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Diffstat (limited to 'tools/node_modules/eslint/lib/rules/no-extra-bind.js')
-rw-r--r-- | tools/node_modules/eslint/lib/rules/no-extra-bind.js | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/tools/node_modules/eslint/lib/rules/no-extra-bind.js b/tools/node_modules/eslint/lib/rules/no-extra-bind.js new file mode 100644 index 0000000000..2d22eff245 --- /dev/null +++ b/tools/node_modules/eslint/lib/rules/no-extra-bind.js @@ -0,0 +1,145 @@ +/** + * @fileoverview Rule to flag unnecessary bind calls + * @author Bence Dányi <bence@danyi.me> + */ +"use strict"; + +//------------------------------------------------------------------------------ +// Requirements +//------------------------------------------------------------------------------ + +const astUtils = require("../ast-utils"); + +//------------------------------------------------------------------------------ +// Rule Definition +//------------------------------------------------------------------------------ + +module.exports = { + meta: { + docs: { + description: "disallow unnecessary calls to `.bind()`", + category: "Best Practices", + recommended: false + }, + + schema: [], + + fixable: "code" + }, + + create(context) { + let scopeInfo = null; + + /** + * Reports a given function node. + * + * @param {ASTNode} node - A node to report. This is a FunctionExpression or + * an ArrowFunctionExpression. + * @returns {void} + */ + function report(node) { + context.report({ + node: node.parent.parent, + message: "The function binding is unnecessary.", + loc: node.parent.property.loc.start, + fix(fixer) { + const firstTokenToRemove = context.getSourceCode() + .getFirstTokenBetween(node.parent.object, node.parent.property, astUtils.isNotClosingParenToken); + + return fixer.removeRange([firstTokenToRemove.range[0], node.parent.parent.range[1]]); + } + }); + } + + /** + * Checks whether or not a given function node is the callee of `.bind()` + * method. + * + * e.g. `(function() {}.bind(foo))` + * + * @param {ASTNode} node - A node to report. This is a FunctionExpression or + * an ArrowFunctionExpression. + * @returns {boolean} `true` if the node is the callee of `.bind()` method. + */ + function isCalleeOfBindMethod(node) { + const parent = node.parent; + const grandparent = parent.parent; + + return ( + grandparent && + grandparent.type === "CallExpression" && + grandparent.callee === parent && + grandparent.arguments.length === 1 && + parent.type === "MemberExpression" && + parent.object === node && + astUtils.getStaticPropertyName(parent) === "bind" + ); + } + + /** + * Adds a scope information object to the stack. + * + * @param {ASTNode} node - A node to add. This node is a FunctionExpression + * or a FunctionDeclaration node. + * @returns {void} + */ + function enterFunction(node) { + scopeInfo = { + isBound: isCalleeOfBindMethod(node), + thisFound: false, + upper: scopeInfo + }; + } + + /** + * Removes the scope information object from the top of the stack. + * At the same time, this reports the function node if the function has + * `.bind()` and the `this` keywords found. + * + * @param {ASTNode} node - A node to remove. This node is a + * FunctionExpression or a FunctionDeclaration node. + * @returns {void} + */ + function exitFunction(node) { + if (scopeInfo.isBound && !scopeInfo.thisFound) { + report(node); + } + + scopeInfo = scopeInfo.upper; + } + + /** + * Reports a given arrow function if the function is callee of `.bind()` + * method. + * + * @param {ASTNode} node - A node to report. This node is an + * ArrowFunctionExpression. + * @returns {void} + */ + function exitArrowFunction(node) { + if (isCalleeOfBindMethod(node)) { + report(node); + } + } + + /** + * Set the mark as the `this` keyword was found in this scope. + * + * @returns {void} + */ + function markAsThisFound() { + if (scopeInfo) { + scopeInfo.thisFound = true; + } + } + + return { + "ArrowFunctionExpression:exit": exitArrowFunction, + FunctionDeclaration: enterFunction, + "FunctionDeclaration:exit": exitFunction, + FunctionExpression: enterFunction, + "FunctionExpression:exit": exitFunction, + ThisExpression: markAsThisFound + }; + } +}; |