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node_modules/eslint/lib/config/flat-config-schema.js

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+/**
+ * @fileoverview Flat config schema
+ * @author Nicholas C. Zakas
+ */
+
+"use strict";
+
+//-----------------------------------------------------------------------------
+// Type Definitions
+//-----------------------------------------------------------------------------
+
+/**
+ * @typedef ObjectPropertySchema
+ * @property {Function|string} merge The function or name of the function to call
+ *      to merge multiple objects with this property.
+ * @property {Function|string} validate The function or name of the function to call
+ *      to validate the value of this property.
+ */
+
+//-----------------------------------------------------------------------------
+// Helpers
+//-----------------------------------------------------------------------------
+
+const ruleSeverities = new Map([
+    [0, 0], ["off", 0],
+    [1, 1], ["warn", 1],
+    [2, 2], ["error", 2]
+]);
+
+const globalVariablesValues = new Set([
+    true, "true", "writable", "writeable",
+    false, "false", "readonly", "readable", null,
+    "off"
+]);
+
+/**
+ * Check if a value is a non-null object.
+ * @param {any} value The value to check.
+ * @returns {boolean} `true` if the value is a non-null object.
+ */
+function isNonNullObject(value) {
+    return typeof value === "object" && value !== null;
+}
+
+/**
+ * Check if a value is undefined.
+ * @param {any} value The value to check.
+ * @returns {boolean} `true` if the value is undefined.
+ */
+function isUndefined(value) {
+    return typeof value === "undefined";
+}
+
+/**
+ * Deeply merges two objects.
+ * @param {Object} first The base object.
+ * @param {Object} second The overrides object.
+ * @returns {Object} An object with properties from both first and second.
+ */
+function deepMerge(first = {}, second = {}) {
+
+    /*
+     * If the second value is an array, just return it. We don't merge
+     * arrays because order matters and we can't know the correct order.
+     */
+    if (Array.isArray(second)) {
+        return second;
+    }
+
+    /*
+     * First create a result object where properties from the second object
+     * overwrite properties from the first. This sets up a baseline to use
+     * later rather than needing to inspect and change every property
+     * individually.
+     */
+    const result = {
+        ...first,
+        ...second
+    };
+
+    for (const key of Object.keys(second)) {
+
+        // avoid hairy edge case
+        if (key === "__proto__") {
+            continue;
+        }
+
+        const firstValue = first[key];
+        const secondValue = second[key];
+
+        if (isNonNullObject(firstValue)) {
+            result[key] = deepMerge(firstValue, secondValue);
+        } else if (isUndefined(firstValue)) {
+            if (isNonNullObject(secondValue)) {
+                result[key] = deepMerge(
+                    Array.isArray(secondValue) ? [] : {},
+                    secondValue
+                );
+            } else if (!isUndefined(secondValue)) {
+                result[key] = secondValue;
+            }
+        }
+    }
+
+    return result;
+
+}
+
+/**
+ * Normalizes the rule options config for a given rule by ensuring that
+ * it is an array and that the first item is 0, 1, or 2.
+ * @param {Array|string|number} ruleOptions The rule options config.
+ * @returns {Array} An array of rule options.
+ */
+function normalizeRuleOptions(ruleOptions) {
+
+    const finalOptions = Array.isArray(ruleOptions)
+        ? ruleOptions.slice(0)
+        : [ruleOptions];
+
+    finalOptions[0] = ruleSeverities.get(finalOptions[0]);
+    return finalOptions;
+}
+
+//-----------------------------------------------------------------------------
+// Assertions
+//-----------------------------------------------------------------------------
+
+/**
+ * Validates that a value is a valid rule options entry.
+ * @param {any} value The value to check.
+ * @returns {void}
+ * @throws {TypeError} If the value isn't a valid rule options.
+ */
+function assertIsRuleOptions(value) {
+
+    if (typeof value !== "string" && typeof value !== "number" && !Array.isArray(value)) {
+        throw new TypeError("Expected a string, number, or array.");
+    }
+}
+
+/**
+ * Validates that a value is valid rule severity.
+ * @param {any} value The value to check.
+ * @returns {void}
+ * @throws {TypeError} If the value isn't a valid rule severity.
+ */
+function assertIsRuleSeverity(value) {
+    const severity = typeof value === "string"
+        ? ruleSeverities.get(value.toLowerCase())
+        : ruleSeverities.get(value);
+
+    if (typeof severity === "undefined") {
+        throw new TypeError("Expected severity of \"off\", 0, \"warn\", 1, \"error\", or 2.");
+    }
+}
+
+/**
+ * Validates that a given string is the form pluginName/objectName.
+ * @param {string} value The string to check.
+ * @returns {void}
+ * @throws {TypeError} If the string isn't in the correct format.
+ */
+function assertIsPluginMemberName(value) {
+    if (!/[@a-z0-9-_$]+(?:\/(?:[a-z0-9-_$]+))+$/iu.test(value)) {
+        throw new TypeError(`Expected string in the form "pluginName/objectName" but found "${value}".`);
+    }
+}
+
+/**
+ * Validates that a value is an object.
+ * @param {any} value The value to check.
+ * @returns {void}
+ * @throws {TypeError} If the value isn't an object.
+ */
+function assertIsObject(value) {
+    if (!isNonNullObject(value)) {
+        throw new TypeError("Expected an object.");
+    }
+}
+
+/**
+ * Validates that a value is an object or a string.
+ * @param {any} value The value to check.
+ * @returns {void}
+ * @throws {TypeError} If the value isn't an object or a string.
+ */
+function assertIsObjectOrString(value) {
+    if ((!value || typeof value !== "object") && typeof value !== "string") {
+        throw new TypeError("Expected an object or string.");
+    }
+}
+
+//-----------------------------------------------------------------------------
+// Low-Level Schemas
+//-----------------------------------------------------------------------------
+
+
+/** @type {ObjectPropertySchema} */
+const numberSchema = {
+    merge: "replace",
+    validate: "number"
+};
+
+/** @type {ObjectPropertySchema} */
+const booleanSchema = {
+    merge: "replace",
+    validate: "boolean"
+};
+
+/** @type {ObjectPropertySchema} */
+const deepObjectAssignSchema = {
+    merge(first = {}, second = {}) {
+        return deepMerge(first, second);
+    },
+    validate: "object"
+};
+
+//-----------------------------------------------------------------------------
+// High-Level Schemas
+//-----------------------------------------------------------------------------
+
+/** @type {ObjectPropertySchema} */
+const globalsSchema = {
+    merge: "assign",
+    validate(value) {
+
+        assertIsObject(value);
+
+        for (const key of Object.keys(value)) {
+
+            // avoid hairy edge case
+            if (key === "__proto__") {
+                continue;
+            }
+
+            if (key !== key.trim()) {
+                throw new TypeError(`Global "${key}" has leading or trailing whitespace.`);
+            }
+
+            if (!globalVariablesValues.has(value[key])) {
+                throw new TypeError(`Key "${key}": Expected "readonly", "writable", or "off".`);
+            }
+        }
+    }
+};
+
+/** @type {ObjectPropertySchema} */
+const parserSchema = {
+    merge: "replace",
+    validate(value) {
+        assertIsObjectOrString(value);
+
+        if (typeof value === "object" && typeof value.parse !== "function" && typeof value.parseForESLint !== "function") {
+            throw new TypeError("Expected object to have a parse() or parseForESLint() method.");
+        }
+
+        if (typeof value === "string") {
+            assertIsPluginMemberName(value);
+        }
+    }
+};
+
+/** @type {ObjectPropertySchema} */
+const pluginsSchema = {
+    merge(first = {}, second = {}) {
+        const keys = new Set([...Object.keys(first), ...Object.keys(second)]);
+        const result = {};
+
+        // manually validate that plugins are not redefined
+        for (const key of keys) {
+
+            // avoid hairy edge case
+            if (key === "__proto__") {
+                continue;
+            }
+
+            if (key in first && key in second && first[key] !== second[key]) {
+                throw new TypeError(`Cannot redefine plugin "${key}".`);
+            }
+
+            result[key] = second[key] || first[key];
+        }
+
+        return result;
+    },
+    validate(value) {
+
+        // first check the value to be sure it's an object
+        if (value === null || typeof value !== "object") {
+            throw new TypeError("Expected an object.");
+        }
+
+        // second check the keys to make sure they are objects
+        for (const key of Object.keys(value)) {
+
+            // avoid hairy edge case
+            if (key === "__proto__") {
+                continue;
+            }
+
+            if (value[key] === null || typeof value[key] !== "object") {
+                throw new TypeError(`Key "${key}": Expected an object.`);
+            }
+        }
+    }
+};
+
+/** @type {ObjectPropertySchema} */
+const processorSchema = {
+    merge: "replace",
+    validate(value) {
+        if (typeof value === "string") {
+            assertIsPluginMemberName(value);
+        } else if (value && typeof value === "object") {
+            if (typeof value.preprocess !== "function" || typeof value.postprocess !== "function") {
+                throw new TypeError("Object must have a preprocess() and a postprocess() method.");
+            }
+        } else {
+            throw new TypeError("Expected an object or a string.");
+        }
+    }
+};
+
+/** @type {ObjectPropertySchema} */
+const rulesSchema = {
+    merge(first = {}, second = {}) {
+
+        const result = {
+            ...first,
+            ...second
+        };
+
+        for (const ruleId of Object.keys(result)) {
+
+            // avoid hairy edge case
+            if (ruleId === "__proto__") {
+
+                /* eslint-disable-next-line no-proto */
+                delete result.__proto__;
+                continue;
+            }
+
+            result[ruleId] = normalizeRuleOptions(result[ruleId]);
+
+            /*
+             * If either rule config is missing, then the correct
+             * config is already present and we just need to normalize
+             * the severity.
+             */
+            if (!(ruleId in first) || !(ruleId in second)) {
+                continue;
+            }
+
+            const firstRuleOptions = normalizeRuleOptions(first[ruleId]);
+            const secondRuleOptions = normalizeRuleOptions(second[ruleId]);
+
+            /*
+             * If the second rule config only has a severity (length of 1),
+             * then use that severity and keep the rest of the options from
+             * the first rule config.
+             */
+            if (secondRuleOptions.length === 1) {
+                result[ruleId] = [secondRuleOptions[0], ...firstRuleOptions.slice(1)];
+                continue;
+            }
+
+            /*
+             * In any other situation, then the second rule config takes
+             * precedence. That means the value at `result[ruleId]` is
+             * already correct and no further work is necessary.
+             */
+        }
+
+        return result;
+    },
+
+    validate(value) {
+        assertIsObject(value);
+
+        let lastRuleId;
+
+        // Performance: One try-catch has less overhead than one per loop iteration
+        try {
+
+            /*
+             * We are not checking the rule schema here because there is no
+             * guarantee that the rule definition is present at this point. Instead
+             * we wait and check the rule schema during the finalization step
+             * of calculating a config.
+             */
+            for (const ruleId of Object.keys(value)) {
+
+                // avoid hairy edge case
+                if (ruleId === "__proto__") {
+                    continue;
+                }
+
+                lastRuleId = ruleId;
+
+                const ruleOptions = value[ruleId];
+
+                assertIsRuleOptions(ruleOptions);
+
+                if (Array.isArray(ruleOptions)) {
+                    assertIsRuleSeverity(ruleOptions[0]);
+                } else {
+                    assertIsRuleSeverity(ruleOptions);
+                }
+            }
+        } catch (error) {
+            error.message = `Key "${lastRuleId}": ${error.message}`;
+            throw error;
+        }
+    }
+};
+
+/** @type {ObjectPropertySchema} */
+const sourceTypeSchema = {
+    merge: "replace",
+    validate(value) {
+        if (typeof value !== "string" || !/^(?:script|module|commonjs)$/u.test(value)) {
+            throw new TypeError("Expected \"script\", \"module\", or \"commonjs\".");
+        }
+    }
+};
+
+//-----------------------------------------------------------------------------
+// Full schema
+//-----------------------------------------------------------------------------
+
+exports.flatConfigSchema = {
+    settings: deepObjectAssignSchema,
+    linterOptions: {
+        schema: {
+            noInlineConfig: booleanSchema,
+            reportUnusedDisableDirectives: booleanSchema
+        }
+    },
+    languageOptions: {
+        schema: {
+            ecmaVersion: numberSchema,
+            sourceType: sourceTypeSchema,
+            globals: globalsSchema,
+            parser: parserSchema,
+            parserOptions: deepObjectAssignSchema
+        }
+    },
+    processor: processorSchema,
+    plugins: pluginsSchema,
+    rules: rulesSchema
+};