/
explicit-function-return-type.ts
132 lines (123 loc) · 3.41 KB
/
explicit-function-return-type.ts
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
/**
* @fileoverview Enforces explicit return type for functions
* @author Scott O'Hara
*/
import { TSESTree, AST_NODE_TYPES } from '@typescript-eslint/typescript-estree';
import * as util from '../util';
type Options = [
{
allowExpressions?: boolean;
}
];
type MessageIds = 'missingReturnType';
export default util.createRule<Options, MessageIds>({
name: 'explicit-function-return-type',
meta: {
type: 'problem',
docs: {
description:
'Require explicit return types on functions and class methods',
category: 'Stylistic Issues',
recommended: 'warn'
},
messages: {
missingReturnType: 'Missing return type on function.'
},
schema: [
{
type: 'object',
properties: {
allowExpressions: {
type: 'boolean'
}
},
additionalProperties: false
}
]
},
defaultOptions: [
{
allowExpressions: true
}
],
create(context, [options]) {
/**
* Checks if the parent of a function expression is a constructor.
* @param parent The parent of a function expression node
*/
function isConstructor(parent: TSESTree.Node): boolean {
return (
parent.type === AST_NODE_TYPES.MethodDefinition &&
parent.kind === 'constructor'
);
}
/**
* Checks if the parent of a function expression is a setter.
* @param parent The parent of a function expression node
*/
function isSetter(parent: TSESTree.Node): boolean {
return (
parent.type === AST_NODE_TYPES.MethodDefinition && parent.kind === 'set'
);
}
/**
* Checks if the parent of a function expression has a type annotation.
* @param parent The parent of a function expression node
*/
function hasTypeAnnotation(parent: TSESTree.Node): boolean {
return (
parent.type === AST_NODE_TYPES.VariableDeclarator &&
'typeAnnotation' in parent.id
);
}
/**
* Checks if a function declaration/expression has a return type.
* @param node The node representing a function.
*/
function checkFunctionReturnType(
node:
| TSESTree.ArrowFunctionExpression
| TSESTree.FunctionDeclaration
| TSESTree.FunctionExpression
): void {
if (
!node.returnType &&
node.parent &&
!isConstructor(node.parent) &&
!isSetter(node.parent) &&
!hasTypeAnnotation(node.parent) &&
util.isTypeScriptFile(context.getFilename())
) {
context.report({
node,
messageId: 'missingReturnType'
});
}
}
/**
* Checks if a function declaration/expression has a return type.
* @param {ASTNode} node The node representing a function.
*/
function checkFunctionExpressionReturnType(
node:
| TSESTree.ArrowFunctionExpression
| TSESTree.FunctionDeclaration
| TSESTree.FunctionExpression
): void {
if (
options.allowExpressions &&
node.parent &&
node.parent.type !== AST_NODE_TYPES.VariableDeclarator &&
node.parent.type !== AST_NODE_TYPES.MethodDefinition
) {
return;
}
checkFunctionReturnType(node);
}
return {
ArrowFunctionExpression: checkFunctionExpressionReturnType,
FunctionDeclaration: checkFunctionReturnType,
FunctionExpression: checkFunctionExpressionReturnType
};
}
});