feat: Add an output buffer, instead of outputting the expression result

Author: Dobefu

internal/evaluator/evaluate.go

@@ -38,3 +38,8 @@ func (e *Evaluator) Evaluate(currentAst ast.ExprNode) (datavalue.Value, error) {
 		)
 	}
 }
+
+// Output returns the current output buffer contents.
+func (e *Evaluator) Output() string {
+	return e.buf.String()
+}

internal/evaluator/evaluator.go

@@ -1,10 +1,18 @@
 // Package evaluator defines logic to evaluate an AST.
 package evaluator
 
+import (
+	"strings"
+)
+
 // Evaluator defines the actual evaluator struct.
-type Evaluator struct{}
+type Evaluator struct {
+	buf strings.Builder
+}
 
 // NewEvaluator creates a new evaluator.
 func NewEvaluator() *Evaluator {
-	return &Evaluator{}
+	return &Evaluator{
+		buf: strings.Builder{},
+	}
 }

main.go

@@ -8,7 +8,6 @@ import (
 	"log/slog"
 	"os"
 
-	"github.com/Dobefu/DLiteScript/internal/datavalue"
 	"github.com/Dobefu/DLiteScript/internal/evaluator"
 	"github.com/Dobefu/DLiteScript/internal/parser"
 	"github.com/Dobefu/DLiteScript/internal/tokenizer"
@@ -20,7 +19,7 @@ type Main struct {
 	onError func(error)
 	outFile io.Writer
 
-	result datavalue.Value
+	result string
 }
 
 // Run actually runs the application.
@@ -58,22 +57,22 @@ func (m *Main) Run() {
 	}
 
 	e := evaluator.NewEvaluator()
-	result, err := e.Evaluate(ast)
+	_, err = e.Evaluate(ast)
 
 	if err != nil {
 		m.onError(err)
 
 		return
 	}
 
-	m.result = result
+	m.result = e.Output()
 
 	// If the output file is io.Discard, we don't need to format the result.
 	if m.outFile == io.Discard {
 		return
 	}
 
-	_, err = fmt.Fprintln(m.outFile, m.result.ToString())
+	_, err = fmt.Fprint(m.outFile, m.result)
 
 	if err != nil {
 		m.onError(err)
@@ -90,6 +89,6 @@ func main() {
 			os.Exit(1)
 		},
 
-		result: datavalue.Null(),
+		result: "",
 	}).Run()
 }

main_test.go

@@ -8,7 +8,6 @@ import (
 	"path/filepath"
 	"testing"
 
-	"github.com/Dobefu/DLiteScript/internal/datavalue"
 	"github.com/Dobefu/DLiteScript/internal/errorutil"
 )
 
@@ -70,19 +69,13 @@ func TestMainRun(t *testing.T) {
 				t.Errorf("expected no error, got '%s'", err.Error())
 			},
 
-			result: datavalue.Null(),
+			result: "",
 		}
 
 		main.Run()
 
-		result, err := main.result.AsNumber()
-
-		if err != nil {
-			t.Fatalf("expected numeric result, got type error: %v", err)
-		}
-
-		if result != test.expected {
-			t.Errorf("expected '%f', got '%f'", test.expected, result)
+		if main.result != "" {
+			t.Errorf("expected empty output, got '%s'", main.result)
 		}
 	}
 }
@@ -135,7 +128,7 @@ func TestMainErr(t *testing.T) {
 				}
 			},
 
-			result: datavalue.Null(),
+			result: "",
 		}
 
 		main.Run()
@@ -174,7 +167,7 @@ func TestMainWriteError(t *testing.T) {
 				mainErr = err
 			}
 		},
-		result: datavalue.Null(),
+		result: "",
 	}
 
 	main.Run()
@@ -194,7 +187,7 @@ func BenchmarkMain(b *testing.B) {
 			onError: func(err error) {
 				b.Errorf("expected no error, got '%s'", err.Error())
 			},
-			result: datavalue.Null(),
+			result: "",
 		}
 
 		main.Run()