279 lines
10 KiB
JavaScript
279 lines
10 KiB
JavaScript
/**
|
|
* @fileoverview Rule to control usage of strict mode directives.
|
|
* @author Brandon Mills
|
|
*/
|
|
|
|
"use strict";
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Requirements
|
|
//------------------------------------------------------------------------------
|
|
|
|
const astUtils = require("../ast-utils");
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Helpers
|
|
//------------------------------------------------------------------------------
|
|
|
|
const 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."
|
|
};
|
|
|
|
/**
|
|
* 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
|
|
//------------------------------------------------------------------------------
|
|
|
|
module.exports = {
|
|
meta: {
|
|
docs: {
|
|
description: "require or disallow strict mode directives",
|
|
category: "Strict Mode",
|
|
recommended: false,
|
|
url: "https://eslint.org/docs/rules/strict"
|
|
},
|
|
|
|
schema: [
|
|
{
|
|
enum: ["never", "global", "function", "safe"]
|
|
}
|
|
],
|
|
|
|
fixable: "code"
|
|
},
|
|
|
|
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} message Message to display.
|
|
* @param {boolean} fix `true` if the directive should be fixed (i.e. removed)
|
|
* @returns {void}
|
|
*/
|
|
function reportSlice(nodes, start, end, message, fix) {
|
|
nodes.slice(start, end).forEach(node => {
|
|
context.report({ node, message, fix: fix ? getFixFunction(node) : null });
|
|
});
|
|
}
|
|
|
|
/**
|
|
* Report all nodes in an array with a given message.
|
|
* @param {ASTNode[]} nodes Nodes.
|
|
* @param {string} message Message to display.
|
|
* @param {boolean} fix `true` if the directive should be fixed (i.e. removed)
|
|
* @returns {void}
|
|
*/
|
|
function reportAll(nodes, message, fix) {
|
|
reportSlice(nodes, 0, nodes.length, message, fix);
|
|
}
|
|
|
|
/**
|
|
* Report all nodes in an array, except the first, with a given message.
|
|
* @param {ASTNode[]} nodes Nodes.
|
|
* @param {string} message Message to display.
|
|
* @param {boolean} fix `true` if the directive should be fixed (i.e. removed)
|
|
* @returns {void}
|
|
*/
|
|
function reportAllExceptFirst(nodes, message, fix) {
|
|
reportSlice(nodes, 1, nodes.length, message, 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], message: messages.nonSimpleParameterList });
|
|
} else if (isParentStrict) {
|
|
context.report({ node: useStrictDirectives[0], message: messages.unnecessary, fix: getFixFunction(useStrictDirectives[0]) });
|
|
} else if (isInClass) {
|
|
context.report({ node: useStrictDirectives[0], message: messages.unnecessaryInClasses, fix: getFixFunction(useStrictDirectives[0]) });
|
|
}
|
|
|
|
reportAllExceptFirst(useStrictDirectives, messages.multiple, true);
|
|
} else if (isParentGlobal) {
|
|
if (isSimpleParameterList(node.params)) {
|
|
context.report({ node, message: messages.function });
|
|
} else {
|
|
context.report({
|
|
node,
|
|
message: messages.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, messages[mode], shouldFix(mode));
|
|
} else {
|
|
context.report({ node: useStrictDirectives[0], message: messages.nonSimpleParameterList });
|
|
reportAllExceptFirst(useStrictDirectives, messages.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, message: messages.global });
|
|
}
|
|
reportAllExceptFirst(useStrictDirectives, messages.multiple, true);
|
|
} else {
|
|
reportAll(useStrictDirectives, messages[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;
|
|
}
|
|
};
|