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node_modules/eslint/lib/rules/prefer-numeric-literals.js

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+/**
+ * @fileoverview Rule to disallow `parseInt()` in favor of binary, octal, and hexadecimal literals
+ * @author Annie Zhang, Henry Zhu
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+/**
+ * Checks to see if a CallExpression's callee node is `parseInt` or
+ * `Number.parseInt`.
+ * @param {ASTNode} calleeNode The callee node to evaluate.
+ * @returns {boolean} True if the callee is `parseInt` or `Number.parseInt`,
+ * false otherwise.
+ */
+function isParseInt(calleeNode) {
+    switch (calleeNode.type) {
+        case "Identifier":
+            return calleeNode.name === "parseInt";
+        case "MemberExpression":
+            return calleeNode.object.type === "Identifier" &&
+                calleeNode.object.name === "Number" &&
+                calleeNode.property.type === "Identifier" &&
+                calleeNode.property.name === "parseInt";
+
+        // no default
+    }
+
+    return false;
+}
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+    meta: {
+        type: "suggestion",
+
+        docs: {
+            description: "disallow `parseInt()` and `Number.parseInt()` in favor of binary, octal, and hexadecimal literals",
+            category: "ECMAScript 6",
+            recommended: false,
+            url: "https://eslint.org/docs/rules/prefer-numeric-literals"
+        },
+
+        schema: [],
+        fixable: "code"
+    },
+
+    create(context) {
+        const sourceCode = context.getSourceCode();
+
+        const radixMap = {
+            2: "binary",
+            8: "octal",
+            16: "hexadecimal"
+        };
+
+        const prefixMap = {
+            2: "0b",
+            8: "0o",
+            16: "0x"
+        };
+
+        //----------------------------------------------------------------------
+        // Public
+        //----------------------------------------------------------------------
+
+        return {
+
+            CallExpression(node) {
+
+                // doesn't check parseInt() if it doesn't have a radix argument
+                if (node.arguments.length !== 2) {
+                    return;
+                }
+
+                // only error if the radix is 2, 8, or 16
+                const radixName = radixMap[node.arguments[1].value];
+
+                if (isParseInt(node.callee) &&
+                    radixName &&
+                    node.arguments[0].type === "Literal"
+                ) {
+                    context.report({
+                        node,
+                        message: "Use {{radixName}} literals instead of {{functionName}}().",
+                        data: {
+                            radixName,
+                            functionName: sourceCode.getText(node.callee)
+                        },
+                        fix(fixer) {
+                            const newPrefix = prefixMap[node.arguments[1].value];
+
+                            if (sourceCode.getCommentsInside(node).length) {
+                                return null;
+                            }
+
+                            if (+(newPrefix + node.arguments[0].value) !== parseInt(node.arguments[0].value, node.arguments[1].value)) {
+
+                                /*
+                                 * If the newly-produced literal would be invalid, (e.g. 0b1234),
+                                 * or it would yield an incorrect parseInt result for some other reason, don't make a fix.
+                                 */
+                                return null;
+                            }
+                            return fixer.replaceText(node, prefixMap[node.arguments[1].value] + node.arguments[0].value);
+                        }
+                    });
+                }
+            }
+        };
+    }
+};