convert compilers to use functional options (#17)

* Refactor compiler creation for machines to use functional options

* Add machine-specific options and refactor evaluator creation for Extism, Risor, and Starlark

* Refactor machine-specific options: move to respective packages and update evaluator creation

* Remove machine-specific options and update type conversions to use 'any'

* rename options to compilerOptions

* lint-fix

* remove extra logger config

* move the common data provider setup code to a private function

Author: robbyt

engine/options/options.go

@@ -20,8 +20,6 @@ type Config struct {
 	dataProvider data.Provider
 	// Loader for the script content
 	loader loader.Loader
-	// Machine-specific options
-	compilerOptions any
 }
 
 // Option is a function that modifies Config
@@ -121,12 +119,7 @@ func (c *Config) GetLoader() loader.Loader {
 	return c.loader
 }
 
-// GetCompilerOptions returns the machine-specific compiler options
-func (c *Config) GetCompilerOptions() any {
-	return c.compilerOptions
-}
-
-// SetCompilerOptions sets the machine-specific compiler options
-func (c *Config) SetCompilerOptions(options any) {
-	c.compilerOptions = options
+// SetLoader sets the loader
+func (c *Config) SetLoader(l loader.Loader) {
+	c.loader = l
 }

engine/options/options_test.go

@@ -108,19 +108,16 @@ func TestConfigGetters(t *testing.T) {
 	testHandler := slog.NewTextHandler(os.Stdout, nil)
 	testDataProvider := data.NewStaticProvider(map[string]any{"test": "value"})
 	testLoader := NewMockLoader()
-	testCompilerOpts := "test-options"
 
 	cfg := &Config{
-		handler:         testHandler,
-		machineType:     types.Starlark,
-		dataProvider:    testDataProvider,
-		loader:          testLoader,
-		compilerOptions: testCompilerOpts,
+		handler:      testHandler,
+		machineType:  types.Starlark,
+		dataProvider: testDataProvider,
+		loader:       testLoader,
 	}
 
 	require.Equal(t, testHandler, cfg.GetHandler())
 	require.Equal(t, types.Starlark, cfg.GetMachineType())
 	require.Equal(t, testDataProvider, cfg.GetDataProvider())
 	require.Equal(t, testLoader, cfg.GetLoader())
-	require.Equal(t, testCompilerOpts, cfg.GetCompilerOptions())
 }

machines/extism/compiler.go

@@ -23,30 +23,55 @@ type Compiler struct {
 	logger         *slog.Logger
 }
 
-type CompilerOptions interface {
-	GetEntryPointName() string
-}
+// NewCompiler creates a new Extism WASM Compiler instance with the provided options.
+func NewCompiler(opts ...CompilerOption) (*Compiler, error) {
+	// Initialize config with defaults
+	cfg := &compilerOptions{}
+	applyDefaults(cfg)
+
+	// Apply all options
+	for _, opt := range opts {
+		if err := opt(cfg); err != nil {
+			return nil, fmt.Errorf("error applying compiler option: %w", err)
+		}
+	}
 
-// NewCompiler creates a new Extism WASM Compiler instance. External config of the compiler not
-// currently supported.
-func NewCompiler(handler slog.Handler, compilerOptions CompilerOptions) *Compiler {
-	handler, logger := helpers.SetupLogger(handler, "extism", "Compiler")
+	// Validate the configuration
+	if err := validate(cfg); err != nil {
+		return nil, fmt.Errorf("invalid compiler configuration: %w", err)
+	}
 
-	entryPointName := compilerOptions.GetEntryPointName()
-	if entryPointName == "" {
-		entryPointName = defaultEntryPoint
+	var handler slog.Handler
+	var logger *slog.Logger
+
+	// Set up logging based on provided options
+	if cfg.Logger != nil {
+		// User provided a custom logger
+		logger = cfg.Logger
+		handler = logger.Handler()
+	} else {
+		// User provided a handler or we're using the default
+		handler, logger = helpers.SetupLogger(cfg.LogHandler, "extism", "Compiler")
 	}
 
-	var funcName atomic.Value
-	funcName.Store(entryPointName)
+	// Set up entry point name in atomic.Value
+	var entryPointAtomicValue atomic.Value
+	entryPointAtomicValue.Store(cfg.EntryPoint)
+
+	// Create compile options from config
+	compileOpts := &compileOptions{
+		EnableWASI:    cfg.EnableWASI,
+		RuntimeConfig: cfg.RuntimeConfig,
+		HostFunctions: cfg.HostFunctions,
+	}
 
 	return &Compiler{
-		entryPointName: funcName,
+		entryPointName: entryPointAtomicValue,
 		ctx:            context.Background(),
-		options:        withDefaultCompileOptions(),
+		options:        compileOpts,
 		logHandler:     handler,
 		logger:         logger,
-	}
+	}, nil
 }
 
 func (c *Compiler) String() string {

machines/extism/compilerOptions.go

@@ -0,0 +1,137 @@
+package extism
+
+import (
+	"fmt"
+	"log/slog"
+	"os"
+
+	extismSDK "github.com/extism/go-sdk"
+	"github.com/tetratelabs/wazero"
+)
+
+// compilerOptions holds the configuration for the Extism compiler
+type compilerOptions struct {
+	EntryPoint    string
+	LogHandler    slog.Handler
+	Logger        *slog.Logger
+	EnableWASI    bool
+	RuntimeConfig wazero.RuntimeConfig
+	HostFunctions []extismSDK.HostFunction
+}
+
+// CompilerOption is a function that configures a compilerOptions instance
+type CompilerOption func(*compilerOptions) error
+
+// WithEntryPoint creates an option to set the entry point for Extism WASM modules
+func WithEntryPoint(entryPoint string) CompilerOption {
+	return func(cfg *compilerOptions) error {
+		if entryPoint == "" {
+			return fmt.Errorf("entry point cannot be empty")
+		}
+		cfg.EntryPoint = entryPoint
+		return nil
+	}
+}
+
+// WithLogHandler creates an option to set the log handler for Extism compiler.
+// This is the preferred option for logging configuration as it provides
+// more flexibility through the slog.Handler interface.
+func WithLogHandler(handler slog.Handler) CompilerOption {
+	return func(cfg *compilerOptions) error {
+		if handler == nil {
+			return fmt.Errorf("log handler cannot be nil")
+		}
+		cfg.LogHandler = handler
+		// Clear logger if handler is explicitly set
+		cfg.Logger = nil
+		return nil
+	}
+}
+
+// WithLogger creates an option to set a specific logger for Extism compiler.
+// This is less flexible than WithLogHandler but allows users to customize
+// their logging group configuration.
+func WithLogger(logger *slog.Logger) CompilerOption {
+	return func(cfg *compilerOptions) error {
+		if logger == nil {
+			return fmt.Errorf("logger cannot be nil")
+		}
+		cfg.Logger = logger
+		// Clear handler if logger is explicitly set
+		cfg.LogHandler = nil
+		return nil
+	}
+}
+
+// WithWASIEnabled creates an option to enable or disable WASI support
+func WithWASIEnabled(enabled bool) CompilerOption {
+	return func(cfg *compilerOptions) error {
+		cfg.EnableWASI = enabled
+		return nil
+	}
+}
+
+// WithRuntimeConfig creates an option to set a custom wazero runtime configuration
+func WithRuntimeConfig(config wazero.RuntimeConfig) CompilerOption {
+	return func(cfg *compilerOptions) error {
+		if config == nil {
+			return fmt.Errorf("runtime config cannot be nil")
+		}
+		cfg.RuntimeConfig = config
+		return nil
+	}
+}
+
+// WithHostFunctions creates an option to set additional host functions
+func WithHostFunctions(funcs []extismSDK.HostFunction) CompilerOption {
+	return func(cfg *compilerOptions) error {
+		cfg.HostFunctions = funcs
+		return nil
+	}
+}
+
+// applyDefaults sets the default values for a compilerConfig
+func applyDefaults(cfg *compilerOptions) {
+	// Default to stderr for logging if neither handler nor logger specified
+	if cfg.LogHandler == nil && cfg.Logger == nil {
+		cfg.LogHandler = slog.NewTextHandler(os.Stderr, nil)
+	}
+
+	// Default entry point
+	if cfg.EntryPoint == "" {
+		cfg.EntryPoint = defaultEntryPoint
+	}
+
+	// Default WASI setting
+	cfg.EnableWASI = true
+
+	// Default runtime config
+	if cfg.RuntimeConfig == nil {
+		cfg.RuntimeConfig = wazero.NewRuntimeConfig()
+	}
+
+	// Default to empty host functions
+	if cfg.HostFunctions == nil {
+		cfg.HostFunctions = []extismSDK.HostFunction{}
+	}
+}
+
+// validate checks if the configuration is valid
+func validate(cfg *compilerOptions) error {
+	// Ensure we have either a logger or a handler
+	if cfg.LogHandler == nil && cfg.Logger == nil {
+		return fmt.Errorf("either log handler or logger must be specified")
+	}
+
+	// Entry point must be non-empty
+	if cfg.EntryPoint == "" {
+		return fmt.Errorf("entry point must be specified")
+	}
+
+	// Runtime config cannot be nil
+	if cfg.RuntimeConfig == nil {
+		return fmt.Errorf("runtime config cannot be nil")
+	}
+
+	return nil
+}