package parser import "github.com/ChrisTrenkamp/goxpath/lexer" //NodeType enumerations const ( Empty lexer.XItemType = "" ) //Node builds an AST tree for operating on XPath expressions type Node struct { Val lexer.XItem Left *Node Right *Node Parent *Node next *Node } var beginPathType = map[lexer.XItemType]bool{ lexer.XItemAbsLocPath: true, lexer.XItemAbbrAbsLocPath: true, lexer.XItemAbbrRelLocPath: true, lexer.XItemRelLocPath: true, lexer.XItemFunction: true, } func (n *Node) add(i lexer.XItem) { if n.Val.Typ == Empty { n.Val = i } else if n.Left == nil { n.Left = &Node{Val: n.Val, Parent: n} n.Val = i } else if beginPathType[n.Val.Typ] { next := &Node{Val: n.Val, Left: n.Left, Parent: n} n.Left = next n.Val = i } else if n.Right == nil { n.Right = &Node{Val: i, Parent: n} } else { next := &Node{Val: n.Val, Left: n.Left, Right: n.Right, Parent: n} n.Left, n.Right = next, nil n.Val = i } n.next = n } func (n *Node) push(i lexer.XItem) { if n.Left == nil { n.Left = &Node{Val: i, Parent: n} n.next = n.Left } else if n.Right == nil { n.Right = &Node{Val: i, Parent: n} n.next = n.Right } else { next := &Node{Val: i, Left: n.Right, Parent: n} n.Right = next n.next = n.Right } } func (n *Node) pushNotEmpty(i lexer.XItem) { if n.Val.Typ == Empty { n.add(i) } else { n.push(i) } } /* func (n *Node) prettyPrint(depth, width int) { nodes := []*Node{} n.getLine(depth, &nodes) fmt.Printf("%*s", (width-depth)*2, "") toggle := true if len(nodes) > 1 { for _, i := range nodes { if i != nil { if toggle { fmt.Print("/ ") } else { fmt.Print("\\ ") } } toggle = !toggle } fmt.Println() fmt.Printf("%*s", (width-depth)*2, "") } for _, i := range nodes { if i != nil { fmt.Print(i.Val.Val, " ") } } fmt.Println() } func (n *Node) getLine(depth int, ret *[]*Node) { if depth <= 0 && n != nil { *ret = append(*ret, n) return } if n.Left != nil { n.Left.getLine(depth-1, ret) } else if depth-1 <= 0 { *ret = append(*ret, nil) } if n.Right != nil { n.Right.getLine(depth-1, ret) } else if depth-1 <= 0 { *ret = append(*ret, nil) } } */