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43 lines
1.3 KiB
Go
43 lines
1.3 KiB
Go
package main
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const EPSILON int = 0
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type State struct {
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content int // Contents of current state
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isEmpty bool // If it is empty - Union operator states will be empty
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isLast bool // If it is the last state (acept state)
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output []*State // The outputs of the current state ie. the 'outward arrows'. A union operator state will have more than one of these.
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transitions map[int]*State // Transitions to different states (can be associated with an int, representing content of destination state)
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}
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type NFA struct {
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start State
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outputs []State
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}
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// verifyLastStatesHelper performs the depth-first recursion needed for verifyLastStates
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func verifyLastStatesHelper(state *State, visited map[*State]bool) {
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if len(state.transitions) == 0 {
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state.isLast = true
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return
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}
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if state.transitions[state.content] == state { // Eg. a*
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state.isLast = true
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return
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}
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if visited[state] == true {
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return
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}
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visited[state] = true
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for k := range state.transitions {
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if state.transitions[k] != state {
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verifyLastStatesHelper(state.transitions[k], visited)
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}
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}
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}
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// verifyLastStates penables the 'isLast' flag for the leaf nodes (last states)
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func verifyLastStates(start []State) {
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verifyLastStatesHelper(&start[0], make(map[*State]bool))
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}
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