sentence.l

这是一个和lex功能差不多的parser编写的程序

%{
{*
 * 基于单词识别的句子分析
   用法 lex Sentence 
 *}

Unit Sentence;

interface
uses
  SysUtils, LexLib, Classes;

const
  Noun=257;
  Pron=258;
  Verb=259;
  Adv= 260;
  Adj= 261;
  Prep=262;
  Conj=263;

  LookUp=0;

type 
  TWord=class(TObject)
  public
    word:string;
    State:integer;//TWordState;
  end;

var
  state:integer;//TWordState; 
  rstate:integer;
  WordList:TStringList;

function LookUpWord(word:string):integer;//TWordState;
function AddWord(State:integer{TWordState}; Word:string):integer;

function yylex: Integer;

implementation

%}
%%
\n	state := LookUp;

\.\n	begin
          state := LookUP;
	  return(0); {* 遇到句子结尾了，注意这里是在yyaction中，不能用result:=0来返回，只能用定义的return函数*}
	end;

^verb	state := Verb;
^adj	state := Adj;
^adv	state := Adv;
^noun	state := Noun;
^prep	state := Prep;
^pron	state := Pron;
^conj	state := Conj;

[a-zA-Z]+  begin
	     if(state <> LookUp) then 
	     	AddWord(state, yytext)
	     else
	     begin
                rstate:=LookUpWord(yytext);
		if rstate<>LookUp then
		begin
		  writeln(format('查找到了%s,返回给yacc', [yytext]));
                  return(rstate);
		end
		else
                  Writeln(format('%s 无法识别', [yytext]));
            end;
          end;

.	{* 忽略剩下的所有的字符串 *} ;

%%

function LookUpWord(word:string):integer;//TWordState;
var
  I:integer;
begin
  I:=WordList.IndexOf(Word);
  if I>-1 then
  begin
    result:=TWord(WordList.Objects[I]).State;
  end
  else
    result:=LookUp;
end;

function AddWord(State:integer{TWordState}; Word:string):integer;
var
  WordObj:TWord;
begin
  if (LookUpWord(Word)<>LookUp) then
  begin
    Writeln(format('!!! %s 已经被定义了', [word]));
    result:=0;
    exit;
  end;
	
  WordObj:= TWord.Create;
  WordObj.Word:=Word;
  WordObj.State:=State;
  WordList.AddObject(Word, WordObj);
  result:=1;
end;

initialization
  WordList:=TStringList.Create;
finalization
  // Todo:释放列表中的WordObj对象
  WordList.Free;
end.