eslint-plugin-formatjs/lib_esnext/rules/no-complex-selectors.js

ESLint plugin for formatjs

import { TYPE, parse, } from '@formatjs/icu-messageformat-parser';
import { getParserServices } from '../context-compat';
import { extractMessages, getSettings } from '../util';
function calculateComplexity(ast) {
    // Dynamic programming: define a complexity function f, where:
    //   f(plural | select) = sum(f(option) for each option) * f(next element),
    //   f(tag) = f(first element of children) * f(next element),
    //   f(other) = f(next element),
    //   f(out of bound) = 1.
    const complexityByNode = new Map();
    return _calculate(ast, 0);
    function _calculate(ast, index) {
        const element = ast[index];
        if (!element) {
            return 1;
        }
        const cachedComplexity = complexityByNode.get(element);
        if (cachedComplexity !== undefined) {
            return cachedComplexity;
        }
        let complexity;
        switch (element.type) {
            case TYPE.plural:
            case TYPE.select: {
                let sumOfOptions = 0;
                for (const { value } of Object.values(element.options)) {
                    sumOfOptions += _calculate(value, 0);
                }
                complexity = sumOfOptions * _calculate(ast, index + 1);
                break;
            }
            case TYPE.tag:
                complexity =
                    _calculate(element.children, 0) * _calculate(ast, index + 1);
                break;
            default:
                complexity = _calculate(ast, index + 1);
                break;
        }
        complexityByNode.set(element, complexity);
        return complexity;
    }
}
function checkNode(context, node) {
    const settings = getSettings(context);
    const msgs = extractMessages(node, settings);
    if (!msgs.length) {
        return;
    }
    const config = {
        limit: 20,
        ...(context.options[0] || {}),
    };
    for (const [{ message: { defaultMessage }, messageNode, },] of msgs) {
        if (!defaultMessage || !messageNode) {
            continue;
        }
        let ast;
        try {
            ast = parse(defaultMessage, {
                ignoreTag: settings.ignoreTag,
            });
        }
        catch (e) {
            context.report({
                node: messageNode,
                messageId: 'parserError',
                data: { message: e instanceof Error ? e.message : String(e) },
            });
            return;
        }
        const complexity = calculateComplexity(ast);
        if (complexity > config.limit) {
            context.report({
                node: messageNode,
                messageId: 'tooComplex',
                data: {
                    complexity,
                    limit: config.limit,
                },
            });
        }
    }
}
export const name = 'no-complex-selectors';
export const rule = {
    meta: {
        type: 'problem',
        docs: {
            description: `Make sure a sentence is not too complex.
Complexity is determined by how many strings are produced when we try to
flatten the sentence given its selectors. For example:
"I have {count, plural, one{a dog} other{many dogs}}"
has the complexity of 2 because flattening the plural selector
results in 2 sentences: "I have a dog" & "I have many dogs".
Default complexity limit is 20
(using Smartling as a reference: https://help.smartling.com/hc/en-us/articles/360008030994-ICU-MessageFormat)
`,
            url: 'https://formatjs.github.io/docs/tooling/linter#no-complex-selectors',
        },
        schema: [
            {
                type: 'object',
                properties: {
                    limit: {
                        type: 'number',
                    },
                },
                additionalProperties: false,
            },
        ],
        fixable: 'code',
        messages: {
            tooComplex: `Message complexity is too high ({{complexity}} vs limit at {{limit}})`,
            parserError: '{{message}}',
        },
    },
    defaultOptions: [{ limit: 20 }],
    create(context) {
        const callExpressionVisitor = (node) => checkNode(context, node);
        const parserServices = getParserServices(context);
        //@ts-expect-error defineTemplateBodyVisitor exists in Vue parser
        if (parserServices?.defineTemplateBodyVisitor) {
            //@ts-expect-error
            return parserServices.defineTemplateBodyVisitor({
                CallExpression: callExpressionVisitor,
            }, {
                CallExpression: callExpressionVisitor,
            });
        }
        return {
            JSXOpeningElement: (node) => checkNode(context, node),
            CallExpression: callExpressionVisitor,
        };
    },
};