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package script
import (
"go/ast"
"go/token"
"reflect"
)
// compiles a (single) assign statement lhs = rhs
func (w *World) compileAssignStmt(a *ast.AssignStmt) Expr {
if len(a.Lhs) != 1 || len(a.Rhs) != 1 {
panic(err(a.Pos(), "multiple assignment not allowed"))
}
lhs, rhs := a.Lhs[0], a.Rhs[0]
r := w.compileExpr(rhs)
switch a.Tok {
default:
panic(err(a.Pos(), a.Tok, "not allowed"))
case token.ASSIGN: // =
return w.compileAssign(a, lhs, r)
case token.DEFINE: // :=
return w.compileDefine(a, lhs, r)
case token.ADD_ASSIGN: // +=
return w.compileAddAssign(a, lhs, r)
case token.SUB_ASSIGN: // -=
return w.compileSubAssign(a, lhs, r)
}
}
// compile a = b
func (w *World) compileAssign(a *ast.AssignStmt, lhs ast.Expr, r Expr) Expr {
l := w.compileLvalue(lhs)
return &assignStmt{lhs: l, rhs: typeConv(a.Pos(), r, inputType(l))}
}
// compile a := b
func (w *World) compileDefine(a *ast.AssignStmt, lhs ast.Expr, r Expr) Expr {
ident, ok := lhs.(*ast.Ident)
if !ok {
panic(err(a.Pos(), "non-name on left side of :="))
}
addr := reflect.New(r.Type())
ok = w.safeDeclare(ident.Name, &reflectLvalue{addr.Elem()})
if !ok {
panic(err(a.Pos(), "already defined: "+ident.Name))
}
return w.compileAssign(a, lhs, r)
}
type assignStmt struct {
lhs LValue
rhs Expr
void
}
func (a *assignStmt) Eval() interface{} {
a.lhs.SetValue(a.rhs.Eval())
return nil
}
func (a *assignStmt) Child() []Expr {
return []Expr{a.lhs, a.rhs}
}
func (w *World) compileAddAssign(a *ast.AssignStmt, lhs ast.Expr, r Expr) Expr {
l := w.compileLvalue(lhs)
x := typeConv(a.Pos(), l, float64_t)
y := typeConv(a.Pos(), r, float64_t)
sum := &add{binaryExpr{x, y}}
return &assignStmt{lhs: l, rhs: typeConv(a.Pos(), sum, inputType(l))}
}
func (w *World) compileSubAssign(a *ast.AssignStmt, lhs ast.Expr, r Expr) Expr {
l := w.compileLvalue(lhs)
x := typeConv(a.Pos(), l, float64_t)
y := typeConv(a.Pos(), r, float64_t)
sub := &sub{binaryExpr{x, y}}
return &assignStmt{lhs: l, rhs: typeConv(a.Pos(), sub, inputType(l))}
}
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