CompilerDesign/RE2NFA.py

import functools


class Edge:
    # 符号 开始状态 结束状态
    def __init__(self, label: chr, start: int, end: int):
        self.label = label
        self.start = start
        self.end = end


class EdgeGroup:
    def __init__(self, start: int, end: int, numOfState: int, edges: list[Edge]):
        self.edges = edges
        self.start = start
        self.end = end
        self.numOfState = numOfState

    def append(self, edges: list[Edge]):
        self.edges += edges


class NFA:
    # ( ) | * . others
    # priority * . |

    def Priority(self, a: chr, b: chr) -> int:  # a > b 1 ,a == b 0 ,a < b -1
        if a == b:
            return 0
        pri = ['|', '.', '*', '(']
        return 1 if pri.index(a) > pri.index(b) else -1

    def EdgePriority(self, a: Edge, b: Edge) -> int:
        a = a.label
        b = b.label
        if a == '~':
            return -1
        if b == '~':
            return 1
        return 1 if ord(b) < ord(a) else -1

    def AddConcat(self, s: str) -> str:
        lt = list(s)
        i = 0
        while i < len(lt):
            if lt[i] in '|.(':
                pass
            elif i + 1 < len(lt) and (lt[i + 1].isalpha() or lt[i + 1] == '('):
                lt.insert(i + 1, '.')
            i += 1
        return ''.join(lt)

    def ToPostfix(self, s: str) -> str:
        tempSt = []
        operSt = []
        for c in s:
            match c:
                case '(':
                    operSt.append(c)
                case ')':
                    while operSt[-1] != '(':
                        tempSt.append(operSt.pop())
                    operSt.pop()
                case '*' | '|' | '.':
                    if len(operSt) == 0 or operSt[-1] == '(':
                        operSt.append(c)
                    else:
                        while len(operSt) != 0 and self.Priority(c, operSt[-1]) != 1:
                            tempSt.append(operSt.pop())
                        operSt.append(c)
                case _:
                    tempSt.append(c)
        while len(operSt) != 0:
            tempSt.append(operSt.pop())
        return ''.join(tempSt)

    def ToNFA(self, s: str) -> EdgeGroup:
        stack = []
        for c in s:
            match c:
                case '|':
                    edgeGroups = stack[-2:]
                    stack = stack[:-2]
                    eg = EdgeGroup(0, edgeGroups[0].numOfState + edgeGroups[1].numOfState - 3,
                                   edgeGroups[0].numOfState + edgeGroups[1].numOfState - 2, [])
                    for edge in edgeGroups[0].edges:
                        if edgeGroups[0].end == edge.end:
                            edge.end = eg.end
                        eg.append([edge])
                    for edge in edgeGroups[1].edges:
                        if edgeGroups[1].end == edge.end:
                            edge.end = eg.end
                        else:
                            edge.end += edgeGroups[0].numOfState - 2
                        edge.start += edgeGroups[0].numOfState - 2 if edge.start != 0 else 0
                        eg.append([edge])
                    stack.append(eg)
                case '.':
                    edgeGroups = stack[-2:]
                    stack = stack[:-2]
                    eg = EdgeGroup(0, edgeGroups[0].numOfState + edgeGroups[1].numOfState - 2,
                                   edgeGroups[0].numOfState + edgeGroups[1].numOfState - 1, edgeGroups[0].edges)
                    for edge in edgeGroups[1].edges:
                        edge.start += edgeGroups[0].numOfState - 1
                        edge.end += edgeGroups[0].numOfState - 1
                        eg.append([edge])
                    stack.append(eg)
                case '*':
                    edgeGroup = stack[-1]
                    stack.pop()
                    eg = EdgeGroup(0, edgeGroup.numOfState, edgeGroup.numOfState + 1, [])
                    for edge in edgeGroup.edges:
                        edge.start += 1
                        edge.end = edgeGroup.start+1 if edge.end == edgeGroup.end else edge.end + 1
                        eg.append([edge])
                    eg.append([Edge('~', 0, 1), Edge('~', 1, eg.end)])
                    stack.append(eg)
                case _:
                    stack.append(EdgeGroup(0, 1, 2, [Edge(c, 0, 1)]))
        return stack[0]

    def printEdge(self, eg: Edge, st: str = '', ed: str = '') -> None:
        # 0‐~‐>1
        print(eg.start - 1 if st == '' else st, '-', eg.label, '->', eg.end - 1 if ed == '' else ed, sep='', end=' ')

    def printNFA(self, eg: EdgeGroup) -> None:
        dt = {}
        for edge in eg.edges:
            if edge.start in dt:
                dt[edge.start].append(edge)
            else:
                dt[edge.start] = [edge]
        i = 0
        while i in dt:
            edges = dt[i]
            edges.sort(key=functools.cmp_to_key(self.EdgePriority))
            if i == 0:
                print('X', end=' ')
                for edge in edges:
                    self.printEdge(edge, st='X')
                print('\nY')
                i += 1
                continue
            print(i - 1, end=' ')
            if i + 1 not in dt:
                for edge in edges:
                    self.printEdge(edge, ed='Y')
            else:
                for edge in edges:
                    self.printEdge(edge)
            print()
            i += 1
        pass

    def f(self, s: str) -> None:
        s = self.AddConcat(s)
        print(s)
        s = self.ToPostfix(s)
        print(s)
        s = self.ToNFA(s)
        self.printNFA(s)


nfa = NFA()
nfa.f("(a|b)*baa")
nfa.f(input().lower())

# print(nfa.AddConcat("(a*b)k"))