@maniascript/mslint/dist/lib/rules/no-unused-variables.js

ManiaScript linter

import {} from '../linter/rule.js';
import { Scope, ScopeType, Variable } from '@maniascript/parser';
const DEFAULT_EXCEPTIONS = [];
export const noUnusedVariables = {
    meta: {
        id: 'no-unused-variables',
        description: 'Forbid unused variables',
        recommended: true,
        settings: {
            exceptions: DEFAULT_EXCEPTIONS
        }
    },
    create(context) {
        const exceptions = Array.isArray(context.settings['exceptions']) ? context.settings['exceptions'] : DEFAULT_EXCEPTIONS;
        function getReportMessage(name, variable, isWrite) {
            let type = '';
            if (variable.isFunctionParameter) {
                type = 'Function parameter';
            }
            else if (variable.isGlobal) {
                type = 'Global variable';
            }
            else if (variable.isForValue) {
                type = 'For value';
            }
            else if (variable.isForeachKey) {
                type = 'Foreach key';
            }
            else if (variable.isForeachValue) {
                type = 'Foreach value';
            }
            else {
                type = 'Variable';
            }
            let action = '';
            if (isWrite) {
                action = 'never read';
            }
            else {
                action = 'never used';
            }
            return `${type} '${name}' is ${action}`;
        }
        function findUnusedVariables(context, scope) {
            if (scope.type !== ScopeType.LabelDeclaration && !scope.couldReferenceVariableInLabel) {
                let hasForeachKey = false;
                let useForeachKey = true;
                for (const [name, variable] of scope.variables) {
                    if (variable.isForeachKey) {
                        hasForeachKey = true;
                    }
                    if (!variable.isForValue && // Allow unused for value
                        (!variable.isForeachValue || !hasForeachKey || !useForeachKey) && // Allow unused foreach value if the key is used
                        !exceptions.includes(name)) {
                        if (variable.references.length === 0) {
                            if (variable.isForeachKey) {
                                useForeachKey = false;
                            }
                            context.report(variable.node, getReportMessage(name, variable, false));
                        }
                        else if (!variable.isTrait && variable.references.every((reference) => reference.isWrite())) {
                            if (variable.isForeachKey) {
                                useForeachKey = false;
                            }
                            context.report(variable.node, getReportMessage(name, variable, true));
                        }
                    }
                }
            }
            for (const child of scope.children) {
                findUnusedVariables(context, child);
            }
        }
        return {
            'Program:exit': () => {
                const scope = context.getScope();
                if (scope !== null)
                    findUnusedVariables(context, scope);
            }
        };
    }
};