config/lang/ast: AST transforms are built-in
This commit is contained in:
parent
db02541d31
commit
1e79861b84
|
@ -6,8 +6,9 @@ import (
|
|||
|
||||
// Node is the interface that all AST nodes must implement.
|
||||
type Node interface {
|
||||
// Accept is called to dispatch to the visitors.
|
||||
Accept(Visitor)
|
||||
// Accept is called to dispatch to the visitors. It must return the
|
||||
// resulting Node (which might be different in an AST transform).
|
||||
Accept(Visitor) Node
|
||||
|
||||
// Pos returns the position of this node in some source.
|
||||
Pos() Pos
|
||||
|
@ -24,11 +25,18 @@ func (p Pos) String() string {
|
|||
|
||||
// Visitors are just implementations of this function.
|
||||
//
|
||||
// The function must return the Node to replace this node with. "nil" is
|
||||
// _not_ a valid return value. If there is no replacement, the original node
|
||||
// should be returned. We build this replacement directly into the visitor
|
||||
// pattern since AST transformations are a common and useful tool and
|
||||
// building it into the AST itself makes it required for future Node
|
||||
// implementations and very easy to do.
|
||||
//
|
||||
// Note that this isn't a true implementation of the visitor pattern, which
|
||||
// generally requires proper type dispatch on the function. However,
|
||||
// implementing this basic visitor pattern style is still very useful even
|
||||
// if you have to type switch.
|
||||
type Visitor func(Node)
|
||||
type Visitor func(Node) Node
|
||||
|
||||
//go:generate stringer -type=Type
|
||||
|
||||
|
|
|
@ -12,12 +12,12 @@ type Call struct {
|
|||
Posx Pos
|
||||
}
|
||||
|
||||
func (n *Call) Accept(v Visitor) {
|
||||
for _, a := range n.Args {
|
||||
a.Accept(v)
|
||||
func (n *Call) Accept(v Visitor) Node {
|
||||
for i, a := range n.Args {
|
||||
n.Args[i] = a.Accept(v)
|
||||
}
|
||||
|
||||
v(n)
|
||||
return v(n)
|
||||
}
|
||||
|
||||
func (n *Call) Pos() Pos {
|
||||
|
|
|
@ -12,12 +12,12 @@ type Concat struct {
|
|||
Posx Pos
|
||||
}
|
||||
|
||||
func (n *Concat) Accept(v Visitor) {
|
||||
for _, n := range n.Exprs {
|
||||
n.Accept(v)
|
||||
func (n *Concat) Accept(v Visitor) Node {
|
||||
for i, expr := range n.Exprs {
|
||||
n.Exprs[i] = expr.Accept(v)
|
||||
}
|
||||
|
||||
v(n)
|
||||
return v(n)
|
||||
}
|
||||
|
||||
func (n *Concat) Pos() Pos {
|
||||
|
|
|
@ -12,8 +12,8 @@ type LiteralNode struct {
|
|||
Posx Pos
|
||||
}
|
||||
|
||||
func (n *LiteralNode) Accept(v Visitor) {
|
||||
v(n)
|
||||
func (n *LiteralNode) Accept(v Visitor) Node {
|
||||
return v(n)
|
||||
}
|
||||
|
||||
func (n *LiteralNode) Pos() Pos {
|
||||
|
|
|
@ -10,8 +10,8 @@ type VariableAccess struct {
|
|||
Posx Pos
|
||||
}
|
||||
|
||||
func (n *VariableAccess) Accept(v Visitor) {
|
||||
v(n)
|
||||
func (n *VariableAccess) Accept(v Visitor) Node {
|
||||
return v(n)
|
||||
}
|
||||
|
||||
func (n *VariableAccess) Pos() Pos {
|
||||
|
|
|
@ -25,9 +25,9 @@ func (c *IdentifierCheck) Visit(root ast.Node) error {
|
|||
return c.err
|
||||
}
|
||||
|
||||
func (c *IdentifierCheck) visit(raw ast.Node) {
|
||||
func (c *IdentifierCheck) visit(raw ast.Node) ast.Node {
|
||||
if c.err != nil {
|
||||
return
|
||||
return raw
|
||||
}
|
||||
|
||||
switch n := raw.(type) {
|
||||
|
@ -42,6 +42,9 @@ func (c *IdentifierCheck) visit(raw ast.Node) {
|
|||
default:
|
||||
c.createErr(n, fmt.Sprintf("unknown node: %#v", raw))
|
||||
}
|
||||
|
||||
// We never do replacement with this visitor
|
||||
return raw
|
||||
}
|
||||
|
||||
func (c *IdentifierCheck) visitCall(n *ast.Call) {
|
||||
|
|
|
@ -37,9 +37,9 @@ func (v *TypeCheck) Visit(root ast.Node) error {
|
|||
return v.err
|
||||
}
|
||||
|
||||
func (v *TypeCheck) visit(raw ast.Node) {
|
||||
func (v *TypeCheck) visit(raw ast.Node) ast.Node {
|
||||
if v.err != nil {
|
||||
return
|
||||
return raw
|
||||
}
|
||||
|
||||
switch n := raw.(type) {
|
||||
|
@ -54,6 +54,8 @@ func (v *TypeCheck) visit(raw ast.Node) {
|
|||
default:
|
||||
v.createErr(n, fmt.Sprintf("unknown node: %#v", raw))
|
||||
}
|
||||
|
||||
return raw
|
||||
}
|
||||
|
||||
func (v *TypeCheck) visitCall(n *ast.Call) {
|
||||
|
|
|
@ -105,9 +105,9 @@ func (v *executeVisitor) Visit(root ast.Node) (interface{}, ast.Type, error) {
|
|||
return result.Value, result.Type, resultErr
|
||||
}
|
||||
|
||||
func (v *executeVisitor) visit(raw ast.Node) {
|
||||
func (v *executeVisitor) visit(raw ast.Node) ast.Node {
|
||||
if v.err != nil {
|
||||
return
|
||||
return raw
|
||||
}
|
||||
|
||||
switch n := raw.(type) {
|
||||
|
@ -122,6 +122,8 @@ func (v *executeVisitor) visit(raw ast.Node) {
|
|||
default:
|
||||
v.err = fmt.Errorf("unknown node: %#v", raw)
|
||||
}
|
||||
|
||||
return raw
|
||||
}
|
||||
|
||||
func (v *executeVisitor) visitCall(n *ast.Call) {
|
||||
|
|
|
@ -64,11 +64,11 @@ func TestLookupType(t *testing.T) {
|
|||
|
||||
type customUntyped struct{}
|
||||
|
||||
func (n customUntyped) Accept(ast.Visitor) {}
|
||||
func (n customUntyped) Pos() (v ast.Pos) { return }
|
||||
func (n customUntyped) Accept(ast.Visitor) ast.Node { return n }
|
||||
func (n customUntyped) Pos() (v ast.Pos) { return }
|
||||
|
||||
type customTyped struct{}
|
||||
|
||||
func (n customTyped) Accept(ast.Visitor) {}
|
||||
func (n customTyped) Accept(ast.Visitor) ast.Node { return n }
|
||||
func (n customTyped) Pos() (v ast.Pos) { return }
|
||||
func (n customTyped) Type(*Scope) (ast.Type, error) { return ast.TypeString, nil }
|
||||
|
|
Loading…
Reference in New Issue