Function tryReuseStructureFromOldProgram

test/fixtures/snapshot/typescript.js:117206–117413

()

            });
        }
        function tryReuseStructureFromOldProgram() {
            var _a;
            if (!oldProgram) {
                return 0 /* StructureIsReused.Not */;
            }
            // check properties that can affect structure of the program or module resolution strategy
            // if any of these properties has changed - structure cannot be reused
            var oldOptions = oldProgram.getCompilerOptions();
            if (ts.changesAffectModuleResolution(oldOptions, options)) {
                return 0 /* StructureIsReused.Not */;
            }
            // there is an old program, check if we can reuse its structure
            var oldRootNames = oldProgram.getRootFileNames();
            if (!ts.arrayIsEqualTo(oldRootNames, rootNames)) {
                return 0 /* StructureIsReused.Not */;
            }
            // Check if any referenced project tsconfig files are different
            if (!canReuseProjectReferences()) {
                return 0 /* StructureIsReused.Not */;
            }
            if (projectReferences) {
                resolvedProjectReferences = projectReferences.map(parseProjectReferenceConfigFile);
            }
            // check if program source files has changed in the way that can affect structure of the program
            var newSourceFiles = [];
            var modifiedSourceFiles = [];
            structureIsReused = 2 /* StructureIsReused.Completely */;
            // If the missing file paths are now present, it can change the progam structure,
            // and hence cant reuse the structure.
            // This is same as how we dont reuse the structure if one of the file from old program is now missing
            if (oldProgram.getMissingFilePaths().some(function (missingFilePath) { return host.fileExists(missingFilePath); })) {
                return 0 /* StructureIsReused.Not */;
            }
            var oldSourceFiles = oldProgram.getSourceFiles();
            var SeenPackageName;
            (function (SeenPackageName) {
                SeenPackageName[SeenPackageName["Exists"] = 0] = "Exists";
                SeenPackageName[SeenPackageName["Modified"] = 1] = "Modified";
            })(SeenPackageName || (SeenPackageName = {}));
            var seenPackageNames = new ts.Map();
            for (var _i = 0, oldSourceFiles_2 = oldSourceFiles; _i < oldSourceFiles_2.length; _i++) {
                var oldSourceFile = oldSourceFiles_2[_i];
                var newSourceFile = host.getSourceFileByPath
                    ? host.getSourceFileByPath(oldSourceFile.fileName, oldSourceFile.resolvedPath, getCreateSourceFileOptions(oldSourceFile.fileName, moduleResolutionCache, host, options), /*onError*/ undefined, shouldCreateNewSourceFile)
                    : host.getSourceFile(oldSourceFile.fileName, getCreateSourceFileOptions(oldSourceFile.fileName, moduleResolutionCache, host, options), /*onError*/ undefined, shouldCreateNewSourceFile); // TODO: GH#18217
                if (!newSourceFile) {
                    return 0 /* StructureIsReused.Not */;
                }
                ts.Debug.assert(!newSourceFile.redirectInfo, "Host should not return a redirect source file from `getSourceFile`");
                var fileChanged = void 0;
                if (oldSourceFile.redirectInfo) {
                    // We got `newSourceFile` by path, so it is actually for the unredirected file.
                    // This lets us know if the unredirected file has changed. If it has we should break the redirect.
                    if (newSourceFile !== oldSourceFile.redirectInfo.unredirected) {
                        // Underlying file has changed. Might not redirect anymore. Must rebuild program.
                        return 0 /* StructureIsReused.Not */;
                    }
                    fileChanged = false;