forked from palantir/tslint
/
strictStringExpressionsRule.ts
157 lines (141 loc) · 5.59 KB
/
strictStringExpressionsRule.ts
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/**
* @license
* Copyright 2018 Palantir Technologies, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import { isTypeFlagSet, isUnionType } from "tsutils";
import * as ts from "typescript";
import * as Lint from "../index";
const OPTION_ALLOW_EMPTY_TYPES = "allow-empty-types";
interface Options {
[OPTION_ALLOW_EMPTY_TYPES]?: boolean;
}
export class Rule extends Lint.Rules.TypedRule {
public static CONVERSION_REQUIRED = "Explicit conversion to string type required";
public static metadata: Lint.IRuleMetadata = {
description: "Disable implicit toString() calls",
descriptionDetails: Lint.Utils.dedent`
Require explicit toString() call for variables used in strings. By default only strings are allowed.
The following nodes are checked:
* String literals ("foo" + bar)
* ES6 templates (\`foo \${bar}\`)`,
hasFix: true,
optionExamples: [
true,
[
true,
{
[OPTION_ALLOW_EMPTY_TYPES]: true,
},
],
],
options: {
properties: {
[OPTION_ALLOW_EMPTY_TYPES]: {
type: "boolean",
},
},
type: "object",
},
optionsDescription: Lint.Utils.dedent`
Following arguments may be optionally provided:
* \`${OPTION_ALLOW_EMPTY_TYPES}\` allows \`null\`, \`undefined\` and \`never\` to be passed into strings without explicit conversion`,
requiresTypeInfo: true,
ruleName: "strict-string-expressions",
type: "functionality",
typescriptOnly: true,
};
public applyWithProgram(sourceFile: ts.SourceFile, program: ts.Program): Lint.RuleFailure[] {
return this.applyWithFunction(
sourceFile,
walk,
this.getRuleOptions(),
program.getTypeChecker(),
);
}
private getRuleOptions(): Options {
if (this.ruleArguments[0] === undefined) {
return {};
} else {
return this.ruleArguments[0] as Options;
}
}
}
function walk(ctx: Lint.WalkContext<Options>, checker: ts.TypeChecker): void {
const { sourceFile, options } = ctx;
ts.forEachChild(sourceFile, function cb(node: ts.Node): void {
switch (node.kind) {
case ts.SyntaxKind.BinaryExpression: {
const binaryExpr = node as ts.BinaryExpression;
if (binaryExpr.operatorToken.kind === ts.SyntaxKind.PlusToken) {
const leftIsPassedAsIs = isTypeConvertsToStringEasily(
checker.getTypeAtLocation(binaryExpr.left),
options,
);
const rightIsPassedAsIs = isTypeConvertsToStringEasily(
checker.getTypeAtLocation(binaryExpr.right),
options,
);
const leftIsFailed = !leftIsPassedAsIs && rightIsPassedAsIs;
const rightIsFailed = leftIsPassedAsIs && !rightIsPassedAsIs;
if (leftIsFailed || rightIsFailed) {
const expression = leftIsFailed ? binaryExpr.left : binaryExpr.right;
addFailure(binaryExpr, expression);
}
}
break;
}
case ts.SyntaxKind.TemplateSpan: {
const templateSpanNode = node as ts.TemplateSpan;
const type = checker.getTypeAtLocation(templateSpanNode.expression);
const shouldPassAsIs = isTypeConvertsToStringEasily(type, options);
if (!shouldPassAsIs) {
const { expression } = templateSpanNode;
addFailure(templateSpanNode, expression);
}
}
}
return ts.forEachChild(node, cb);
});
function addFailure(node: ts.Node, expression: ts.Expression) {
const fix = Lint.Replacement.replaceFromTo(
expression.getStart(),
expression.end,
`String(${expression.getText()})`,
);
ctx.addFailureAtNode(node, Rule.CONVERSION_REQUIRED, fix);
}
}
const isEmptyType = (type: ts.Type): boolean =>
isTypeFlagSet(type, ts.TypeFlags.Null) ||
isTypeFlagSet(type, ts.TypeFlags.VoidLike) ||
isTypeFlagSet(type, ts.TypeFlags.Undefined) ||
isTypeFlagSet(type, ts.TypeFlags.Never);
function isTypeConvertsToStringEasily(type: ts.Type, options: Options): boolean {
if (isUnionType(type)) {
return type.types.every(unionAtomicType =>
isTypeConvertsToStringEasily(unionAtomicType, options),
);
}
if (options[OPTION_ALLOW_EMPTY_TYPES] && isEmptyType(type)) {
return true;
}
return (
isTypeFlagSet(type, ts.TypeFlags.BooleanLike) ||
isTypeFlagSet(type, ts.TypeFlags.StringOrNumberLiteral) ||
isTypeFlagSet(type, ts.TypeFlags.NumberLike) ||
isTypeFlagSet(type, ts.TypeFlags.StringLike) ||
isTypeFlagSet(type, ts.TypeFlags.Any)
);
}