func (buffer *lexBuffer) factor() *types.TreeNode {
var node *types.TreeNode
var err error
switch buffer.token.TokenType {
case types.NUM:
node = newExpNode(types.ConstK, buffer.token.Lineno)
if buffer.token.TokenType == types.NUM {
node.Val, err = strconv.Atoi(buffer.token.TokenString)
if err != nil {
panic(err)
}
}
buffer.match(types.NUM)
case types.ID:
node = newExpNode(types.IdK, buffer.token.Lineno)
if buffer.token.TokenType == types.ID {
node.Name = buffer.token.TokenString
}
buffer.match(types.ID)
case types.STRING:
node = newExpNode(types.StringK, buffer.token.Lineno)
node.ValString = buffer.token.TokenString
buffer.match(types.STRING)
case types.LPAREN:
buffer.match(types.LPAREN)
node = buffer.exp()
buffer.match(types.RPAREN)
default:
syntaxError(buffer.token)
}
return node
}
