whisper/filter.go


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// Contains the message filter for fine grained subscriptions.

package whisper

import (
    "crypto/ecdsa"

    "github.com/ethereum/go-ethereum/event/filter"
)

// Filter is used to subscribe to specific types of whisper messages.
type Filter struct {
    To     *ecdsa.PublicKey   // Recipient of the message
    From   *ecdsa.PublicKey   // Sender of the message
    Topics [][]Topic          // Topics to filter messages with
    Fn     func(msg *Message) // Handler in case of a match
}

// filterer is the internal, fully initialized filter ready to match inbound
// messages to a variety of criteria.
type filterer struct {
    to      string                 // Recipient of the message
    from    string                 // Sender of the message
    matcher *topicMatcher          // Topics to filter messages with
    fn      func(data interface{}) // Handler in case of a match
}

// Compare checks if the specified filter matches the current one.
func (self filterer) Compare(f filter.Filter) bool {
    filter := f.(filterer)

    // Check the message sender and recipient
    if len(self.to) > 0 && self.to != filter.to {
        return false
    }
    if len(self.from) > 0 && self.from != filter.from {
        return false
    }
    // Check the topic filtering
    topics := make([]Topic, len(filter.matcher.conditions))
    for i, group := range filter.matcher.conditions {
        // Message should contain a single topic entry, extract
        for topics[i], _ = range group {
            break
        }
    }
    if !self.matcher.Matches(topics) {
        return false
    }
    return true
}

// Trigger is called when a filter successfully matches an inbound message.
func (self filterer) Trigger(data interface{}) {
    self.fn(data)
}