  context: Printer,
+  node: t.EnumBooleanMember | t.EnumNumberMember | t.EnumStringMember,
+) {
   const { id, init } = node;
   context.print(id, node);
   context.space();
@@ -258,7 +261,10 @@ export function EnumStringMember(this: Printer, node: t.EnumStringMember) {
   enumInitializedMember(this, node);
 }
 
-function FlowExportDeclaration(this: Printer, node: any) {
+function FlowExportDeclaration(
+  this: Printer,
+  node: t.DeclareExportDeclaration,
+) {
   if (node.declaration) {
     const declar = node.declaration;
     this.print(declar, node);
@@ -384,7 +390,16 @@ export function _interfaceish(
   this.print(node.body, node);
 }
 
-export function _variance(this: Printer, node) {
+export function _variance(
+  this: Printer,
+  node:
+    | t.TypeParameter
+    | t.ObjectTypeIndexer
+    | t.ObjectTypeProperty
+    | t.ClassProperty
+    | t.ClassPrivateProperty
+    | t.ClassAccessorProperty,
+) {
   if (node.variance) {
     if (node.variance.kind === "plus") {
       this.token("+");

packages/babel-generator/src/generators/jsx.ts

@@ -54,7 +54,7 @@ export function JSXSpreadChild(this: Printer, node: t.JSXSpreadChild) {
 export function JSXText(this: Printer, node: t.JSXText) {
   const raw = this.getPossibleRaw(node);
 
-  if (raw != null) {
+  if (raw !== undefined) {
     this.token(raw);
   } else {
     this.token(node.value);