Merge pull request #622 from nspcc-dev/feature/byteconst

compiler: allow to convert string constants to []byte

pkg/compiler/byte_conversion_test.go

@@ -54,3 +54,28 @@ func TestByteConversionDirectlyInFunctionCall(t *testing.T) {
 	`
 	eval(t, src, []byte("foo"))
 }
+
+func TestByteConversionOfConstant(t *testing.T) {
+	src := `
+	package foo
+	const foo = "foo"
+	func Main() []byte {
+		b := []byte(foo)
+		return b
+	}
+	`
+	eval(t, src, []byte("foo"))
+}
+
+func TestByteConversionOfVariable(t *testing.T) {
+	src := `
+	package foo
+	func Main() []byte {
+		a := "fo"
+		a = a + "o"
+		b := []byte(a)
+		return b
+	}
+	`
+	eval(t, src, []byte("foo"))
+}

pkg/compiler/codegen.go

@@ -349,6 +349,8 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 				return nil
 			}
 			c.emitLoadConst(value)
+		} else if tv := c.typeInfo.Types[n]; tv.Value != nil {
+			c.emitLoadConst(tv)
 		} else {
 			c.emitLoadLocal(n.Name)
 		}
@@ -481,11 +483,9 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 				return nil
 			}
 		case *ast.ArrayType:
-			// For now we will assume that there is only 1 argument passed which
+			// For now we will assume that there are only byte slice conversions.
-			// will be a basic literal (string kind). This only to handle string
+			// E.g. []byte("foobar") or []byte(scriptHash).
-			// to byte slice conversions. E.G. []byte("foobar")
+			ast.Walk(c, n.Args[0])
-			arg := n.Args[0].(*ast.BasicLit)
-			c.emitLoadConst(c.typeInfo.Types[arg])
 			return nil
 		}
 
@@ -672,6 +672,13 @@ func (c *codegen) getByteArray(expr ast.Expr) []byte {
 			buf[i] = byte(val)
 		}
 		return buf
+	case *ast.CallExpr:
+		if tv := c.typeInfo.Types[t.Args[0]]; tv.Value != nil {
+			val := constant.StringVal(tv.Value)
+			return []byte(val)
+		}
+
+		return nil
 	default:
 		return nil
 	}

pkg/compiler/interop_test.go

@@ -100,6 +100,27 @@ func TestAppCall(t *testing.T) {
 		_, err := compiler.Compile(strings.NewReader(src))
 		require.Error(t, err)
 	})
+
+	t.Run("convert from string constant", func(t *testing.T) {
+		src := `
+		package foo
+		import "github.com/CityOfZion/neo-go/pkg/interop/engine"
+		const scriptHash = ` + fmt.Sprintf("%#v", string(ih.BytesBE())) + `
+		func Main() int {
+			x := 13
+			y := 29
+			result := engine.AppCall([]byte(scriptHash), []interface{}{x, y})
+			return result.(int)
+		}
+		`
+
+		v := vmAndCompile(t, src)
+		v.SetScriptGetter(getScript)
+
+		require.NoError(t, v.Run())
+
+		assertResult(t, v, big.NewInt(42))
+	})
 }
 
 func getAppCallScript(h string) string {