source: branches/HeuristicLab.Problems.GPDL/SyntaxAnalyzer/Scanner.cs @ 12341

using System;
using System.IO;
using System.Collections;

namespace SyntaxAnalyzer {

public class Token {
  public int kind;    // token kind
  public int pos;     // token position in bytes in the source text (starting at 0)
  public int charPos;  // token position in characters in the source text (starting at 0)
  public int col;     // token column (starting at 1)
  public int line;    // token line (starting at 1)
  public string val;  // token value
  public Token next;  // ML 2005-03-11 Tokens are kept in linked list
}

//-----------------------------------------------------------------------------------
// Buffer
//-----------------------------------------------------------------------------------
public class Buffer {
  // This Buffer supports the following cases:
  // 1) seekable stream (file)
  //    a) whole stream in buffer
  //    b) part of stream in buffer
  // 2) non seekable stream (network, console)

  public const int EOF = char.MaxValue + 1;
  const int MIN_BUFFER_LENGTH = 1024; // 1KB
  const int MAX_BUFFER_LENGTH = MIN_BUFFER_LENGTH * 64; // 64KB
  byte[] buf;         // input buffer
  int bufStart;       // position of first byte in buffer relative to input stream
  int bufLen;         // length of buffer
  int fileLen;        // length of input stream (may change if the stream is no file)
  int bufPos;         // current position in buffer
  Stream stream;      // input stream (seekable)
  bool isUserStream;  // was the stream opened by the user?
  
  public Buffer (Stream s, bool isUserStream) {
    stream = s; this.isUserStream = isUserStream;
    
    if (stream.CanSeek) {
      fileLen = (int) stream.Length;
      bufLen = Math.Min(fileLen, MAX_BUFFER_LENGTH);
      bufStart = Int32.MaxValue; // nothing in the buffer so far
    } else {
      fileLen = bufLen = bufStart = 0;
    }

    buf = new byte[(bufLen>0) ? bufLen : MIN_BUFFER_LENGTH];
    if (fileLen > 0) Pos = 0; // setup buffer to position 0 (start)
    else bufPos = 0; // index 0 is already after the file, thus Pos = 0 is invalid
    if (bufLen == fileLen && stream.CanSeek) Close();
  }
  
  protected Buffer(Buffer b) { // called in UTF8Buffer constructor
    buf = b.buf;
    bufStart = b.bufStart;
    bufLen = b.bufLen;
    fileLen = b.fileLen;
    bufPos = b.bufPos;
    stream = b.stream;
    // keep destructor from closing the stream
    b.stream = null;
    isUserStream = b.isUserStream;
  }

  ~Buffer() { Close(); }
  
  protected void Close() {
    if (!isUserStream && stream != null) {
      stream.Close();
      stream = null;
    }
  }
  
  public virtual int Read () {
    if (bufPos < bufLen) {
      return buf[bufPos++];
    } else if (Pos < fileLen) {
      Pos = Pos; // shift buffer start to Pos
      return buf[bufPos++];
    } else if (stream != null && !stream.CanSeek && ReadNextStreamChunk() > 0) {
      return buf[bufPos++];
    } else {
      return EOF;
    }
  }

  public int Peek () {
    int curPos = Pos;
    int ch = Read();
    Pos = curPos;
    return ch;
  }
  
  // beg .. begin, zero-based, inclusive, in byte
  // end .. end, zero-based, exclusive, in byte
  public string GetString (int beg, int end) {
    int len = 0;
    char[] buf = new char[end - beg];
    int oldPos = Pos;
    Pos = beg;
    while (Pos < end) buf[len++] = (char) Read();
    Pos = oldPos;
    return new String(buf, 0, len);
  }

  public int Pos {
    get { return bufPos + bufStart; }
    set {
      if (value >= fileLen && stream != null && !stream.CanSeek) {
        // Wanted position is after buffer and the stream
        // is not seek-able e.g. network or console,
        // thus we have to read the stream manually till
        // the wanted position is in sight.
        while (value >= fileLen && ReadNextStreamChunk() > 0);
      }

      if (value < 0 || value > fileLen) {
        throw new FatalError("buffer out of bounds access, position: " + value);
      }

      if (value >= bufStart && value < bufStart + bufLen) { // already in buffer
        bufPos = value - bufStart;
      } else if (stream != null) { // must be swapped in
        stream.Seek(value, SeekOrigin.Begin);
        bufLen = stream.Read(buf, 0, buf.Length);
        bufStart = value; bufPos = 0;
      } else {
        // set the position to the end of the file, Pos will return fileLen.
        bufPos = fileLen - bufStart;
      }
    }
  }
  
  // Read the next chunk of bytes from the stream, increases the buffer
  // if needed and updates the fields fileLen and bufLen.
  // Returns the number of bytes read.
  private int ReadNextStreamChunk() {
    int free = buf.Length - bufLen;
    if (free == 0) {
      // in the case of a growing input stream
      // we can neither seek in the stream, nor can we
      // foresee the maximum length, thus we must adapt
      // the buffer size on demand.
      byte[] newBuf = new byte[bufLen * 2];
      Array.Copy(buf, newBuf, bufLen);
      buf = newBuf;
      free = bufLen;
    }
    int read = stream.Read(buf, bufLen, free);
    if (read > 0) {
      fileLen = bufLen = (bufLen + read);
      return read;
    }
    // end of stream reached
    return 0;
  }
}

//-----------------------------------------------------------------------------------
// UTF8Buffer
//-----------------------------------------------------------------------------------
public class UTF8Buffer: Buffer {
  public UTF8Buffer(Buffer b): base(b) {}

  public override int Read() {
    int ch;
    do {
      ch = base.Read();
      // until we find a utf8 start (0xxxxxxx or 11xxxxxx)
    } while ((ch >= 128) && ((ch & 0xC0) != 0xC0) && (ch != EOF));
    if (ch < 128 || ch == EOF) {
      // nothing to do, first 127 chars are the same in ascii and utf8
      // 0xxxxxxx or end of file character
    } else if ((ch & 0xF0) == 0xF0) {
      // 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
      int c1 = ch & 0x07; ch = base.Read();
      int c2 = ch & 0x3F; ch = base.Read();
      int c3 = ch & 0x3F; ch = base.Read();
      int c4 = ch & 0x3F;
      ch = (((((c1 << 6) | c2) << 6) | c3) << 6) | c4;
    } else if ((ch & 0xE0) == 0xE0) {
      // 1110xxxx 10xxxxxx 10xxxxxx
      int c1 = ch & 0x0F; ch = base.Read();
      int c2 = ch & 0x3F; ch = base.Read();
      int c3 = ch & 0x3F;
      ch = (((c1 << 6) | c2) << 6) | c3;
    } else if ((ch & 0xC0) == 0xC0) {
      // 110xxxxx 10xxxxxx
      int c1 = ch & 0x1F; ch = base.Read();
      int c2 = ch & 0x3F;
      ch = (c1 << 6) | c2;
    }
    return ch;
  }
}

//-----------------------------------------------------------------------------------
// Scanner
//-----------------------------------------------------------------------------------
public class Scanner {
  const char EOL = '\n';
  const int eofSym = 0; /* pdt */
  const int maxT = 30;
  const int noSym = 30;


  public Buffer buffer; // scanner buffer
  
  Token t;          // current token
  int ch;           // current input character
  int pos;          // byte position of current character
  int charPos;      // position by unicode characters starting with 0
  int col;          // column number of current character
  int line;         // line number of current character
  int oldEols;      // EOLs that appeared in a comment;
  static readonly Hashtable start; // maps first token character to start state

  Token tokens;     // list of tokens already peeked (first token is a dummy)
  Token pt;         // current peek token
  
  char[] tval = new char[128]; // text of current token
  int tlen;         // length of current token
  
  static Scanner() {
    start = new Hashtable(128);
    for (int i = 65; i <= 90; ++i) start[i] = 1;
    for (int i = 97; i <= 122; ++i) start[i] = 1;
    start[60] = 2; 
    start[62] = 4; 
    start[46] = 15; 
    start[61] = 7; 
    start[124] = 8; 
    start[40] = 9; 
    start[41] = 10; 
    start[91] = 11; 
    start[93] = 12; 
    start[123] = 13; 
    start[125] = 14; 
    start[Buffer.EOF] = -1;

  }
  
  public Scanner (string fileName) {
    try {
      Stream stream = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read);
      buffer = new Buffer(stream, false);
      Init();
    } catch (IOException) {
      throw new FatalError("Cannot open file " + fileName);
    }
  }
  
  public Scanner (Stream s) {
    buffer = new Buffer(s, true);
    Init();
  }
  
  void Init() {
    pos = -1; line = 1; col = 0; charPos = -1;
    oldEols = 0;
    NextCh();
    if (ch == 0xEF) { // check optional byte order mark for UTF-8
      NextCh(); int ch1 = ch;
      NextCh(); int ch2 = ch;
      if (ch1 != 0xBB || ch2 != 0xBF) {
        throw new FatalError(String.Format("illegal byte order mark: EF {0,2:X} {1,2:X}", ch1, ch2));
      }
      buffer = new UTF8Buffer(buffer); col = 0; charPos = -1;
      NextCh();
    }
    pt = tokens = new Token();  // first token is a dummy
  }
  
  void NextCh() {
    if (oldEols > 0) { ch = EOL; oldEols--; } 
    else {
      pos = buffer.Pos;
      // buffer reads unicode chars, if UTF8 has been detected
      ch = buffer.Read(); col++; charPos++;
      // replace isolated '\r' by '\n' in order to make
      // eol handling uniform across Windows, Unix and Mac
      if (ch == '\r' && buffer.Peek() != '\n') ch = EOL;
      if (ch == EOL) { line++; col = 0; }
    }

  }

  void AddCh() {
    if (tlen >= tval.Length) {
      char[] newBuf = new char[2 * tval.Length];
      Array.Copy(tval, 0, newBuf, 0, tval.Length);
      tval = newBuf;
    }
    if (ch != Buffer.EOF) {
      tval[tlen++] = (char) ch;
      NextCh();
    }
  }



  bool Comment0() {
    int level = 1, pos0 = pos, line0 = line, col0 = col, charPos0 = charPos;
    NextCh();
    if (ch == '/') {
      NextCh();
      for(;;) {
        if (ch == 13) {
          level--;
          if (level == 0) { oldEols = line - line0; NextCh(); return true; }
          NextCh();
        } else if (ch == Buffer.EOF) return false;
        else NextCh();
      }
    } else {
      buffer.Pos = pos0; NextCh(); line = line0; col = col0; charPos = charPos0;
    }
    return false;
  }

  bool Comment1() {
    int level = 1, pos0 = pos, line0 = line, col0 = col, charPos0 = charPos;
    NextCh();
    if (ch == '*') {
      NextCh();
      for(;;) {
        if (ch == '*') {
          NextCh();
          if (ch == '/') {
            level--;
            if (level == 0) { oldEols = line - line0; NextCh(); return true; }
            NextCh();
          }
        } else if (ch == '/') {
          NextCh();
          if (ch == '*') {
            level++; NextCh();
          }
        } else if (ch == Buffer.EOF) return false;
        else NextCh();
      }
    } else {
      buffer.Pos = pos0; NextCh(); line = line0; col = col0; charPos = charPos0;
    }
    return false;
  }


  void CheckLiteral() {
    switch (t.val) {
      case "PROBLEM": t.kind = 2; break;
      case "CODE": t.kind = 3; break;
      case "INIT": t.kind = 6; break;
      case "NONTERMINALS": t.kind = 7; break;
      case "TERMINALS": t.kind = 8; break;
      case "RULES": t.kind = 9; break;
      case "MAXIMIZE": t.kind = 10; break;
      case "MINIMIZE": t.kind = 11; break;
      case "END": t.kind = 12; break;
      case "LOCAL": t.kind = 14; break;
      case "SEM": t.kind = 15; break;
      case "CONSTRAINTS": t.kind = 16; break;
      case "IN": t.kind = 17; break;
      case "SET": t.kind = 18; break;
      case "RANGE": t.kind = 19; break;
      case "EPS": t.kind = 23; break;
      default: break;
    }
  }

  Token NextToken() {
    while (ch == ' ' ||
      ch >= 9 && ch <= 10 || ch == 13
    ) NextCh();
    if (ch == '/' && Comment0() ||ch == '/' && Comment1()) return NextToken();
    int recKind = noSym;
    int recEnd = pos;
    t = new Token();
    t.pos = pos; t.col = col; t.line = line; t.charPos = charPos;
    int state;
    if (start.ContainsKey(ch)) { state = (int) start[ch]; }
    else { state = 0; }
    tlen = 0; AddCh();
    
    switch (state) {
      case -1: { t.kind = eofSym; break; } // NextCh already done
      case 0: {
        if (recKind != noSym) {
          tlen = recEnd - t.pos;
          SetScannerBehindT();
        }
        t.kind = recKind; break;
      } // NextCh already done
      case 1:
        recEnd = pos; recKind = 1;
        if (ch >= '0' && ch <= '9' || ch >= 'A' && ch <= 'Z' || ch >= 'a' && ch <= 'z') {AddCh(); goto case 1;}
        else {t.kind = 1; t.val = new String(tval, 0, tlen); CheckLiteral(); return t;}
      case 2:
        if (ch == '<') {AddCh(); goto case 3;}
        else {goto case 0;}
      case 3:
        {t.kind = 4; break;}
      case 4:
        if (ch == '>') {AddCh(); goto case 5;}
        else {goto case 0;}
      case 5:
        {t.kind = 5; break;}
      case 6:
        {t.kind = 20; break;}
      case 7:
        {t.kind = 21; break;}
      case 8:
        {t.kind = 22; break;}
      case 9:
        {t.kind = 24; break;}
      case 10:
        {t.kind = 25; break;}
      case 11:
        {t.kind = 26; break;}
      case 12:
        {t.kind = 27; break;}
      case 13:
        {t.kind = 28; break;}
      case 14:
        {t.kind = 29; break;}
      case 15:
        recEnd = pos; recKind = 13;
        if (ch == '.') {AddCh(); goto case 6;}
        else {t.kind = 13; break;}

    }
    t.val = new String(tval, 0, tlen);
    return t;
  }
  
  private void SetScannerBehindT() {
    buffer.Pos = t.pos;
    NextCh();
    line = t.line; col = t.col; charPos = t.charPos;
    for (int i = 0; i < tlen; i++) NextCh();
  }
  
  // get the next token (possibly a token already seen during peeking)
  public Token Scan () {
    if (tokens.next == null) {
      return NextToken();
    } else {
      pt = tokens = tokens.next;
      return tokens;
    }
  }

  // peek for the next token, ignore pragmas
  public Token Peek () {
    do {
      if (pt.next == null) {
        pt.next = NextToken();
      }
      pt = pt.next;
    } while (pt.kind > maxT); // skip pragmas
  
    return pt;
  }

  // make sure that peeking starts at the current scan position
  public void ResetPeek () { pt = tokens; }

} // end Scanner
}