stred-go

main.go (6597B)

---

 package subex
 
 import (
 	"main/walk"
 )
 
 type Transducer struct {
 	storeSize int
 	initialState SubexState
 }
 
 type StoreItem struct {}
 // Where slots are stored
 type Store []walk.OutputList
 // Return a new store with all the data from this one
 func (store Store) clone() Store {
 	newStore := make([]walk.OutputList, len(store))
 	copy(newStore, store)
 	return newStore
 }
 // Return a copy of this store but with an additional slot set
 func (store Store) withValue(key int, value walk.OutputList) Store {
 	newStore := store.clone()
 	newStore[key] = value
 	return newStore
 }
 
 type SlotMap struct {
 	nextId int
 	ids map[rune]int
 }
 func (m *SlotMap) getId(slot rune) int {
 	id, exists := m.ids[slot]
 	if exists {
 		return id
 	}
 	id = m.nextId
 	m.nextId++
 	m.ids[slot] = id
 	return id
 }
 
 // Compile the SubexAST into a transducer SubexState that can be run
 func CompileTransducer(transducerAst SubexAST) Transducer {
 	slotMap := SlotMap {
 		nextId: 0,
 		ids: make(map[rune]int),
 	}
 	initial := transducerAst.compileWith(&SubexNoneState{}, &slotMap, false)
 	return Transducer {
 		storeSize: slotMap.nextId,
 		initialState: initial,
 	}
 }
 
 // An immutable stack for outputting to
 type OutputStack struct {
 	head walk.OutputList
 	tail *OutputStack
 }
 func (stack OutputStack) pop() (walk.OutputList, OutputStack) {
 	return stack.head, *stack.tail
 }
 func (stack OutputStack) push(atoms walk.OutputList) OutputStack {
 	return OutputStack {
 		head: atoms,
 		tail: &stack,
 	}
 }
 func (stack OutputStack) replace(atoms walk.OutputList) OutputStack {
 	return OutputStack {
 		head: atoms,
 		tail: stack.tail,
 	}
 }
 func (stack OutputStack) peek() walk.OutputList {
 	return stack.head
 }
 
 func topAppend(outputStack OutputStack, values []walk.Value) OutputStack {
 	head, isValues := outputStack.peek().(walk.ValueList)
 	if !isValues {
 		panic("Tried to append a value to an output of non-values")
 	}
 	head = append(walk.ValueList{}, head...)
 	head = append(head, values...)
 	return outputStack.replace(head)
 }
 
 func topAppendRunes(outputStack OutputStack, runes walk.RuneList) OutputStack {
 	head, isRunes := outputStack.peek().(walk.RuneList)
 	if !isRunes {
 		panic("Tried to append runes to a non-rune list")
 	}
 	head = append(walk.RuneList{}, head...)
 	head = append(head, runes...)
 	return outputStack.replace(head)
 }
 
 // Addition state that goes along with a subex state in an execution branch
 type auxiliaryState struct {
 	// Content of slots in this branch
 	store Store
 	// The output stack. At the end of the program, whatever is on top of this will be output
 	// States may push or pop to the stack as they wish, creating sort of a call stack that allows states to capture the output of other states
 	outputStack OutputStack
 	// How deeply nested the current execution is inside of the overall value
 	// i.e. starts at zero, is incremented to one when entering an array
 	nesting int
 }
 
 func (aux auxiliaryState) cloneStore() auxiliaryState {
 	aux.store = aux.store.clone()
 	return aux
 }
 
 func (aux auxiliaryState) withValue(slot int, value walk.OutputList) auxiliaryState {
 	aux.store = aux.store.withValue(slot, value)
 	return aux
 }
 
 func (aux auxiliaryState) pushOutput(data walk.OutputList) auxiliaryState {
 	aux.outputStack = aux.outputStack.push(data)
 	return aux
 }
 
 func (aux auxiliaryState) popOutput() (walk.OutputList, auxiliaryState) {
 	data, output := aux.outputStack.pop()
 	aux.outputStack = output
 	return data, aux
 }
 
 func (aux auxiliaryState) topAppend(values walk.OutputList) auxiliaryState {
 	switch output := values.(type) {
 	case walk.ValueList:
 		aux.outputStack = topAppend(aux.outputStack, output)
 	case walk.RuneList:
 		aux.outputStack = topAppendRunes(aux.outputStack, output)
 	}
 	return aux
 }
 
 func (aux auxiliaryState) incNest() auxiliaryState {
 	aux.nesting++
 	return aux
 }
 
 func (aux auxiliaryState) decNest() auxiliaryState {
 	aux.nesting--
 	return aux
 }
 
 // One branch of subex execution
 type SubexBranch struct {
 	// State in this branch
 	state SubexState
 	// Axiliary state
 	aux auxiliaryState
 }
 // Read a single character and return all the branches resulting from this branch consuming it
 func (pair SubexBranch) eat(char walk.Edible) []SubexBranch {
 	return pair.state.eat(pair.aux, char)
 }
 func (pair SubexBranch) accepting() []OutputStack {
 	return pair.state.accepting(pair.aux)
 }
 
 func equalStates(left SubexBranch, right SubexBranch) bool {
 	// Only care about if they are the same pointer
 	return left.state == right.state && left.aux.nesting == right.aux.nesting
 }
 
 // If two branches have the same state, only the first has a chance of being successful
 // This function removes all of the pointless execution branches to save execution time
 func pruneStates(states []SubexBranch) []SubexBranch {
 	uniqueStates := 0
 	outer: for _, state := range states {
 		for i := 0; i < uniqueStates; i++ {
 			if equalStates(state, states[i]) {
 				continue outer
 			}
 		}
 		states[uniqueStates] = state
 		uniqueStates++
 	}
 	return states[:uniqueStates]
 }
 
 func processInput(states []SubexBranch, input walk.StructureIter, nesting int) []SubexBranch {
 	if len(states) == 0 {
 		return states
 	}
 	var tmp []SubexBranch
 	newStates := make([]SubexBranch, 0, 2)
 	for {
 		piece := input.Next()
 		if piece == nil {
 			break
 		}
 
 		// TODO: break if there are no states at this nesting level left
 		// TODO: What to do if there are remaining nested states after all pieces have been used?
 		for _, state := range states {
 			if state.aux.nesting == nesting {
 				newStates = append(newStates, state.eat(piece)...)
 			} else {
 				newStates = append(newStates, state)
 			}
 		}
 
 		structure, isStructure := piece.(walk.Structure)
 		if isStructure {
 			iter := structure.Iter()
 			newStates = processInput(newStates, iter, nesting + 1)
 		}
 
 		tmp = states
 		states = pruneStates(newStates)
 		newStates = tmp[:0]
 		if len(states) == 0 {
 			return states
 		}
 	}
 	return states
 }
 
 // Run the subex transducer
 func RunTransducer(transducer Transducer, input walk.ValueList) (output []walk.Value, err bool) {
 	states := []SubexBranch{{
 		state: transducer.initialState,
 		aux: auxiliaryState {
 			outputStack: OutputStack {
 				head: walk.ValueList{},
 				tail: nil,
 			},
 			store: make([]walk.OutputList, transducer.storeSize),
 			nesting: 0,
 		},
 	}}
 
 	states = processInput(states, walk.NewValueIter(input), 0)
 
 	for _, state := range states {
 		acceptingStacks := state.accepting()
 		for _, stack := range acceptingStacks {
 			output, isValues := stack.head.(walk.ValueList)
 			if !isValues {
 				panic("Tried to output a non-values list")
 			}
 			return output, false
 		}
 	}
 	return nil, true
 }