/**
* @fileoverview Common utils for AST.
* @author Gyandeep Singh
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const esutils = require("esutils");
const espree = require("espree");
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
const anyFunctionPattern = /^(?:Function(?:Declaration|Expression)|ArrowFunctionExpression)$/;
const anyLoopPattern = /^(?:DoWhile|For|ForIn|ForOf|While)Statement$/;
const arrayOrTypedArrayPattern = /Array$/;
const arrayMethodPattern = /^(?:every|filter|find|findIndex|forEach|map|some)$/;
const bindOrCallOrApplyPattern = /^(?:bind|call|apply)$/;
const breakableTypePattern = /^(?:(?:Do)?While|For(?:In|Of)?|Switch)Statement$/;
const thisTagPattern = /^[\s*]*@this/m;
const COMMENTS_IGNORE_PATTERN = /^\s*(?:eslint|jshint\s+|jslint\s+|istanbul\s+|globals?\s+|exported\s+|jscs)/;
const LINEBREAKS = new Set(["\r\n", "\r", "\n", "\u2028", "\u2029"]);
const LINEBREAK_MATCHER = /\r\n|[\r\n\u2028\u2029]/;
const SHEBANG_MATCHER = /^#!([^\r\n]+)/;
// A set of node types that can contain a list of statements
const STATEMENT_LIST_PARENTS = new Set(["Program", "BlockStatement", "SwitchCase"]);
/**
* Checks reference if is non initializer and writable.
* @param {Reference} reference - A reference to check.
* @param {int} index - The index of the reference in the references.
* @param {Reference[]} references - The array that the reference belongs to.
* @returns {boolean} Success/Failure
* @private
*/
function isModifyingReference(reference, index, references) {
const identifier = reference.identifier;
/*
* Destructuring assignments can have multiple default value, so
* possibly there are multiple writeable references for the same
* identifier.
*/
const modifyingDifferentIdentifier = index === 0 ||
references[index - 1].identifier !== identifier;
return (identifier &&
reference.init === false &&
reference.isWrite() &&
modifyingDifferentIdentifier
);
}
/**
* Checks whether the given string starts with uppercase or not.
*
* @param {string} s - The string to check.
* @returns {boolean} `true` if the string starts with uppercase.
*/
function startsWithUpperCase(s) {
return s[0] !== s[0].toLocaleLowerCase();
}
/**
* Checks whether or not a node is a constructor.
* @param {ASTNode} node - A function node to check.
* @returns {boolean} Wehether or not a node is a constructor.
*/
function isES5Constructor(node) {
return (node.id && startsWithUpperCase(node.id.name));
}
/**
* Finds a function node from ancestors of a node.
* @param {ASTNode} node - A start node to find.
* @returns {Node|null} A found function node.
*/
function getUpperFunction(node) {
for (let currentNode = node; currentNode; currentNode = currentNode.parent) {
if (anyFunctionPattern.test(currentNode.type)) {
return currentNode;
}
}
return null;
}
/**
* Checks whether a given node is a function node or not.
* The following types are function nodes:
*
* - ArrowFunctionExpression
* - FunctionDeclaration
* - FunctionExpression
*
* @param {ASTNode|null} node - A node to check.
* @returns {boolean} `true` if the node is a function node.
*/
function isFunction(node) {
return Boolean(node && anyFunctionPattern.test(node.type));
}
/**
* Checks whether a given node is a loop node or not.
* The following types are loop nodes:
*
* - DoWhileStatement
* - ForInStatement
* - ForOfStatement
* - ForStatement
* - WhileStatement
*
* @param {ASTNode|null} node - A node to check.
* @returns {boolean} `true` if the node is a loop node.
*/
function isLoop(node) {
return Boolean(node && anyLoopPattern.test(node.type));
}
/**
* Checks whether the given node is in a loop or not.
*
* @param {ASTNode} node - The node to check.
* @returns {boolean} `true` if the node is in a loop.
*/
function isInLoop(node) {
for (let currentNode = node; currentNode && !isFunction(currentNode); currentNode = currentNode.parent) {
if (isLoop(currentNode)) {
return true;
}
}
return false;
}
/**
* Checks whether or not a node is `null` or `undefined`.
* @param {ASTNode} node - A node to check.
* @returns {boolean} Whether or not the node is a `null` or `undefined`.
* @public
*/
function isNullOrUndefined(node) {
return (
module.exports.isNullLiteral(node) ||
(node.type === "Identifier" && node.name === "undefined") ||
(node.type === "UnaryExpression" && node.operator === "void")
);
}
/**
* Checks whether or not a node is callee.
* @param {ASTNode} node - A node to check.
* @returns {boolean} Whether or not the node is callee.
*/
function isCallee(node) {
return node.parent.type === "CallExpression" && node.parent.callee === node;
}
/**
* Checks whether or not a node is `Reflect.apply`.
* @param {ASTNode} node - A node to check.
* @returns {boolean} Whether or not the node is a `Reflect.apply`.
*/
function isReflectApply(node) {
return (
node.type === "MemberExpression" &&
node.object.type === "Identifier" &&
node.object.name === "Reflect" &&
node.property.type === "Identifier" &&
node.property.name === "apply" &&
node.computed === false
);
}
/**
* Checks whether or not a node is `Array.from`.
* @param {ASTNode} node - A node to check.
* @returns {boolean} Whether or not the node is a `Array.from`.
*/
function isArrayFromMethod(node) {
return (
node.type === "MemberExpression" &&
node.object.type === "Identifier" &&
arrayOrTypedArrayPattern.test(node.object.name) &&
node.property.type === "Identifier" &&
node.property.name === "from" &&
node.computed === false
);
}
/**
* Checks whether or not a node is a method which has `thisArg`.
* @param {ASTNode} node - A node to check.
* @returns {boolean} Whether or not the node is a method which has `thisArg`.
*/
function isMethodWhichHasThisArg(node) {
for (
let currentNode = node;
currentNode.type === "MemberExpression" && !currentNode.computed;
currentNode = currentNode.property
) {
if (currentNode.property.type === "Identifier") {
return arrayMethodPattern.test(currentNode.property.name);
}
}
return false;
}
/**
* Creates the negate function of the given function.
* @param {Function} f - The function to negate.
* @returns {Function} Negated function.
*/
function negate(f) {
return token => !f(token);
}
/**
* Checks whether or not a node has a `@this` tag in its comments.
* @param {ASTNode} node - A node to check.
* @param {SourceCode} sourceCode - A SourceCode instance to get comments.
* @returns {boolean} Whether or not the node has a `@this` tag in its comments.
*/
function hasJSDocThisTag(node, sourceCode) {
const jsdocComment = sourceCode.getJSDocComment(node);
if (jsdocComment && thisTagPattern.test(jsdocComment.value)) {
return true;
}
// Checks `@this` in its leading comments for callbacks,
// because callbacks don't have its JSDoc comment.
// e.g.
// sinon.test(/* @this sinon.Sandbox */function() { this.spy(); });
return sourceCode.getCommentsBefore(node).some(comment => thisTagPattern.test(comment.value));
}
/**
* Determines if a node is surrounded by parentheses.
* @param {SourceCode} sourceCode The ESLint source code object
* @param {ASTNode} node The node to be checked.
* @returns {boolean} True if the node is parenthesised.
* @private
*/
function isParenthesised(sourceCode, node) {
const previousToken = sourceCode.getTokenBefore(node),
nextToken = sourceCode.getTokenAfter(node);
return Boolean(previousToken && nextToken) &&
previousToken.value === "(" && previousToken.range[1] <= node.range[0] &&
nextToken.value === ")" && nextToken.range[0] >= node.range[1];
}
/**
* Checks if the given token is an arrow token or not.
*
* @param {Token} token - The token to check.
* @returns {boolean} `true` if the token is an arrow token.
*/
function isArrowToken(token) {
return token.value === "=>" && token.type === "Punctuator";
}
/**
* Checks if the given token is a comma token or not.
*
* @param {Token} token - The token to check.
* @returns {boolean} `true` if the token is a comma token.
*/
function isCommaToken(token) {
return token.value === "," && token.type === "Punctuator";
}
/**
* Checks if the given token is a semicolon token or not.
*
* @param {Token} token - The token to check.
* @returns {boolean} `true` if the token is a semicolon token.
*/
function isSemicolonToken(token) {
return token.value === ";" && token.type === "Punctuator";
}
/**
* Checks if the given token is a colon token or not.
*
* @param {Token} token - The token to check.
* @returns {boolean} `true` if the token is a colon token.
*/
function isColonToken(token) {
return token.value === ":" && token.type === "Punctuator";
}
/**
* Checks if the given token is an opening parenthesis token or not.
*
* @param {Token} token - The token to check.
* @returns {boolean} `true` if the token is an opening parenthesis token.
*/
function isOpeningParenToken(token) {
return token.value === "(" && token.type === "Punctuator";
}
/**
* Checks if the given token is a closing parenthesis token or not.
*
* @param {Token} token - The token to check.
* @returns {boolean} `true` if the token is a closing parenthesis token.
*/
function isClosingParenToken(token) {
return token.value === ")" && token.type === "Punctuator";
}
/**
* Checks if the given token is an opening square bracket token or not.
*
* @param {Token} token - The token to check.
* @returns {boolean} `true` if the token is an opening square bracket token.
*/
function isOpeningBracketToken(token) {
return token.value === "[" && token.type === "Punctuator";
}
/**
* Checks if the given token is a closing square bracket token or not.
*
* @param {Token} token - The token to check.
* @returns {boolean} `true` if the token is a closing square bracket token.
*/
function isClosingBracketToken(token) {
return token.value === "]" && token.type === "Punctuator";
}
/**
* Checks if the given token is an opening brace token or not.
*
* @param {Token} token - The token to check.
* @returns {boolean} `true` if the token is an opening brace token.
*/
function isOpeningBraceToken(token) {
return token.value === "{" && token.type === "Punctuator";
}
/**
* Checks if the given token is a closing brace token or not.
*
* @param {Token} token - The token to check.
* @returns {boolean} `true` if the token is a closing brace token.
*/
function isClosingBraceToken(token) {
return token.value === "}" && token.type === "Punctuator";
}
/**
* Checks if the given token is a comment token or not.
*
* @param {Token} token - The token to check.
* @returns {boolean} `true` if the token is a comment token.
*/
function isCommentToken(token) {
return token.type === "Line" || token.type === "Block" || token.type === "Shebang";
}
/**
* Checks if the given token is a keyword token or not.
*
* @param {Token} token - The token to check.
* @returns {boolean} `true` if the token is a keyword token.
*/
function isKeywordToken(token) {
return token.type === "Keyword";
}
/**
* Gets the `(` token of the given function node.
*
* @param {ASTNode} node - The function node to get.
* @param {SourceCode} sourceCode - The source code object to get tokens.
* @returns {Token} `(` token.
*/
function getOpeningParenOfParams(node, sourceCode) {
return node.id
? sourceCode.getTokenAfter(node.id, isOpeningParenToken)
: sourceCode.getFirstToken(node, isOpeningParenToken);
}
/**
* Creates a version of the LINEBREAK_MATCHER regex with the global flag.
* Global regexes are mutable, so this needs to be a function instead of a constant.
* @returns {RegExp} A global regular expression that matches line terminators
*/
function createGlobalLinebreakMatcher() {
return new RegExp(LINEBREAK_MATCHER.source, "g");
}
/**
* Checks whether or not the tokens of two given nodes are same.
* @param {ASTNode} left - A node 1 to compare.
* @param {ASTNode} right - A node 2 to compare.
* @param {SourceCode} sourceCode - The ESLint source code object.
* @returns {boolean} the source code for the given node.
*/
function equalTokens(left, right, sourceCode) {
const tokensL = sourceCode.getTokens(left);
const tokensR = sourceCode.getTokens(right);
if (tokensL.length !== tokensR.length) {
return false;
}
for (let i = 0; i < tokensL.length; ++i) {
if (tokensL[i].type !== tokensR[i].type ||
tokensL[i].value !== tokensR[i].value
) {
return false;
}
}
return true;
}
//------------------------------------------------------------------------------
// Public Interface
//------------------------------------------------------------------------------
module.exports = {
COMMENTS_IGNORE_PATTERN,
LINEBREAKS,
LINEBREAK_MATCHER,
SHEBANG_MATCHER,
STATEMENT_LIST_PARENTS,
/**
* Determines whether two adjacent tokens are on the same line.
* @param {Object} left - The left token object.
* @param {Object} right - The right token object.
* @returns {boolean} Whether or not the tokens are on the same line.
* @public
*/
isTokenOnSameLine(left, right) {
return left.loc.end.line === right.loc.start.line;
},
isNullOrUndefined,
isCallee,
isES5Constructor,
getUpperFunction,
isFunction,
isLoop,
isInLoop,
isArrayFromMethod,
isParenthesised,
createGlobalLinebreakMatcher,
equalTokens,
isArrowToken,
isClosingBraceToken,
isClosingBracketToken,
isClosingParenToken,
isColonToken,
isCommaToken,
isCommentToken,
isKeywordToken,
isNotClosingBraceToken: negate(isClosingBraceToken),
isNotClosingBracketToken: negate(isClosingBracketToken),
isNotClosingParenToken: negate(isClosingParenToken),
isNotColonToken: negate(isColonToken),
isNotCommaToken: negate(isCommaToken),
isNotOpeningBraceToken: negate(isOpeningBraceToken),
isNotOpeningBracketToken: negate(isOpeningBracketToken),
isNotOpeningParenToken: negate(isOpeningParenToken),
isNotSemicolonToken: negate(isSemicolonToken),
isOpeningBraceToken,
isOpeningBracketToken,
isOpeningParenToken,
isSemicolonToken,
/**
* Checks whether or not a given node is a string literal.
* @param {ASTNode} node - A node to check.
* @returns {boolean} `true` if the node is a string literal.
*/
isStringLiteral(node) {
return (
(node.type === "Literal" && typeof node.value === "string") ||
node.type === "TemplateLiteral"
);
},
/**
* Checks whether a given node is a breakable statement or not.
* The node is breakable if the node is one of the following type:
*
* - DoWhileStatement
* - ForInStatement
* - ForOfStatement
* - ForStatement
* - SwitchStatement
* - WhileStatement
*
* @param {ASTNode} node - A node to check.
* @returns {boolean} `true` if the node is breakable.
*/
isBreakableStatement(node) {
return breakableTypePattern.test(node.type);
},
/**
* Gets the label if the parent node of a given node is a LabeledStatement.
*
* @param {ASTNode} node - A node to get.
* @returns {string|null} The label or `null`.
*/
getLabel(node) {
if (node.parent.type === "LabeledStatement") {
return node.parent.label.name;
}
return null;
},
/**
* Gets references which are non initializer and writable.
* @param {Reference[]} references - An array of references.
* @returns {Reference[]} An array of only references which are non initializer and writable.
* @public
*/
getModifyingReferences(references) {
return references.filter(isModifyingReference);
},
/**
* Validate that a string passed in is surrounded by the specified character
* @param {string} val The text to check.
* @param {string} character The character to see if it's surrounded by.
* @returns {boolean} True if the text is surrounded by the character, false if not.
* @private
*/
isSurroundedBy(val, character) {
return val[0] === character && val[val.length - 1] === character;
},
/**
* Returns whether the provided node is an ESLint directive comment or not
* @param {Line|Block} node The comment token to be checked
* @returns {boolean} `true` if the node is an ESLint directive comment
*/
isDirectiveComment(node) {
const comment = node.value.trim();
return (
node.type === "Line" && comment.indexOf("eslint-") === 0 ||
node.type === "Block" && (
comment.indexOf("global ") === 0 ||
comment.indexOf("eslint ") === 0 ||
comment.indexOf("eslint-") === 0
)
);
},
/**
* Gets the trailing statement of a given node.
*
* if (code)
* consequent;
*
* When taking this `IfStatement`, returns `consequent;` statement.
*
* @param {ASTNode} A node to get.
* @returns {ASTNode|null} The trailing statement's node.
*/
getTrailingStatement: esutils.ast.trailingStatement,
/**
* Finds the variable by a given name in a given scope and its upper scopes.
*
* @param {eslint-scope.Scope} initScope - A scope to start find.
* @param {string} name - A variable name to find.
* @returns {eslint-scope.Variable|null} A found variable or `null`.
*/
getVariableByName(initScope, name) {
let scope = initScope;
while (scope) {
const variable = scope.set.get(name);
if (variable) {
return variable;
}
scope = scope.upper;
}
return null;
},
/**
* Checks whether or not a given function node is the default `this` binding.
*
* First, this checks the node:
*
* - The function name does not start with uppercase (it's a constructor).
* - The function does not have a JSDoc comment that has a @this tag.
*
* Next, this checks the location of the node.
* If the location is below, this judges `this` is valid.
*
* - The location is not on an object literal.
* - The location is not assigned to a variable which starts with an uppercase letter.
* - The location is not on an ES2015 class.
* - Its `bind`/`call`/`apply` method is not called directly.
* - The function is not a callback of array methods (such as `.forEach()`) if `thisArg` is given.
*
* @param {ASTNode} node - A function node to check.
* @param {SourceCode} sourceCode - A SourceCode instance to get comments.
* @returns {boolean} The function node is the default `this` binding.
*/
isDefaultThisBinding(node, sourceCode) {
if (isES5Constructor(node) || hasJSDocThisTag(node, sourceCode)) {
return false;
}
const isAnonymous = node.id === null;
let currentNode = node;
while (currentNode) {
const parent = currentNode.parent;
switch (parent.type) {
/*
* Looks up the destination.
* e.g., obj.foo = nativeFoo || function foo() { ... };
*/
case "LogicalExpression":
case "ConditionalExpression":
currentNode = parent;
break;
/*
* If the upper function is IIFE, checks the destination of the return value.
* e.g.
* obj.foo = (function() {
* // setup...
* return function foo() { ... };
* })();
* obj.foo = (() =>
* function foo() { ... }
* )();
*/
case "ReturnStatement": {
const func = getUpperFunction(parent);
if (func === null || !isCallee(func)) {
return true;
}
currentNode = func.parent;
break;
}
case "ArrowFunctionExpression":
if (currentNode !== parent.body || !isCallee(parent)) {
return true;
}
currentNode = parent.parent;
break;
/*
* e.g.
* var obj = { foo() { ... } };
* var obj = { foo: function() { ... } };
* class A { constructor() { ... } }
* class A { foo() { ... } }
* class A { get foo() { ... } }
* class A { set foo() { ... } }
* class A { static foo() { ... } }
*/
case "Property":
case "MethodDefinition":
return parent.value !== currentNode;
/*
* e.g.
* obj.foo = function foo() { ... };
* Foo = function() { ... };
* [obj.foo = function foo() { ... }] = a;
* [Foo = function() { ... }] = a;
*/
case "AssignmentExpression":
case "AssignmentPattern":
if (parent.left.type === "MemberExpression") {
return false;
}
if (
isAnonymous &&
parent.left.type === "Identifier" &&
startsWithUpperCase(parent.left.name)
) {
return false;
}
return true;
/*
* e.g.
* var Foo = function() { ... };
*/
case "VariableDeclarator":
return !(
isAnonymous &&
parent.init === currentNode &&
parent.id.type === "Identifier" &&
startsWithUpperCase(parent.id.name)
);
/*
* e.g.
* var foo = function foo() { ... }.bind(obj);
* (function foo() { ... }).call(obj);
* (function foo() { ... }).apply(obj, []);
*/
case "MemberExpression":
return (
parent.object !== currentNode ||
parent.property.type !== "Identifier" ||
!bindOrCallOrApplyPattern.test(parent.property.name) ||
!isCallee(parent) ||
parent.parent.arguments.length === 0 ||
isNullOrUndefined(parent.parent.arguments[0])
);
/*
* e.g.
* Reflect.apply(function() {}, obj, []);
* Array.from([], function() {}, obj);
* list.forEach(function() {}, obj);
*/
case "CallExpression":
if (isReflectApply(parent.callee)) {
return (
parent.arguments.length !== 3 ||
parent.arguments[0] !== currentNode ||
isNullOrUndefined(parent.arguments[1])
);
}
if (isArrayFromMethod(parent.callee)) {
return (
parent.arguments.length !== 3 ||
parent.arguments[1] !== currentNode ||
isNullOrUndefined(parent.arguments[2])
);
}
if (isMethodWhichHasThisArg(parent.callee)) {
return (
parent.arguments.length !== 2 ||
parent.arguments[0] !== currentNode ||
isNullOrUndefined(parent.arguments[1])
);
}
return true;
// Otherwise `this` is default.
default:
return true;
}
}
/* istanbul ignore next */
return true;
},
/**
* Get the precedence level based on the node type
* @param {ASTNode} node node to evaluate
* @returns {int} precedence level
* @private
*/
getPrecedence(node) {
switch (node.type) {
case "SequenceExpression":
return 0;
case "AssignmentExpression":
case "ArrowFunctionExpression":
case "YieldExpression":
return 1;
case "ConditionalExpression":
return 3;
case "LogicalExpression":
switch (node.operator) {
case "||":
return 4;
case "&&":
return 5;
// no default
}
/* falls through */
case "BinaryExpression":
switch (node.operator) {
case "|":
return 6;
case "^":
return 7;
case "&":
return 8;
case "==":
case "!=":
case "===":
case "!==":
return 9;
case "<":
case "<=":
case ">":
case ">=":
case "in":
case "instanceof":
return 10;
case "<<":
case ">>":
case ">>>":
return 11;
case "+":
case "-":
return 12;
case "*":
case "/":
case "%":
return 13;
case "**":
return 15;
// no default
}
/* falls through */
case "UnaryExpression":
case "AwaitExpression":
return 16;
case "UpdateExpression":
return 17;
case "CallExpression":
return 18;
case "NewExpression":
return 19;
default:
return 20;
}
},
/**
* Checks whether the given node is an empty block node or not.
*
* @param {ASTNode|null} node - The node to check.
* @returns {boolean} `true` if the node is an empty block.
*/
isEmptyBlock(node) {
return Boolean(node && node.type === "BlockStatement" && node.body.length === 0);
},
/**
* Checks whether the given node is an empty function node or not.
*
* @param {ASTNode|null} node - The node to check.
* @returns {boolean} `true` if the node is an empty function.
*/
isEmptyFunction(node) {
return isFunction(node) && module.exports.isEmptyBlock(node.body);
},
/**
* Gets the property name of a given node.
* The node can be a MemberExpression, a Property, or a MethodDefinition.
*
* If the name is dynamic, this returns `null`.
*
* For examples:
*
* a.b // => "b"
* a["b"] // => "b"
* a['b'] // => "b"
* a[`b`] // => "b"
* a[100] // => "100"
* a[b] // => null
* a["a" + "b"] // => null
* a[tag`b`] // => null
* a[`${b}`] // => null
*
* let a = {b: 1} // => "b"
* let a = {["b"]: 1} // => "b"
* let a = {['b']: 1} // => "b"
* let a = {[`b`]: 1} // => "b"
* let a = {[100]: 1} // => "100"
* let a = {[b]: 1} // => null
* let a = {["a" + "b"]: 1} // => null
* let a = {[tag`b`]: 1} // => null
* let a = {[`${b}`]: 1} // => null
*
* @param {ASTNode} node - The node to get.
* @returns {string|null} The property name if static. Otherwise, null.
*/
getStaticPropertyName(node) {
let prop;
switch (node && node.type) {
case "Property":
case "MethodDefinition":
prop = node.key;
break;
case "MemberExpression":
prop = node.property;
break;
// no default
}
switch (prop && prop.type) {
case "Literal":
return String(prop.value);
case "TemplateLiteral":
if (prop.expressions.length === 0 && prop.quasis.length === 1) {
return prop.quasis[0].value.cooked;
}
break;
case "Identifier":
if (!node.computed) {
return prop.name;
}
break;
// no default
}
return null;
},
/**
* Get directives from directive prologue of a Program or Function node.
* @param {ASTNode} node - The node to check.
* @returns {ASTNode[]} The directives found in the directive prologue.
*/
getDirectivePrologue(node) {
const directives = [];
// Directive prologues only occur at the top of files or functions.
if (
node.type === "Program" ||
node.type === "FunctionDeclaration" ||
node.type === "FunctionExpression" ||
/*
* Do not check arrow functions with implicit return.
* `() => "use strict";` returns the string `"use strict"`.
*/
(node.type === "ArrowFunctionExpression" && node.body.type === "BlockStatement")
) {
const statements = node.type === "Program" ? node.body : node.body.body;
for (const statement of statements) {
if (
statement.type === "ExpressionStatement" &&
statement.expression.type === "Literal"
) {
directives.push(statement);
} else {
break;
}
}
}
return directives;
},
/**
* Determines whether this node is a decimal integer literal. If a node is a decimal integer literal, a dot added
* after the node will be parsed as a decimal point, rather than a property-access dot.
* @param {ASTNode} node - The node to check.
* @returns {boolean} `true` if this node is a decimal integer.
* @example
*
* 5 // true
* 5. // false
* 5.0 // false
* 05 // false
* 0x5 // false
* 0b101 // false
* 0o5 // false
* 5e0 // false
* '5' // false
*/
isDecimalInteger(node) {
return node.type === "Literal" && typeof node.value === "number" && /^(0|[1-9]\d*)$/.test(node.raw);
},
/**
* Gets the name and kind of the given function node.
*
* - `function foo() {}` .................... `function 'foo'`
* - `(function foo() {})` .................. `function 'foo'`
* - `(function() {})` ...................... `function`
* - `function* foo() {}` ................... `generator function 'foo'`
* - `(function* foo() {})` ................. `generator function 'foo'`
* - `(function*() {})` ..................... `generator function`
* - `() => {}` ............................. `arrow function`
* - `async () => {}` ....................... `async arrow function`
* - `({ foo: function foo() {} })` ......... `method 'foo'`
* - `({ foo: function() {} })` ............. `method 'foo'`
* - `({ ['foo']: function() {} })` ......... `method 'foo'`
* - `({ [foo]: function() {} })` ........... `method`
* - `({ foo() {} })` ....................... `method 'foo'`
* - `({ foo: function* foo() {} })` ........ `generator method 'foo'`
* - `({ foo: function*() {} })` ............ `generator method 'foo'`
* - `({ ['foo']: function*() {} })` ........ `generator method 'foo'`
* - `({ [foo]: function*() {} })` .......... `generator method`
* - `({ *foo() {} })` ...................... `generator method 'foo'`
* - `({ foo: async function foo() {} })` ... `async method 'foo'`
* - `({ foo: async function() {} })` ....... `async method 'foo'`
* - `({ ['foo']: async function() {} })` ... `async method 'foo'`
* - `({ [foo]: async function() {} })` ..... `async method`
* - `({ async foo() {} })` ................. `async method 'foo'`
* - `({ get foo() {} })` ................... `getter 'foo'`
* - `({ set foo(a) {} })` .................. `setter 'foo'`
* - `class A { constructor() {} }` ......... `constructor`
* - `class A { foo() {} }` ................. `method 'foo'`
* - `class A { *foo() {} }` ................ `generator method 'foo'`
* - `class A { async foo() {} }` ........... `async method 'foo'`
* - `class A { ['foo']() {} }` ............. `method 'foo'`
* - `class A { *['foo']() {} }` ............ `generator method 'foo'`
* - `class A { async ['foo']() {} }` ....... `async method 'foo'`
* - `class A { [foo]() {} }` ............... `method`
* - `class A { *[foo]() {} }` .............. `generator method`
* - `class A { async [foo]() {} }` ......... `async method`
* - `class A { get foo() {} }` ............. `getter 'foo'`
* - `class A { set foo(a) {} }` ............ `setter 'foo'`
* - `class A { static foo() {} }` .......... `static method 'foo'`
* - `class A { static *foo() {} }` ......... `static generator method 'foo'`
* - `class A { static async foo() {} }` .... `static async method 'foo'`
* - `class A { static get foo() {} }` ...... `static getter 'foo'`
* - `class A { static set foo(a) {} }` ..... `static setter 'foo'`
*
* @param {ASTNode} node - The function node to get.
* @returns {string} The name and kind of the function node.
*/
getFunctionNameWithKind(node) {
const parent = node.parent;
const tokens = [];
if (parent.type === "MethodDefinition" && parent.static) {
tokens.push("static");
}
if (node.async) {
tokens.push("async");
}
if (node.generator) {
tokens.push("generator");
}
if (node.type === "ArrowFunctionExpression") {
tokens.push("arrow", "function");
} else if (parent.type === "Property" || parent.type === "MethodDefinition") {
if (parent.kind === "constructor") {
return "constructor";
}
if (parent.kind === "get") {
tokens.push("getter");
} else if (parent.kind === "set") {
tokens.push("setter");
} else {
tokens.push("method");
}
} else {
tokens.push("function");
}
if (node.id) {
tokens.push(`'${node.id.name}'`);
} else {
const name = module.exports.getStaticPropertyName(parent);
if (name) {
tokens.push(`'${name}'`);
}
}
return tokens.join(" ");
},
/**
* Gets the location of the given function node for reporting.
*
* - `function foo() {}`
* ^^^^^^^^^^^^
* - `(function foo() {})`
* ^^^^^^^^^^^^
* - `(function() {})`
* ^^^^^^^^
* - `function* foo() {}`
* ^^^^^^^^^^^^^
* - `(function* foo() {})`
* ^^^^^^^^^^^^^
* - `(function*() {})`
* ^^^^^^^^^
* - `() => {}`
* ^^
* - `async () => {}`
* ^^
* - `({ foo: function foo() {} })`
* ^^^^^^^^^^^^^^^^^
* - `({ foo: function() {} })`
* ^^^^^^^^^^^^^
* - `({ ['foo']: function() {} })`
* ^^^^^^^^^^^^^^^^^
* - `({ [foo]: function() {} })`
* ^^^^^^^^^^^^^^^
* - `({ foo() {} })`
* ^^^
* - `({ foo: function* foo() {} })`
* ^^^^^^^^^^^^^^^^^^
* - `({ foo: function*() {} })`
* ^^^^^^^^^^^^^^
* - `({ ['foo']: function*() {} })`
* ^^^^^^^^^^^^^^^^^^
* - `({ [foo]: function*() {} })`
* ^^^^^^^^^^^^^^^^
* - `({ *foo() {} })`
* ^^^^
* - `({ foo: async function foo() {} })`
* ^^^^^^^^^^^^^^^^^^^^^^^
* - `({ foo: async function() {} })`
* ^^^^^^^^^^^^^^^^^^^
* - `({ ['foo']: async function() {} })`
* ^^^^^^^^^^^^^^^^^^^^^^^
* - `({ [foo]: async function() {} })`
* ^^^^^^^^^^^^^^^^^^^^^
* - `({ async foo() {} })`
* ^^^^^^^^^
* - `({ get foo() {} })`
* ^^^^^^^
* - `({ set foo(a) {} })`
* ^^^^^^^
* - `class A { constructor() {} }`
* ^^^^^^^^^^^
* - `class A { foo() {} }`
* ^^^
* - `class A { *foo() {} }`
* ^^^^
* - `class A { async foo() {} }`
* ^^^^^^^^^
* - `class A { ['foo']() {} }`
* ^^^^^^^
* - `class A { *['foo']() {} }`
* ^^^^^^^^
* - `class A { async ['foo']() {} }`
* ^^^^^^^^^^^^^
* - `class A { [foo]() {} }`
* ^^^^^
* - `class A { *[foo]() {} }`
* ^^^^^^
* - `class A { async [foo]() {} }`
* ^^^^^^^^^^^
* - `class A { get foo() {} }`
* ^^^^^^^
* - `class A { set foo(a) {} }`
* ^^^^^^^
* - `class A { static foo() {} }`
* ^^^^^^^^^^
* - `class A { static *foo() {} }`
* ^^^^^^^^^^^
* - `class A { static async foo() {} }`
* ^^^^^^^^^^^^^^^^
* - `class A { static get foo() {} }`
* ^^^^^^^^^^^^^^
* - `class A { static set foo(a) {} }`
* ^^^^^^^^^^^^^^
*
* @param {ASTNode} node - The function node to get.
* @param {SourceCode} sourceCode - The source code object to get tokens.
* @returns {string} The location of the function node for reporting.
*/
getFunctionHeadLoc(node, sourceCode) {
const parent = node.parent;
let start = null;
let end = null;
if (node.type === "ArrowFunctionExpression") {
const arrowToken = sourceCode.getTokenBefore(node.body, isArrowToken);
start = arrowToken.loc.start;
end = arrowToken.loc.end;
} else if (parent.type === "Property" || parent.type === "MethodDefinition") {
start = parent.loc.start;
end = getOpeningParenOfParams(node, sourceCode).loc.start;
} else {
start = node.loc.start;
end = getOpeningParenOfParams(node, sourceCode).loc.start;
}
return {
start: Object.assign({}, start),
end: Object.assign({}, end)
};
},
/**
* Gets the parenthesized text of a node. This is similar to sourceCode.getText(node), but it also includes any parentheses
* surrounding the node.
* @param {SourceCode} sourceCode The source code object
* @param {ASTNode} node An expression node
* @returns {string} The text representing the node, with all surrounding parentheses included
*/
getParenthesisedText(sourceCode, node) {
let leftToken = sourceCode.getFirstToken(node);
let rightToken = sourceCode.getLastToken(node);
while (
sourceCode.getTokenBefore(leftToken) &&
sourceCode.getTokenBefore(leftToken).type === "Punctuator" &&
sourceCode.getTokenBefore(leftToken).value === "(" &&
sourceCode.getTokenAfter(rightToken) &&
sourceCode.getTokenAfter(rightToken).type === "Punctuator" &&
sourceCode.getTokenAfter(rightToken).value === ")"
) {
leftToken = sourceCode.getTokenBefore(leftToken);
rightToken = sourceCode.getTokenAfter(rightToken);
}
return sourceCode.getText().slice(leftToken.range[0], rightToken.range[1]);
},
/*
* Determine if a node has a possiblity to be an Error object
* @param {ASTNode} node ASTNode to check
* @returns {boolean} True if there is a chance it contains an Error obj
*/
couldBeError(node) {
switch (node.type) {
case "Identifier":
case "CallExpression":
case "NewExpression":
case "MemberExpression":
case "TaggedTemplateExpression":
case "YieldExpression":
case "AwaitExpression":
return true; // possibly an error object.
case "AssignmentExpression":
return module.exports.couldBeError(node.right);
case "SequenceExpression": {
const exprs = node.expressions;
return exprs.length !== 0 && module.exports.couldBeError(exprs[exprs.length - 1]);
}
case "LogicalExpression":
return module.exports.couldBeError(node.left) || module.exports.couldBeError(node.right);
case "ConditionalExpression":
return module.exports.couldBeError(node.consequent) || module.exports.couldBeError(node.alternate);
default:
return false;
}
},
/**
* Determines whether the given node is a `null` literal.
* @param {ASTNode} node The node to check
* @returns {boolean} `true` if the node is a `null` literal
*/
isNullLiteral(node) {
/*
* Checking `node.value === null` does not guarantee that a literal is a null literal.
* When parsing values that cannot be represented in the current environment (e.g. unicode
* regexes in Node 4), `node.value` is set to `null` because it wouldn't be possible to
* set `node.value` to a unicode regex. To make sure a literal is actually `null`, check
* `node.regex` instead. Also see: https://github.com/eslint/eslint/issues/8020
*/
return node.type === "Literal" && node.value === null && !node.regex;
},
/**
* Determines whether two tokens can safely be placed next to each other without merging into a single token
* @param {Token|string} leftValue The left token. If this is a string, it will be tokenized and the last token will be used.
* @param {Token|string} rightValue The right token. If this is a string, it will be tokenized and the first token will be used.
* @returns {boolean} If the tokens cannot be safely placed next to each other, returns `false`. If the tokens can be placed
* next to each other, behavior is undefined (although it should return `true` in most cases).
*/
canTokensBeAdjacent(leftValue, rightValue) {
let leftToken;
if (typeof leftValue === "string") {
const leftTokens = espree.tokenize(leftValue, { ecmaVersion: 2015 });
leftToken = leftTokens[leftTokens.length - 1];
} else {
leftToken = leftValue;
}
const rightToken = typeof rightValue === "string" ? espree.tokenize(rightValue, { ecmaVersion: 2015 })[0] : rightValue;
if (leftToken.type === "Punctuator" || rightToken.type === "Punctuator") {
if (leftToken.type === "Punctuator" && rightToken.type === "Punctuator") {
const PLUS_TOKENS = new Set(["+", "++"]);
const MINUS_TOKENS = new Set(["-", "--"]);
return !(
PLUS_TOKENS.has(leftToken.value) && PLUS_TOKENS.has(rightToken.value) ||
MINUS_TOKENS.has(leftToken.value) && MINUS_TOKENS.has(rightToken.value)
);
}
return true;
}
if (
leftToken.type === "String" || rightToken.type === "String" ||
leftToken.type === "Template" || rightToken.type === "Template"
) {
return true;
}
if (leftToken.type !== "Numeric" && rightToken.type === "Numeric" && rightToken.value.startsWith(".")) {
return true;
}
return false;
}
};