yq/pkg/yqlib/path_parser.go

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package yqlib
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import (
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"strconv"
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"strings"
)
type PathParser interface {
ParsePath(path string) []string
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MatchesNextPathElement(nodeContext NodeContext, nodeKey string) bool
IsPathExpression(pathElement string) bool
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}
type pathParser struct{}
func NewPathParser() PathParser {
return &pathParser{}
}
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func matchesString(expression string, value string) bool {
var prefixMatch = strings.TrimSuffix(expression, "*")
if prefixMatch != expression {
log.Debug("prefix match, %v", strings.HasPrefix(value, prefixMatch))
return strings.HasPrefix(value, prefixMatch)
}
return value == expression
}
func (p *pathParser) IsPathExpression(pathElement string) bool {
return pathElement == "*" || pathElement == "**" || strings.Contains(pathElement, "==")
}
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/**
* node: node that we may traverse/visit
* head: path element expression to match against
* tail: remaining path element expressions
* pathStack: stack of actual paths we've matched to get to node
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* nodeKey: actual value of this nodes 'key' or index.
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*/
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func (p *pathParser) MatchesNextPathElement(nodeContext NodeContext, nodeKey string) bool {
head := nodeContext.Head
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if head == "**" || head == "*" {
return true
}
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if strings.Contains(head, "==") {
log.Debug("ooh deep recursion time")
result := strings.SplitN(head, "==", 2)
path := strings.TrimSpace(result[0])
value := strings.TrimSpace(result[1])
log.Debug("path %v", path)
log.Debug("value %v", value)
DebugNode(nodeContext.Node)
navigationStrategy := FilterMatchingNodesNavigationStrategy(value)
navigator := NewDataNavigator(navigationStrategy)
err := navigator.Traverse(nodeContext.Node, p.ParsePath(path))
if err != nil {
log.Error("Error deep recursing - ignoring")
log.Error(err.Error())
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}
log.Debug("done deep recursing, found %v matches", len(navigationStrategy.GetVisitedNodes()))
return len(navigationStrategy.GetVisitedNodes()) > 0
}
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if head == "+" {
log.Debug("head is +, nodeKey is %v", nodeKey)
var _, err = strconv.ParseInt(nodeKey, 10, 64) // nolint
if err == nil {
return true
}
}
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return matchesString(head, nodeKey)
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}
func (p *pathParser) ParsePath(path string) []string {
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if path == "" {
return []string{}
}
return p.parsePathAccum([]string{}, path)
}
func (p *pathParser) parsePathAccum(paths []string, remaining string) []string {
head, tail := p.nextYamlPath(remaining)
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if tail == "" {
return append(paths, head)
}
return p.parsePathAccum(append(paths, head), tail)
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}
func (p *pathParser) nextYamlPath(path string) (pathElement string, remaining string) {
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switch path[0] {
case '[':
// e.g [0].blah.cat -> we need to return "0" and "blah.cat"
return p.search(path[1:], []uint8{']'}, true)
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case '"':
// e.g "a.b".blah.cat -> we need to return "a.b" and "blah.cat"
return p.search(path[1:], []uint8{'"'}, true)
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case '(':
// e.g "a.b".blah.cat -> we need to return "a.b" and "blah.cat"
return p.search(path[1:], []uint8{')'}, true)
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default:
// e.g "a.blah.cat" -> return "a" and "blah.cat"
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return p.search(path[0:], []uint8{'.', '[', '"', '('}, false)
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}
}
func (p *pathParser) search(path string, matchingChars []uint8, skipNext bool) (pathElement string, remaining string) {
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for i := 0; i < len(path); i++ {
var char = path[i]
if p.contains(matchingChars, char) {
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var remainingStart = i + 1
if skipNext {
remainingStart = remainingStart + 1
} else if !skipNext && char != '.' {
remainingStart = i
}
if remainingStart > len(path) {
remainingStart = len(path)
}
return path[0:i], path[remainingStart:]
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}
}
return path, ""
}
func (p *pathParser) contains(matchingChars []uint8, candidate uint8) bool {
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for _, a := range matchingChars {
if a == candidate {
return true
}
}
return false
}