func (p *parser) postfixExpr() ast.Node {
line := p.line()
left := p.callExpr()
if ast.IsPostfixOp(p.tok) {
op := p.tok
p.next()
return &ast.PostfixExpr{Op: op, Left: left, NodeInfo: ast.NodeInfo{line}}
}
return left
}
func (c *compiler) VisitUnaryExpr(node *ast.UnaryExpr, data interface{}) {
var reg int
expr, exprok := data.(*exprdata)
if exprok {
reg = expr.rega
} else {
reg = c.genRegister()
}
value, ok := c.constFold(node)
if ok {
if exprok && expr.propagate {
expr.regb = OpConstOffset + c.addConst(value)
return
}
c.emitABx(OpLoadconst, reg, c.addConst(value), node.NodeInfo.Line)
} else if ast.IsPostfixOp(node.Op) {
op := OpAdd
if node.Op == ast.TokenMinusminus {
op = OpSub
}
exprdata := exprdata{true, reg, reg}
node.Right.Accept(c, &exprdata)
one := OpConstOffset + c.addConst(Number(1))
c.emitABC(op, exprdata.regb, exprdata.regb, one, node.NodeInfo.Line)
// don't bother moving if we're not in an expression
if exprok {
c.emitAB(OpMove, reg, exprdata.regb, node.NodeInfo.Line)
}
} else {
var op Opcode
switch node.Op {
case ast.TokenMinus:
op = OpUnm
case ast.TokenNot, ast.TokenBang:
op = OpNot
case ast.TokenTilde:
op = OpCmpl
}
exprdata := exprdata{true, reg, reg}
node.Right.Accept(c, &exprdata)
c.emitABx(op, reg, exprdata.regb, node.NodeInfo.Line)
if exprok && expr.propagate {
expr.regb = reg
}
}
}
