Current File : /var/www/html/node_modules/eslint/lib/rules/strict.js
/**
* @fileoverview Rule to control usage of strict mode directives.
* @author Brandon Mills
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const astUtils = require("./utils/ast-utils");
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
/**
* Gets all of the Use Strict Directives in the Directive Prologue of a group of
* statements.
* @param {ASTNode[]} statements Statements in the program or function body.
* @returns {ASTNode[]} All of the Use Strict Directives.
*/
function getUseStrictDirectives(statements) {
const directives = [];
for (let i = 0; i < statements.length; i++) {
const statement = statements[i];
if (
statement.type === "ExpressionStatement" &&
statement.expression.type === "Literal" &&
statement.expression.value === "use strict"
) {
directives[i] = statement;
} else {
break;
}
}
return directives;
}
/**
* Checks whether a given parameter is a simple parameter.
* @param {ASTNode} node A pattern node to check.
* @returns {boolean} `true` if the node is an Identifier node.
*/
function isSimpleParameter(node) {
return node.type === "Identifier";
}
/**
* Checks whether a given parameter list is a simple parameter list.
* @param {ASTNode[]} params A parameter list to check.
* @returns {boolean} `true` if the every parameter is an Identifier node.
*/
function isSimpleParameterList(params) {
return params.every(isSimpleParameter);
}
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../shared/types').Rule} */
module.exports = {
meta: {
type: "suggestion",
docs: {
description: "require or disallow strict mode directives",
recommended: false,
url: "https://eslint.org/docs/rules/strict"
},
schema: [
{
enum: ["never", "global", "function", "safe"]
}
],
fixable: "code",
messages: {
function: "Use the function form of 'use strict'.",
global: "Use the global form of 'use strict'.",
multiple: "Multiple 'use strict' directives.",
never: "Strict mode is not permitted.",
unnecessary: "Unnecessary 'use strict' directive.",
module: "'use strict' is unnecessary inside of modules.",
implied: "'use strict' is unnecessary when implied strict mode is enabled.",
unnecessaryInClasses: "'use strict' is unnecessary inside of classes.",
nonSimpleParameterList: "'use strict' directive inside a function with non-simple parameter list throws a syntax error since ES2016.",
wrap: "Wrap {{name}} in a function with 'use strict' directive."
}
},
create(context) {
const ecmaFeatures = context.parserOptions.ecmaFeatures || {},
scopes = [],
classScopes = [];
let mode = context.options[0] || "safe";
if (ecmaFeatures.impliedStrict) {
mode = "implied";
} else if (mode === "safe") {
mode = ecmaFeatures.globalReturn ? "global" : "function";
}
/**
* Determines whether a reported error should be fixed, depending on the error type.
* @param {string} errorType The type of error
* @returns {boolean} `true` if the reported error should be fixed
*/
function shouldFix(errorType) {
return errorType === "multiple" || errorType === "unnecessary" || errorType === "module" || errorType === "implied" || errorType === "unnecessaryInClasses";
}
/**
* Gets a fixer function to remove a given 'use strict' directive.
* @param {ASTNode} node The directive that should be removed
* @returns {Function} A fixer function
*/
function getFixFunction(node) {
return fixer => fixer.remove(node);
}
/**
* Report a slice of an array of nodes with a given message.
* @param {ASTNode[]} nodes Nodes.
* @param {string} start Index to start from.
* @param {string} end Index to end before.
* @param {string} messageId Message to display.
* @param {boolean} fix `true` if the directive should be fixed (i.e. removed)
* @returns {void}
*/
function reportSlice(nodes, start, end, messageId, fix) {
nodes.slice(start, end).forEach(node => {
context.report({ node, messageId, fix: fix ? getFixFunction(node) : null });
});
}
/**
* Report all nodes in an array with a given message.
* @param {ASTNode[]} nodes Nodes.
* @param {string} messageId Message id to display.
* @param {boolean} fix `true` if the directive should be fixed (i.e. removed)
* @returns {void}
*/
function reportAll(nodes, messageId, fix) {
reportSlice(nodes, 0, nodes.length, messageId, fix);
}
/**
* Report all nodes in an array, except the first, with a given message.
* @param {ASTNode[]} nodes Nodes.
* @param {string} messageId Message id to display.
* @param {boolean} fix `true` if the directive should be fixed (i.e. removed)
* @returns {void}
*/
function reportAllExceptFirst(nodes, messageId, fix) {
reportSlice(nodes, 1, nodes.length, messageId, fix);
}
/**
* Entering a function in 'function' mode pushes a new nested scope onto the
* stack. The new scope is true if the nested function is strict mode code.
* @param {ASTNode} node The function declaration or expression.
* @param {ASTNode[]} useStrictDirectives The Use Strict Directives of the node.
* @returns {void}
*/
function enterFunctionInFunctionMode(node, useStrictDirectives) {
const isInClass = classScopes.length > 0,
isParentGlobal = scopes.length === 0 && classScopes.length === 0,
isParentStrict = scopes.length > 0 && scopes[scopes.length - 1],
isStrict = useStrictDirectives.length > 0;
if (isStrict) {
if (!isSimpleParameterList(node.params)) {
context.report({ node: useStrictDirectives[0], messageId: "nonSimpleParameterList" });
} else if (isParentStrict) {
context.report({ node: useStrictDirectives[0], messageId: "unnecessary", fix: getFixFunction(useStrictDirectives[0]) });
} else if (isInClass) {
context.report({ node: useStrictDirectives[0], messageId: "unnecessaryInClasses", fix: getFixFunction(useStrictDirectives[0]) });
}
reportAllExceptFirst(useStrictDirectives, "multiple", true);
} else if (isParentGlobal) {
if (isSimpleParameterList(node.params)) {
context.report({ node, messageId: "function" });
} else {
context.report({
node,
messageId: "wrap",
data: { name: astUtils.getFunctionNameWithKind(node) }
});
}
}
scopes.push(isParentStrict || isStrict);
}
/**
* Exiting a function in 'function' mode pops its scope off the stack.
* @returns {void}
*/
function exitFunctionInFunctionMode() {
scopes.pop();
}
/**
* Enter a function and either:
* - Push a new nested scope onto the stack (in 'function' mode).
* - Report all the Use Strict Directives (in the other modes).
* @param {ASTNode} node The function declaration or expression.
* @returns {void}
*/
function enterFunction(node) {
const isBlock = node.body.type === "BlockStatement",
useStrictDirectives = isBlock
? getUseStrictDirectives(node.body.body) : [];
if (mode === "function") {
enterFunctionInFunctionMode(node, useStrictDirectives);
} else if (useStrictDirectives.length > 0) {
if (isSimpleParameterList(node.params)) {
reportAll(useStrictDirectives, mode, shouldFix(mode));
} else {
context.report({ node: useStrictDirectives[0], messageId: "nonSimpleParameterList" });
reportAllExceptFirst(useStrictDirectives, "multiple", true);
}
}
}
const rule = {
Program(node) {
const useStrictDirectives = getUseStrictDirectives(node.body);
if (node.sourceType === "module") {
mode = "module";
}
if (mode === "global") {
if (node.body.length > 0 && useStrictDirectives.length === 0) {
context.report({ node, messageId: "global" });
}
reportAllExceptFirst(useStrictDirectives, "multiple", true);
} else {
reportAll(useStrictDirectives, mode, shouldFix(mode));
}
},
FunctionDeclaration: enterFunction,
FunctionExpression: enterFunction,
ArrowFunctionExpression: enterFunction
};
if (mode === "function") {
Object.assign(rule, {
// Inside of class bodies are always strict mode.
ClassBody() {
classScopes.push(true);
},
"ClassBody:exit"() {
classScopes.pop();
},
"FunctionDeclaration:exit": exitFunctionInFunctionMode,
"FunctionExpression:exit": exitFunctionInFunctionMode,
"ArrowFunctionExpression:exit": exitFunctionInFunctionMode
});
}
return rule;
}
};
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