text: package tree
  
  import (
  	"fmt"
  	"math"
  	"strconv"
  	"strings"
  )
  
  //Boolean strings
  const (
  	True  = "true"
  	False = "false"
  )
  
  //Bool is a boolean XPath type
  type Bool bool
  
  //ResValue satisfies the Res interface for Bool
  func (b Bool) String() string {
  	if b {
  		return True
  	}
  
  	return False
  }
  
  //Bool satisfies the HasBool interface for Bool's
  func (b Bool) Bool() Bool {
  	return b
  }
  
  //Num satisfies the HasNum interface for Bool's
  func (b Bool) Num() Num {
  	if b {
  		return Num(1)
  	}
  
  	return Num(0)
  }
  
  //Num is a number XPath type
  type Num float64
  
  //ResValue satisfies the Res interface for Num
  func (n Num) String() string {
  	if math.IsInf(float64(n), 0) {
  		if math.IsInf(float64(n), 1) {
  			return "Infinity"
  		}
  		return "-Infinity"
  	}
  	return fmt.Sprintf("%g", float64(n))
  }
  
  //Bool satisfies the HasBool interface for Num's
  func (n Num) Bool() Bool {
  	return n != 0
  }
  
  //Num satisfies the HasNum interface for Num's
  func (n Num) Num() Num {
  	return n
  }
  
  //String is string XPath type
  type String string
  
  //ResValue satisfies the Res interface for String
  func (s String) String() string {
  	return string(s)
  }
  
  //Bool satisfies the HasBool interface for String's
  func (s String) Bool() Bool {
  	return Bool(len(s) > 0)
  }
  
  //Num satisfies the HasNum interface for String's
  func (s String) Num() Num {
  	num, err := strconv.ParseFloat(strings.TrimSpace(string(s)), 64)
  	if err != nil {
  		return Num(math.NaN())
  	}
  	return Num(num)
  }
  
  //NodeSet is a node-set XPath type
  type NodeSet []Node
  
  //GetNodeNum converts the node to a string-value and to a number
  func GetNodeNum(n Node) Num {
  	return String(n.ResValue()).Num()
  }
  
  //String satisfies the Res interface for NodeSet
  func (n NodeSet) String() string {
  	if len(n) == 0 {
  		return ""
  	}
  
  	return n[0].ResValue()
  }
  
  //Bool satisfies the HasBool interface for node-set's
  func (n NodeSet) Bool() Bool {
  	return Bool(len(n) > 0)
  }
  
  //Num satisfies the HasNum interface for NodeSet's
  func (n NodeSet) Num() Num {
  	return String(n.String()).Num()
  }
  