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package optimizer
import (
"fmt"
. "github.com/antonmedv/expr/ast"
"github.com/antonmedv/expr/file"
"reflect"
"strings"
)
type constExpr struct {
applied bool
err error
fns map[string]reflect.Value
}
func (*constExpr) Enter(*Node) {}
func (c *constExpr) Exit(node *Node) {
defer func() {
if r := recover(); r != nil {
msg := fmt.Sprintf("%v", r)
// Make message more actual, it's a runtime error, but at compile step.
msg = strings.Replace(msg, "runtime error:", "compile error:", 1)
c.err = &file.Error{
Location: (*node).Location(),
Message: msg,
}
}
}()
patch := func(newNode Node) {
c.applied = true
Patch(node, newNode)
}
switch n := (*node).(type) {
case *FunctionNode:
fn, ok := c.fns[n.Name]
if ok {
in := make([]reflect.Value, len(n.Arguments))
for i := 0; i < len(n.Arguments); i++ {
arg := n.Arguments[i]
var param interface{}
switch a := arg.(type) {
case *NilNode:
param = nil
case *IntegerNode:
param = a.Value
case *FloatNode:
param = a.Value
case *BoolNode:
param = a.Value
case *StringNode:
param = a.Value
case *ConstantNode:
param = a.Value
default:
return // Const expr optimization not applicable.
}
if param == nil && reflect.TypeOf(param) == nil {
// In case of nil value and nil type use this hack,
// otherwise reflect.Call will panic on zero value.
in[i] = reflect.ValueOf(¶m).Elem()
} else {
in[i] = reflect.ValueOf(param)
}
}
out := fn.Call(in)
constNode := &ConstantNode{Value: out[0].Interface()}
patch(constNode)
}
}
}
|
