itec.minicompiler
Class Scanner

java.lang.Object
  itec.minicompiler.Scanner

All Implemented Interfaces:

ConstantsInterface

public class Scanner

extends java.lang.Object

implements ConstantsInterface

The Scanner implements the actions necessary to extract the Token out of the source code. These are reading the source code characterwise and mainly distinguishing between SimpleToken, NumberToken and IdentToken and handling the comments.

Version:

1.0 (29.09.2004)

Author:

Stefan Leitner, Stefan Schauer

Field Summary

private char	actChar The character the Scanner just works on
private int	column The actual column in sourceCode
private java.util.HashSet	digits The set of digits
private ErrorHandler	errorhandler The Errorhandler used by the actual Scanner
private java.util.HashSet	keywords The set of keywords
private java.util.HashSet	letters The set of letters
private int	line The actual line in sourceCode
private int	position The next position in sourceCode (column number)
private java.util.HashSet	singles The set of special characters
private java.lang.String	sourceCode The source code the Scanner works on

Fields inherited from interface itec.minicompiler.ConstantsInterface

ACTUALPARAMETERS, AND, ARRAY, ARRAYTYPE, ASSIGNMENT, BECOMES, BEGIN, COLON, COMMA, CONST, DECLARATIONS, DIV, DO, ELSE, ELSIF, EMPTY, END, EPSILON, EQUAL, ERR_EXP_ARRAY, ERR_EXP_BECOMES, ERR_EXP_COLON, ERR_EXP_COMMA, ERR_EXP_DO, ERR_EXP_END, ERR_EXP_EQUAL, ERR_EXP_IDENT, ERR_EXP_IF, ERR_EXP_LPAREN, ERR_EXP_MODULE, ERR_EXP_OF, ERR_EXP_PERIOD, ERR_EXP_PROCEDURE, ERR_EXP_RBRAK, ERR_EXP_RECORD, ERR_EXP_REPEAT, ERR_EXP_RPAREN, ERR_EXP_SEMICOLON, ERR_EXP_THEN, ERR_EXP_UNTIL, ERR_EXP_WHILE, ERR_INV_FACTOR, ERR_INV_STATEMENT, ERR_INV_TYPE, ERR_INVALID_CHARACTER, ERR_NOT_EXP_DECLARATIONS, ERR_NOT_EXP_FACTOR, ERR_NOT_EXP_STATEMENT, ERR_NOT_EXP_TYPE, ERR_NOT_TERMINATED, ERR_NUMBER_TOO_HIGH, EXPRESSION, FACTOR, FIELDLIST, FORMALPARAMETERS, FPSECTION, GEQ, GREATER, IDENT, IDENTLIST, IF, IFSTATEMENT, KEYWORD, LBRAK, LEQ, LESS, LPAREN, MINICOMP, MINUS, MOD, MODULE, NOT, NOTEQUAL, NUMBER, OF, OR, PERIOD, PLUS, PROCEDURE, PROCEDUREBODY, PROCEDURECALL, PROCEDUREDECLARATION, PROCEDUREHEADING, RBRAK, RECORD, RECORDTYPE, REPEAT, REPEATSTATEMENT, RPAREN, SELECTOR, SEMICOLON, SIMPLEEXPRESSION, SINGLE, STATEMENT, STATEMENTSEQUENCE, TERM, THEN, TIMES, TYP, TYPE, UNTIL, VAR, WHILE, WHILESTATEMENT

Constructor Summary

Scanner(java.lang.String sc, ErrorHandler e)
Initialize the Scanner with a source code sc and an ErrorHandler e.

Method Summary

private void	comment() Ignore any comment, i.e. read until a close comment (*)) is found or the end of sourceCode is reached
int	getColumn() Return the column of the actual Scanner.
int	getLine() Return the line of the actual Scanner.
private Token	ident() Get the identifier or keyword starting with actChar
private void	initDigits() Initialize the set of digits.
private void	initKeywords() Initialize the set of keywords.
private void	initLetters() Initialize the set of letters.
private void	initSingles() Initialize the set of special characters.
private void	nextChar() Get the next character from sourceCode.
Token	nextToken() Get the next token from sourceCode.
private NumberToken	number() Get the number starting with actChar.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

keywords

private java.util.HashSet keywords

The set of keywords

letters

private java.util.HashSet letters

The set of letters

digits

private java.util.HashSet digits

The set of digits

singles

private java.util.HashSet singles

The set of special characters

errorhandler

private ErrorHandler errorhandler

The Errorhandler used by the actual Scanner

sourceCode

private java.lang.String sourceCode

The source code the Scanner works on

position

private int position

The next position in sourceCode (column number)

line

private int line

The actual line in sourceCode

column

private int column

The actual column in sourceCode

actChar

private char actChar

The character the Scanner just works on

Constructor Detail

Scanner

public Scanner(java.lang.String sc,
               ErrorHandler e)

Initialize the Scanner with a source code sc and an ErrorHandler e. Furthermore set the position, the line and column to the right value in he source code (i.e. at the position 1:0).

Parameters:

sc - The source code the Scanner should work on

e - The ErrorHandler the Scanner should use

Method Detail

getLine

public int getLine()

Return the line of the actual Scanner.

Returns:

The line the Scanner is currently working in

getColumn

public int getColumn()

Return the column of the actual Scanner.

Returns:

The column the Scanner is currently working in

initKeywords

private void initKeywords()

Initialize the set of keywords.

initLetters

private void initLetters()

Initialize the set of letters.

initDigits

private void initDigits()

Initialize the set of digits.

initSingles

private void initSingles()

Initialize the set of special characters.

nextChar

private void nextChar()

Get the next character from sourceCode.

number

private NumberToken number()

Get the number starting with actChar.

Returns:

A NumberToken containing the value of the whole number

ident

private Token ident()

Get the identifier or keyword starting with actChar

Returns:

A SimpleToken if a keyword is found, an IdentToken otherwise

comment

private void comment()

Ignore any comment, i.e. read until a close comment (*)) is found or the end of sourceCode is reached

nextToken

public Token nextToken()

Get the next token from sourceCode.

Returns:

An IdentToken if an identifier is found, a NumberToken if a number is found or a SimpleToken if a keyword or an operation is found. If the end of sourceCode is reached, a SimpleToken "EMPTY" is returned.