Add printTrailingComma (#18773)

src/language-js/print/array.js

@@ -21,7 +21,7 @@ import {
   isObjectExpression,
   isTupleType,
 } from "../utilities/node-types.js";
-import { shouldPrintComma } from "../utilities/should-print-comma.js";
+import { shouldPrintTrailingComma } from "../utilities/should-print-trailing-comma.js";
 import {
   printDanglingCommentsInList,
   printOptionalToken,
@@ -92,7 +92,7 @@ function printArray(path, options, print) {
       ? ""
       : needsForcedTrailingComma
         ? ","
-        : !shouldPrintComma(options)
+        : !shouldPrintTrailingComma(options)
           ? ""
           : shouldUseConciseFormatting
             ? ifBreak(",", "", { groupId })

src/language-js/print/arrow-function.js

@@ -25,10 +25,10 @@ import {
   isJsxElement,
   isObjectExpression,
 } from "../utilities/node-types.js";
-import { shouldPrintComma } from "../utilities/should-print-comma.js";
 import { startsWithNoLookaheadToken } from "../utilities/starts-with-no-lookahead-token.js";
 import { printReturnType, shouldPrintParamsWithoutParens } from "./function.js";
 import { printFunctionParameters } from "./function-parameters.js";
+import { printTrailingComma } from "./miscellaneous.js";
 
 /**
  * @import AstPath from "../../common/ast-path.js"
@@ -291,8 +291,9 @@ function printArrowFunctionBody(
 ) {
   const { node, parent } = path;
 
-  const trailingComma =
-    args.expandLastArg && shouldPrintComma(options, "all") ? ifBreak(",") : "";
+  const trailingComma = args.expandLastArg
+    ? printTrailingComma(options, "all")
+    : "";
 
   // if the arrow function is expanded as last argument, we are adding a
   // level of indentation and need to add a softline to align the closing )

src/language-js/print/call-arguments.js

@@ -4,7 +4,6 @@ import {
   conditionalGroup,
   group,
   hardline,
-  ifBreak,
   indent,
   line,
   softline,
@@ -34,10 +33,12 @@ import {
   isRegExpLiteral,
   isStringLiteral,
 } from "../utilities/node-types.js";
-import { shouldPrintComma } from "../utilities/should-print-comma.js";
 import { stripChainElementWrappers } from "../utilities/strip-chain-element-wrappers.js";
 import { isConciselyPrintedArray } from "./array.js";
-import { printDanglingCommentsInList } from "./miscellaneous.js";
+import {
+  printDanglingCommentsInList,
+  printTrailingComma,
+} from "./miscellaneous.js";
 
 /*
 - `NewExpression`
@@ -89,20 +90,19 @@ function printCallArguments(path, options, print) {
     printedArguments.push(argDoc);
   });
 
-  const maybeTrailingComma =
+  const trailingComma =
     // Angular does not allow trailing comma
     path.root.type !== "NGRoot" &&
     // Dynamic imports cannot have trailing commas
     node.type !== "ImportExpression" &&
     node.type !== "TSImportType" &&
-    node.type !== "TSExternalModuleReference" &&
-    shouldPrintComma(options, "all")
-      ? ","
+    node.type !== "TSExternalModuleReference"
+      ? printTrailingComma(options, "all")
       : "";
 
   function allArgsBrokenOut() {
     return group(
-      ["(", indent([line, ...printedArguments]), maybeTrailingComma, line, ")"],
+      ["(", indent([line, ...printedArguments]), trailingComma, line, ")"],
       { shouldBreak: true },
     );
   }
@@ -187,7 +187,7 @@ function printCallArguments(path, options, print) {
   const contents = [
     "(",
     indent([softline, ...printedArguments]),
-    ifBreak(maybeTrailingComma),
+    trailingComma,
     softline,
     ")",
   ];

src/language-js/print/class-body.js

@@ -17,8 +17,8 @@ import {
 } from "../utilities/comments.js";
 import { createTypeCheckFunction } from "../utilities/create-type-check-function.js";
 import { isNextLineEmpty } from "../utilities/is-next-line-empty.js";
-import { shouldPrintComma } from "../utilities/should-print-comma.js";
 import { shouldHugTheOnlyParameter } from "./function-parameters.js";
+import { printTrailingComma } from "./miscellaneous.js";
 
 /*
 - `ClassBody`
@@ -49,8 +49,8 @@ function printClassBody(path, options, print) {
 
       if (parent.inexact || !isLast) {
         parts.push(",");
-      } else if (shouldPrintComma(options)) {
-        parts.push(ifBreak(","));
+      } else {
+        parts.push(printTrailingComma(options));
       }
     }
 

src/language-js/print/function-parameters.js

@@ -2,7 +2,6 @@ import { ArgExpansionBailout } from "../../common/errors.js";
 import {
   group,
   hardline,
-  ifBreak,
   indent,
   line,
   removeLines,
@@ -25,9 +24,11 @@ import {
   isObjectExpression,
   isObjectType,
 } from "../utilities/node-types.js";
-import { shouldPrintComma } from "../utilities/should-print-comma.js";
 import { isTestCall } from "../utilities/test-libraries.js";
-import { printDanglingCommentsInList } from "./miscellaneous.js";
+import {
+  printDanglingCommentsInList,
+  printTrailingComma,
+} from "./miscellaneous.js";
 
 /** @import AstPath from "../../common/ast-path.js" */
 
@@ -184,11 +185,7 @@ function printFunctionParameters(
     typeParametersDoc,
     "(",
     indent([softline, ...printed]),
-    ifBreak(
-      !hasRestParameter(functionNode) && shouldPrintComma(options, "all")
-        ? ","
-        : "",
-    ),
+    !hasRestParameter(functionNode) ? printTrailingComma(options, "all") : "",
     softline,
     ")",
   ];

src/language-js/print/index-signature.js

@@ -1,12 +1,6 @@
-import {
-  group,
-  ifBreak,
-  indent,
-  join,
-  softline,
-} from "../../document/index.js";
-import { shouldPrintComma } from "../utilities/should-print-comma.js";
+import { group, indent, join, softline } from "../../document/index.js";
 import { printClassMemberSemicolon } from "./class.js";
+import { printTrailingComma } from "./miscellaneous.js";
 import { printTypeAnnotationProperty } from "./type-annotation.js";
 
 function printIndexSignature(path, options, print) {
@@ -16,9 +10,7 @@ function printIndexSignature(path, options, print) {
   // aren't, this is more like a computed property name than an array.
   // So we leave off the trailing comma when there's just one parameter.
   const trailingComma =
-    node.parameters.length > 1
-      ? ifBreak(shouldPrintComma(options) ? "," : "")
-      : "";
+    node.parameters.length > 1 ? printTrailingComma(options) : "";
 
   const parametersGroup = group([
     indent([softline, join([", ", softline], path.map(print, "parameters"))]),

src/language-js/print/miscellaneous.js

@@ -1,6 +1,7 @@
 import {
   group,
   hardline,
+  ifBreak,
   indent,
   line,
   softline,
@@ -12,6 +13,7 @@ import {
   isCallExpression,
   isMemberExpression,
 } from "../utilities/node-types.js";
+import { shouldPrintTrailingComma } from "../utilities/should-print-trailing-comma.js";
 
 /**
 @import AstPath from "../../common/ast-path.js"
@@ -192,6 +194,14 @@ function printDanglingCommentsInList(path, options, filter) {
     : "";
 }
 
+/**
+ * @param {("es5" | "all")} [level]
+ * @returns {Doc}
+ */
+function printTrailingComma(options, level = "es5") {
+  return shouldPrintTrailingComma(options, level) ? ifBreak(",") : "";
+}
+
 export {
   adjustClause,
   printAbstractToken,
@@ -201,6 +211,7 @@ export {
   printIfOrWhileCondition as printDoWhileStatementCondition,
   printIfOrWhileCondition as printIfStatementCondition,
   printOptionalToken,
+  printTrailingComma,
   printTypeScriptAccessibilityToken,
   printIfOrWhileCondition as printWhileStatementCondition,
 };

src/language-js/print/module.js

@@ -1,7 +1,6 @@
 import {
   group,
   hardline,
-  ifBreak,
   indent,
   join,
   line,
@@ -18,9 +17,8 @@ import getTextWithoutComments from "../utilities/get-text-without-comments.js";
 import { isShorthandSpecifier } from "../utilities/is-shorthand-specifier.js";
 import { needsHardlineAfterDanglingComment } from "../utilities/needs-hardline-after-dangling-comment.js";
 import { isStringLiteral } from "../utilities/node-types.js";
-import { shouldPrintComma } from "../utilities/should-print-comma.js";
 import { printDecoratorsBeforeExport } from "./decorators.js";
-import { printDeclareToken } from "./miscellaneous.js";
+import { printDeclareToken, printTrailingComma } from "./miscellaneous.js";
 import { printObject } from "./object.js";
 
 /**
@@ -211,7 +209,7 @@ function printModuleSpecifiers(path, options, print) {
               options.bracketSpacing ? line : softline,
               join([",", line], groupedSpecifiers),
             ]),
-            ifBreak(shouldPrintComma(options) ? "," : ""),
+            printTrailingComma(options),
             options.bracketSpacing ? line : softline,
             "}",
           ]),

src/language-js/print/object.js

@@ -2,7 +2,6 @@ import * as assert from "#universal/assert";
 import {
   group,
   hardline,
-  ifBreak,
   indent,
   line,
   softline,
@@ -21,11 +20,11 @@ import { createTypeCheckFunction } from "../utilities/create-type-check-function
 import getTextWithoutComments from "../utilities/get-text-without-comments.js";
 import { isNextLineEmpty } from "../utilities/is-next-line-empty.js";
 import { isObjectType } from "../utilities/node-types.js";
-import { shouldPrintComma } from "../utilities/should-print-comma.js";
 import { shouldHugTheOnlyParameter } from "./function-parameters.js";
 import {
   printDanglingCommentsInList,
   printOptionalToken,
+  printTrailingComma,
 } from "./miscellaneous.js";
 import { printTypeAnnotationProperty } from "./type-annotation.js";
 
@@ -149,7 +148,7 @@ function printObject(path, options, print) {
     content = [
       "{",
       indent([spacing, ...parts]),
-      ifBreak(canHaveTrailingSeparator && shouldPrintComma(options) ? "," : ""),
+      canHaveTrailingSeparator ? printTrailingComma(options) : "",
       spacing,
       "}",
       printOptionalToken(path),

src/language-js/print/type-parameters.js

@@ -1,7 +1,6 @@
 import {
   group,
   hardline,
-  ifBreak,
   indent,
   indentIfBreak,
   join,
@@ -15,9 +14,9 @@ import { locEnd } from "../loc.js";
 import { CommentCheckFlags, hasComment } from "../utilities/comments.js";
 import { getFunctionParameters } from "../utilities/function-parameters.js";
 import { isObjectType } from "../utilities/node-types.js";
-import { shouldPrintComma } from "../utilities/should-print-comma.js";
 import { isTestCall } from "../utilities/test-libraries.js";
 import { isArrowFunctionVariableDeclarator } from "./assignment.js";
+import { printTrailingComma } from "./miscellaneous.js";
 import {
   printTypeAnnotationProperty,
   shouldHugType,
@@ -108,9 +107,7 @@ function printTypeParameters(path, options, print, paramsKey) {
       ? ""
       : shouldForceTrailingComma(path, options, paramsKey)
         ? ","
-        : shouldPrintComma(options)
-          ? ifBreak(",")
-          : "";
+        : printTrailingComma(options);
 
   return group([
     "<",

src/language-js/utilities/should-print-trailing-comma.js

@@ -3,11 +3,11 @@
  * @param {("es5" | "all")} [level]
  * @returns {boolean}
  */
-function shouldPrintComma(options, level = "es5") {
+function shouldPrintTrailingComma(options, level = "es5") {
   return (
     (options.trailingComma === "es5" && level === "es5") ||
     (options.trailingComma === "all" && (level === "all" || level === "es5"))
   );
 }
 
-export { shouldPrintComma };
+export { shouldPrintTrailingComma };