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|
package optimizer
import (
"math"
"reflect"
. "github.com/antonmedv/expr/ast"
"github.com/antonmedv/expr/file"
)
type fold struct {
applied bool
err *file.Error
}
func (*fold) Enter(*Node) {}
func (fold *fold) Exit(node *Node) {
patch := func(newNode Node) {
fold.applied = true
Patch(node, newNode)
}
// for IntegerNode the type may have been changed from int->float
// preserve this information by setting the type after the Patch
patchWithType := func(newNode Node, leafType reflect.Type) {
patch(newNode)
newNode.SetType(leafType)
}
switch n := (*node).(type) {
case *UnaryNode:
switch n.Operator {
case "-":
if i, ok := n.Node.(*IntegerNode); ok {
patchWithType(&IntegerNode{Value: -i.Value}, n.Node.Type())
}
case "+":
if i, ok := n.Node.(*IntegerNode); ok {
patchWithType(&IntegerNode{Value: i.Value}, n.Node.Type())
}
}
case *BinaryNode:
switch n.Operator {
case "+":
if a, ok := n.Left.(*IntegerNode); ok {
if b, ok := n.Right.(*IntegerNode); ok {
patchWithType(&IntegerNode{Value: a.Value + b.Value}, a.Type())
}
}
if a, ok := n.Left.(*StringNode); ok {
if b, ok := n.Right.(*StringNode); ok {
patch(&StringNode{Value: a.Value + b.Value})
}
}
case "-":
if a, ok := n.Left.(*IntegerNode); ok {
if b, ok := n.Right.(*IntegerNode); ok {
patchWithType(&IntegerNode{Value: a.Value - b.Value}, a.Type())
}
}
case "*":
if a, ok := n.Left.(*IntegerNode); ok {
if b, ok := n.Right.(*IntegerNode); ok {
patchWithType(&IntegerNode{Value: a.Value * b.Value}, a.Type())
}
}
case "/":
if a, ok := n.Left.(*IntegerNode); ok {
if b, ok := n.Right.(*IntegerNode); ok {
if b.Value == 0 {
fold.err = &file.Error{
Location: (*node).Location(),
Message: "integer divide by zero",
}
return
}
patchWithType(&IntegerNode{Value: a.Value / b.Value}, a.Type())
}
}
case "%":
if a, ok := n.Left.(*IntegerNode); ok {
if b, ok := n.Right.(*IntegerNode); ok {
if b.Value == 0 {
fold.err = &file.Error{
Location: (*node).Location(),
Message: "integer divide by zero",
}
return
}
patch(&IntegerNode{Value: a.Value % b.Value})
}
}
case "**":
if a, ok := n.Left.(*IntegerNode); ok {
if b, ok := n.Right.(*IntegerNode); ok {
patch(&FloatNode{Value: math.Pow(float64(a.Value), float64(b.Value))})
}
}
}
case *ArrayNode:
if len(n.Nodes) > 0 {
for _, a := range n.Nodes {
if _, ok := a.(*IntegerNode); !ok {
goto string
}
}
{
value := make([]int, len(n.Nodes))
for i, a := range n.Nodes {
value[i] = a.(*IntegerNode).Value
}
patch(&ConstantNode{Value: value})
}
string:
for _, a := range n.Nodes {
if _, ok := a.(*StringNode); !ok {
return
}
}
{
value := make([]string, len(n.Nodes))
for i, a := range n.Nodes {
value[i] = a.(*StringNode).Value
}
patch(&ConstantNode{Value: value})
}
}
}
}
|
