@dlenroc/tag-expression

Parser and evaluator for boolean tag expressions.

Installation

npm install @dlenroc/tag-expression

Usage

Parse once, evaluate against many items:

import { parse } from "@dlenroc/tag-expression";

const result = parse("catalog & !end-to-end");

if (!result.ok) {
  throw new Error(result.error);
}

const items = [
  { name: "A", tags: new Set(["catalog", "smoke"]) },
  { name: "B", tags: new Set(["catalog", "end-to-end"]) },
  { name: "C", tags: new Set(["shipping"]) },
];

const matched = items.filter((item) => result.value.evaluate(item.tags));
// [{ name: 'A', tags: Set { 'catalog', 'smoke' } }]

Syntax

Tag expressions are boolean expressions with the operators !, & and |. Parentheses ( ) can be used to adjust for operator precedence.

Two special expressions are supported: any() matches when any tags are present, and none() matches when no tags are present. Both can be combined with other expressions just like regular tags.

Operators

| Operator | Meaning | Associativity | | -------- | ------- | ------------- | | ! | not | right | | & | and | left | | \| | or | left |

Tag rules

A tag must not be blank and must not contain whitespace or any of the following reserved characters: ( ) & | !

Examples

| Expression | Selection | | ------------------------------------------------ | ----------------------------------------------------------- | | product | product | | catalog \| shipping | catalog or shipping | | catalog & shipping | catalog and shipping | | product & !end-to-end | product, excluding end-to-end | | (micro \| integration) & (product \| shipping) | micro or integration within product or shipping |