func sourceMode()

in mockgen/parse.go [45:98]
46 lines of code
10 McCabe index (conditional complexity)

func sourceMode(source string) (*model.Package, error) {
	srcDir, err := filepath.Abs(filepath.Dir(source))
	if err != nil {
		return nil, fmt.Errorf("failed getting source directory: %v", err)
	}

	packageImport, err := parsePackageImport(srcDir)
	if err != nil {
		return nil, err
	}

	fs := token.NewFileSet()
	file, err := parser.ParseFile(fs, source, nil, 0)
	if err != nil {
		return nil, fmt.Errorf("failed parsing source file %v: %v", source, err)
	}

	p := &fileParser{
		fileSet:            fs,
		imports:            make(map[string]importedPackage),
		importedInterfaces: make(map[string]map[string]*ast.InterfaceType),
		auxInterfaces:      make(map[string]map[string]*ast.InterfaceType),
		srcDir:             srcDir,
	}

	// Handle -imports.
	dotImports := make(map[string]bool)
	if *imports != "" {
		for _, kv := range strings.Split(*imports, ",") {
			eq := strings.Index(kv, "=")
			k, v := kv[:eq], kv[eq+1:]
			if k == "." {
				dotImports[v] = true
			} else {
				p.imports[k] = importedPkg{path: v}
			}
		}
	}

	// Handle -aux_files.
	if err := p.parseAuxFiles(*auxFiles); err != nil {
		return nil, err
	}
	p.addAuxInterfacesFromFile(packageImport, file) // this file

	pkg, err := p.parseFile(packageImport, file)
	if err != nil {
		return nil, err
	}
	for pkgPath := range dotImports {
		pkg.DotImports = append(pkg.DotImports, pkgPath)
	}
	return pkg, nil
}