pref: reduce memory consumption

lib/util/entrypoints.js

@@ -86,7 +86,7 @@ module.exports.processExportsField = function processExportsField(
 ) {
 	return createFieldProcessor(
 		buildExportsField(exportsField),
-		"",
+		request => (request.length === 0 ? "." : "./" + request),
 		assertExportsFieldRequest,
 		assertExportTarget
 	);
@@ -101,24 +101,29 @@ module.exports.processImportsField = function processImportsField(
 ) {
 	return createFieldProcessor(
 		buildImportsField(importsField),
-		"#",
+		request => "#" + request,
 		assertImportsFieldRequest,
 		assertImportTarget
 	);
 };
 
 /**
  * @param {ExportsField | ImportsField} field root
- * @param {string} prefix Request prefix, for `imports` field it is `#`, for `exports` field it is `./`.
+ * @param {(s: string) => string} normalizeRequest Normalize request, for `imports` field it adds `#`, for `exports` field it adds `.` or `./`
  * @param {(s: string) => string} assertRequest assertRequest
  * @param {(s: string, f: boolean) => void} assertTarget assertTarget
  * @returns {FieldProcessor} field processor
  */
-function createFieldProcessor(field, prefix, assertRequest, assertTarget) {
+function createFieldProcessor(
+	field,
+	normalizeRequest,
+	assertRequest,
+	assertTarget
+) {
 	return function fieldProcessor(request, conditionNames) {
 		request = assertRequest(request);
 
-		const match = findMatch(prefix + request, field);
+		const match = findMatch(normalizeRequest(request), field);
 
 		if (match === null) return [];
 
@@ -270,10 +275,8 @@ function findMatch(request, field) {
 		!request.endsWith("/")
 	) {
 		const target = field[request];
-		const isSubpathMapping =
-			typeof target === "string" ? target.endsWith("/") : false;
 
-		return [target, "", isSubpathMapping, false];
+		return [target, "", false, false];
 	}
 
 	let bestMatch = "";
@@ -310,15 +313,6 @@ function findMatch(request, field) {
 			bestMatch = key;
 			bestMatchSubpath = request.slice(key.length);
 		}
-		// For legacy `./`
-		else if (
-			key === "./" &&
-			patternKeyCompare(bestMatch, key) === 1 &&
-			request.length > 0
-		) {
-			bestMatch = key;
-			bestMatchSubpath = request.slice(key.length - 2);
-		}
 	}
 
 	if (bestMatch === "") return null;
@@ -512,10 +506,9 @@ function conditionalMapping(conditionalMapping_, conditionNames) {
 function buildExportsField(field) {
 	// handle syntax sugar, if exports field is direct mapping for "."
 	if (typeof field === "string" || Array.isArray(field)) {
-		return { "": field };
+		return { ".": field };
 	}
 
-	const newField = /** @type {ExportsField} */ ({});
 	const keys = Object.keys(field);
 
 	for (let i = 0; i < keys.length; i++) {
@@ -536,7 +529,7 @@ function buildExportsField(field) {
 					i++;
 				}
 
-				return { "": field };
+				return { ".": field };
 			}
 
 			throw new Error(
@@ -547,8 +540,6 @@ function buildExportsField(field) {
 		}
 
 		if (key.length === 1) {
-			newField[""] = field[key];
-
 			continue;
 		}
 
@@ -559,12 +550,9 @@ function buildExportsField(field) {
 				)})`
 			);
 		}
-
-		// Keep "./" for legacy `{ "./": "./" }`
-		newField[key.slice(2) || "./"] = field[key];
 	}
 
-	return newField;
+	return field;
 }
 
 /**

test/exportsField.js

@@ -594,6 +594,56 @@ describe("Process exports field", function exportsField() {
 				[]
 			]
 		},
+		{
+			name: "Direct mapping #11",
+			expect: ["./foo.js"],
+			suite: [
+				{
+					"./": "./",
+					"./*": "./*",
+					"./dist/index.js": "./dist/index.js"
+				},
+				"./foo.js",
+				[]
+			]
+		},
+		{
+			name: "Direct mapping #12",
+			expect: ["./foo/bar/baz.js"],
+			suite: [
+				{
+					"./": "./",
+					"./*": "./*",
+					"./dist/index.js": "./dist/index.js"
+				},
+				"./foo/bar/baz.js",
+				[]
+			]
+		},
+		{
+			name: "Direct mapping #13",
+			expect: ["./foo/bar/baz.js"],
+			suite: [
+				{
+					"./": "./",
+					"./dist/index.js": "./dist/index.js"
+				},
+				"./foo/bar/baz.js",
+				[]
+			]
+		},
+		{
+			name: "Direct mapping #14",
+			expect: ["./foo/bar/baz.js"],
+			suite: [
+				{
+					"./*": "./*",
+					"./dist/index.js": "./dist/index.js"
+				},
+				"./foo/bar/baz.js",
+				[]
+			]
+		},
 		//#endregion
 
 		//#region Direct and conditional mapping