/
getter-return.js
143 lines (125 loc) · 4.48 KB
/
getter-return.js
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/**
* @fileoverview Enforces that a return statement is present in property getters.
* @author Aladdin-ADD(hh_2013@foxmail.com)
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const astUtils = require("../ast-utils");
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
const TARGET_NODE_TYPE = /^(?:Arrow)?FunctionExpression$/;
/**
* Checks a given code path segment is reachable.
*
* @param {CodePathSegment} segment - A segment to check.
* @returns {boolean} `true` if the segment is reachable.
*/
function isReachable(segment) {
return segment.reachable;
}
/**
* Gets a readable location.
*
* - FunctionExpression -> the function name or `function` keyword.
* - ArrowFunctionExpression -> `=>` token.
*
* @param {ASTNode} node - A function node to get.
* @param {SourceCode} sourceCode - A source code to get tokens.
* @returns {ASTNode|Token} The node or the token of a location.
*/
function getLocation(node, sourceCode) {
if (node.type === "ArrowFunctionExpression") {
return sourceCode.getTokenBefore(node.body);
}
return node.id || node;
}
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = {
meta: {
docs: {
description: "enforce `return` statements in getters",
category: "Best Practices",
recommended: false
},
schema: []
},
create(context) {
let funcInfo = {
upper: null,
codePath: null,
hasReturn: false,
shouldCheck: false,
node: null
};
/**
* Checks whether or not the last code path segment is reachable.
* Then reports this function if the segment is reachable.
*
* If the last code path segment is reachable, there are paths which are not
* returned or thrown.
*
* @param {ASTNode} node - A node to check.
* @returns {void}
*/
function checkLastSegment(node) {
if (funcInfo.shouldCheck &&
funcInfo.codePath.currentSegments.some(isReachable)
) {
context.report({
node,
loc: getLocation(node, context.getSourceCode()).loc.start,
message: funcInfo.hasReturn
? "Expected to return a value at the end of {{name}}."
: "Expected to return a value in {{name}}.",
data: {
name: astUtils.getFunctionNameWithKind(funcInfo.node)
}
});
}
}
return {
// Stacks this function's information.
onCodePathStart(codePath, node) {
funcInfo = {
upper: funcInfo,
codePath,
hasReturn: false,
shouldCheck:
TARGET_NODE_TYPE.test(node.type) &&
node.body.type === "BlockStatement" &&
node.parent.kind === "get" &&
!node.async &&
!node.generator,
node
};
},
// Pops this function's information.
onCodePathEnd() {
funcInfo = funcInfo.upper;
},
// Checks the return statement is valid.
ReturnStatement(node) {
if (funcInfo.shouldCheck) {
funcInfo.hasReturn = true;
if (!node.argument) {
context.report({
node,
message: "Expected to return a value in {{name}}.",
data: {
name: astUtils.getFunctionNameWithKind(funcInfo.node)
}
});
}
}
},
// Reports a given function if the last path is reachable.
"FunctionExpression:exit": checkLastSegment,
"ArrowFunctionExpression:exit": checkLastSegment
};
}
};