For compatability, emit the \n within the library, not the cmd (#137)

* For compatability, emit the \n within the library, not the commandline tool
* Also add manifestString to library

builtins.go

@@ -17,6 +17,7 @@ limitations under the License.
 package jsonnet
 
 import (
+	"bytes"
 	"crypto/md5"
 	"encoding/hex"
 	"fmt"
@@ -240,11 +241,12 @@ func builtinToString(e *evaluator, xp potentialValue) (value, error) {
 	case *valueString:
 		return x, nil
 	}
-	s, err := e.i.manifestAndSerializeJSON(e.trace, x, false, "")
+	var buf bytes.Buffer
+	err = e.i.manifestAndSerializeJSON(&buf, e.trace, x, false, "")
 	if err != nil {
 		return nil, err
 	}
-	return makeValueString(s), nil
+	return makeValueString(buf.String()), nil
 }
 
 func builtinMakeArray(e *evaluator, szp potentialValue, funcp potentialValue) (value, error) {

interpreter.go

@@ -723,16 +723,28 @@ func serializeJSON(v interface{}, multiline bool, indent string, buf *bytes.Buff
 	}
 }
 
-func (i *interpreter) manifestAndSerializeJSON(trace *TraceElement, v value, multiline bool, indent string) (string, error) {
+func (i *interpreter) manifestAndSerializeJSON(
-	var buf bytes.Buffer
+		buf *bytes.Buffer, trace *TraceElement, v value, multiline bool, indent string) error {
 	manifested, err := i.manifestJSON(trace, v)
 	if err != nil {
-		return "", err
+		return err
 	}
-	serializeJSON(manifested, multiline, indent, &buf)
+	serializeJSON(manifested, multiline, indent, buf)
-	return buf.String(), nil
+	return nil
 }
 
+// manifestString expects the value to be a string and returns it.
+func (i *interpreter) manifestString(buf *bytes.Buffer, trace *TraceElement, v value) error {
+	switch v := v.(type) {
+	case *valueString:
+		buf.WriteString(v.getString())
+		return nil
+	default:
+		return makeRuntimeError(fmt.Sprint("Expected string result, got: " + v.getType().name), i.getCurrentStackTrace(trace))
+	}
+}
+
+
 func jsonToValue(e *evaluator, v interface{}) (value, error) {
 	switch v := v.(type) {
 	case nil:
@@ -879,7 +891,8 @@ func makeInitialEnv(filename string, baseStd valueObject) environment {
 }
 
 // TODO(sbarzowski) this function takes far too many arguments - build interpreter in vm instead
-func evaluate(node ast.Node, ext vmExtMap, tla vmExtMap, nativeFuncs map[string]*NativeFunction, maxStack int, importer Importer) (string, error) {
+func evaluate(node ast.Node, ext vmExtMap, tla vmExtMap, nativeFuncs map[string]*NativeFunction,
+              maxStack int, importer Importer, stringOutput bool) (string, error) {
 	i, err := buildInterpreter(ext, nativeFuncs, maxStack, importer)
 	if err != nil {
 		return "", err
@@ -915,9 +928,15 @@ func evaluate(node ast.Node, ext vmExtMap, tla vmExtMap, nativeFuncs map[string]
 	manifestationTrace := &TraceElement{
 		loc: &manifestationLoc,
 	}
-	s, err := i.manifestAndSerializeJSON(manifestationTrace, result, true, "")
+	var buf bytes.Buffer
+	if stringOutput {
+		err = i.manifestString(&buf, manifestationTrace, result)
+	} else {
+		err = i.manifestAndSerializeJSON(&buf, manifestationTrace, result, true, "")
+	}
 	if err != nil {
 		return "", err
 	}
-	return s, nil
+	buf.WriteString("\n")
+	return buf.String(), nil
 }

jsonnet/cmd.go

@@ -114,5 +114,5 @@ func main() {
 		fmt.Fprintf(os.Stderr, "%v\n", err.Error())
 		os.Exit(2)
 	}
-	fmt.Println(json)
+	fmt.Print(json)
 }

main_test.go

@@ -127,8 +127,8 @@ func TestMain(t *testing.T) {
 				// TODO(sbarzowski) perhaps somehow mark that we are processing
 				// an error. But for now we can treat them the same.
 				output = errFormatter.format(err)
-			}
 				output += "\n"
+			}
 			if *update {
 				err := ioutil.WriteFile(test.golden, []byte(output), 0666)
 				if err != nil {
@@ -260,13 +260,13 @@ func TestCustomImporter(t *testing.T) {
 		},
 	})
 	input := `[import "a.jsonnet", importstr "b.jsonnet"]`
-	expected := `[ 4, "3 + 3" ]`
+	expected := `[ 4, "3 + 3" ] `
 	actual, err := vm.EvaluateSnippet("custom_import.jsonnet", input)
 	if err != nil {
 		t.Errorf("Unexpected error: %v", err)
 	}
 	actual = removeExcessiveWhitespace(actual)
 	if actual != expected {
-		t.Errorf("Expected %v, but got %v", expected, actual)
+		t.Errorf("Expected %q, but got %q", expected, actual)
 	}
 }

vm.go

@@ -38,6 +38,7 @@ type VM struct {
 	nativeFuncs map[string]*NativeFunction
 	importer    Importer
 	ef          ErrorFormatter
+	StringOutput bool
 }
 
 // External variable or top level argument provided before execution
@@ -98,7 +99,7 @@ func (vm *VM) evaluateSnippet(filename string, snippet string) (output string, e
 	if err != nil {
 		return "", err
 	}
-	output, err = evaluate(node, vm.ext, vm.tla, vm.nativeFuncs, vm.MaxStack, vm.importer)
+	output, err = evaluate(node, vm.ext, vm.tla, vm.nativeFuncs, vm.MaxStack, vm.importer, vm.StringOutput)
 	if err != nil {
 		return "", err
 	}