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Generalize 'not' to handle any predicate expression #10

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Generalize 'not' to handle any predicate expression #10

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4 changes: 4 additions & 0 deletions all_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -240,6 +240,10 @@ var libraryTable = []struct {
{"//*[contains(born,'1922')]/name", "Charles M Schulz"},
{"library/book[not(@id)]", exists(false)},
{"library/book[not(@foo) and @id='b0883556316']/isbn", []string{"0883556316"}},
{"library/book[not(@id='b0883556316')]/isbn", []string{"0836217462"}},
{"library/book/character[not(@id='Snoopy' and ./born='1950-10-04')]", exists(true)},
{"library/book/character[@id='Snoopy' and ./born='1950-10-04' or not(@id='Lucy') and ./born='1952-03-03']/born", []string{"1950-10-04"}},
{"library/book[@id='b0836217462']/character[not(@id='Snoopy' and ./born='1950-10-04' or @id='Lucy' and ./born='1952-03-03')]/born", []string{"1966-08-22", "1951-05-30"}},

// Multiple predicates.
{"library/book/character[@id='Snoopy' and ./born='1950-10-04']/born", []string{"1950-10-04"}},
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2 changes: 1 addition & 1 deletion doc.go
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Expand Up @@ -15,7 +15,7 @@
// - All axes are supported ("child", "following-sibling", etc)
// - All abbreviated forms are supported (".", "//", etc)
// - All node types except for namespace are supported
// - Predicates may be [N], [path], [not(path)], [path=literal] or [contains(path, literal)]
// - Predicates may be [N], [path], [not(predicate)], [path=literal] or [contains(path, literal)]
// - Predicates may be joined with "or", "and", and parenthesis
// - Richer expressions and namespaces are not supported
//
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27 changes: 11 additions & 16 deletions path.go
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Original file line number Diff line number Diff line change
Expand Up @@ -156,10 +156,7 @@ func (s *pathStepState) test(pred predicate) bool {
}
}
case notPredicate:
iter := pred.path.Iter(s.node)
if !iter.Next() {
return true
}
return !s.test(pred.uniSub)
case andPredicate:
for _, sub := range pred.sub {
if !s.test(sub) {
Expand Down Expand Up @@ -382,7 +379,7 @@ type containsPredicate struct {
}

type notPredicate struct {
path *Path
uniSub predicate
}

type andPredicate struct {
Expand Down Expand Up @@ -565,13 +562,14 @@ func (c *pathCompiler) parsePath() (path *Path, err error) {
type state struct {
sub []predicate
and bool
not bool
}
var stack []state
var sub []predicate
var and bool
NextPred:
if c.skipByte('(') {
stack = append(stack, state{sub, and})
stack = append(stack, state{sub: sub, and: and})
sub = nil
and = false
}
Expand Down Expand Up @@ -601,16 +599,10 @@ func (c *pathCompiler) parsePath() (path *Path, err error) {
}
next = containsPredicate{path, value}
} else if c.skipString("not(") {
// TODO Generalize to handle any predicate expression.
path, err := c.parsePath()
if err != nil {
return nil, err
}
c.skipSpaces()
if !c.skipByte(')') {
return nil, c.errorf("not() missing ')'")
}
next = notPredicate{path}
stack = append(stack, state{sub: sub, and: and, not: true})
sub = nil
and = false
goto NextPred
} else {
path, err := c.parsePath()
if err != nil {
Expand Down Expand Up @@ -669,6 +661,9 @@ func (c *pathCompiler) parsePath() (path *Path, err error) {
stack = stack[:len(stack)-1]
sub = s.sub
and = s.and
if s.not {
next = notPredicate{next}
}
goto HandleNext
}
if len(stack) > 0 {
Expand Down