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package main
type PathFilter struct {
initial PathFilterState
}
func (filter PathFilter) exec(space WalkItem) bool {
pathFilterState := make(map[PathFilterState]struct{})
pathFilterState[filter.initial] = struct{}{}
for _, segment := range space.path {
nextPathFilterState := make(map[PathFilterState]struct{})
for curState := range pathFilterState {
for nextState := range curState.eat(segment) {
nextPathFilterState[nextState] = struct{}{}
}
}
pathFilterState = nextPathFilterState
}
for pathState := range pathFilterState {
if pathState.accept() {
return true
}
}
return false
}
type MapTerminalFilter struct {}
func (filter MapTerminalFilter) exec(space WalkItem) bool {
terminal, isTerminal := space.value.(TerminalValue)
if !isTerminal {
return false
}
return terminal == MapBegin || terminal == MapEnd
}
type NonTerminalFilter struct {}
func (filter NonTerminalFilter) exec(space WalkItem) bool {
_, isTerminal := space.value.(TerminalValue)
return !isTerminal
}
type RangeFilter struct {
start Filter
end Filter
active bool
}
func (filter *RangeFilter) exec(space WalkItem) bool {
if filter.active {
if filter.end.exec(space) {
filter.active = false
}
return true
} else {
if filter.start.exec(space) {
filter.active = true
}
return filter.active
}
}
type BeginTerminalFilter struct {}
func (filter BeginTerminalFilter) exec(space WalkItem) bool {
terminal, isTerminal := space.value.(TerminalValue)
if !isTerminal {
return false
}
return terminal == ArrayBegin || terminal == MapBegin
}
type EndTerminalFilter struct {}
func (filter EndTerminalFilter) exec(space WalkItem) bool {
terminal, isTerminal := space.value.(TerminalValue)
if !isTerminal {
return false
}
return terminal == ArrayEnd || terminal == MapEnd
}
type Filter interface {
exec(WalkItem) bool
}
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