Update: Implement FlatConfigArray (refs #13481) (#14321)

* Update: Implement FlatConfigArray (refs #13481)

* Upgrade config-array package

* Add schemas for linterOptions, processor, plugins

* Continue implementing config schemas

* RulesSchema start

* Add initial finalization step

* Default config

* Strict mode

* Start rule validation

* Finish FlatConfigArray implementation

* Remove too-new syntax

* Fix default config

* fix test

* Update tests/lib/config/flat-config-array.js

Co-authored-by: Brandon Mills <btmills@users.noreply.github.com>

* Update tests/lib/config/flat-config-array.js

Co-authored-by: Brandon Mills <btmills@users.noreply.github.com>

* Update tests/lib/config/flat-config-array.js

Co-authored-by: Brandon Mills <btmills@users.noreply.github.com>

* Update tests/lib/config/flat-config-array.js

Co-authored-by: Brandon Mills <btmills@users.noreply.github.com>

* Update tests

* fix test

* Allow old-style plugin names

* Fix reportUnusedDisableDirectives and add JSDoc

* Add more tests

* address review comments

* Ignore only .git directory

* Allow null for global settings

* writeable -> writable

* Remove incorrect comment

* Validate severity-only rule options

* Add key to global error message

* deeply merge parserOptions and settings

* Rename defaultResultConfig

* Normalize and fix rule validations

* Fix rule options merging

* Fix various errors

* Rebase onto master

Co-authored-by: Brandon Mills <btmills@users.noreply.github.com>

lib/config/default-config.js

@@ -0,0 +1,52 @@
+/**
+ * @fileoverview Default configuration
+ * @author Nicholas C. Zakas
+ */
+
+"use strict";
+
+//-----------------------------------------------------------------------------
+// Requirements
+//-----------------------------------------------------------------------------
+
+const Rules = require("../rules");
+
+//-----------------------------------------------------------------------------
+// Helpers
+//-----------------------------------------------------------------------------
+
+
+exports.defaultConfig = [
+    {
+        plugins: {
+            "@": {
+                parsers: {
+                    espree: require("espree")
+                },
+
+                /*
+                 * Because we try to delay loading rules until absolutely
+                 * necessary, a proxy  allows us to hook into the lazy-loading
+                 * aspect of the rules map while still keeping all of the
+                 * relevant configuration inside of the config array.
+                 */
+                rules: new Proxy({}, {
+                    get(target, property) {
+                        return Rules.get(property);
+                    },
+
+                    has(target, property) {
+                        return Rules.has(property);
+                    }
+                })
+            }
+        },
+        ignores: [
+            "**/node_modules/**",
+            ".git/**"
+        ],
+        languageOptions: {
+            parser: "@/espree"
+        }
+    }
+];

lib/config/flat-config-array.js

@@ -0,0 +1,125 @@
+/**
+ * @fileoverview Flat Config Array
+ * @author Nicholas C. Zakas
+ */
+
+"use strict";
+
+//-----------------------------------------------------------------------------
+// Requirements
+//-----------------------------------------------------------------------------
+
+const { ConfigArray, ConfigArraySymbol } = require("@humanwhocodes/config-array");
+const { flatConfigSchema } = require("./flat-config-schema");
+const { RuleValidator } = require("./rule-validator");
+const { defaultConfig } = require("./default-config");
+const recommendedConfig = require("../../conf/eslint-recommended");
+const allConfig = require("../../conf/eslint-all");
+
+//-----------------------------------------------------------------------------
+// Helpers
+//-----------------------------------------------------------------------------
+
+const ruleValidator = new RuleValidator();
+
+/**
+ * Splits a plugin identifier in the form a/b/c into two parts: a/b and c.
+ * @param {string} identifier The identifier to parse.
+ * @returns {{objectName: string, pluginName: string}} The parts of the plugin
+ *      name.
+ */
+function splitPluginIdentifier(identifier) {
+    const parts = identifier.split("/");
+
+    return {
+        objectName: parts.pop(),
+        pluginName: parts.join("/")
+    };
+}
+
+//-----------------------------------------------------------------------------
+// Exports
+//-----------------------------------------------------------------------------
+
+/**
+ * Represents an array containing configuration information for ESLint.
+ */
+class FlatConfigArray extends ConfigArray {
+
+    /**
+     * Creates a new instance.
+     * @param {*[]} configs An array of configuration information.
+     * @param {{basePath: string, baseConfig: FlatConfig}} options The options
+     *      to use for the config array instance.
+     */
+    constructor(configs, { basePath, baseConfig = defaultConfig }) {
+        super(configs, {
+            basePath,
+            schema: flatConfigSchema
+        });
+
+        this.unshift(baseConfig);
+    }
+
+    /* eslint-disable class-methods-use-this */
+    /**
+     * Replaces a config with another config to allow us to put strings
+     * in the config array that will be replaced by objects before
+     * normalization.
+     * @param {Object} config The config to preprocess.
+     * @returns {Object} The preprocessed config.
+     */
+    [ConfigArraySymbol.preprocessConfig](config) {
+        if (config === "eslint:recommended") {
+            return recommendedConfig;
+        }
+
+        if (config === "eslint:all") {
+            return allConfig;
+        }
+
+        return config;
+    }
+
+    /**
+     * Finalizes the config by replacing plugin references with their objects
+     * and validating rule option schemas.
+     * @param {Object} config The config to finalize.
+     * @returns {Object} The finalized config.
+     * @throws {TypeError} If the config is invalid.
+     */
+    [ConfigArraySymbol.finalizeConfig](config) {
+
+        const { plugins, languageOptions, processor } = config;
+
+        // Check parser value
+        if (languageOptions && languageOptions.parser && typeof languageOptions.parser === "string") {
+            const { pluginName, objectName: parserName } = splitPluginIdentifier(languageOptions.parser);
+
+            if (!plugins || !plugins[pluginName] || !plugins[pluginName].parsers || !plugins[pluginName].parsers[parserName]) {
+                throw new TypeError(`Key "parser": Could not find "${parserName}" in plugin "${pluginName}".`);
+            }
+
+            languageOptions.parser = plugins[pluginName].parsers[parserName];
+        }
+
+        // Check processor value
+        if (processor && typeof processor === "string") {
+            const { pluginName, objectName: processorName } = splitPluginIdentifier(processor);
+
+            if (!plugins || !plugins[pluginName] || !plugins[pluginName].processors || !plugins[pluginName].processors[processorName]) {
+                throw new TypeError(`Key "processor": Could not find "${processorName}" in plugin "${pluginName}".`);
+            }
+
+            config.processor = plugins[pluginName].processors[processorName];
+        }
+
+        ruleValidator.validate(config);
+
+        return config;
+    }
+    /* eslint-enable class-methods-use-this */
+
+}
+
+exports.FlatConfigArray = FlatConfigArray;