node: implement shorthand assignment operators, callable rvalues

node.go

@@ -644,7 +644,7 @@ func (this *conversionState) convertNoFreeFloating(n_ node.Node) (string, error)
 		// Assignment expressions can take on better error-handling behaviour
 		// when we know the assignment is a top-level expression
 		if a, ok := n.Expr.(*assign.Assign); ok {
-			return this.convertAssignment(a, true)
+			return this.convertAssignAssign(a, true)
 		}
 
 		// Non-assignment expression
@@ -909,7 +909,71 @@ func (this *conversionState) convertNoFreeFloating(n_ node.Node) (string, error)
 	//
 
 	case *assign.Assign:
-		return this.convertAssignment(n, false /* no reason to believe we are a top-level statement */)
+		return this.convertAssignAssign(n, false /* no reason to believe we are a top-level statement */)
+
+	// Go has a limited set of assignment shorthands:
+	//
+	// ```
+	//     assign_op = [ add_op | mul_op ] "=" .
+	//
+	//     [...]
+	//
+	//     add_op     = "+" | "-" | "|" | "^" .
+	//     mul_op     = "*" | "/" | "%" | "<<" | ">>" | "&" | "&^" .
+	// ```
+
+	case *assign.BitwiseAnd:
+		return this.convertAssignment(n, n.Variable, n.Expression, false, `&=`)
+
+	case *assign.BitwiseOr:
+		return this.convertAssignment(n, n.Variable, n.Expression, false, `|=`)
+
+	case *assign.BitwiseXor:
+		return this.convertAssignment(n, n.Variable, n.Expression, false, `^=`)
+
+	case *assign.Coalesce:
+		// Null coaslecing assignment expression - $x ??= $y;
+		// We don't have a natural equivalent for the coalescing operator
+		// We don't have an implementation of *binary.Coalesce yet either
+		// But when we do this will need an rvalue transformation to use it
+
+		return this.convert(assign.NewAssign(n.Variable, binary.NewCoalesce(n.Variable, n.Expression))) // FIXME also handle position/freefloating
+
+	case *assign.Concat:
+		return this.convertAssignment(n, n.Variable, n.Expression, false, `+=`)
+
+	case *assign.Div:
+		return this.convertAssignment(n, n.Variable, n.Expression, false, `/=`)
+
+	case *assign.Minus:
+		return this.convertAssignment(n, n.Variable, n.Expression, false, `-=`)
+
+	//case *assign.Mod:
+	// TODO
+
+	case *assign.Mul:
+		return this.convertAssignment(n, n.Variable, n.Expression, false, `*=`)
+
+	case *assign.Plus:
+		return this.convertAssignment(n, n.Variable, n.Expression, false, `+=`)
+
+	//case *assign.Pow:
+	// TODO
+
+	//case *assign.Reference:
+
+	case *assign.ShiftLeft:
+		return this.convertAssignment(n, n.Variable, n.Expression, false, `<<=`)
+
+	case *assign.ShiftRight:
+		return this.convertAssignment(n, n.Variable, n.Expression, false, `>>=`)
+
+	//
+	// name
+	//
+
+	case *name.Name:
+		return this.resolveName(n)
 
 	//
 	// expr
@@ -919,7 +983,11 @@ func (this *conversionState) convertNoFreeFloating(n_ node.Node) (string, error)
 		// All our generated functions return err, but this AST node may be in a single-rvalue context
 		// TODO do something more intelligent here
 		// We can't necessarily hoist the whole call, in case we are on the right-hand side of a && operator
-		funcName, err := this.resolveName(n.Function)
+
+		// We might be calling by name, or, we might be calling by an rvalue expression
+		// e.g. foo()()() or $x()
+		// Use full conversion logic for name resolution
+		funcName, err := this.convert(n.Function)
 		if err != nil {
 			return "", parseErr{n, err}
 		}
@@ -1526,14 +1594,23 @@ func (this *conversionState) resolveName(n node.Node) (string, error) {
 	return ret, nil
 }
 
-func (this *conversionState) convertAssignment(n *assign.Assign, isTopLevelStatement bool) (string, error) {
+func (this *conversionState) convertAssignAssign(n *assign.Assign, isTopLevelStatement bool) (string, error) {
+	return this.convertAssignment(n, n.Variable, n.Expression, isTopLevelStatement, `=`)
+}
 
-	rvalue, err := this.convert(n.Expression)
+func (this *conversionState) convertAssignment(n, nLValue, nRValue node.Node, isTopLevelStatement bool, operator string) (string, error) {
+
+	rvalue, err := this.convert(nRValue)
 	if err != nil {
 		return "", parseErr{n, err}
 	}
 
-	if dimf, ok := n.Variable.(*expr.ArrayDimFetch); ok && dimf.Dim == nil {
+	if dimf, ok := nLValue.(*expr.ArrayDimFetch); ok && dimf.Dim == nil {
+
+		if operator != `=` {
+			return "", parseErr{n, fmt.Errorf("can't yet handle complex shorthand append assignment operator statement")}
+		}
+
 		// Special handling for the case of foo[] = bar
 		// Transform into append()
 		arrayVar, err := this.convert(dimf.Variable)
@@ -1551,7 +1628,7 @@ func (this *conversionState) convertAssignment(n *assign.Assign, isTopLevelState
 
 		// Normal assignment
 
-		lvalue, err := this.convert(n.Variable) // might be a more complicated lvalue
+		lvalue, err := this.convert(nLValue) // might be a more complicated lvalue
 		if err != nil {
 			return "", parseErr{n, err}
 		}
@@ -1563,8 +1640,16 @@ func (this *conversionState) convertAssignment(n *assign.Assign, isTopLevelState
 
 			// If this is a simple expression (func call; indirect/method call; assignment of func/method call) then
 			// we need to propagate errors
-			switch n.Expression.(type) {
+			switch nRValue.(type) {
 			case *expr.FunctionCall, *expr.StaticCall, *expr.New:
+
+				if operator != `=` {
+					// We need to perform the variable assignment + err check, but we are in shorthand assignment context
+					// and can't just mess with the left hand of the expression
+					// Need to create a temporary accumulator variable
+					return "", parseErr{n, fmt.Errorf("can't yet handle err value extraction for function call in shorthand append assignment operator statement")}
+				}
+
 				ret := lvalue + ", err = " + rvalue + "\n"
 				ret += "if err != nil {\n"
 				ret += this.currentErrHandler
@@ -1577,7 +1662,7 @@ func (this *conversionState) convertAssignment(n *assign.Assign, isTopLevelState
 			}
 
 		} else {
-			return lvalue + " = " + rvalue, nil // Just the basic assignment - without trailing NL
+			return lvalue + " " + operator + " " + rvalue, nil // Just the basic assignment - without trailing NL
 
 		}
 	}