Function validateLocaleAndSetLanguage

test/fixtures/snapshot/typescript.js:12671–12723

* Checks to see if the locale is in the appropriate format, * and if it is, attempts to set the appropriate language.

(locale, sys, errors)

     * and if it is, attempts to set the appropriate language.
     */
    function validateLocaleAndSetLanguage(locale, sys, errors) {
        var lowerCaseLocale = locale.toLowerCase();
        var matchResult = /^([a-z]+)([_\-]([a-z]+))?$/.exec(lowerCaseLocale);
        if (!matchResult) {
            if (errors) {
                errors.push(ts.createCompilerDiagnostic(ts.Diagnostics.Locale_must_be_of_the_form_language_or_language_territory_For_example_0_or_1, "en", "ja-jp"));
            }
            return;
        }
        var language = matchResult[1];
        var territory = matchResult[3];
        // First try the entire locale, then fall back to just language if that's all we have.
        // Either ways do not fail, and fallback to the English diagnostic strings.
        if (ts.contains(ts.supportedLocaleDirectories, lowerCaseLocale) && !trySetLanguageAndTerritory(language, territory, errors)) {
            trySetLanguageAndTerritory(language, /*territory*/ undefined, errors);
        }
        // Set the UI locale for string collation
        ts.setUILocale(locale);
        function trySetLanguageAndTerritory(language, territory, errors) {
            var compilerFilePath = ts.normalizePath(sys.getExecutingFilePath());
            var containingDirectoryPath = ts.getDirectoryPath(compilerFilePath);
            var filePath = ts.combinePaths(containingDirectoryPath, language);
            if (territory) {
                filePath = filePath + "-" + territory;
            }
            filePath = sys.resolvePath(ts.combinePaths(filePath, "diagnosticMessages.generated.json"));
            if (!sys.fileExists(filePath)) {
                return false;
            }
            // TODO: Add codePage support for readFile?
            var fileContents = "";
            try {
                fileContents = sys.readFile(filePath);
            }
            catch (e) {
                if (errors) {
                    errors.push(ts.createCompilerDiagnostic(ts.Diagnostics.Unable_to_open_file_0, filePath));
                }
                return false;
            }
            try {
                // this is a global mutation (or live binding update)!
                ts.setLocalizedDiagnosticMessages(JSON.parse(fileContents));
            }
            catch (_a) {
                if (errors) {
                    errors.push(ts.createCompilerDiagnostic(ts.Diagnostics.Corrupted_locale_file_0, filePath));
                }
                return false;
            }
            return true;
        }
    }
    ts.validateLocaleAndSetLanguage = validateLocaleAndSetLanguage;
    function getOriginalNode(node, nodeTest) {
        if (node) {