_state_class_private.py

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from io import StringIO
 
from .state_interface import CurrentState, IStateBehavior, IStateContext, SpecialCase
 
 
def _CurrentStateToString(state : CurrentState) -> str:
    stateAsString = ""
 
    match state:
        case CurrentState.Initial:
            stateAsString = "Initial"
 
        case CurrentState.NormalText:
            stateAsString = "NormalText"
 
        case CurrentState.DoubleQuotedText:
            stateAsString = "DoubleQuotedText"
 
        case CurrentState.SingleQuotedText:
            stateAsString = "SingleQuotedText"
 
        case CurrentState.EscapedDoubleQuoteText:
            stateAsString = "EscapedDoubleQuoteText"
 
        case CurrentState.EscapedSingleQuoteText:
            stateAsString = "EscapedSingleQuoteText"
 
        case CurrentState.StartComment:
            stateAsString = "StartComment"
 
        case CurrentState.LineComment:
            stateAsString = "LineComment"
 
        case CurrentState.BlockComment:
            stateAsString = "BlockComment"
 
        case CurrentState.EndBlockComment:
            stateAsString = "EndBlockComment"
 
        case CurrentState.Done:
            stateAsString = "Done"
 
        case _:
            stateAsString = "Unknown ({0})".format(state)
 
    return stateAsString
 
 
#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
# State class definitions
#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
 
class State_NormalText(IStateBehavior):
 
    
    def GoNext(self, context : IStateContext) -> CurrentState:
        nextState = CurrentState.NormalText
        character = context.GetNextCharacter()
 
        match character:
            case SpecialCase.EOF_CHAR:
                nextState = CurrentState.Done
 
            case '"':
                context.OutputCharacter(character)
                nextState = CurrentState.DoubleQuotedText
 
            case '\'':
                context.OutputCharacter(character)
                nextState = CurrentState.SingleQuotedText
 
            case '/':
                nextState = CurrentState.StartComment
 
            case _:
                context.OutputCharacter(character)
 
        return nextState
 
 
 
 
 
 
class State_DoubleQuotedText(IStateBehavior):
 
    
    def GoNext(self, context : IStateContext) -> CurrentState:
        nextState = CurrentState.DoubleQuotedText
 
        character = context.GetNextCharacter()
 
        match character:
            case SpecialCase.EOF_CHAR:
                nextState = CurrentState.Done
 
            case '"':
                context.OutputCharacter(character)
                nextState = CurrentState.NormalText
 
            case '\\':
                context.OutputCharacter(character)
                nextState = CurrentState.EscapedDoubleQuoteText
 
            case _:
                context.OutputCharacter(character)
 
        return nextState
 
 
 
 
 
 
class State_SingleQuotedText(IStateBehavior):
 
    
    def GoNext(self, context : IStateContext) -> CurrentState:
        nextState = CurrentState.SingleQuotedText
 
        character = context.GetNextCharacter()
 
        match character:
            case SpecialCase.EOF_CHAR:
                nextState = CurrentState.Done
 
            case '\'':
                context.OutputCharacter(character)
                nextState = CurrentState.NormalText
 
            case '\\':
                context.OutputCharacter(character)
                nextState = CurrentState.EscapedSingleQuoteText
 
            case _:
                context.OutputCharacter(character)
 
        return nextState
 
 
 
 
 
 
class State_EscapedDoubleQuoteText(IStateBehavior):
 
    
    def GoNext(self, context : IStateContext) -> CurrentState:
        nextState = CurrentState.DoubleQuotedText
 
        character = context.GetNextCharacter()
 
        match character:
            case SpecialCase.EOF_CHAR:
                nextState = CurrentState.Done
 
            case _:
                context.OutputCharacter(character)
 
        return nextState
 
 
 
 
 
 
class State_EscapedSingleQuoteText(IStateBehavior):
 
    
    def GoNext(self, context : IStateContext) -> CurrentState:
        nextState = CurrentState.SingleQuotedText
 
        character = context.GetNextCharacter()
 
        match character:
            case SpecialCase.EOF_CHAR:
                nextState = CurrentState.Done
 
            case _:
                context.OutputCharacter(character)
 
        return nextState
 
 
 
 
 
 
class State_StartComment(IStateBehavior):
 
    
    def GoNext(self, context : IStateContext) -> CurrentState:
        nextState = CurrentState.StartComment
 
        character = context.GetNextCharacter()
 
        match character:
            case SpecialCase.EOF_CHAR:
                nextState = CurrentState.Done
 
            case '/':
                nextState = CurrentState.LineComment
 
            case '*':
                nextState = CurrentState.BlockComment
 
            case _:
                # Is not the start of a comment so output the leading slash
                # that led to the state followed by the character we just
                # processed.
                context.OutputCharacter('/')
                context.OutputCharacter(character)
                nextState = CurrentState.NormalText
 
        return nextState
 
 
 
 
 
 
class State_LineComment(IStateBehavior):
 
    
    def GoNext(self, context : IStateContext) -> CurrentState:
        nextState = CurrentState.LineComment
 
        character = context.GetNextCharacter()
 
        match character:
            case SpecialCase.EOF_CHAR:
                nextState = CurrentState.Done
 
            case '\n':
                context.OutputCharacter(character)
                nextState = CurrentState.NormalText
 
            case _:
                # We are in a comment to be removed, so do nothing here.
                pass
 
        return nextState
 
 
 
 
 
 
class State_BlockComment(IStateBehavior):
 
    
    def GoNext(self, context : IStateContext) -> CurrentState:
        nextState = CurrentState.BlockComment
 
        character = context.GetNextCharacter()
 
        match character:
            case SpecialCase.EOF_CHAR:
                nextState = CurrentState.Done
 
            case '*':
                nextState = CurrentState.EndBlockComment
 
            case _:
                # We are in a comment to be removed, so do nothing here.
                pass
 
        return nextState
 
 
 
 
 
 
class State_EndBlockComment(IStateBehavior):
 
    
    def GoNext(self, context : IStateContext) -> CurrentState:
        nextState = CurrentState.BlockComment
 
        character = context.GetNextCharacter()
 
        match character:
            case SpecialCase.EOF_CHAR:
                nextState = CurrentState.Done
 
            case '/':
                nextState = CurrentState.NormalText
 
            case _:
                # We are still in a block comment to be removed, so do nothing here.
                pass
 
        return nextState
 
 
 
 
 
 
class State_Done(IStateBehavior):
 
    
    def GoNext(self, context : IStateContext) -> CurrentState:
        # Do nothing (Yes!  Another Null Object example!)
        return CurrentState.Done
 
 
#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
# State class factory definition
#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
 
 
class State_Factory:
 
    
    def CreateState(state : CurrentState) -> IStateBehavior:
        stateBehavior = None # type: IStateBehavior
        match state:
            case CurrentState.NormalText:
                stateBehavior = State_NormalText()
 
            case CurrentState.DoubleQuotedText:
                stateBehavior = State_DoubleQuotedText()
 
            case CurrentState.SingleQuotedText:
                stateBehavior = State_SingleQuotedText()
 
            case CurrentState.EscapedDoubleQuoteText:
                stateBehavior = State_EscapedDoubleQuoteText()
 
            case CurrentState.EscapedSingleQuoteText:
                stateBehavior = State_EscapedSingleQuoteText()
 
            case CurrentState.StartComment:
                stateBehavior = State_StartComment()
 
            case CurrentState.LineComment:
                stateBehavior = State_LineComment()
 
            case CurrentState.BlockComment:
                stateBehavior = State_BlockComment()
 
            case CurrentState.EndBlockComment:
                stateBehavior = State_EndBlockComment()
 
            case CurrentState.Done:
                stateBehavior = State_Done()
 
            case _:
                msg = "Unknown state: {0}.  Cannot create a state class.".format(
                    _CurrentStateToString(state))
                raise ValueError(msg)
 
        return stateBehavior
 
 
#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
# State Context implementation class definition
#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
 
 
class StateContext_ClassImpl(IStateContext):
 
    #--------------------------------------------------------------------
    # StateContext_Class implementation.
    #--------------------------------------------------------------------
 
    
    def _SetNextState(self, newState : CurrentState) -> None:
        if newState != self._currentState:
            if newState not in self._stateBehaviors:
                self._stateBehaviors[newState] = State_Factory.CreateState(newState)
 
            print("    --> State Transition: {0} -> {1}".format(
                    _CurrentStateToString(self._currentState),
                    _CurrentStateToString(newState)))
 
            self._currentStateBehavior = self._stateBehaviors[newState]
            self._currentState = newState
 
 
    
    def __init__(self) -> None:
        self._inputText = ""
        self._textIndex = 0
        self._outputText = StringIO()
        self._stateBehaviors = {} # type: dict[CurrentState, IStateBehavior]
        self._currentState = CurrentState.Initial
        self._currentStateBehavior = None # type: IStateBehavior
 
    
    
 
    #--------------------------------------------------------------------
    # StateContext_Class public entry points.
    #--------------------------------------------------------------------
 
    
    def RemoveComments(self, text : str) -> str:
        self._inputText = text
        self._textIndex = 0;
        self._outputText.close()
        self._outputText = StringIO()
        self._currentState = CurrentState.Initial
        self._SetNextState(CurrentState.NormalText)
 
        while (self._currentState != CurrentState.Done):
            nextState = self._currentStateBehavior.GoNext(self)
            self._SetNextState(nextState)
 
        return self._outputText.getvalue()
 
 
    #--------------------------------------------------------------------
    # IStateContext interface implementation.
    #--------------------------------------------------------------------
 
    
    def GetNextCharacter(self) -> int:
        character = SpecialCase.EOF_CHAR
 
        if self._textIndex < len(self._inputText):
            character = self._inputText[self._textIndex]
            self._textIndex += 1
        return character
 
    
    def OutputCharacter(self, character : int) -> None:
        if character != SpecialCase.EOF_CHAR:
            self._outputText.write(character)