policy: implement partial matching, to evaluate in multiple steps with fail early
This commit is contained in:
Michael Muré
@@ -8,8 +8,6 @@ import (
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"github.com/ipld/go-ipld-prime/node/basicnode"
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)
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// TODO: remove entirely?
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var Bool = basicnode.NewBool
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var Int = basicnode.NewInt
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var Float = basicnode.NewFloat
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@@ -12,141 +12,215 @@ import (
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// Match determines if the IPLD node satisfies the policy.
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func (p Policy) Match(node datamodel.Node) bool {
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for _, stmt := range p {
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ok := matchStatement(stmt, node)
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if !ok {
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res, _ := matchStatement(stmt, node)
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switch res {
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case matchResultNoData, matchResultFalse:
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return false
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case matchResultTrue:
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// continue
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}
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}
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return true
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}
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func matchStatement(statement Statement, node ipld.Node) bool {
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switch statement.Kind() {
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case KindEqual:
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if s, ok := statement.(equality); ok {
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res, err := s.selector.Select(node)
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if err != nil {
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return false
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// PartialMatch returns false IIF one of the Statement has the corresponding data and doesn't match.
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// If the data is missing or the Statement is matching, true is returned.
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//
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// This allows performing the policy checking in multiple steps, and find immediately if a Statement already failed.
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// A final call to Match is necessary to make sure that the policy is fully matched, with no missing data
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// (apart from optional values).
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//
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// The first Statement failing to match is returned as well.
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func (p Policy) PartialMatch(node datamodel.Node) (bool, Statement) {
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for _, stmt := range p {
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res, leaf := matchStatement(stmt, node)
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switch res {
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case matchResultFalse:
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return false, leaf
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case matchResultNoData, matchResultTrue:
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// continue
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}
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return datamodel.DeepEqual(s.value, res)
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}
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return true, nil
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}
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type matchResult int8
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const (
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matchResultTrue matchResult = iota
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matchResultFalse
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matchResultNoData
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)
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// matchStatement evaluate the policy against the given ipld.Node and returns:
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// - matchResultTrue: if the selector matched and the statement evaluated to true.
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// - matchResultFalse: if the selector matched and the statement evaluated to false.
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// - matchResultNoData: if the selector didn't match the expected data.
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// For matchResultTrue and matchResultNoData, the leaf-most (innermost) statement failing to be true is returned,
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// as well as the corresponding root-most encompassing statement.
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func matchStatement(cur Statement, node ipld.Node) (_ matchResult, leafMost Statement) {
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var boolToRes = func(v bool) (matchResult, Statement) {
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if v {
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return matchResultTrue, nil
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} else {
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return matchResultFalse, cur
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}
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}
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switch cur.Kind() {
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case KindEqual:
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if s, ok := cur.(equality); ok {
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res, err := s.selector.Select(node)
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if err != nil || res == nil {
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return matchResultNoData, cur
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}
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return boolToRes(datamodel.DeepEqual(s.value, res))
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}
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case KindGreaterThan:
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if s, ok := statement.(equality); ok {
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if s, ok := cur.(equality); ok {
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res, err := s.selector.Select(node)
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if err != nil {
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return false
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if err != nil || res == nil {
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return matchResultNoData, cur
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}
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return isOrdered(s.value, res, gt)
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return boolToRes(isOrdered(s.value, res, gt))
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}
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case KindGreaterThanOrEqual:
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if s, ok := statement.(equality); ok {
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if s, ok := cur.(equality); ok {
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res, err := s.selector.Select(node)
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if err != nil {
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return false
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if err != nil || res == nil {
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return matchResultNoData, cur
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}
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return isOrdered(s.value, res, gte)
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return boolToRes(isOrdered(s.value, res, gte))
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}
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case KindLessThan:
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if s, ok := statement.(equality); ok {
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if s, ok := cur.(equality); ok {
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res, err := s.selector.Select(node)
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if err != nil {
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return false
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if err != nil || res == nil {
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return matchResultNoData, cur
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}
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return isOrdered(s.value, res, lt)
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return boolToRes(isOrdered(s.value, res, lt))
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}
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case KindLessThanOrEqual:
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if s, ok := statement.(equality); ok {
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if s, ok := cur.(equality); ok {
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res, err := s.selector.Select(node)
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if err != nil {
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return false
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if err != nil || res == nil {
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return matchResultNoData, cur
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}
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return isOrdered(s.value, res, lte)
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return boolToRes(isOrdered(s.value, res, lte))
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}
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case KindNot:
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if s, ok := statement.(negation); ok {
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return !matchStatement(s.statement, node)
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if s, ok := cur.(negation); ok {
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res, leaf := matchStatement(s.statement, node)
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switch res {
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case matchResultNoData:
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return matchResultNoData, leaf
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case matchResultTrue:
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return matchResultFalse, leaf
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case matchResultFalse:
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return matchResultTrue, leaf
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}
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}
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case KindAnd:
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if s, ok := statement.(connective); ok {
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if s, ok := cur.(connective); ok {
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for _, cs := range s.statements {
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r := matchStatement(cs, node)
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if !r {
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return false
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res, leaf := matchStatement(cs, node)
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switch res {
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case matchResultNoData:
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return matchResultNoData, leaf
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case matchResultTrue:
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// continue
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case matchResultFalse:
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return matchResultFalse, leaf
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}
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}
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return true
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return matchResultTrue, nil
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}
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case KindOr:
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if s, ok := statement.(connective); ok {
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if s, ok := cur.(connective); ok {
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if len(s.statements) == 0 {
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return true
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return matchResultTrue, nil
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}
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for _, cs := range s.statements {
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r := matchStatement(cs, node)
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if r {
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return true
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res, leaf := matchStatement(cs, node)
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switch res {
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case matchResultNoData:
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return matchResultNoData, leaf
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case matchResultTrue:
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return matchResultTrue, leaf
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case matchResultFalse:
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// continue
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}
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}
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return false
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return matchResultFalse, cur
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}
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case KindLike:
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if s, ok := statement.(wildcard); ok {
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if s, ok := cur.(wildcard); ok {
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res, err := s.selector.Select(node)
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if err != nil {
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return false
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if err != nil || res == nil {
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return matchResultNoData, cur
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}
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v, err := res.AsString()
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if err != nil {
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return false // not a string
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return matchResultFalse, cur // not a string
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}
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return s.pattern.Match(v)
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return boolToRes(s.pattern.Match(v))
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}
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case KindAll:
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if s, ok := statement.(quantifier); ok {
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if s, ok := cur.(quantifier); ok {
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res, err := s.selector.Select(node)
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if err != nil {
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return false
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if err != nil || res == nil {
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return matchResultNoData, cur
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}
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it := res.ListIterator()
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if it == nil {
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return false // not a list
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return matchResultFalse, cur // not a list
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}
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for !it.Done() {
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_, v, err := it.Next()
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if err != nil {
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return false
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panic("should never happen")
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}
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ok := matchStatement(s.statement, v)
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if !ok {
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return false
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matchRes, leaf := matchStatement(s.statement, v)
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switch matchRes {
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case matchResultNoData:
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return matchResultNoData, leaf
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case matchResultTrue:
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// continue
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case matchResultFalse:
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return matchResultFalse, leaf
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}
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}
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return true
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return matchResultTrue, nil
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}
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case KindAny:
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if s, ok := statement.(quantifier); ok {
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if s, ok := cur.(quantifier); ok {
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res, err := s.selector.Select(node)
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if err != nil {
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return false
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if err != nil || res == nil {
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return matchResultNoData, cur
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}
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it := res.ListIterator()
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if it == nil {
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return false // not a list
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return matchResultFalse, cur // not a list
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}
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for !it.Done() {
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_, v, err := it.Next()
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if err != nil {
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return false
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panic("should never happen")
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}
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ok := matchStatement(s.statement, v)
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if ok {
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return true
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matchRes, leaf := matchStatement(s.statement, v)
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switch matchRes {
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case matchResultNoData:
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return matchResultNoData, leaf
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case matchResultTrue:
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return matchResultTrue, nil
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case matchResultFalse:
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// continue
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}
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}
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return false
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return matchResultFalse, cur
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}
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}
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panic(fmt.Errorf("unimplemented statement kind: %s", statement.Kind()))
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panic(fmt.Errorf("unimplemented statement kind: %s", cur.Kind()))
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}
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func isOrdered(expected ipld.Node, actual ipld.Node, satisfies func(order int) bool) bool {
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@@ -9,7 +9,6 @@ import (
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)
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var (
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identity = Selector{segment{str: ".", identity: true}}
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indexRegex = regexp.MustCompile(`^-?\d+$`)
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sliceRegex = regexp.MustCompile(`^((\-?\d+:\-?\d*)|(\-?\d*:\-?\d+))$`)
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fieldRegex = regexp.MustCompile(`^\.[a-zA-Z_]*?$`)
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@@ -23,7 +22,7 @@ func Parse(str string) (Selector, error) {
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return nil, newParseError("selector must start with identity segment '.'", str, 0, string(str[0]))
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}
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if str == "." {
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return identity, nil
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return Selector{segment{str: ".", identity: true}}, nil
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}
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if str == ".?" {
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return Selector{segment{str: ".?", identity: true, optional: true}}, nil
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