peridot/vendor/github.com/antchfx/xpath/build.go
2022-07-07 22:13:21 +02:00

523 lines
14 KiB
Go

package xpath
import (
"errors"
"fmt"
)
type flag int
const (
noneFlag flag = iota
filterFlag
)
// builder provides building an XPath expressions.
type builder struct {
depth int
flag flag
firstInput query
}
// axisPredicate creates a predicate to predicating for this axis node.
func axisPredicate(root *axisNode) func(NodeNavigator) bool {
// get current axix node type.
typ := ElementNode
switch root.AxeType {
case "attribute":
typ = AttributeNode
case "self", "parent":
typ = allNode
default:
switch root.Prop {
case "comment":
typ = CommentNode
case "text":
typ = TextNode
// case "processing-instruction":
// typ = ProcessingInstructionNode
case "node":
typ = allNode
}
}
nametest := root.LocalName != "" || root.Prefix != ""
predicate := func(n NodeNavigator) bool {
if typ == n.NodeType() || typ == allNode || typ == TextNode {
if nametest {
if root.LocalName == n.LocalName() && root.Prefix == n.Prefix() {
return true
}
} else {
return true
}
}
return false
}
return predicate
}
// processAxisNode processes a query for the XPath axis node.
func (b *builder) processAxisNode(root *axisNode) (query, error) {
var (
err error
qyInput query
qyOutput query
predicate = axisPredicate(root)
)
if root.Input == nil {
qyInput = &contextQuery{}
} else {
if root.AxeType == "child" && (root.Input.Type() == nodeAxis) {
if input := root.Input.(*axisNode); input.AxeType == "descendant-or-self" {
var qyGrandInput query
if input.Input != nil {
qyGrandInput, _ = b.processNode(input.Input)
} else {
qyGrandInput = &contextQuery{}
}
// fix #20: https://github.com/antchfx/htmlquery/issues/20
filter := func(n NodeNavigator) bool {
v := predicate(n)
switch root.Prop {
case "text":
v = v && n.NodeType() == TextNode
case "comment":
v = v && n.NodeType() == CommentNode
}
return v
}
qyOutput = &descendantQuery{Input: qyGrandInput, Predicate: filter, Self: true}
return qyOutput, nil
}
}
qyInput, err = b.processNode(root.Input)
if err != nil {
return nil, err
}
}
switch root.AxeType {
case "ancestor":
qyOutput = &ancestorQuery{Input: qyInput, Predicate: predicate}
case "ancestor-or-self":
qyOutput = &ancestorQuery{Input: qyInput, Predicate: predicate, Self: true}
case "attribute":
qyOutput = &attributeQuery{Input: qyInput, Predicate: predicate}
case "child":
filter := func(n NodeNavigator) bool {
v := predicate(n)
switch root.Prop {
case "text":
v = v && n.NodeType() == TextNode
case "node":
v = v && (n.NodeType() == ElementNode || n.NodeType() == TextNode)
case "comment":
v = v && n.NodeType() == CommentNode
}
return v
}
qyOutput = &childQuery{Input: qyInput, Predicate: filter}
case "descendant":
qyOutput = &descendantQuery{Input: qyInput, Predicate: predicate}
case "descendant-or-self":
qyOutput = &descendantQuery{Input: qyInput, Predicate: predicate, Self: true}
case "following":
qyOutput = &followingQuery{Input: qyInput, Predicate: predicate}
case "following-sibling":
qyOutput = &followingQuery{Input: qyInput, Predicate: predicate, Sibling: true}
case "parent":
qyOutput = &parentQuery{Input: qyInput, Predicate: predicate}
case "preceding":
qyOutput = &precedingQuery{Input: qyInput, Predicate: predicate}
case "preceding-sibling":
qyOutput = &precedingQuery{Input: qyInput, Predicate: predicate, Sibling: true}
case "self":
qyOutput = &selfQuery{Input: qyInput, Predicate: predicate}
case "namespace":
// haha,what will you do someting??
default:
err = fmt.Errorf("unknown axe type: %s", root.AxeType)
return nil, err
}
return qyOutput, nil
}
// processFilterNode builds query for the XPath filter predicate.
func (b *builder) processFilterNode(root *filterNode) (query, error) {
b.flag |= filterFlag
qyInput, err := b.processNode(root.Input)
if err != nil {
return nil, err
}
qyCond, err := b.processNode(root.Condition)
if err != nil {
return nil, err
}
qyOutput := &filterQuery{Input: qyInput, Predicate: qyCond}
return qyOutput, nil
}
// processFunctionNode processes query for the XPath function node.
func (b *builder) processFunctionNode(root *functionNode) (query, error) {
var qyOutput query
switch root.FuncName {
case "starts-with":
arg1, err := b.processNode(root.Args[0])
if err != nil {
return nil, err
}
arg2, err := b.processNode(root.Args[1])
if err != nil {
return nil, err
}
qyOutput = &functionQuery{Input: b.firstInput, Func: startwithFunc(arg1, arg2)}
case "ends-with":
arg1, err := b.processNode(root.Args[0])
if err != nil {
return nil, err
}
arg2, err := b.processNode(root.Args[1])
if err != nil {
return nil, err
}
qyOutput = &functionQuery{Input: b.firstInput, Func: endwithFunc(arg1, arg2)}
case "contains":
arg1, err := b.processNode(root.Args[0])
if err != nil {
return nil, err
}
arg2, err := b.processNode(root.Args[1])
if err != nil {
return nil, err
}
qyOutput = &functionQuery{Input: b.firstInput, Func: containsFunc(arg1, arg2)}
case "substring":
//substring( string , start [, length] )
if len(root.Args) < 2 {
return nil, errors.New("xpath: substring function must have at least two parameter")
}
var (
arg1, arg2, arg3 query
err error
)
if arg1, err = b.processNode(root.Args[0]); err != nil {
return nil, err
}
if arg2, err = b.processNode(root.Args[1]); err != nil {
return nil, err
}
if len(root.Args) == 3 {
if arg3, err = b.processNode(root.Args[2]); err != nil {
return nil, err
}
}
qyOutput = &functionQuery{Input: b.firstInput, Func: substringFunc(arg1, arg2, arg3)}
case "substring-before", "substring-after":
//substring-xxxx( haystack, needle )
if len(root.Args) != 2 {
return nil, errors.New("xpath: substring-before function must have two parameters")
}
var (
arg1, arg2 query
err error
)
if arg1, err = b.processNode(root.Args[0]); err != nil {
return nil, err
}
if arg2, err = b.processNode(root.Args[1]); err != nil {
return nil, err
}
qyOutput = &functionQuery{
Input: b.firstInput,
Func: substringIndFunc(arg1, arg2, root.FuncName == "substring-after"),
}
case "string-length":
// string-length( [string] )
if len(root.Args) < 1 {
return nil, errors.New("xpath: string-length function must have at least one parameter")
}
arg1, err := b.processNode(root.Args[0])
if err != nil {
return nil, err
}
qyOutput = &functionQuery{Input: b.firstInput, Func: stringLengthFunc(arg1)}
case "normalize-space":
if len(root.Args) == 0 {
return nil, errors.New("xpath: normalize-space function must have at least one parameter")
}
argQuery, err := b.processNode(root.Args[0])
if err != nil {
return nil, err
}
qyOutput = &functionQuery{Input: argQuery, Func: normalizespaceFunc}
case "replace":
//replace( string , string, string )
if len(root.Args) != 3 {
return nil, errors.New("xpath: replace function must have three parameters")
}
var (
arg1, arg2, arg3 query
err error
)
if arg1, err = b.processNode(root.Args[0]); err != nil {
return nil, err
}
if arg2, err = b.processNode(root.Args[1]); err != nil {
return nil, err
}
if arg3, err = b.processNode(root.Args[2]); err != nil {
return nil, err
}
qyOutput = &functionQuery{Input: b.firstInput, Func: replaceFunc(arg1, arg2, arg3)}
case "translate":
//translate( string , string, string )
if len(root.Args) != 3 {
return nil, errors.New("xpath: translate function must have three parameters")
}
var (
arg1, arg2, arg3 query
err error
)
if arg1, err = b.processNode(root.Args[0]); err != nil {
return nil, err
}
if arg2, err = b.processNode(root.Args[1]); err != nil {
return nil, err
}
if arg3, err = b.processNode(root.Args[2]); err != nil {
return nil, err
}
qyOutput = &functionQuery{Input: b.firstInput, Func: translateFunc(arg1, arg2, arg3)}
case "not":
if len(root.Args) == 0 {
return nil, errors.New("xpath: not function must have at least one parameter")
}
argQuery, err := b.processNode(root.Args[0])
if err != nil {
return nil, err
}
qyOutput = &functionQuery{Input: argQuery, Func: notFunc}
case "name", "local-name", "namespace-uri":
if len(root.Args) > 1 {
return nil, fmt.Errorf("xpath: %s function must have at most one parameter", root.FuncName)
}
var (
arg query
err error
)
if len(root.Args) == 1 {
arg, err = b.processNode(root.Args[0])
if err != nil {
return nil, err
}
}
switch root.FuncName {
case "name":
qyOutput = &functionQuery{Input: b.firstInput, Func: nameFunc(arg)}
case "local-name":
qyOutput = &functionQuery{Input: b.firstInput, Func: localNameFunc(arg)}
case "namespace-uri":
qyOutput = &functionQuery{Input: b.firstInput, Func: namespaceFunc(arg)}
}
case "true", "false":
val := root.FuncName == "true"
qyOutput = &functionQuery{
Input: b.firstInput,
Func: func(_ query, _ iterator) interface{} {
return val
},
}
case "last":
qyOutput = &functionQuery{Input: b.firstInput, Func: lastFunc}
case "position":
qyOutput = &functionQuery{Input: b.firstInput, Func: positionFunc}
case "boolean", "number", "string":
inp := b.firstInput
if len(root.Args) > 1 {
return nil, fmt.Errorf("xpath: %s function must have at most one parameter", root.FuncName)
}
if len(root.Args) == 1 {
argQuery, err := b.processNode(root.Args[0])
if err != nil {
return nil, err
}
inp = argQuery
}
f := &functionQuery{Input: inp}
switch root.FuncName {
case "boolean":
f.Func = booleanFunc
case "string":
f.Func = stringFunc
case "number":
f.Func = numberFunc
}
qyOutput = f
case "count":
//if b.firstInput == nil {
// return nil, errors.New("xpath: expression must evaluate to node-set")
//}
if len(root.Args) == 0 {
return nil, fmt.Errorf("xpath: count(node-sets) function must with have parameters node-sets")
}
argQuery, err := b.processNode(root.Args[0])
if err != nil {
return nil, err
}
qyOutput = &functionQuery{Input: argQuery, Func: countFunc}
case "sum":
if len(root.Args) == 0 {
return nil, fmt.Errorf("xpath: sum(node-sets) function must with have parameters node-sets")
}
argQuery, err := b.processNode(root.Args[0])
if err != nil {
return nil, err
}
qyOutput = &functionQuery{Input: argQuery, Func: sumFunc}
case "ceiling", "floor", "round":
if len(root.Args) == 0 {
return nil, fmt.Errorf("xpath: ceiling(node-sets) function must with have parameters node-sets")
}
argQuery, err := b.processNode(root.Args[0])
if err != nil {
return nil, err
}
f := &functionQuery{Input: argQuery}
switch root.FuncName {
case "ceiling":
f.Func = ceilingFunc
case "floor":
f.Func = floorFunc
case "round":
f.Func = roundFunc
}
qyOutput = f
case "concat":
if len(root.Args) < 2 {
return nil, fmt.Errorf("xpath: concat() must have at least two arguments")
}
var args []query
for _, v := range root.Args {
q, err := b.processNode(v)
if err != nil {
return nil, err
}
args = append(args, q)
}
qyOutput = &functionQuery{Input: b.firstInput, Func: concatFunc(args...)}
case "reverse":
if len(root.Args) == 0 {
return nil, fmt.Errorf("xpath: reverse(node-sets) function must with have parameters node-sets")
}
argQuery, err := b.processNode(root.Args[0])
if err != nil {
return nil, err
}
qyOutput = &transformFunctionQuery{Input: argQuery, Func: reverseFunc}
default:
return nil, fmt.Errorf("not yet support this function %s()", root.FuncName)
}
return qyOutput, nil
}
func (b *builder) processOperatorNode(root *operatorNode) (query, error) {
left, err := b.processNode(root.Left)
if err != nil {
return nil, err
}
right, err := b.processNode(root.Right)
if err != nil {
return nil, err
}
var qyOutput query
switch root.Op {
case "+", "-", "div", "mod": // Numeric operator
var exprFunc func(interface{}, interface{}) interface{}
switch root.Op {
case "+":
exprFunc = plusFunc
case "-":
exprFunc = minusFunc
case "div":
exprFunc = divFunc
case "mod":
exprFunc = modFunc
}
qyOutput = &numericQuery{Left: left, Right: right, Do: exprFunc}
case "=", ">", ">=", "<", "<=", "!=":
var exprFunc func(iterator, interface{}, interface{}) interface{}
switch root.Op {
case "=":
exprFunc = eqFunc
case ">":
exprFunc = gtFunc
case ">=":
exprFunc = geFunc
case "<":
exprFunc = ltFunc
case "<=":
exprFunc = leFunc
case "!=":
exprFunc = neFunc
}
qyOutput = &logicalQuery{Left: left, Right: right, Do: exprFunc}
case "or", "and":
isOr := false
if root.Op == "or" {
isOr = true
}
qyOutput = &booleanQuery{Left: left, Right: right, IsOr: isOr}
case "|":
qyOutput = &unionQuery{Left: left, Right: right}
}
return qyOutput, nil
}
func (b *builder) processNode(root node) (q query, err error) {
if b.depth = b.depth + 1; b.depth > 1024 {
err = errors.New("the xpath expressions is too complex")
return
}
switch root.Type() {
case nodeConstantOperand:
n := root.(*operandNode)
q = &constantQuery{Val: n.Val}
case nodeRoot:
q = &contextQuery{Root: true}
case nodeAxis:
q, err = b.processAxisNode(root.(*axisNode))
b.firstInput = q
case nodeFilter:
q, err = b.processFilterNode(root.(*filterNode))
case nodeFunction:
q, err = b.processFunctionNode(root.(*functionNode))
case nodeOperator:
q, err = b.processOperatorNode(root.(*operatorNode))
}
return
}
// build builds a specified XPath expressions expr.
func build(expr string) (q query, err error) {
defer func() {
if e := recover(); e != nil {
switch x := e.(type) {
case string:
err = errors.New(x)
case error:
err = x
default:
err = errors.New("unknown panic")
}
}
}()
root := parse(expr)
b := &builder{}
return b.processNode(root)
}