1 files changed, 153 insertions, 0 deletions
diff --git a/cmd/vartan-go/generate.go b/cmd/vartan-go/generate.go
new file mode 100644
index 0000000..27f7236
--- /dev/null
+++ b/cmd/vartan-go/generate.go
@@ -0,0 +1,153 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"runtime/debug"
+
+	mldriver "github.com/nihei9/maleeni/driver"
+	"github.com/nihei9/vartan/driver"
+	"github.com/nihei9/vartan/spec"
+	"github.com/spf13/cobra"
+)
+
+func Execute() error {
+	err := generateCmd.Execute()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "%v\n", err)
+		return err
+	}
+
+	return nil
+}
+
+var generateFlags = struct {
+	pkgName *string
+}{}
+
+var generateCmd = &cobra.Command{
+	Use:           "vartan-go",
+	Short:         "Generate a parser for Go",
+	Long:          `vartan-go generates a parser for Go.`,
+	Example:       `  vartan-go grammar.json`,
+	Args:          cobra.ExactArgs(1),
+	RunE:          runGenerate,
+	SilenceErrors: true,
+	SilenceUsage:  true,
+}
+
+func init() {
+	generateFlags.pkgName = generateCmd.Flags().StringP("package", "p", "main", "package name")
+}
+
+func runGenerate(cmd *cobra.Command, args []string) (retErr error) {
+	defer func() {
+		panicked := false
+		v := recover()
+		if v != nil {
+			err, ok := v.(error)
+			if !ok {
+				retErr = fmt.Errorf("an unexpected error occurred: %v", v)
+				fmt.Fprintf(os.Stderr, "%v:\n%v", retErr, string(debug.Stack()))
+				return
+			}
+
+			retErr = err
+			panicked = true
+		}
+
+		if retErr != nil {
+			if panicked {
+				fmt.Fprintf(os.Stderr, "%v:\n%v", retErr, string(debug.Stack()))
+			} else {
+				fmt.Fprintf(os.Stderr, "%v\n", retErr)
+			}
+		}
+	}()
+
+	cgram, err := readCompiledGrammar(args[0])
+	if err != nil {
+		return fmt.Errorf("Cannot read a compiled grammar: %w", err)
+	}
+
+	{
+		b, err := mldriver.GenLexer(cgram.LexicalSpecification.Maleeni.Spec, *generateFlags.pkgName)
+		if err != nil {
+			return fmt.Errorf("Failed to generate a lexer: %w", err)
+		}
+
+		filePath := fmt.Sprintf("%v_lexer.go", cgram.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)
+		}
+	}
+
+	{
+		b, err := driver.GenParser(cgram, *generateFlags.pkgName)
+		if err != nil {
+			return fmt.Errorf("Failed to generate a parser: %w", err)
+		}
+
+		filePath := fmt.Sprintf("%v_parser.go", cgram.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 parser source code: %v", err)
+		}
+	}
+
+	{
+		b, err := driver.GenSemanticAction(*generateFlags.pkgName)
+		if err != nil {
+			return fmt.Errorf("Failed to generate a semantic action set: %w", err)
+		}
+
+		filePath := fmt.Sprintf("%v_semantic_action.go", cgram.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 semantic action source code: %v", err)
+		}
+	}
+
+	return nil
+}
+
+func readCompiledGrammar(path string) (*spec.CompiledGrammar, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	data, err := ioutil.ReadAll(f)
+	if err != nil {
+		return nil, err
+	}
+	cgram := &spec.CompiledGrammar{}
+	err = json.Unmarshal(data, cgram)
+	if err != nil {
+		return nil, err
+	}
+	return cgram, nil
+}