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package goxpath
import (
"encoding/xml"
"fmt"
"github.com/ChrisTrenkamp/goxpath/internal/execxp"
"github.com/ChrisTrenkamp/goxpath/internal/parser"
"github.com/ChrisTrenkamp/goxpath/tree"
)
//Opts defines namespace mappings and custom functions for XPath expressions.
type Opts struct {
NS map[string]string
Funcs map[xml.Name]tree.Wrap
Vars map[string]tree.Result
}
//FuncOpts is a function wrapper for Opts.
type FuncOpts func(*Opts)
//XPathExec is the XPath executor, compiled from an XPath string
type XPathExec struct {
n *parser.Node
}
//Parse parses the XPath expression, xp, returning an XPath executor.
func Parse(xp string) (XPathExec, error) {
n, err := parser.Parse(xp)
return XPathExec{n: n}, err
}
//MustParse is like Parse, but panics instead of returning an error.
func MustParse(xp string) XPathExec {
ret, err := Parse(xp)
if err != nil {
panic(err)
}
return ret
}
//Exec executes the XPath expression, xp, against the tree, t, with the
//namespace mappings, ns, and returns the result as a stringer.
func (xp XPathExec) Exec(t tree.Node, opts ...FuncOpts) (tree.Result, error) {
o := &Opts{
NS: make(map[string]string),
Funcs: make(map[xml.Name]tree.Wrap),
Vars: make(map[string]tree.Result),
}
for _, i := range opts {
i(o)
}
return execxp.Exec(xp.n, t, o.NS, o.Funcs, o.Vars)
}
//ExecBool is like Exec, except it will attempt to convert the result to its boolean value.
func (xp XPathExec) ExecBool(t tree.Node, opts ...FuncOpts) (bool, error) {
res, err := xp.Exec(t, opts...)
if err != nil {
return false, err
}
b, ok := res.(tree.IsBool)
if !ok {
return false, fmt.Errorf("Cannot convert result to a boolean")
}
return bool(b.Bool()), nil
}
//ExecNum is like Exec, except it will attempt to convert the result to its number value.
func (xp XPathExec) ExecNum(t tree.Node, opts ...FuncOpts) (float64, error) {
res, err := xp.Exec(t, opts...)
if err != nil {
return 0, err
}
n, ok := res.(tree.IsNum)
if !ok {
return 0, fmt.Errorf("Cannot convert result to a number")
}
return float64(n.Num()), nil
}
//ExecNode is like Exec, except it will attempt to return the result as a node-set.
func (xp XPathExec) ExecNode(t tree.Node, opts ...FuncOpts) (tree.NodeSet, error) {
res, err := xp.Exec(t, opts...)
if err != nil {
return nil, err
}
n, ok := res.(tree.NodeSet)
if !ok {
return nil, fmt.Errorf("Cannot convert result to a node-set")
}
return n, nil
}
//MustExec is like Exec, but panics instead of returning an error.
func (xp XPathExec) MustExec(t tree.Node, opts ...FuncOpts) tree.Result {
res, err := xp.Exec(t, opts...)
if err != nil {
panic(err)
}
return res
}
//ParseExec parses the XPath string, xpstr, and runs Exec.
func ParseExec(xpstr string, t tree.Node, opts ...FuncOpts) (tree.Result, error) {
xp, err := Parse(xpstr)
if err != nil {
return nil, err
}
return xp.Exec(t, opts...)
}
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