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