unit highlighterDFAs;

interface
uses DFAs, classes, lexer_interfaces;

{ colors: "green" "cyan" "bold" "blue" "red" "magenta" }

// TODO brace-matching.

type
  THighlighterDFAState = class(TDFAState)
  private
    fColorSymbol : string;
  published
    property ColorSymbol : string read fColorSymbol write fColorSymbol;
  end;
  
function LoadJOESyntaxDefintionFile(aSourceFileName : String) : IDFAAutomaton;

implementation
uses sysutils;

type
  TStringArray = array of String;

function Pos(const source : String; SplitAt : Char; startPosition : Integer) : Integer; inline;
var
  i : Integer;
begin
  Result := -1;
  
  for i := startPosition to Length(source) do
    if source[i] = SplitAt then begin
      Result := i;
    end;
end;

// TODO limit.
function GreedySplit(const source : String; const SplitAt : Char) : TStringArray;
var 
  i : Integer;
  previous : Integer;
  item : string;
begin
  SetLength(Result, 0);
  previous := 0;
  i := 0;
  repeat
    previous := i;
    i := Pos(source, splitAt, i + 1);
    if (i = -1) then
      i := Length(source);

    if previous = i + 1 then
      Continue;

    item := Copy(source, previous + 1, i - previous);

    SetLength(Result, Length(Result) + 1);
    Result[High(Result)] := item;
    
  until i = Length(source);
end;

function LoadJOESyntaxDefintionFile(aSourceFileName : String) : IDFAAutomaton;
var
  colorDefinitions : TStringList; // space-separated list of color names ("blue", "bold" etc)
  dfaState : THighlighterDFAState; // FIXME free (sometimes).
  stateNames : TStringList; // FIXME free.
  first : Char;
  
  // TODO speed up?
  function LookupState(const aName : string) : Cardinal;
  var
    i : Cardinal;
  begin
    Result := StateInvalid;
    if stateNames.Count > 0 then
    for i := 0 to stateNames.Count - 1 do 
      if stateNames[i] = aName then begin
        Result := i;
        Break;
      end;
  end;
  
  procedure AddTransition(forInputSpec : string; transition : TDFATransition);
  var 
    inputChar : Char;
    endChar : Char;
    i : Integer;
    rangeP : Boolean;
  begin
    i := 1;
    while i < Length(forInputSpec) do begin
      inputChar := forInputSpec[i];
      Inc(i);
      
      rangeP := (i + 1 < Length(forInputSpec));
      
      if rangeP then
        rangeP := forInputSpec[i] = '-';
        
      if not rangeP then begin
        dfaState.Add(inputChar, transition);
        Inc(i);
      end else begin // range
        endChar := forInputSpec[i + 1];
        
        while inputChar <= endChar do begin
          dfaState.Add(inputChar, transition);
          Inc(inputChar);
        end;
        Inc(i, 2);
      end;
    end;
  end;

var
  items : array of string;
  key : string;
  transition : TDFATransition;
  sourceFile : TStringList; // TODO Free.
  line : String;
  lineNumber : Integer;
  stateIndex : Cardinal;
begin
  dfaState := nil;
  sourceFile := TStringList.Create;
  sourceFile.LoadFromFile(aSourceFileName);
  
  colorDefinitions := TStringList.Create;
  stateNames := TStringList.Create;
  
  Result := TDFAAutomaton.Create;
  Result.Add(TDFAState.Create); // "invalid".
  
  for lineNumber := 0 to sourceFile.Count - 1 do begin
    line := sourceFile[lineNumber];
    
    if (Length(line) >= 1) and (line[1] = '#') then // comment.
      Continue;

    line := Trim(line);
    
    if Length(line) = 0 then // Empty line.
      Continue;

    assert(Length(line) > 0);
    first := line[1];
    if first = '=' then begin // color definition. '=Comment    bold green', '=Idle'
      items := GreedySplit(line, ' ');
      key := items[0];
      colorDefinitions.Values[key] := Trim(Copy(line, Length(key) + 1, Length(line)));
    end;
    
    if first = ':' then begin // start new state definition, ':idle Idle' (':<name> <color_defintion_name>')
      // finish old state.
      
      items := GreedySplit(line, ' ');
      //TODO if Length(items) < 1 then 
      //  FormatError;

      if Assigned(dfaState) then begin
        Result.Add(dfaState);
      end;

      // start new state.
      stateIndex := LookupState(items[0]);
      if stateIndex <> StateInvalid then begin
        dfaState := THighlighterDFAState(Result.States[stateIndex]);
        // check whether the state is still unused, if not, throw "duplicate state name" exception.
        if dfaState.ColorSymbol <> '' then begin
          // FIXME throw exception "duplicate state name".
        end;
      end else begin
        dfaState := THighlighterDFAState.Create;
        stateNames.Add(items[0]);
        // TODO set label IN instance?
      end;
      dfaState.ColorSymbol := items[1]; // TODO check bounds.
    end;

    if (first = '*') or (first = '"') then begin // TODO remember this fill-up default.
      // TODO handle recolor: "comment_1       recolor=-1".
      // TODO handle ident: "\"a-z\" ident buffer"
      items := GreedySplit(line, ' ');
      
      key := items[0]; // TODO check limits.

      transition := TDFATransition.Create;
      
      // TODO delay this until all the state's objects are known.
      stateIndex := LookupState(key);
      if stateIndex = StateInvalid then
        transition.NewState := THighlighterDFAState.Create // this is a workaround since we can't just put a symbol, we use a symbol-like DFA state that will be updated by the actual definition later.
      else
        transition.NewState := Result.States[stateIndex];

      if first = '*' then
        dfaState.DefaultTransition := transition
      else begin
        assert(items[0][1] = '"'); // TODO bounds check.
        //assert(items[0][High(items[0])] = '"'); // TODO bounds check.
        AddTransition(Copy(items[0], 1, Length(items[0]) - 2), transition);
      end;
    end;
  end;
  
  if Assigned(dfaState) then begin // XXX always adds an useless state at the end.
    Result.Add(dfaState);
  end;
end;

end.