diff options
Merge pull request #594 from 0xProject/improvement/addCustomTslintRules
Add more tslint rules
Diffstat (limited to 'packages/tslint-config/rules/customNoMagicNumbersRule.ts')
-rw-r--r-- | packages/tslint-config/rules/customNoMagicNumbersRule.ts | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/packages/tslint-config/rules/customNoMagicNumbersRule.ts b/packages/tslint-config/rules/customNoMagicNumbersRule.ts new file mode 100644 index 000000000..e358221eb --- /dev/null +++ b/packages/tslint-config/rules/customNoMagicNumbersRule.ts @@ -0,0 +1,76 @@ +import * as Lint from 'tslint'; +import { isPrefixUnaryExpression } from 'tsutils'; +import * as ts from 'typescript'; + +/** + * A modified version of the no-magic-numbers rule that allows for magic numbers + * when instantiating a BigNumber instance. + * E.g We want to be able to write: + * const amount = new BigNumber(5); + * Original source: https://github.com/palantir/tslint/blob/42b058a6baa688f8be8558b277eb056c3ff79818/src/rules/noMagicNumbersRule.ts + */ +export class Rule extends Lint.Rules.AbstractRule { + public static ALLOWED_NODES = new Set<ts.SyntaxKind>([ + ts.SyntaxKind.ExportAssignment, + ts.SyntaxKind.FirstAssignment, + ts.SyntaxKind.LastAssignment, + ts.SyntaxKind.PropertyAssignment, + ts.SyntaxKind.ShorthandPropertyAssignment, + ts.SyntaxKind.VariableDeclaration, + ts.SyntaxKind.VariableDeclarationList, + ts.SyntaxKind.EnumMember, + ts.SyntaxKind.PropertyDeclaration, + ts.SyntaxKind.Parameter, + ]); + + public static DEFAULT_ALLOWED = [-1, 0, 1]; + + public apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] { + const allowedNumbers = this.ruleArguments.length > 0 ? this.ruleArguments : Rule.DEFAULT_ALLOWED; + return this.applyWithWalker( + new CustomNoMagicNumbersWalker(sourceFile, this.ruleName, new Set(allowedNumbers.map(String))), + ); + } +} + +// tslint:disable-next-line:max-classes-per-file +class CustomNoMagicNumbersWalker extends Lint.AbstractWalker<Set<string>> { + public static FAILURE_STRING = "'magic numbers' are not allowed"; + private static _isNegativeNumberLiteral( + node: ts.Node, + ): node is ts.PrefixUnaryExpression & { operand: ts.NumericLiteral } { + return ( + isPrefixUnaryExpression(node) && + node.operator === ts.SyntaxKind.MinusToken && + node.operand.kind === ts.SyntaxKind.NumericLiteral + ); + } + public walk(sourceFile: ts.SourceFile): void { + const cb = (node: ts.Node): void => { + if (node.kind === ts.SyntaxKind.NumericLiteral) { + return this.checkNumericLiteral(node, (node as ts.NumericLiteral).text); + } + if (CustomNoMagicNumbersWalker._isNegativeNumberLiteral(node)) { + return this.checkNumericLiteral(node, `-${(node.operand as ts.NumericLiteral).text}`); + } + return ts.forEachChild(node, cb); + }; + return ts.forEachChild(sourceFile, cb); + } + + // tslint:disable:no-non-null-assertion + // tslint:disable-next-line:underscore-private-and-protected + private checkNumericLiteral(node: ts.Node, num: string): void { + if (!Rule.ALLOWED_NODES.has(node.parent!.kind) && !this.options.has(num)) { + if (node.parent!.kind === ts.SyntaxKind.NewExpression) { + const className = (node.parent! as any).expression.escapedText; + const BIG_NUMBER_NEW_EXPRESSION = 'BigNumber'; + if (className === BIG_NUMBER_NEW_EXPRESSION) { + return; // noop + } + } + this.addFailureAtNode(node, CustomNoMagicNumbersWalker.FAILURE_STRING); + } + } + // tslint:enable:no-non-null-assertion +} |