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package jsonpath
import (
"fmt"
"strings"
//base "src.userspace.com.au/query"
"src.userspace.com.au/query/json"
"src.userspace.com.au/query/lexer"
)
type Parser struct {
l *lexer.Lexer
pos int
tok *lexer.Token
}
func NewParser() (*Parser, error) {
return &Parser{}, nil
}
func (p *Parser) next() (done bool) {
p.tok, done = p.l.NextToken()
if p.tok != nil {
p.pos = p.tok.Position
}
fmt.Printf("%s(%d): '%s'\n", tokenNames[p.tok.Type], p.tok.Type, p.tok.Value)
return p.tok != nil && !done
}
func (p *Parser) Parse(input string) (Selector, error) {
p.l = lexer.New(input, pathState)
p.l.Start()
// First token
p.next()
if p.tok.Type != TAbsolute {
return nil, fmt.Errorf("expected root, got %s", p.tok.Value)
}
result, err := p.parseQualifiedSelector()
if err != nil {
return nil, err
}
return childSelector(rootSelector, result), nil
}
// parseQualifiedSelector
func (p *Parser) parseQualifiedSelector() (result Selector, err error) {
p.next()
switch p.tok.Type {
case TRecursive:
nr, _ := p.parseStepSelector()
result = recursiveSelector(nr)
case TChildDot, TChildStart:
result, err = p.parseStepSelector()
default:
return nil, fmt.Errorf("expected . or .. or something, got %s", p.tok.Value)
}
return result, nil
}
func (p *Parser) parseStepSelector() (result Selector, err error) {
p.next()
result, err = p.parseNodeTestSelector()
if err != nil {
return nil, err
}
p.next()
if p.tok.Type == TPredicateStart {
// TODO
}
return result, nil
}
func (p *Parser) parseNodeTestSelector() (result Selector, err error) {
switch p.tok.Type {
case TName:
/*
switch p.tok.Value {
case "object", "array", "string", "number", "boolean", "null":
// TODO
//result = typeSelector(p.tok.Value)
default:
}
*/
result = nameSelector(p.tok.Value)
case TWildcard:
result = wildcardSelector
default:
fmt.Println("here: ", tokenNames[p.tok.Type])
}
return result, err
}
func (p *Parser) parseChildSelector() Selector {
var result Selector
p.next()
switch p.tok.Type {
case TQuotedName:
result = nameSelector(strings.Trim(p.tok.Value, `"'`))
case TName:
result = nameSelector(p.tok.Value)
}
p.next()
return result
}
// rootSelector checks node is root
func rootSelector(n *json.Node) bool {
result := (n.Type == json.DocumentNode)
fmt.Printf("rootSelector => type: %s, val: %s, result: %t\n", json.NodeNames[n.Type], n.Data, result)
return result
}
// wildcardSelector returns true
func wildcardSelector(n *json.Node) bool {
return true
}
// childSelector creates a selector for c being a child of p
func childSelector(p, c Selector) Selector {
return func(n *json.Node) bool {
fmt.Printf("childSelector => type: %s, val: %s\n", json.NodeNames[n.Type], n.Data)
result := (c(n) && n.Parent != nil && p(n.Parent))
fmt.Printf("childSelector => type: %s, val: %s, result: %t\n", json.NodeNames[n.Type], n.Data, result)
return result
}
}
// nameSelector generates selector for object key == k
func nameSelector(k string) Selector {
return func(n *json.Node) bool {
result := (n.Type == json.ElementNode && n.Data == k)
fmt.Printf("nameSelector => type: %s, val: %s, result: %t\n", json.NodeNames[n.Type], n.Data, result)
return result
}
}
// recursiveSelector matches any node below which matches a
func recursiveSelector(a Selector) Selector {
return func(n *json.Node) bool {
if n.Type != json.ElementNode {
return false
}
return hasRecursiveMatch(n, a)
}
}
func hasRecursiveMatch(n *json.Node, a Selector) bool {
for c := n.FirstChild; c != nil; c = c.NextSibling {
if a(c) || (c.Type == json.ElementNode && hasRecursiveMatch(c, a)) {
return true
}
}
return false
}
// typeSelector matches a node with type t
func typeSelector(t string) Selector {
return func(n *json.Node) bool {
if n.DataType == t {
return true
}
return false
}
}
|
