package subex import ( "main/walk" ) // A state of execution for the transducer type SubexState interface { // Eat a Atom and transition to any number of new states eat(store Store, char walk.Atom) []SubexBranch // Find accepting states reachable through epsilon transitions and return their outputs accepting(store Store) [][]walk.Atom } // Try first, if it fails then try second type SubexGroupState struct { first, second SubexState } func (state SubexGroupState) eat(store Store, char walk.Atom) []SubexBranch { otherStore := store.clone() return append(state.first.eat(store, char), state.second.eat(otherStore, char)...) } func (state SubexGroupState) accepting(store Store) [][]walk.Atom { return append(state.first.accepting(store), state.second.accepting(store)...) } // Run the match machine and store the output in a slot for later use // Output nothing type SubexStoreState struct { match SubexState slot rune next SubexState toStore []walk.Atom } func (state SubexStoreState) eat(store Store, char walk.Atom) (nextStates []SubexBranch) { acceptedOutputs := state.match.accepting(store) for _, acceptedOutput := range acceptedOutputs { nextStore := store.withValue(state.slot, walk.ConcatData(state.toStore, acceptedOutput)) nextStates = append(nextStates, state.next.eat(nextStore.clone(), char)...) } nextMatchStates := state.match.eat(store.clone(), char) for _, matchState := range nextMatchStates { nextStates = append(nextStates, SubexBranch { state: &SubexStoreState { match: matchState.state, slot: state.slot, next: state.next, toStore: walk.ConcatData(state.toStore, matchState.output), }, output: nil, store: store.clone(), }) } return nextStates } func (state SubexStoreState) accepting(store Store) (outputs [][]walk.Atom) { acceptedOutputs := state.match.accepting(store) for _, acceptedOutput := range acceptedOutputs { nextStore := store.withValue(state.slot, walk.ConcatData(state.toStore, acceptedOutput)) outputs = append(outputs, state.next.accepting(nextStore)...) } return outputs } // A part of an output literal, either an Atom or a slot from which to load type OutputContent interface { // Given the current store, return the []Atom produced by the TransducerOutput build(Store) []walk.Atom } // An OutputContent which is just an Atom literal type OutputAtomLiteral struct { atom walk.Atom } func (replacement OutputAtomLiteral) build(store Store) []walk.Atom { return []walk.Atom{replacement.atom} } // An OutputContent which is a slot that is loaded from type OutputLoad struct { slot rune } func (replacement OutputLoad) build(store Store) []walk.Atom { return store[replacement.slot] } // Don't read in anything, just output the series of data and slots specified type SubexOutputState struct { content []OutputContent next SubexState } // Given a store, return what is outputted by an epsilon transition from this state func (state SubexOutputState) build(store Store) []walk.Atom { var result []walk.Atom for _, part := range state.content { result = append(result, part.build(store)...) } return result } func (state SubexOutputState) eat(store Store, char walk.Atom) []SubexBranch { content := state.build(store) nextStates := state.next.eat(store, char) for i := range nextStates { nextStates[i].output = walk.ConcatData(content, nextStates[i].output) } return nextStates } func (state SubexOutputState) accepting(store Store) [][]walk.Atom { content := state.build(store) outputs := state.next.accepting(store) for i := range outputs { outputs[i] = walk.ConcatData(content, outputs[i]) } return outputs } // A final state, transitions to nothing but is accepting type SubexNoneState struct {} func (state SubexNoneState) eat(store Store, char walk.Atom) []SubexBranch { return nil } func (state SubexNoneState) accepting(store Store) [][]walk.Atom { return [][]walk.Atom{nil} } // Read in a specific Atom and output it type SubexCopyAtomState struct { atom walk.Atom next SubexState } func (state SubexCopyAtomState) eat(store Store, char walk.Atom) []SubexBranch { // TODO can I compare Atom values with == ? if char == state.atom { return []SubexBranch{{ state: state.next, output: []walk.Atom{char}, store: store, }} } return nil } func (state SubexCopyAtomState) accepting(store Store) [][]walk.Atom { return nil } // Read in any Atom and output it type SubexCopyAnyState struct { next SubexState } func (state SubexCopyAnyState) eat(store Store, char walk.Atom) []SubexBranch { return []SubexBranch{{ state: state.next, output: []walk.Atom{char}, store: store, }} } func (state SubexCopyAnyState) accepting(store Store) [][]walk.Atom { return nil } // Read in an Atom and apply a map to generate an Atom to output // If the input isn't in the map transition to nothing type SubexRangeState struct { parts map[walk.Atom]walk.Atom next SubexState } func (state SubexRangeState) eat(store Store, char walk.Atom) []SubexBranch { out, exists := state.parts[char] if !exists { return nil } else { return []SubexBranch{{ state: state.next, output: []walk.Atom{out}, store: store, }} } } func (state SubexRangeState) accepting(store Store) [][]walk.Atom { return nil }