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45 lines
1.4 KiB
Go
45 lines
1.4 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 (maps a character (int representation) to a _list of states. This is useful if one character can lead multiple states eg. ab|aa)
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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 len(state.transitions) == 1 && len(state.transitions[state.content]) == 1 && state.transitions[state.content][0] == 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 _, states := range state.transitions {
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for i := range states {
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if states[i] != state {
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verifyLastStatesHelper(states[i], visited)
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}
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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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