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app_vue/node_modules/webpack-sources/lib/helpers/stringBufferUtils.js

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+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Mark Knichel @mknichel
+*/
+
+"use strict";
+
+let dualStringBufferCaching = true;
+
+/**
+ * @returns {boolean} Whether the optimization to cache copies of both the
+ * string and buffer version of source content is enabled. This is enabled by
+ * default to improve performance but can consume more memory since values are
+ * stored twice.
+ */
+function isDualStringBufferCachingEnabled() {
+	return dualStringBufferCaching;
+}
+
+/**
+ * Enables an optimization to save both string and buffer in memory to avoid
+ * repeat conversions between the two formats when they are requested. This
+ * is enabled by default. This option can improve performance but can consume
+ * additional memory since values are stored twice.
+ *
+ * @returns {void}
+ */
+function enableDualStringBufferCaching() {
+	dualStringBufferCaching = true;
+}
+
+/**
+ * Disables the optimization to save both string and buffer in memory. This
+ * may increase performance but should reduce memory usage in the Webpack
+ * compiler.
+ *
+ * @returns {void}
+ */
+function disableDualStringBufferCaching() {
+	dualStringBufferCaching = false;
+}
+
+const interningStringMap = new Map();
+
+/**
+ * Saves the string in a map to ensure that only one copy of the string exists
+ * in memory at a given time. This is controlled by {@link enableStringInterning}
+ * and {@link disableStringInterning}. Callers are expect to manage the memory
+ * of the interned strings by calling {@link disableStringInterning} after the
+ * compiler no longer needs to save the interned memory.
+ *
+ * @param {string} str A string to be interned.
+ * @returns {string} The original string or a reference to an existing string of the same value if it has already been interned.
+ */
+function internString(str) {
+	if (
+		!isStringInterningEnabled() ||
+		!str ||
+		str.length < 128 ||
+		typeof str !== "string"
+	) {
+		return str;
+	}
+	let internedString = interningStringMap.get(str);
+	if (internedString === undefined) {
+		internedString = str;
+		interningStringMap.set(str, internedString);
+	}
+	return internedString;
+}
+
+let enableStringInterningRefCount = 0;
+
+/**
+ * @returns {boolean} value
+ */
+function isStringInterningEnabled() {
+	return enableStringInterningRefCount > 0;
+}
+
+/**
+ * Starts a memory optimization to avoid repeat copies of the same string in
+ * memory by caching a single reference to the string. This can reduce memory
+ * usage if the same string is repeated many times in the compiler, such as
+ * when Webpack layers are used with the same files.
+ *
+ * {@link exitStringInterningRange} should be called when string interning is
+ * no longer necessary to free up the memory used by the interned strings. If
+ * {@link enterStringInterningRange} has been called multiple times, then
+ * this method may not immediately free all the memory until
+ * {@link exitStringInterningRange} has been called to end all string
+ * interning ranges.
+ *
+ * @returns {void}
+ */
+function enterStringInterningRange() {
+	enableStringInterningRefCount++;
+}
+
+/**
+ * Stops the current string interning range. Once all string interning ranges
+ * have been exited, this method will free all the memory used by the interned
+ * strings. This method should be called once for each time that
+ * {@link enterStringInterningRange} was called.
+ *
+ * @returns {void}
+ */
+function exitStringInterningRange() {
+	if (--enableStringInterningRefCount <= 0) {
+		interningStringMap.clear();
+		enableStringInterningRefCount = 0;
+	}
+}
+
+module.exports = {
+	disableDualStringBufferCaching,
+	enableDualStringBufferCaching,
+	internString,
+	isDualStringBufferCachingEnabled,
+	enterStringInterningRange,
+	exitStringInterningRange
+};