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-rw-r--r--subex/main.go60
-rw-r--r--subex/subexast.go16
-rw-r--r--subex/subexstate.go211
3 files changed, 119 insertions, 168 deletions
diff --git a/subex/main.go b/subex/main.go
index 2a5f5ad..4451a00 100644
--- a/subex/main.go
+++ b/subex/main.go
@@ -29,25 +29,58 @@ func CompileTransducer(transducerAst SubexAST) SubexState {
return transducerAst.compileWith(SubexNoneState{})
}
+// An immutable stack for outputting to
+type OutputStack interface {
+ pop() ([]walk.Atom, OutputStack)
+ push(atoms []walk.Atom) OutputStack
+}
+
+type OutputStackNil struct {}
+func (stack OutputStackNil) pop() ([]walk.Atom, OutputStack) {
+ panic("Tried to pop from an empty OutputStack")
+}
+func (stack OutputStackNil) push(atoms []walk.Atom) OutputStack {
+ return &OutputStackCons {
+ head: atoms,
+ tail: stack,
+ }
+}
+
+type OutputStackCons struct {
+ head []walk.Atom
+ tail OutputStack
+}
+func (stack OutputStackCons) pop() ([]walk.Atom, OutputStack) {
+ return stack.head, stack.tail
+}
+func (stack OutputStackCons) push(atoms []walk.Atom) OutputStack {
+ return &OutputStackCons {
+ head: atoms,
+ tail: stack,
+ }
+}
+
+func topAppend(outputStack OutputStack, atoms []walk.Atom) OutputStack {
+ head, tail := outputStack.pop()
+ return tail.push(walk.ConcatData(head, atoms))
+}
+
// One branch of subex execution
type SubexBranch struct {
// Content of slots in this branch
store Store
// State in this branch
state SubexState
- // Output so far in this branch
- output []walk.Atom
+ // 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
}
// Read a single character and return all the branches resulting from this branch consuming it
func (pair SubexBranch) eat(char walk.Atom) []SubexBranch {
- states := pair.state.eat(pair.store, char)
- for i := range states {
- states[i].output = walk.ConcatData(pair.output, states[i].output)
- }
- return states
+ return pair.state.eat(pair.store, pair.outputStack, char)
}
-func (pair SubexBranch) accepting() [][]walk.Atom {
- return pair.state.accepting(pair.store)
+func (pair SubexBranch) accepting() []OutputStack {
+ return pair.state.accepting(pair.store, pair.outputStack)
}
func equalStates(left SubexBranch, right SubexBranch) bool {
@@ -73,7 +106,7 @@ func pruneStates(states []SubexBranch) (newStates []SubexBranch) {
func RunTransducer(transducer SubexState, input <-chan walk.Atom) (output []walk.Atom, err bool) {
states := []SubexBranch{{
state: transducer,
- output: nil,
+ outputStack: OutputStackNil{}.push(nil),
store: make(Store),
}}
for piece := range input {
@@ -84,9 +117,10 @@ func RunTransducer(transducer SubexState, input <-chan walk.Atom) (output []walk
states = pruneStates(newStates)
}
for _, state := range states {
- outputEnds := state.accepting()
- for _, outputEnd := range outputEnds {
- return walk.ConcatData(state.output, outputEnd), false
+ acceptingStacks := state.accepting()
+ for _, stack := range acceptingStacks {
+ output, _ := stack.pop()
+ return output, false
}
}
return nil, true
diff --git a/subex/subexast.go b/subex/subexast.go
index 9e7067b..cec75f7 100644
--- a/subex/subexast.go
+++ b/subex/subexast.go
@@ -27,10 +27,11 @@ type SubexASTStore struct {
slot rune
}
func (ast SubexASTStore) compileWith(next SubexState) SubexState {
- return &SubexStoreState {
- match: ast.match.compileWith(&SubexNoneState{}),
- slot: ast.slot,
- next: next,
+ return &SubexStoreBeginState {
+ next: ast.match.compileWith(&SubexStoreEndState {
+ slot: ast.slot,
+ next: next,
+ }),
}
}
func (ast SubexASTStore) String() string {
@@ -188,8 +189,9 @@ type SubexASTSum struct {
content SubexAST
}
func (ast SubexASTSum) compileWith(next SubexState) SubexState {
- return &SubexSumState {
- inputState: ast.content.compileWith(&SubexNoneState{}),
- next: next,
+ return &SubexSumBeginState {
+ next: ast.content.compileWith(&SubexSumEndState {
+ next: next,
+ }),
}
}
diff --git a/subex/subexstate.go b/subex/subexstate.go
index 855d44a..dbc8340 100644
--- a/subex/subexstate.go
+++ b/subex/subexstate.go
@@ -9,106 +9,48 @@ import (
// 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
+ eat(store Store, outputStack OutputStack, char walk.Atom) []SubexBranch
// Find accepting states reachable through epsilon transitions and return their outputs
- accepting(store Store) [][]walk.Atom
-}
-
-type SubexParentState interface {
- SubexState
- // Get the child
- child() SubexState
- // The child outputted output, what should be passed as accumulator data into the next version of the parent state
- nextAcc(output []walk.Atom) interface{}
- // Given the final accumulated data, run the next state after the parent, immutably borrows store
- feedNext(acc interface{}, store Store, char walk.Atom) []SubexBranch
- // Given the final accumulated data, get the accepted outputs from the next state, immutably borrows store
- acceptNext(acc interface{}, store Store) [][]walk.Atom
- // Given the next child and next accumulator data, generate the next parent
- nextParent(child SubexState, acc interface{}) SubexState
+ accepting(store Store, outputStack OutputStack) []OutputStack
}
// Try first, if it fails then try second
type SubexGroupState struct {
first, second SubexState
}
-func (state SubexGroupState) eat(store Store, char walk.Atom) []SubexBranch {
+func (state SubexGroupState) eat(store Store, outputStack OutputStack, char walk.Atom) []SubexBranch {
otherStore := store.clone()
- return append(state.first.eat(store, char), state.second.eat(otherStore, char)...)
+ return append(state.first.eat(store, outputStack, char), state.second.eat(otherStore, outputStack, char)...)
}
-func (state SubexGroupState) accepting(store Store) [][]walk.Atom {
- return append(state.first.accepting(store), state.second.accepting(store)...)
+func (state SubexGroupState) accepting(store Store, outputStack OutputStack) []OutputStack {
+ return append(state.first.accepting(store, outputStack), state.second.accepting(store, outputStack)...)
}
-// Helper so states that are actually collections of states distinguished by a child state
-// can pass eaten characters on to their children more easily
-func feedChild(parent SubexParentState, store Store, char walk.Atom) (nextStates []SubexBranch) {
- child := parent.child()
- accepteds := child.accepting(store)
- for _, accepted := range accepteds {
- acc := parent.nextAcc(accepted)
- nextStates = append(nextStates, parent.feedNext(acc, store, char)...)
- }
- nextChildren := child.eat(store, char)
- for _, nextChild := range nextChildren {
- acc := parent.nextAcc(nextChild.output)
- nextStates = append(nextStates, SubexBranch{
- state: parent.nextParent(nextChild.state, acc),
- output: nil,
- store: nextChild.store,
- })
- }
- return nextStates
+// Push an empty value onto the OutputStack and epsilon transition to next
+// This value will be added to until SubexStoreEndState is reached when it will be stored
+type SubexStoreBeginState struct {
+ next SubexState
}
-
-func acceptChild(parent SubexParentState, store Store) (outputs [][]walk.Atom) {
- child := parent.child()
- accepteds := child.accepting(store)
- for _, accepted := range accepteds {
- acc := parent.nextAcc(accepted)
- outputs = append(outputs, parent.acceptNext(acc, store)...)
- }
- return outputs
+func (state SubexStoreBeginState) eat(store Store, outputStack OutputStack, char walk.Atom) []SubexBranch {
+ return state.next.eat(store, outputStack.push(nil), char)
+}
+func (state SubexStoreBeginState) accepting(store Store, outputStack OutputStack) []OutputStack {
+ return state.next.accepting(store, outputStack.push(nil))
}
-// Run the match machine and store the output in a slot for later use
-// Output nothing
-type SubexStoreState struct {
- match SubexState
+// Pop the top of the OutputStack which contains the stuff outputted since the start of the store
+// This outputted data gets stored in a slot
+type SubexStoreEndState struct {
slot rune
next SubexState
- toStore []walk.Atom
-}
-func (state SubexStoreState) child() SubexState {
- return state.match
-}
-func (state SubexStoreState) nextAcc(output []walk.Atom) interface{} {
- return walk.ConcatData(state.toStore, output)
-}
-func (state SubexStoreState) feedNext(acc interface{}, store Store, char walk.Atom) []SubexBranch {
- toStore := acc.([]walk.Atom)
- nextStore := store.withValue(state.slot, toStore)
- return state.next.eat(nextStore, char)
-}
-func (state SubexStoreState) acceptNext(acc interface{}, store Store) [][]walk.Atom {
- toStore := acc.([]walk.Atom)
- nextStore := store.withValue(state.slot, toStore)
- return state.next.accepting(nextStore)
-}
-func (state SubexStoreState) nextParent(match SubexState, acc interface{}) SubexState {
- toStore := acc.([]walk.Atom)
- return &SubexStoreState {
- match: match,
- slot: state.slot,
- next: state.next,
- toStore: toStore,
- }
}
-func (state SubexStoreState) eat(store Store, char walk.Atom) (nextStates []SubexBranch) {
- return feedChild(state, store, char)
+func (state SubexStoreEndState) eat(store Store, outputStack OutputStack, char walk.Atom) []SubexBranch {
+ toStore, newStack := outputStack.pop()
+ return state.next.eat(store.withValue(state.slot, toStore), newStack, char)
}
-func (state SubexStoreState) accepting(store Store) (outputs [][]walk.Atom) {
- return acceptChild(state, store)
+func (state SubexStoreEndState) accepting(store Store, outputStack OutputStack) []OutputStack {
+ toStore, newStack := outputStack.pop()
+ return state.next.accepting(store.withValue(state.slot, toStore), newStack)
}
// A part of an output literal, either an Atom or a slot from which to load
@@ -146,38 +88,32 @@ func (state SubexOutputState) build(store Store) []walk.Atom {
}
return result
}
-func (state SubexOutputState) eat(store Store, char walk.Atom) []SubexBranch {
+func (state SubexOutputState) eat(store Store, outputStack OutputStack, 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)
- }
+ nextStates := state.next.eat(store, topAppend(outputStack, content), char)
return nextStates
}
-func (state SubexOutputState) accepting(store Store) [][]walk.Atom {
+func (state SubexOutputState) accepting(store Store, outputStack OutputStack) []OutputStack {
content := state.build(store)
- outputs := state.next.accepting(store)
- for i := range outputs {
- outputs[i] = walk.ConcatData(content, outputs[i])
- }
- return outputs
+ outputStacks := state.next.accepting(store, topAppend(outputStack, content))
+ return outputStacks
}
// A final state, transitions to nothing but is accepting
type SubexNoneState struct {}
-func (state SubexNoneState) eat(store Store, char walk.Atom) []SubexBranch {
+func (state SubexNoneState) eat(store Store, outputStack OutputStack, char walk.Atom) []SubexBranch {
return nil
}
-func (state SubexNoneState) accepting(store Store) [][]walk.Atom {
- return [][]walk.Atom{nil}
+func (state SubexNoneState) accepting(store Store, outputStack OutputStack) []OutputStack {
+ return []OutputStack{outputStack}
}
// A dead end state, handy for making internals work nicer but technically redundant
type SubexDeadState struct {}
-func (state SubexDeadState) eat(store Store, char walk.Atom) []SubexBranch {
+func (state SubexDeadState) eat(store Store, outputStack OutputStack, char walk.Atom) []SubexBranch {
return nil
}
-func (state SubexDeadState) accepting (store Store) [][]walk.Atom {
+func (state SubexDeadState) accepting (store Store, outputStack OutputStack) []OutputStack {
return nil
}
@@ -186,18 +122,18 @@ type SubexCopyAtomState struct {
atom walk.Atom
next SubexState
}
-func (state SubexCopyAtomState) eat(store Store, char walk.Atom) []SubexBranch {
+func (state SubexCopyAtomState) eat(store Store, outputStack OutputStack, char walk.Atom) []SubexBranch {
// TODO can I compare Atom values with == ?
if char == state.atom {
return []SubexBranch{{
state: state.next,
- output: []walk.Atom{char},
+ outputStack: topAppend(outputStack, []walk.Atom{char}),
store: store,
}}
}
return nil
}
-func (state SubexCopyAtomState) accepting(store Store) [][]walk.Atom {
+func (state SubexCopyAtomState) accepting(store Store, outputStack OutputStack) []OutputStack {
return nil
}
@@ -205,14 +141,14 @@ func (state SubexCopyAtomState) accepting(store Store) [][]walk.Atom {
type SubexCopyAnyState struct {
next SubexState
}
-func (state SubexCopyAnyState) eat(store Store, char walk.Atom) []SubexBranch {
+func (state SubexCopyAnyState) eat(store Store, outputStack OutputStack, char walk.Atom) []SubexBranch {
return []SubexBranch{{
state: state.next,
- output: []walk.Atom{char},
+ outputStack: topAppend(outputStack, []walk.Atom{char}),
store: store,
}}
}
-func (state SubexCopyAnyState) accepting(store Store) [][]walk.Atom {
+func (state SubexCopyAnyState) accepting(store Store, outputStack OutputStack) []OutputStack {
return nil
}
@@ -222,19 +158,19 @@ type SubexRangeState struct {
parts map[walk.Atom]walk.Atom
next SubexState
}
-func (state SubexRangeState) eat(store Store, char walk.Atom) []SubexBranch {
+func (state SubexRangeState) eat(store Store, outputStack OutputStack, char walk.Atom) []SubexBranch {
out, exists := state.parts[char]
if !exists {
return nil
} else {
return []SubexBranch{{
state: state.next,
- output: []walk.Atom{out},
+ outputStack: topAppend(outputStack, []walk.Atom{out}),
store: store,
}}
}
}
-func (state SubexRangeState) accepting(store Store) [][]walk.Atom {
+func (state SubexRangeState) accepting(store Store, outputStack OutputStack) []OutputStack {
return nil
}
@@ -267,56 +203,35 @@ func sumValues(atoms []walk.Atom) (walk.ValueNumber, error) {
return walk.ValueNumber(sum), nil
}
-// Run the inputState machine and sum any values output, output the sum
-// Cast non numbers into numbers, branch dies if it is not castable
-type SubexSumState struct {
- inputState SubexState
+// At the start of a sum, just pushes to the OutputStack allowing the end to capture what was output in the middle
+// Tries to cast values to numbers to sum them and rejects if values are not castable
+type SubexSumBeginState struct {
next SubexState
- acc []walk.Atom
}
-func (state SubexSumState) child() SubexState {
- return state.inputState
+func (state SubexSumBeginState) eat(store Store, outputStack OutputStack, char walk.Atom) []SubexBranch {
+ return state.next.eat(store, outputStack.push(nil), char)
}
-func (state SubexSumState) nextAcc(output []walk.Atom) interface{} {
- return walk.ConcatData(state.acc, output)
+func (state SubexSumBeginState) accepting(store Store, outputStack OutputStack) []OutputStack {
+ return state.next.accepting(store, outputStack.push(nil))
}
-func (state SubexSumState) feedNext(acc interface{}, store Store, char walk.Atom) []SubexBranch {
- childOutput := acc.([]walk.Atom)
- total, err := sumValues(childOutput)
+
+// At the end of a sum, pops what has been output since the start, sums and outputs it
+type SubexSumEndState struct {
+ next SubexState
+}
+func (state SubexSumEndState) eat(store Store, outputStack OutputStack, char walk.Atom) []SubexBranch {
+ toSum, newStack := outputStack.pop()
+ sum, err := sumValues(toSum)
if err != nil {
return nil
}
- output := []walk.Atom{total}
- nextStates := state.next.eat(store.clone(), char)
- for i := range nextStates {
- nextStates[i].output = walk.ConcatData(output, nextStates[i].output)
- }
- return nextStates
+ return state.next.eat(store, topAppend(newStack, []walk.Atom{sum}), char)
}
-func (state SubexSumState) acceptNext(acc interface{}, store Store) [][]walk.Atom {
- childOutput := acc.([]walk.Atom)
- total, err := sumValues(childOutput)
+func (state SubexSumEndState) accepting(store Store, outputStack OutputStack) []OutputStack {
+ toSum, newStack := outputStack.pop()
+ sum, err := sumValues(toSum)
if err != nil {
return nil
}
- output := []walk.Atom{total}
- outputs := state.next.accepting(store.clone())
- for i := range outputs {
- outputs[i] = walk.ConcatData(output, outputs[i])
- }
- return outputs
-}
-func (state SubexSumState) nextParent(child SubexState, acc interface{}) SubexState {
- childOutput := acc.([]walk.Atom)
- return &SubexSumState {
- inputState: child,
- next: state.next,
- acc: childOutput,
- }
-}
-func (state SubexSumState) eat(store Store, char walk.Atom) (nextStates []SubexBranch) {
- return feedChild(state, store, char)
-}
-func (state SubexSumState) accepting(store Store) (outputs [][]walk.Atom) {
- return acceptChild(state, store)
+ return state.next.accepting(store, topAppend(newStack, []walk.Atom{sum}))
}