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/**
* @fileoverview Rule to check the spacing around the * in generator functions.
* @author Jamund Ferguson
*/
"use strict";
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
const OVERRIDE_SCHEMA = {
oneOf: [
{
enum: ["before", "after", "both", "neither"]
},
{
type: "object",
properties: {
before: { type: "boolean" },
after: { type: "boolean" }
},
additionalProperties: false
}
]
};
/** @type {import('../shared/types').Rule} */
module.exports = {
meta: {
type: "layout",
docs: {
description: "Enforce consistent spacing around `*` operators in generator functions",
recommended: false,
url: "https://eslint.org/docs/rules/generator-star-spacing"
},
fixable: "whitespace",
schema: [
{
oneOf: [
{
enum: ["before", "after", "both", "neither"]
},
{
type: "object",
properties: {
before: { type: "boolean" },
after: { type: "boolean" },
named: OVERRIDE_SCHEMA,
anonymous: OVERRIDE_SCHEMA,
method: OVERRIDE_SCHEMA
},
additionalProperties: false
}
]
}
],
messages: {
missingBefore: "Missing space before *.",
missingAfter: "Missing space after *.",
unexpectedBefore: "Unexpected space before *.",
unexpectedAfter: "Unexpected space after *."
}
},
create(context) {
const optionDefinitions = {
before: { before: true, after: false },
after: { before: false, after: true },
both: { before: true, after: true },
neither: { before: false, after: false }
};
/**
* Returns resolved option definitions based on an option and defaults
* @param {any} option The option object or string value
* @param {Object} defaults The defaults to use if options are not present
* @returns {Object} the resolved object definition
*/
function optionToDefinition(option, defaults) {
if (!option) {
return defaults;
}
return typeof option === "string"
? optionDefinitions[option]
: Object.assign({}, defaults, option);
}
const modes = (function(option) {
const defaults = optionToDefinition(option, optionDefinitions.before);
return {
named: optionToDefinition(option.named, defaults),
anonymous: optionToDefinition(option.anonymous, defaults),
method: optionToDefinition(option.method, defaults)
};
}(context.options[0] || {}));
const sourceCode = context.getSourceCode();
/**
* Checks if the given token is a star token or not.
* @param {Token} token The token to check.
* @returns {boolean} `true` if the token is a star token.
*/
function isStarToken(token) {
return token.value === "*" && token.type === "Punctuator";
}
/**
* Gets the generator star token of the given function node.
* @param {ASTNode} node The function node to get.
* @returns {Token} Found star token.
*/
function getStarToken(node) {
return sourceCode.getFirstToken(
(node.parent.method || node.parent.type === "MethodDefinition") ? node.parent : node,
isStarToken
);
}
/**
* capitalize a given string.
* @param {string} str the given string.
* @returns {string} the capitalized string.
*/
function capitalize(str) {
return str[0].toUpperCase() + str.slice(1);
}
/**
* Checks the spacing between two tokens before or after the star token.
* @param {string} kind Either "named", "anonymous", or "method"
* @param {string} side Either "before" or "after".
* @param {Token} leftToken `function` keyword token if side is "before", or
* star token if side is "after".
* @param {Token} rightToken Star token if side is "before", or identifier
* token if side is "after".
* @returns {void}
*/
function checkSpacing(kind, side, leftToken, rightToken) {
if (!!(rightToken.range[0] - leftToken.range[1]) !== modes[kind][side]) {
const after = leftToken.value === "*";
const spaceRequired = modes[kind][side];
const node = after ? leftToken : rightToken;
const messageId = `${spaceRequired ? "missing" : "unexpected"}${capitalize(side)}`;
context.report({
node,
messageId,
fix(fixer) {
if (spaceRequired) {
if (after) {
return fixer.insertTextAfter(node, " ");
}
return fixer.insertTextBefore(node, " ");
}
return fixer.removeRange([leftToken.range[1], rightToken.range[0]]);
}
});
}
}
/**
* Enforces the spacing around the star if node is a generator function.
* @param {ASTNode} node A function expression or declaration node.
* @returns {void}
*/
function checkFunction(node) {
if (!node.generator) {
return;
}
const starToken = getStarToken(node);
const prevToken = sourceCode.getTokenBefore(starToken);
const nextToken = sourceCode.getTokenAfter(starToken);
let kind = "named";
if (node.parent.type === "MethodDefinition" || (node.parent.type === "Property" && node.parent.method)) {
kind = "method";
} else if (!node.id) {
kind = "anonymous";
}
// Only check before when preceded by `function`|`static` keyword
if (!(kind === "method" && starToken === sourceCode.getFirstToken(node.parent))) {
checkSpacing(kind, "before", prevToken, starToken);
}
checkSpacing(kind, "after", starToken, nextToken);
}
return {
FunctionDeclaration: checkFunction,
FunctionExpression: checkFunction
};
}
};