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kitabcitab/node_modules/jsx-ast-utils/src/values/expressions/UnaryExpression.js

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+/**
+ * Extractor function for a UnaryExpression type value node.
+ * A unary expression is an expression with a unary operator.
+ * For example, !"foobar" will evaluate to false, so this will return false.
+ *
+ * @param - value - AST Value object with type `UnaryExpression`
+ * @returns - The extracted value converted to correct type.
+ */
+export default function extractValueFromUnaryExpression(value) {
+  // eslint-disable-next-line global-require
+  const getValue = require('.').default;
+  const { operator, argument } = value;
+
+  switch (operator) {
+    case '-':
+      return -getValue(argument);
+    case '+':
+      return +getValue(argument); // eslint-disable-line no-implicit-coercion
+    case '!':
+      return !getValue(argument);
+    case '~':
+      return ~getValue(argument); // eslint-disable-line no-bitwise
+    case 'delete':
+      // I believe delete statements evaluate to true.
+      return true;
+    case 'typeof':
+    case 'void':
+    default:
+      return undefined;
+  }
+}