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uScanner.h
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uScanner.h
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// **************************************************************************
// * *
// * u S C A N N E R General purpose C++ tokenizer *
// * *
// * Usage: *
// * TScanner sc = new TScanner(); *
// * sc.stream = <A stream>; // eg sc.stream = File.OpenRead (fileName); *
// * sc.startScanner(); *
// * sc.nextToken(); *
// * if (sc.token == TScanner.TTokenCodes.tEndOFStreamToken) *
// * exit; *
// * *
// * Copyright (c) 2004 by Herbert Sauro *
// * Licenced under the Artistic open source licence *
// * *
// **************************************************************************
//using System;
//using System.IO;
//using System.Collections;
#include <istream>
#include <streambuf>
#include <map>
#include <cstring>
#include <string>
#include <cmath>
namespace uScanner {
// Declare a Scanner exception type
class EScannerException {
public:
std::string eMessage;
EScannerException (std::string message) {
eMessage = message;
}
};
// Different types of recognised tokens
enum TTokenCode
{
tEmptyToken, tEndOfStreamToken, tIntToken, tDoubleToken, tComplexToken,
tStringToken, tWordToken, tEolToken, tSemiColonToken, tCommaToken,
tEqualsToken, tPlusToken, tMinusToken, tMultToken, tDivToken,
tLParenToken, tRParenToken, tLBracToken, tRBracToken, tLCBracToken,
tRCBracToken, tOrToken, tAndToken, tNotToken, tXorToken,
tPowerToken, tLessThanToken, tLessThanOrEqualToken, tMoreThanToken, tMoreThanOrEqualToken,
tNotEqualToken, tReversibleArrow, tIrreversibleArrow, tStartComment, tInternalToken,
tExternalToken, tParameterToken, tIfToken, tWhileToken, tModelToken,
tEndToken
};
/* // This class is Experimental....
public class tokenClass
{
private string description;
public TTokenCode tokenCode;
public override string ToString () { return description; }
public tokenClass (TTokenCode token, string value)
{
this.tokenCode = token;
this.description = value;
}
}*/
// This is currently used to store the previous token and support simple look ahead
class TToken
{
public:
enum TTokenCode tokenCode;
std::string tokenString;
int tokenInteger;
double tokenDouble;
double tokenValue; // Used to retrieve int or double
TToken()
{
tokenCode = tEmptyToken;
tokenString = "";
tokenInteger = 0;
tokenDouble = 0.0;
tokenValue = 0.0;
}
};
// -------------------------------------------------------------------
// Start of TScanner Class
// -------------------------------------------------------------------
class TScanner
{
private:
const static char EOFCHAR;
const static char CR;
//SRI const static char LF;
enum TCharCode {
cLETTER,
cDIGIT,
cPOINT,
cDOUBLEQUOTE,
cUNDERSCORE,
cSPECIAL,
cWHITESPACE,
cETX
};
// private variables
TCharCode FCharTable[255];
char buffer[255]; // Input buffer
int bufferPtr; // Index of position in buffer containing current char
int bufferLength;
int yylineno; // Current line number
std::istream* myFStream;
TTokenCode ftoken;
std::map<std::string, int> wordTable;
void initScanner()
{
int ch;
for (ch=0; ch < 255; ch++)
FCharTable[ch] = cSPECIAL;
for (ch=(int)'0'; ch <= (int)'9'; ch++)
FCharTable[ch] = cDIGIT;
for (ch=(int)'A'; ch <= (int)'Z'; ch++)
FCharTable[ch] = cLETTER;
for (ch=(int)'a'; ch <= (int)'z'; ch++)
FCharTable[ch] = cLETTER;
FCharTable[(int)'.'] = cPOINT;
FCharTable[(int)'"'] = cDOUBLEQUOTE;
FCharTable[(int)'_'] = cUNDERSCORE;
FCharTable[(int)'\t'] = cWHITESPACE;
FCharTable[(int)' '] = cWHITESPACE;
FCharTable[(int)EOFCHAR] = cETX;
//wordTable["and"] = tAndToken;
//wordTable["or"] = tOrToken;
//wordTable["not"] = tNotToken;
//wordTable["xor"] = tXorToken;
wordTable["model"] = tModelToken;
wordTable["if"] = tIfToken;
wordTable["while"] = tWhileToken;
wordTable["end"] = tEndToken;
wordTable["internal"] = tInternalToken;
wordTable["external"] = tExternalToken;
wordTable["parameter"] = tParameterToken;
}
char getCharFromBuffer()
{
char ch;
// If the buffer is empty, read a new chuck of text from the
// input stream, this might be a stream or console
if (bufferPtr == 0)
{
// Read a chunck of data from the input stream
myFStream->read(buffer, 255);
bufferLength = (int) myFStream->gcount();
if (bufferLength == 0)
return EOFCHAR;
}
ch = (char) buffer[bufferPtr];
bufferPtr++;
if (bufferPtr >= bufferLength)
bufferPtr = 0; // Indicates the buffer is empty
return ch;
}
// -------------------------------------------------------------------
// Scan for a word, words start with letter or underscore then continue
// with letters, digits or underscore
// -------------------------------------------------------------------
void getWord()
{
std::string tempfch;
while ((FCharTable[(int)fch] == cLETTER)
|| (FCharTable[(int)fch] == cDIGIT)
|| (FCharTable[(int)fch] == cUNDERSCORE))
{
tokenString = tokenString + fch; // Inefficient but convenient
nextChar();
}
if ( wordTable.find (tokenString) != wordTable.end() )
ftoken = (TTokenCode) wordTable[tokenString];
else
ftoken = tWordToken;
}
// -------------------------------------------------------------------
// Scan for a number, integer, double or complex
// -------------------------------------------------------------------
void getNumber()
{
const int MAX_DIGIT_COUNT = 3; // Max number of digits in exponent
int single_digit;
double scale;
double evalue;
int exponent_sign;
int digit_count;
tokenInteger = 0;
tokenDouble = 0.0;
tokenScalar = 0.0;
evalue = 0.0;
exponent_sign = 1;
// Assume first it's an integer
ftoken = tIntToken;
// Pick up number before any decimal place
if (fch != '.')
try
{
do
{
single_digit = fch - '0';
tokenInteger = 10*tokenInteger + single_digit;
tokenScalar = tokenInteger;
nextChar();
} while (FCharTable[(int)fch] == cDIGIT);
}
catch (...)
{
throw new EScannerException ("Integer Overflow - constant value too large to read");
}
scale = 1;
if (fch == '.')
{
// Then it's a float. Start collecting fractional part
ftoken = tDoubleToken;
tokenDouble = tokenInteger;
nextChar();
if (FCharTable[(int)fch] != cDIGIT)
throw new EScannerException ("Syntax error: expecting number after decimal point");
try
{
while (FCharTable[(int)fch] == cDIGIT)
{
scale = scale * 0.1;
single_digit = fch - '0';
tokenDouble = tokenDouble + (single_digit * scale);
tokenScalar = tokenDouble;
nextChar();
}
}
catch (...)
{
throw new EScannerException ("Floating point overflow - constant value too large to read in");
}
}
// Next check for scientific notation
if ((fch == 'e') || (fch == 'E'))
{
// Then it's a float. Start collecting exponent part
if (ftoken == tIntToken)
{
ftoken = tDoubleToken;
tokenDouble = tokenInteger;
tokenScalar = tokenInteger;
}
nextChar();
if ((fch == '-') || (fch == '+'))
{
if (fch == '-') exponent_sign = -1;
nextChar();
}
// accumulate exponent, check that first ch is a digit
if (FCharTable[(int)fch] != cDIGIT)
throw new EScannerException ("Syntax error: number expected in exponent");
digit_count = 0;
try {
do {
digit_count++;
single_digit = fch - '0';
evalue = 10*evalue + single_digit;
nextChar();
} while ((FCharTable[(int)fch] == cDIGIT) && (digit_count <= MAX_DIGIT_COUNT));
}
catch (...)
{
throw new EScannerException ("Floating point overflow - Constant value too large to read");
}
if (digit_count > MAX_DIGIT_COUNT)
throw new EScannerException ("Syntax error: too many digits in exponent");
evalue = evalue * exponent_sign;
if (evalue > 300)
throw new EScannerException ("Exponent overflow while parsing floating point number");
evalue = pow (10.0, evalue);
tokenDouble = tokenDouble * evalue;
tokenScalar = tokenDouble;
}
// Check for complex number
if ((fch == 'i') || (fch == 'j'))
{
if (ftoken == tIntToken)
tokenDouble = tokenInteger;
ftoken = tComplexToken;
nextChar();
}
}
bool IsDoubleQuote (char ch) {
if (FCharTable[(int)ch] == cDOUBLEQUOTE)
return true;
else
return false;
}
// -------------------------------------------------------------------
// Scan for string, "abc"
// -------------------------------------------------------------------
void getString() {
bool OldIgnoreNewLines;
tokenString = "";
nextChar();
ftoken = tStringToken;
while (fch != EOFCHAR)
{
// Check for escape characters
if (fch == '\\')
{
nextChar();
switch (fch)
{
case '\\' : tokenString = tokenString + '\\';
break;
case 'n' : tokenString = tokenString + CR;
break;
//SRI case 'n' : tokenString = tokenString + CR + LF;
//SRI break;
case 'r' : tokenString = tokenString + CR;
break;
//SRI case 'f' : tokenString = tokenString + LF;
//SRI break;
case 't' : tokenString = tokenString + " ";
break;
default:
throw new EScannerException ("Syntax error: Unrecognised control code in string");
}
nextChar();
}
else
{
OldIgnoreNewLines = IgnoreNewLines;
if (IsDoubleQuote (fch))
{
// Just in case the double quote is at the end of a line and another string
// start immediately in the next line, if we ignore newlines we'll
// pick up a double quote rather than the end of a string
IgnoreNewLines = false;
nextChar();
if (IsDoubleQuote (fch))
{
tokenString = tokenString + fch;
nextChar();
}
else
{
if (OldIgnoreNewLines)
{
while (fch == CR)
{
nextChar();
//SRI while (fch == LF)
//SRI nextChar();
}
}
IgnoreNewLines = OldIgnoreNewLines;
return;
}
}
else
{
tokenString = tokenString + fch;
nextChar();
}
IgnoreNewLines = OldIgnoreNewLines;
}
}
if (fch == EOFCHAR)
throw new EScannerException ("Syntax error: String without terminating quotation mark");
}
// -------------------------------------------------------------------
// Scan for special characters
// -------------------------------------------------------------------
void getSpecial() {
char tch;
switch (fch) {
case 13: ftoken = tEolToken;
nextChar();
break;
case ';': ftoken = tSemiColonToken;
nextChar();
break;
case ',': ftoken = tCommaToken;
nextChar();
break;
case '=': nextChar();
if (fch == '>')
{
ftoken = tReversibleArrow;
nextChar();
}
else
ftoken = tEqualsToken;
break;
case '+': ftoken = tPlusToken;
nextChar();
break;
case '-': nextChar();
if (fch == '>')
{
ftoken = tIrreversibleArrow;
nextChar();
}
else
ftoken = tMinusToken;
break;
case '*': nextChar();
ftoken = tMultToken;
break;
case '/': // look ahead at next ch
tch = nextChar();
if (tch == '/')
{
ftoken = tStartComment;
nextChar();
}
else
ftoken = tDivToken;
break;
case '(': nextChar();
ftoken = tLParenToken;
break;
case ')': nextChar();
ftoken = tRParenToken;
break;
case '[': nextChar();
ftoken = tLBracToken;
break;
case ']': nextChar();
ftoken = tRBracToken;
break;
case '{': nextChar();
ftoken = tLCBracToken;
break;
case '}': nextChar();
ftoken = tRCBracToken;
break;
case '^': nextChar();
ftoken = tPowerToken;
break;
case '<': nextChar();
if (fch == '=')
{
ftoken = tLessThanOrEqualToken;
nextChar();
}
else
ftoken = tLessThanToken;
break;
case '>': nextChar();
if (fch == '=')
{
ftoken = tMoreThanOrEqualToken;
nextChar();
}
else
ftoken = tMoreThanToken;
break;
case '!': nextChar();
if (fch == '=')
{
ftoken = tNotEqualToken;
nextChar();
}
break;
default:
std::string message;
message = "Syntax error: Unknown special token [" + fch;
message = message + "]";
throw new EScannerException (message);
}
}
void nextTokenInternal() {
// check if a token has been pushed back into the token stream, if so use it first
if (previousToken->tokenCode != tEmptyToken) {
ftoken = previousToken->tokenCode;
tokenString = previousToken->tokenString;
tokenDouble = previousToken->tokenDouble;
tokenInteger = previousToken->tokenInteger;
previousToken->tokenCode = tEmptyToken;
return;
}
skipBlanks();
tokenString = "";
switch (FCharTable[(int)fch]) {
case cLETTER :
case cUNDERSCORE : getWord();
break;
case cDIGIT : getNumber();
break;
case cDOUBLEQUOTE : getString();
break;
case cETX : ftoken = tEndOfStreamToken;
break;
default : getSpecial();
break;
}
}
// Public Variables
public:
TToken* currentToken;
TToken* previousToken;
bool IgnoreNewLines;
std::string tokenString;
int tokenInteger;
double tokenDouble;
double tokenScalar; // Used to retrieve int or double
char fch;
// -------------------------------------------------------------------
// Constructor
// -------------------------------------------------------------------
TScanner()
{
//wordTable = new Hashtable();
previousToken = new TToken();
currentToken = new TToken();
IgnoreNewLines = true;
initScanner();
}
// -------------------------------------------------------------------
// Destructor
// -------------------------------------------------------------------
/* ~TScanner()
{
delete previousToken;
delete currentToken;
}*/
// Create a readonly property for the current line number
int getLineNumber() {
return yylineno;
}
// writeonly stream property
void setStream(std::istream* inputStream) {
//istream inputStream(sb);
myFStream = inputStream;
}
// readonly current token property
TTokenCode getToken() {
return ftoken;
}
// Must be called before using nextToken()
void startScanner() {
yylineno = 1;
bufferPtr = 0;
nextChar();
}
// -------------------------------------------------------------------
// Fetches next character from input stream and filters NL if required
// -------------------------------------------------------------------
char nextChar() {
fch = getCharFromBuffer();
if (IgnoreNewLines)
{
// Turn any CFs or LFs into space characters
if (fch == CR) {
yylineno++;
fch = ' ';
return fch;
}
//SRI if (fch == LF)
//SRI fch = ' ';
//SRI return fch;
}
else
{
if (fch == CR)
yylineno++;
}
return fch;
}
// -------------------------------------------------------------------
// Skips any blanks, ie TAB, ' '
// -------------------------------------------------------------------
void skipBlanks() {
while (FCharTable[(int)fch] == cWHITESPACE) {
//SRI if ((fch == LF) || (fch == CR))
if (fch == CR)
return;
nextChar();
}
}
// -------------------------------------------------------------------
// Retrieve next token in stream, returns tEndOfStreamToken
// if it reaches the end of the stream
// -------------------------------------------------------------------
void nextToken()
{
nextTokenInternal();
while (ftoken == tStartComment)
{
// Comment ends with an end of line char
while ((fch != CR) && (fch != EOFCHAR))
fch = getCharFromBuffer();
//SRI while ((fch == LF) && (fch != EOFCHAR))
//SRI fch = getCharFromBuffer();
while (fch == CR)
{
yylineno++;
//SRI while (fch == LF)
//SRI nextChar(); // Dump the linefeed
fch = nextChar();
}
nextTokenInternal(); // get the real next token
}
}
// -------------------------------------------------------------------
// Allows one token look ahead
// Push token back into token stream
// -------------------------------------------------------------------
void UnGetToken()
{
previousToken->tokenCode = ftoken;
previousToken->tokenString = tokenString;
previousToken->tokenInteger = tokenInteger;
previousToken->tokenDouble = tokenDouble;
}
// -------------------------------------------------------------------
// Given a token, this function returns the string eqauivalent
// -------------------------------------------------------------------
std::string tokenToString (TTokenCode code) {
std::string strtokenInteger;
std::string strtokenDouble;
char buffer[100];
switch (code) {
case tIntToken : sprintf(buffer, "%d", tokenInteger);
strtokenInteger = buffer;
return "<Integer: " + strtokenInteger + ">";
break;
case tDoubleToken : sprintf(buffer, "%lf", tokenDouble);
strtokenDouble = buffer;
return "<Double: " + strtokenDouble + ">";
break;
case tComplexToken : return "<Complex: " + strtokenDouble + "i>";
break;
case tStringToken : return "<String: " + tokenString + ">";
break;
case tWordToken : //return "<Identifier: " + tokenString + ">";
return "(" + tokenString + ")";
break;
case tEndOfStreamToken : return "<end of stream>";
break;
case tEolToken : return "<EOLN>";
break;
case tSemiColonToken : return "<;>";
break;
case tCommaToken : return "<,>";
break;
case tEqualsToken : return "<=>";
break;
case tPlusToken : return "<+>";
break;
case tMinusToken : return "<->";
break;
case tMultToken : return "<*>";
break;
case tDivToken : return "</>";
break;
case tPowerToken : return "<^>";
break;
case tLParenToken : return "<(>";
break;
case tRParenToken : return "<)>";
break;
case tLBracToken : return "<[>";
break;
case tRBracToken : return "<]>";
break;
case tLCBracToken : return "<{>";
break;
case tRCBracToken : return "<}>";
break;
/*case tOrToken : return "<or>";
break;
case tAndToken : return "<and>";
break;
case tNotToken : return "<not>";
break;
case tXorToken : return "<xor>";
break;*/
case tLessThanToken : return "[<]";
break;
case tLessThanOrEqualToken : return "[<=]";
break;
case tMoreThanToken : return "[>]";
break;
case tMoreThanOrEqualToken : return "[>=]";
break;
case tNotEqualToken : return "!=";
break;
case tReversibleArrow : return "[=>]";
break;
case tIrreversibleArrow : return "[->]";
break;
case tIfToken : return "<if>";
break;
case tWhileToken : return "<while>";
break;
case tModelToken : return "<model>";
break;
case tEndToken : return "<end>";
break;
case tInternalToken : return "<Internal>";
break;
case tExternalToken : return "<External>";
break;
case tParameterToken : return "<Parameter>";
break;
default:
return "<unknown>";
}
}
}; // end of TScanner class
const char TScanner::EOFCHAR = '\x7F'; // Deemed end of string marker, used internally
const char TScanner::CR = (char)10;
//SRI const char TScanner::CR = (char)13;
//SRI const char TScanner::LF = (char)10;
} // end of uScanner namespace