Class SimulaScanner

java.lang.Object
simula.compiler.parsing.DefaultScanner
simula.compiler.parsing.SimulaScanner
public final class SimulaScanner extends DefaultScanner

The Simula Scanner.

Link to GitHub: Source File.

Author:
Øystein Myhre Andersen

  • Field Details

    • EOF_MARK

      private static final int EOF_MARK
      ISO EM(EndMedia) character used to denote end-of-input
      See Also:

    • EOF_SEEN

      private boolean EOF_SEEN
      Set 'true' when EOF-character ( -1 ) was read.

    • puchBackStack

      private Stack<Character> puchBackStack
      The pushBack stack

    • accum

      private StringBuilder accum
      StringBuilder used to accumulate input strings for Simula Editor.

    • editorMode

      private final boolean editorMode
      Editor mode. Set when the scanner is used by Simula Editor

    • tokenQueue

      private LinkedList<Token> tokenQueue
      The Token queue. The method nextToken will pick Tokens from the queue first.

    • sourceFileReader

      SourceFileReader sourceFileReader
      The current source file reader;

    • selector

      public static boolean[] selector
      The selector array.

    • pardepth

      private int pardepth

      The depth of nested parentheses (round brackets).

      NOTE: An initial "-" in array upper bound may follow directly after : (cf. 1.3).

      The scanner will treat ":-" within parentheses as two separate symbols ":" and "-" thus solving this ambiguity in the syntax.

      This variable is used to cover such situations.

    • prevChar

      private int prevChar
      The previous character read.

    • current

      private int current
      The current character read.

  • Constructor Details

    • SimulaScanner

      public SimulaScanner(Reader reader, boolean editorMode)
      Constructs a new SimulaScanner that produces Items scanned from the specified source.
      Parameters:
      reader - The character source to scan
      editorMode - true: delivers tokens to the SimulaEditor

  • Method Details

    • insert

      void insert(File file)
      Insert a file.
      Parameters:
      file - the file to be inserted

    • close

      void close()
      Close the scanner.

    • nextToken

      public Token nextToken()
      Description copied from class: DefaultScanner
      Returns the next Token.
      Overrides:
      nextToken in class DefaultScanner
      Returns:
      the next Token

    • scanToken

      private Token scanToken()

      Scan and return a Token.

      End-Condition: current is last character of construct
               getNext will return first character after construct
      Returns:
      next Token

    • scanBasic

      private Token scanBasic()
      Scan basic Token
      Returns:
      next Token

    • javaKeyword

      private Token javaKeyword(String name)
      Scanner Utility: Create a Java-name Token.
      Parameters:
      name - the Token's Java-name
      Returns:
      an identifier Token

    • identifierToken

      private Token identifierToken(String name)
      Scanner Utility: Create an identifier Token.
      Parameters:
      name - the Token's name
      Returns:
      an identifier Token

    • scanIdentifier

      private Token scanIdentifier()

      Scan and return an identifier Token.

      End-Condition: current is last character of construct
               getNext will return first character after construct
      Returns:
      next Token

    • scanNumber

      private Token scanNumber()

      Scan a unsigned number.

       Reference-Syntax:
     unsigned-number
       = decimal-number  [  exponent-part  ]
       | exponent-part
     decimal-number
       = unsigned-integer  [  decimal-fraction  ]
       | decimal-fraction
     decimal-fraction
       = .  unsigned-integer
     exponent-part
       =  ( & | && )  [ + | - ]  unsigned-integer
     unsigned-integer
       =  digit  {  digit  |  _  }
       |  radix  R  radix-digit  {  radix-digit  |  _  radix-digit  }
     radix
       =  2  |  4  |  8  |  16
     radix-digit
       =  digit  |  A  |  B  |  C  |  D  |  E  |  F

      End-Condition:

      • current is last character of construct
      • getNext will return first character after construct
      Returns:
      A Token representing a unsigned number.

    • scanDotDigit

      private Token scanDotDigit(StringBuilder number)

      Scan decimal-fraction possibly followed by an exponent-part. And append it to the given number.

      Reference-Syntax:

     decimal-fraction =  .  unsigned-integer
     
     
End-Condition: current is last character of construct                 
               getNext will return first character after construct
      Parameters:
      number - The edited number so far
      Returns:
      next Token

    • scanDigitsExp

      private Token scanDigitsExp(StringBuilder number)

      Scan exponent-part. And append it to the given number.

      Reference-Syntax:

     exponent-part =  ( & | && )  [ + | - ]  unsigned-integer

      Pre-Condition: First & is already read

      End-Condition: current is last character of construct
      getNext will return first character after construct

      Parameters:
      number - The edited number so far
      Returns:
      next Token

    • scanName

      private String scanName()

      Scan identifier or reserved name.

      Reference-Syntax:

   identifier = letter  { letter  |  digit  |  _  }
   
   
End-Condition: current is last character of construct
               getNext will return first character after construct
      Returns:
      the resulting identifier

    • scanCharacterConstant

      private Token scanCharacterConstant()

      Scan and deliver a Character constant.

       Reference-Syntax:   
                                                  
     character-constant  = '  character-designator  '
     
     character-designator
        = iso-code
        |  non-quote-character
        |  "
        
        iso-code =  ! digit  [ digit ]  [ digit ]  !
      
      
End-Condition: current is last character of construct
               getNext will return first character after construct
      Returns:
      next Token

    • scanTextConstant

      private Token scanTextConstant()

      Scan and deliver a Text constant.

       Reference-Syntax:   
                                                  
     string = simple-string  {  string-separator  simple-string  }
     
        simple-string = " { iso-code |  non-quote-character  |  ""  }  "
        
           iso-code = ! digit  [ digit ]  [ digit ]  !
           
        string-separator = token-separator  {  token-separator  }
        
           token-separator
               = a direct comment
               | a space  { except in simple strings and character constants }
               | a format effector  { except as noted for spaces }
               | the separation of consecutive lines
       
       
End-Condition: current is last character of construct
               getNext will return first character after construct
      Returns:
      next Token

    • currentIsStringSeparator

      private boolean currentIsStringSeparator()

      Scanner Utility: Check if current is a string separator.

       Reference-Syntax:
 
     string-separator = token-separator  {  token-separator  }
     
        token-separator
           = a direct comment
           | a space  { except in simple strings and character constants }
           | a format effector  { except as noted for spaces }
           | the separation of consecutive lines
       
       
End-Condition: current is last character of construct
               getNext will return first character after construct
      Returns:
      true if current is a string separator

    • scanPossibleIsoCode

      private int scanPossibleIsoCode()

      Scanner Utility: Scan possible iso-code.

       Reference-Syntax:
 
     iso-code =  ! digit  [ digit ]  [ digit ]  !
      

Pre-Condition: The leading character ! is already read

End-Condition: current is last character of construct
               getNext will return first character after construct
      Returns:
      the resulting iso-code

    • scanDirectiveLine

      private Token scanDirectiveLine()

      Scan a %Directive line.

       Reference-Syntax:
 
     directive =  % { any character except end-of-line }

 A conditional line takes the form:
   
		%selector-expression text-line

	where text-line represents the line to be conditionally included
	and the selector-expression has the form:

		Selector-expression
			= selector-group { selector-group }

		Selector-group
			= + letter_or_digit { letter_or_digit }
			| - letter_or_digit { letter_or_digit }

	i.e. a string of letters and signs, with the first character being a sign.
	The selector-expression is terminated by a SPACE.


End-Condition: current is last character of construct
               getNext will return first character after construct
      Returns:
      a Comment Token

    • readUntilEndofLine

      private String readUntilEndofLine()
      Utility: Read until end-of-line.
      Returns:
      the string read

    • setSelectors

      private void setSelectors()

      %SELECT select-character { select-character }

      Set selectors for conditional compilation.

    • lineSelected

      private boolean lineSelected()
      Determine if current line is selected.
      Returns:
      true if current line is selected

    • scanComment

      private Token scanComment()

      Scan a Comment.

      Reference-Syntax:

      comment = COMMENT { any character except semicolon } ;
      
      
End-Condition: current is last character of construct 
               getNext will return first character after construct
      Returns:
      a Comment Token

    • scanCommentToEndOfLine

      private Token scanCommentToEndOfLine()

      Scan Comment to end-of-line.

      Reference-Syntax:

      comment = -- { any character until end-of-line }
      
      
End-Condition: current is last character of construct 
               getNext will return first character after construct
      Returns:
      a Comment Token

    • scanEndComment

      private Token scanEndComment()

      Scan end-comment.

      reference-Syntax:

      The sequence:
      
         END { any sequence of printable characters not containing END, ELSE, WHEN, OTHERWISE or ; }
         
      is equivalent to:
      
         END


End-Condition: current is last character of construct
               getNext will return first character after construct
      Returns:
      next Token

    • getNext

      private int getNext()
      Returns next input character.
      Returns:
      next input character

    • pushBack

      private void pushBack(int chr)
      Push a character onto the puchBackStack.
      Parameters:
      chr - character to be pushed

    • pushBack

      private void pushBack(String s)
      Push a string onto the puchBackStack.
      Parameters:
      s - string to be pushed

    • newToken

      private Token newToken(int keyWord, Object value)
      Create a new Token
      Parameters:
      keyWord - the KeyWord
      value - the value
      Returns:
      the newly created Token

    • newToken

      private Token newToken(int keyWord)
      Create a new Token without a value
      Parameters:
      keyWord - the KeyWord
      Returns:
      the newly created Token

    • edcurrent

      private String edcurrent()
      Utility: Edit current character.
      Returns:
      edited current character

    • isHexDigit

      private boolean isHexDigit(int c)
      Utility: Check if a character is a hex digit.
      Parameters:
      c - the character
      Returns:
      true if character c is a hex digit

    • isPrintable

      private boolean isPrintable(int c)
      Utility: Check if a character is printable.
      Parameters:
      c - the character
      Returns:
      true if character c is printable

    • isWhiteSpace

      private boolean isWhiteSpace(int c)
      Utility: Check if a character is a whiteSpace.
      Parameters:
      c - the character
      Returns:
      true if character c is a whiteSpace