cmd/uclang: Add -o flag to specify output path.

cmd/uclang/uclang.go

@@ -11,11 +11,14 @@
 //        disable colors in output
 //   -no-nested-functions
 //        disable support for nested functions
+//   -o string
+//        output path
 package main
 
 import (
 	"flag"
 	"fmt"
+	"io"
 	"log"
 	"os"
 
@@ -47,11 +50,15 @@ func main() {
 		// goccLexer specifies whether to use the Gocc generated lexer, instead of
 		// the hand-written lexer.
 		goccLexer bool
-		noColors  bool
+		// noColors specifies whether to disable colors in output.
+		noColors bool
+		// outputPath specifies the output path for the generated LLVM IR.
+		outputPath string
 	)
 	flag.BoolVar(&goccLexer, "gocc-lexer", false, "use Gocc generated lexer")
 	flag.BoolVar(&noColors, "no-colors", false, "disable colors in output")
 	flag.BoolVar(&semcheck.NoNestedFunctions, "no-nested-functions", false, "disable support for nested functions")
+	flag.StringVar(&outputPath, "o", "", "output path")
 	flag.Usage = usage
 	flag.Parse()
 	semerrors.UseColor = !noColors
@@ -64,20 +71,25 @@ func main() {
 	semcheck.NoNestedFunctions = true
 
 	// Parse input.
+	output := os.Stdout
+	if len(outputPath) > 0 {
+		var err error
+		output, err = os.Create(outputPath)
+		if err != nil {
+			log.Fatal(errutil.Err(err))
+		}
+		defer output.Close()
+	}
 	for _, path := range flag.Args() {
-		err := compileFile(path, goccLexer)
+		err := compileFile(path, output, goccLexer)
 		if err != nil {
-			if _, ok := err.(*semerrors.Error); ok {
-				elog.Print(err)
-			} else {
-				log.Print(err)
-			}
+			log.Fatal(err)
 		}
 	}
 }
 
 // checkFile performs a static semantic analysis check on the given file.
-func compileFile(path string, goccLexer bool) error {
+func compileFile(path string, output io.Writer, goccLexer bool) error {
 	// Lexical analysis
 	// Syntactic analysis
 	// Semantic analysis
@@ -129,12 +141,9 @@ func compileFile(path string, goccLexer bool) error {
 
 	// Generate LLVM IR module based on the syntax tree of the given file.
 	module := irgen.Gen(file, info)
-	log.Printf("=== [ LLVM IR module ] ===\n\n")
-	fmt.Println(module)
+	if _, err := fmt.Fprint(output, module); err != nil {
+		return errutil.Err(err)
+	}
 
 	return nil
 }
-
-// elog represents a logger with no prefix or flags, which logs errors to
-// standard error.
-var elog = log.New(os.Stderr, "", 0)