Module Simula

Package simula.runtime

Class RTS_TXT

java.lang.Object

simula.runtime.RTS_TXT

public final class RTS_TXT
extends Object

The type text.

The type text serves to declare or specify a text variable quantity.

A text value is a string, i.e. an ordered sequence (possibly empty) of characters. The number of characters is called the "length" of the text value.

A text frame is a memory device which contains a nonempty text value. A text frame has a fixed length and can only contain text values of this length. A text frame may be "alterable" or "constant". A constant frame always contains the same text value. An alterable text frame may have its contents modified. The maximum length of a text frame is implementation-defined.

A text reference identifies a text frame. The reference is said to possess a value, which is the contents of the identified frame. The special text reference notext identifies "no frame". The value of notext is the empty text value.

A text variable is conceptually an instance of a composite structure

        ref(TEXTOBJ) OBJ; integer START, LENGTH, POS;
 

It references (and has as its value the contents of) some text frame defined by the three first components. POS identifies the current character. See 3.1.2.

Link to GitHub: Source File.

Author:

SIMULA Standards Group, Øystein Myhre Andersen

Field Summary

Fields

Modifier and Type	Field	Description
(package private) int	LENGTH	The length of this text.
(package private) RTS_TEXTOBJ	OBJ	The Text object referred.
(package private) int	POS	Current index of OBJ.MAIN[], counting from zero.
(package private) int	START	Start index of OBJ.MAIN[], counting from zero.
private static final int	UNICODE_MINUS_SIGN	Unicode minus sign = 8722 = 0x2212

Constructor Summary

Constructors

Constructor	Description
RTS_TXT()	Create a new _TXT.
RTS_TXT(String s)	Create a new _TXT containing the string s.

Method Summary

Modifier and Type	Method	Description
private static String	addPlussExponent(String s)	Real Edit Utility: Add plus exponent to the given string
private static void	checkAssignable(RTS_TXT T)	Check if it is legal to assign to the given text reference.
static boolean	constant(RTS_TXT T)	Procedure constant.
(package private) String	edStripedText()	Utility: Edit stripped text into a String.
(package private) String	edText()	Utility: Edit text into a String.
(package private) String	edTextToPos()	Utility: Edit text until current pos into a String.
static char	getchar(RTS_TXT T)	Procedure getchar.
static int	getfrac(RTS_TXT T)	Procedure getfrac.
private static String	getFracItem(RTS_TXT T)	Scan the input text for a fraction item.
static int	getint(RTS_TXT T)	Procedure getint.
private static String	getIntegerItem(RTS_TXT T)	Scan the input text for an integer item.
static double	getreal(RTS_TXT T)	Procedure getreal.
private static String	getRealItem(RTS_TXT T)	Scan the input text for a real item.
static int	length(RTS_TXT T)	Procedure length.
static RTS_TXT	main(RTS_TXT T)	Procedure main.
static boolean	more(RTS_TXT T)	Procedure more.
static int	pos(RTS_TXT T)	Procedure pos.
static void	putchar(RTS_TXT T, char c)	Procedure putchar.
static void	putfix(RTS_TXT T, double r, int n)	Procedure putfix.
static void	putfrac(RTS_TXT T, int val, int n)	Procedure putfrac.
static void	putint(RTS_TXT T, int i)	Procedure putint.
static void	putreal(RTS_TXT T, double r, int n)	Procedure putreal.
static void	putreal(RTS_TXT T, float r, int n)	Procedure putreal.
private static void	putRealResult(RTS_TXT T, String output)	Put the result of putReal type operation into the text T.
private static void	putResult(RTS_TXT T, String s)	Put the result of put... operation into the text T.
static void	setpos(RTS_TXT T, int p)	Procedure setpos.
static int	start(RTS_TXT T)	Procedure start.
static RTS_TXT	strip(RTS_TXT T)	Procedure strip.
static RTS_TXT	sub(RTS_TXT T, int i, int n)	Procedure sub.
String	toString()

Methods inherited from class java.lang.Object

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

Field Details

UNICODE_MINUS_SIGN

private static final int UNICODE_MINUS_SIGN

Unicode minus sign = 8722 = 0x2212

See Also:

• Constant Field Values

OBJ

RTS_TEXTOBJ OBJ

The Text object referred.

START

int START

Start index of OBJ.MAIN[], counting from zero.

Note this differ from Simula Definition.

LENGTH

int LENGTH

The length of this text.

POS

int POS

Current index of OBJ.MAIN[], counting from zero.

Note this differ from Simula Definition.

Constructor Details

RTS_TXT

public RTS_TXT()

Create a new _TXT.

RTS_TXT

public RTS_TXT(String s)

Create a new _TXT containing the string s.

Parameters:

s - initial string value

Method Details

toString

public String toString()

Overrides:

toString in class Object

edText

String edText()

Utility: Edit text into a String.

Returns:

the resulting String

edStripedText

String edStripedText()

Utility: Edit stripped text into a String.

Returns:

the resulting String

edTextToPos

String edTextToPos()

Utility: Edit text until current pos into a String.

Returns:

the resulting String

constant

public static boolean constant(RTS_TXT T)

Procedure constant.

Parameters:

T - the argument text reference

Returns:

true if T is constant, otherwise false

start

public static int start(RTS_TXT T)

Procedure start.

Parameters:

T - the argument text reference

Returns:

the start position of T within T'main frame

length

public static int length(RTS_TXT T)

Procedure length.

Parameters:

T - the argument text reference

Returns:

the length of T

main

public static RTS_TXT main(RTS_TXT T)

Procedure main.

"X.main" is a reference to the main frame which contains the frame referenced by X.

The following relations are true for any text variable X:

          X.main.length  >=  X.length
          X.main.main    ==  X.main
 

In addition,

          notext.main    ==  notext
          "ABC".main     =   "ABC" 
         (but "ABC".main =/= "ABC")
 

Parameters:

T - the argument text reference

Returns:

the main frame of T

pos

public static int pos(RTS_TXT T)

Procedure pos.

                integer procedure pos; pos := POS;
 

Parameters:

T - the argument text reference

Returns:

the current POS

setpos

public static void setpos(RTS_TXT T,
 int p)

Procedure setpos.

                procedure setpos(i); integer i;
                        POS := if i < 1 or i > LENGTH + 1 then LENGTH + 1 else i;
 

Parameters:

T - the argument text reference

p - the new POS

more

public static boolean more(RTS_TXT T)

Procedure more.

Parameters:

T - the argument text reference

Returns:

true if T.pos < T.length, otherwise false

getchar

public static char getchar(RTS_TXT T)

Procedure getchar.

Get the character at the current POS of T. POS is then incremented.

Parameters:

T - the argument text reference

Returns:

the character at the current pos

Throws:

RTS_SimulaRuntimeError - if the operation fail

checkAssignable

private static void checkAssignable(RTS_TXT T)

Check if it is legal to assign to the given text reference.

Parameters:

T - the given text reference

Throws:

RTS_SimulaRuntimeError - if assignment is illegal

putchar

public static void putchar(RTS_TXT T,
 char c)

Procedure putchar.

Put the character c into the text T at the current POS. POS is then incremented.

Parameters:

T - the argument text reference

c - the argument character

Throws:

RTS_SimulaRuntimeError - if the operation fail

sub

public static RTS_TXT sub(RTS_TXT T,
 int i,
 int n)

Procedure sub.

If legal, "X.sub(i,n)" references that subframe of X whose first character is character number i of X, and which contains n consecutive characters. The POS attribute of the expression defines a local numbering of the characters within the subframe. If n = 0, the expression references notext.

If legal, the following Boolean expressions are true for any text variable X:

        X.sub(i,n).sub(j,m) == X.sub(i+j-1,m)
 
        n ne 0  imp  X.main == X.sub(i,n).main
 
        X.main.sub(X.start,X.length) == X
 

Parameters:

T - the argument text reference

i - first character index

n - number of charaters

Returns:

the resulting text reference

Throws:

RTS_SimulaRuntimeError - if the operation fail

strip

public static RTS_TXT strip(RTS_TXT T)

Procedure strip.

The expression "X.strip" is equivalent to "X.sub(1,n)", where n indicates the position of the last non-blank character in X. If X does not contain any non-blank character, notext is returned.

Let X and Y be text variables. Then after the value assignment "X:=Y", if legal, the relation "X.strip = Y.strip" has the value true, while "X = Y" is true only if X.length = Y.length.

Parameters:

T - the argument text reference

Returns:

the resulting text reference

getIntegerItem

private static String getIntegerItem(RTS_TXT T)

Scan the input text for an integer item.

 INTEGER-ITEM = SIGN-PART DIGITS

    SIGN-PART = BLANKS [ SIGN ] BLANKS

       SIGN = + | -

       DIGITS = DIGIT { DIGIT }

       DIGIT = 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
 

Parameters:

T - the input text

Returns:

the resulting string

getint

public static int getint(RTS_TXT T)

Procedure getint.

 INTEGER-ITEM = SIGN-PART DIGITS

    SIGN-PART = BLANKS [ SIGN ] BLANKS

       SIGN = + | -

       DIGITS = DIGIT { DIGIT }

       DIGIT = 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
 

The procedure locates an INTEGER ITEM. The function value is equal to the corresponding integer.

Parameters:

T - the text reference

Returns:

the resulting real

getRealItem

private static String getRealItem(RTS_TXT T)

Scan the input text for a real item.

 REAL-ITEM = DECIMAL-ITEM [ EXPONENT ] | SIGN-PART EXPONENT

    DECIMAL-ITEM = INTEGER-ITEM [ FRACTION ] | SIGN-PART FRACTION

       INTEGER-ITEM = SIGN-PART DIGITS

       FRACTION = DECIMAL-MARK DIGITS

       SIGN-PART = BLANKS [ SIGN ] BLANKS

    EXPONENT = LOWTEN-CHARACTER INTEGER-ITEM

          SIGN = + | -

          DIGITS = DIGIT { DIGIT }

          DIGIT = 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9

          LOWTEN-CHARACTER = & | ...

          DECIMAL-MARK = . | ,

          BLANKS = { BLANK | TAB }
 

Parameters:

T - the input text

Returns:

the resulting string

getreal

public static double getreal(RTS_TXT T)

Procedure getreal.

 REAL-ITEM = DECIMAL-ITEM [ EXPONENT ] | SIGN-PART EXPONENT

    DECIMAL-ITEM = INTEGER-ITEM [ FRACTION ] | SIGN-PART FRACTION

       INTEGER-ITEM = SIGN-PART DIGITS

       FRACTION = DECIMAL-MARK DIGITS

       SIGN-PART = BLANKS [ SIGN ] BLANKS

    EXPONENT = LOWTEN-CHARACTER INTEGER-ITEM

          SIGN = + | -

          DIGITS = DIGIT { DIGIT }

          DIGIT = 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9

          LOWTEN-CHARACTER = & | ...

          DECIMAL-MARK = . | ,

          BLANKS = { BLANK | TAB }
 

The procedure locates a REAL ITEM. The function value is equal to or approximates to the corresponding number. An INTEGER ITEM exceeding a certain implementation-defined range may lose precision when converted to long real.

Parameters:

T - the text reference

Returns:

the resulting real

getFracItem

private static String getFracItem(RTS_TXT T)

Scan the input text for a fraction item.

 GROUPED-ITEM = SIGN-PART GROUPS [ DECIMAL-MARK GROUPS ]
              | SIGN-PART DECIMAL-MARK GROUPS

 SIGN-PART = BLANKS [ SIGN ] BLANKS

 SIGN = + | -

 GROUPS = DIGITS { BLANK DIGITS } DIGITS = DIGIT { DIGIT }

 DIGIT = 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
 

Parameters:

T - the input text

Returns:

the resulting string

getfrac

public static int getfrac(RTS_TXT T)

Procedure getfrac.

 GROUPED-ITEM = SIGN-PART GROUPS [ DECIMAL-MARK GROUPS ]
              | SIGN-PART DECIMAL-MARK GROUPS

 SIGN-PART = BLANKS [ SIGN ] BLANKS

 SIGN = + | -

 GROUPS = DIGITS { BLANK DIGITS } DIGITS = DIGIT { DIGIT }

 DIGIT = 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
 

The procedure locates a GROUPED ITEM. The function value is equal to the resulting integer. The digits of a GROUPED ITEM may be interspersed with BLANKS and a single DECIMAL MARK which are ignored by the procedure.

Parameters:

T - the text reference

Returns:

the resulting integer

putRealResult

private static void putRealResult(RTS_TXT T,
 String output)

Put the result of putReal type operation into the text T.

Parameters:

T - the text reference

output - the result of putReal

putResult

private static void putResult(RTS_TXT T,
 String s)

Put the result of put... operation into the text T.

If the text frame is too short to contain the resulting numeric item, the text frame into which the number was to be edited is filled with asterisks. The final value of the position indicator of X is X.length+1.

Parameters:

T - the text reference

s - the result of put... operation

putint

public static void putint(RTS_TXT T,
 int i)

Procedure putint.

The value of the parameter is converted to an INTEGER ITEM which designates an integer equal to that value.

Parameters:

T - the text reference

i - the integer value to be edited

putfix

public static void putfix(RTS_TXT T,
 double r,
 int n)

Procedure putfix.

The resulting numeric item is an INTEGER ITEM if n=0 or a DECIMAL ITEM with a FRACTION of n digits if n>0. It designates a number equal to the value of r or an approximation to the value of r, correctly rounded to n decimal places. If n<0, a run-time error is caused.

Parameters:

T - the text reference

r - the long real value to be edited

n - the number of digits after decimal sign

putreal

public static void putreal(RTS_TXT T,
 double r,
 int n)

Procedure putreal.

The resulting numeric item is a REAL ITEM containing an EXPONENT with a fixed implementation-defined number of characters. The EXPONENT is preceded by a SIGN PART if n=0, or by an INTEGER ITEM with one digit if n=1, or if n>1, by a DECIMAL ITEM with an INTEGER ITEM of 1 digit only, and a fraction of n-1 digits. If n<0 a runtime error is caused.

Parameters:

T - the text reference

r - the long real value to be edited

n - the number of digits after decimal sign

putreal

public static void putreal(RTS_TXT T,
 float r,
 int n)

Procedure putreal.

See putreal(RTS_TXT,double,int)

Parameters:

T - the text reference

r - the real value to be edited

n - the number of digits after decimal sign

addPlussExponent

private static String addPlussExponent(String s)

Real Edit Utility: Add plus exponent to the given string

Parameters:

s - the given string

Returns:

the resulting string

putfrac

public static void putfrac(RTS_TXT T,
 int val,
 int n)

Procedure putfrac.

The resulting numeric item is a GROUPED ITEM with no DECIMAL MARK if n<=0, and with a DECIMAL MARK followed by total of n digits if n>0. Each digit group consists of 3 digits, except possibly the first one, and possibly the last one following a DECIMAL MARK. The numeric item is an exact representation of the number i * 10**(-n).

Parameters:

T - the text reference

val - an integer value

n - number of digits after a decimal mark