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| import * as ts from "typescript";
import * as Lint from "tslint";
import {
createInvalidNode,
CheckNodeResult,
createCheckNodeTypedRule,
InvalidNode
} from "./shared/check-node";
import * as Ignore from "./shared/ignore";
type Options = Ignore.IgnoreMutationFollowingAccessorOption &
Ignore.IgnorePrefixOption;
type EntryAccessor = ts.ElementAccessExpression | ts.PropertyAccessExpression;
// tslint:disable-next-line:variable-name
export const Rule = createCheckNodeTypedRule(
checkTypedNode,
"Mutating an array is not allowed."
);
const arrPropAccessors: ReadonlyArray<ts.SyntaxKind> = [
ts.SyntaxKind.ElementAccessExpression,
ts.SyntaxKind.PropertyAccessExpression
];
const forbidArrPropOnLeftSideOf: ReadonlyArray<ts.SyntaxKind> = [
ts.SyntaxKind.EqualsToken,
ts.SyntaxKind.PlusEqualsToken,
ts.SyntaxKind.MinusEqualsToken,
ts.SyntaxKind.AsteriskEqualsToken,
ts.SyntaxKind.AsteriskAsteriskEqualsToken,
ts.SyntaxKind.SlashEqualsToken,
ts.SyntaxKind.PercentEqualsToken,
ts.SyntaxKind.LessThanLessThanEqualsToken,
ts.SyntaxKind.GreaterThanGreaterThanEqualsToken,
ts.SyntaxKind.GreaterThanGreaterThanGreaterThanEqualsToken,
ts.SyntaxKind.AmpersandEqualsToken,
ts.SyntaxKind.BarEqualsToken,
ts.SyntaxKind.CaretEqualsToken
];
const forbidUnaryOps: ReadonlyArray<ts.SyntaxKind> = [
ts.SyntaxKind.PlusPlusToken,
ts.SyntaxKind.MinusMinusToken
];
/**
* Methods that mutate an array.
*
* @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/prototype#Methods#Mutator_methods
*/
const mutatorMethods: ReadonlyArray<string> = [
"copyWithin",
"fill",
"pop",
"push",
"reverse",
"shift",
"sort",
"splice",
"unshift"
];
/**
* Methods that return a new array without mutating the original.
*
* @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/prototype#Methods#Accessor_methods
*/
const accessorMethods: ReadonlyArray<string> = [
"concat",
"slice",
"toSource" // TODO: This is a non standardized method, should it me including?
];
function isArrayType(type: ts.Type): boolean {
return type.symbol !== undefined && type.symbol.name === "Array";
}
function checkTypedNode(
node: ts.BinaryExpression,
ctx: Lint.WalkContext<Options>,
checker: ts.TypeChecker
): CheckNodeResult {
return { invalidNodes: getInvalidNodes(node, ctx, checker) };
}
function getInvalidNodes(
node: ts.Node,
ctx: Lint.WalkContext<Options>,
checker: ts.TypeChecker
): ReadonlyArray<InvalidNode> {
switch (node.kind) {
case ts.SyntaxKind.BinaryExpression:
return checkBinaryExpression(node as ts.BinaryExpression, ctx, checker);
case ts.SyntaxKind.DeleteExpression:
return checkDeleteExpression(node as ts.DeleteExpression, ctx, checker);
case ts.SyntaxKind.PrefixUnaryExpression:
return checkPrefixUnaryExpression(
node as ts.PrefixUnaryExpression,
ctx,
checker
);
case ts.SyntaxKind.PostfixUnaryExpression:
return checkPostfixUnaryExpression(
node as ts.PostfixUnaryExpression,
ctx,
checker
);
case ts.SyntaxKind.CallExpression:
return checkCallExpression(node as ts.CallExpression, ctx, checker);
default:
return [];
}
}
/**
* No assignment with array[index] on the left.
* No assignment with array.property on the left (e.g. array.length).
*/
function checkBinaryExpression(
node: ts.BinaryExpression,
ctx: Lint.WalkContext<Options>,
checker: ts.TypeChecker
): ReadonlyArray<InvalidNode> {
if (
arrPropAccessors.some(k => k === node.left.kind) &&
forbidArrPropOnLeftSideOf.some(k => k === node.operatorToken.kind) &&
!Ignore.isIgnoredPrefix(
node.getText(node.getSourceFile()),
ctx.options.ignorePrefix
)
) {
const left = node.left as EntryAccessor;
const leftExpressionType = checker.getTypeAtLocation(left.expression);
if (isArrayType(leftExpressionType)) {
return [createInvalidNode(node, [])];
}
}
return [];
}
/**
* No deleting array properties/values.
*/
function checkDeleteExpression(
node: ts.DeleteExpression,
ctx: Lint.WalkContext<Options>,
checker: ts.TypeChecker
): ReadonlyArray<InvalidNode> {
const delExp = node as ts.DeleteExpression;
if (
arrPropAccessors.some(k => k === delExp.expression.kind) &&
!Ignore.isIgnoredPrefix(
delExp.expression.getText(node.getSourceFile()),
ctx.options.ignorePrefix
)
) {
const delExpExp = delExp.expression as EntryAccessor;
const expressionType = checker.getTypeAtLocation(delExpExp.expression);
if (isArrayType(expressionType)) {
return [createInvalidNode(node, [])];
}
}
return [];
}
/**
* No prefix inc/dec.
*/
function checkPrefixUnaryExpression(
node: ts.PrefixUnaryExpression,
ctx: Lint.WalkContext<Options>,
checker: ts.TypeChecker
): ReadonlyArray<InvalidNode> {
const preExp = node as ts.PrefixUnaryExpression;
if (
arrPropAccessors.some(k => k === preExp.operand.kind) &&
forbidUnaryOps.some(o => o === preExp.operator) &&
!Ignore.isIgnoredPrefix(
preExp.operand.getText(node.getSourceFile()),
ctx.options.ignorePrefix
)
) {
const operand = preExp.operand as EntryAccessor;
const operandExpressionType = checker.getTypeAtLocation(operand.expression);
if (isArrayType(operandExpressionType)) {
return [createInvalidNode(node, [])];
}
}
return [];
}
/**
* No postfix inc/dec.
*/
function checkPostfixUnaryExpression(
node: ts.PostfixUnaryExpression,
ctx: Lint.WalkContext<Options>,
checker: ts.TypeChecker
): ReadonlyArray<InvalidNode> {
const postExp = node as ts.PostfixUnaryExpression;
if (
arrPropAccessors.some(k => k === postExp.operand.kind) &&
forbidUnaryOps.some(o => o === postExp.operator) &&
!Ignore.isIgnoredPrefix(
postExp.getText(node.getSourceFile()),
ctx.options.ignorePrefix
)
) {
const operand = postExp.operand as EntryAccessor;
const operandExpressionType = checker.getTypeAtLocation(operand.expression);
if (isArrayType(operandExpressionType)) {
return [createInvalidNode(node, [])];
}
}
return [];
}
/**
* No calls to array mutating methods.
*/
function checkCallExpression(
node: ts.CallExpression,
ctx: Lint.WalkContext<Options>,
checker: ts.TypeChecker
): ReadonlyArray<InvalidNode> {
const callExp = node as ts.CallExpression;
if (ts.SyntaxKind.PropertyAccessExpression === callExp.expression.kind) {
const propAccExp = callExp.expression as ts.PropertyAccessExpression;
if (
mutatorMethods.some(m => m === propAccExp.name.text) &&
!Ignore.isIgnoredPrefix(
callExp.getText(node.getSourceFile()),
ctx.options.ignorePrefix
) &&
(!ctx.options.ignoreMutationFollowingAccessor ||
!isInChainCallAndFollowsAccessor(propAccExp))
) {
// Do the type checking as late as possible (as it is expensive).
const expressionType = checker.getTypeAtLocation(propAccExp.expression);
if (isArrayType(expressionType)) {
return [createInvalidNode(node, [])];
}
}
}
return [];
}
/**
* Check if the given the given PropertyAccessExpression is part of a chain and
* immediately follows an accessor method call.
*
* If this is the case, then the given PropertyAccessExpression is allowed to be a mutator method call.
*/
function isInChainCallAndFollowsAccessor(
propAccExp: ts.PropertyAccessExpression
): boolean {
if (ts.SyntaxKind.CallExpression === propAccExp.expression.kind) {
const subCallExp = propAccExp.expression as ts.CallExpression;
Eif (ts.SyntaxKind.PropertyAccessExpression === subCallExp.expression.kind) {
const subPropAccExp = subCallExp.expression as ts.PropertyAccessExpression;
Eif (accessorMethods.some(m => m === subPropAccExp.name.text)) {
return true;
}
}
}
return false;
}
|