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