func (c *compiler) VisitAssignment(node *ast.Assignment, data interface{}) {
if node.Op == ast.TokenColoneq {
// short variable declaration
var names []*ast.Id
for _, id := range node.Left {
names = append(names, id.(*ast.Id))
}
c.declare(names, node.Right)
return
} else if node.Op != ast.TokenEq {
// compound assignment
// a += b -> a = a + b
bin := ast.BinaryExpr{Op: ast.CompoundOp(node.Op), Left: node.Left[0], Right: node.Right[0]}
fake := ast.Assignment{Op: ast.TokenEq, Left: node.Left, Right: []ast.Node{&bin}}
fake.Accept(c, nil)
return
}
// regular assignment, if the left-side is an identifier
// then it has to be declared already
varCount, valueCount := len(node.Left), len(node.Right)
_, isCall := node.Right[valueCount-1].(*ast.CallExpr)
_, isUnpack := node.Right[valueCount-1].(*ast.VarArg)
start := c.block.register
current := start
end := start + varCount - 1
// evaluate all expressions first with temp registers
for i, _ := range node.Left {
reg := start + i
exprdata := exprdata{false, reg, reg}
if i == valueCount-1 && (isCall || isUnpack) {
exprdata.regb, current = end, end
node.Right[i].Accept(c, &exprdata)
break
}
if i < valueCount {
node.Right[i].Accept(c, &exprdata)
current = reg + 1
}
}
// assign the results to the variables
for i, variable := range node.Left {
valueReg := start + i
// don't touch variables without a corresponding value
if valueReg >= current {
break
}
c.assignmentHelper(variable, current+1, valueReg)
}
}
func (p *prettyprinter) VisitAssignment(node *ast.Assignment, data interface{}) {
p.buf.WriteString("(assignment")
p.indent++
for _, node := range node.Left {
p.buf.WriteString("\n")
p.doIndent()
node.Accept(p, nil)
}
p.buf.WriteString("\n")
p.doIndent()
p.buf.WriteString(node.Op.String())
for _, node := range node.Right {
p.buf.WriteString("\n")
p.doIndent()
node.Accept(p, nil)
}
p.indent--
p.buf.WriteString(")")
}