Add name field to the lexical specification

1 files changed, 27 insertions, 2 deletions

diff --git a/cmd/maleeni-go/generate.go b/cmd/maleeni-go/generate.go
index d37defd..d31daed 100644
--- a/cmd/maleeni-go/generate.go
+++ b/cmd/maleeni-go/generate.go
@@ -24,13 +24,14 @@ func Execute() error {
 
 var generateFlags = struct {
 	pkgName *string
+	output  *string
 }{}
 
 var generateCmd = &cobra.Command{
 	Use:           "maleeni-go",
 	Short:         "Generate a lexer for Go",
 	Long:          `maleeni-go generates a lexer for Go. The lexer recognizes the lexical specification specified as the argument.`,
-	Example:       `  maleeni-go clexspec.json > lexer.go`,
+	Example:       `  maleeni-go clexspec.json`,
 	Args:          cobra.ExactArgs(1),
 	RunE:          runGenerate,
 	SilenceErrors: true,
@@ -39,6 +40,7 @@ var generateCmd = &cobra.Command{
 
 func init() {
 	generateFlags.pkgName = generateCmd.Flags().StringP("package", "p", "main", "package name")
+	generateFlags.output = generateCmd.Flags().StringP("output", "o", "", "output file path")
 }
 
 func runGenerate(cmd *cobra.Command, args []string) (retErr error) {
@@ -47,7 +49,30 @@ func runGenerate(cmd *cobra.Command, args []string) (retErr error) {
 		return fmt.Errorf("Cannot read a compiled lexical specification: %w", err)
 	}
 
-	return driver.GenLexer(clspec, *generateFlags.pkgName)
+	b, err := driver.GenLexer(clspec, *generateFlags.pkgName)
+	if err != nil {
+		return fmt.Errorf("Failed to generate a lexer: %v", err)
+	}
+
+	var filePath string
+	if *generateFlags.output != "" {
+		filePath = *generateFlags.output
+	} else {
+		filePath = fmt.Sprintf("%v_lexer.go", clspec.Name)
+	}
+
+	f, err := os.OpenFile(filePath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
+	if err != nil {
+		return fmt.Errorf("Failed to create an output file: %v", err)
+	}
+	defer f.Close()
+
+	_, err = f.Write(b)
+	if err != nil {
+		return fmt.Errorf("Failed to write lexer source code: %v", err)
+	}
+
+	return nil
 }
 
 func readCompiledLexSpec(path string) (*spec.CompiledLexSpec, error) {