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apostrophe :

'

space :

Space has no graphical representation.

3.1.2. Commentaries

The line which begins from the sign “!” or the part of line which follows the sign “!” is a commentary.

3.1.3. Tokens

There are 5 classes of tokens: identificators, key-words, constants, operation signs, delimiters.

Spaces, LF, commentaries are considered tokens’ delimiters and have no influence on the program semantics.

3.1.4. Identificators

identificator :

letter { { digit, letter } }*

The letters of upper register differ from the ones of low register. Identificators can have any length. The number of the meaningful symbols is defined in the specification of the translator’s source language (usually first 6 symbols are meaningful).

3.1.5. Key words

These key-words are used in the language:

3.1.6. Constants

constant :

arithm-constant

string

arithm-constant:

int-constant

real-constant

double-constant

int-constant :

{ digit }⁺

real-constant :

body [ E [ { +,- } ] power ]

double-constant :

body [ D [ { +,- } ] power ]

body :

int-constant . int-constant

power

int-constant

string

‘ { { symbol-not-apostrophe, ‘‘ } }⁺‘

symbol-not-apostrophe:

letter

digit

special- symbol-not-apostrophe

supplementary-symbol

The rules of writing constants are similar to the ones in the Fortran language.

The type and the value of the constant is defined by the way of its representation. These are examples of arithmetical constants :

101 999 0.1 1.0

10.5E-6 1.0E+7 1.0E7 0.1D-8 15.333D4

These records are not arithmetical constants:

.1 1. 1E-1 1.E5

These are examples of the strings :

'Hello, world!'

'Об ''ем тела = '

3.1.7. Signs of operations

operation :

{rel-operation, log-operation, arithm-operation }

rel-operation:

{ =,>,<,<=,>=,<>,>< }

rel-except-not-equal-operation :

{ =,>,<,>=,<= }

log-operation :

{ AND, OR, NOT }

arithm-operation :

{ +,-,*,/,** }

Symbols >= and <= are used for comparisons and , <> and >< symbols - for .

3.1.8. Delimiters

delimiter :

{ space,/,(,),[,],!,?,’,,,.,# }

3.2. Names

name :

identificator

list-name :

name { , name }*

Name is an identificator. It has a particular meaning and defines a particular program’s object (e.g. variable, domain, part of the program). There can’t be two definitions of the objects which have the same name.

The rule of name localization is true for every program element (part or function). The names declared in the program element are localized in it. There is no notion “global variable“ in this language. The names of the functions or the parts if they are actual or formal parameters of other parts or functions are indicated in the external names declaration EXTERNAL FUNCTION or EXTERNAL PART [see 5.16].

Half-underlined syntactical symbols e.g. name-set are syntactically equivalent to symbol name. Underlined part of the construction has additional semantic information.

Symbol list-name substitutes non-empty list of the names enumerated by comma.

3.3. Basic data types

There are basic data types specified in the language:

integer, real, double, logical, string

Value from the set of integers is assigned to the element of integer data type. There are arithmetical and comparison operations (rel-operation) for integer type elements.

Value from the set of real numbers is assigned to the element of real data type. There are arithmetical and comparison operations (rel-operation) for real type elements.

Value from the set of real numbers is assigned to the element of double data type and it allows to use double precious real numbers. There are arithmetical and comparison operations (rel-operation) for double type elements.

There are variables of integer, real and double type in the language.

Value “true” and “false” is assigned to the element of logical data type. It is used for definition of condition. There are logical operations for logical type elements. There are no variables of logical type in the language.

The element of string data type is a set of symbols from principal symbol set and supplementary symbol set. There are only constants but no variables and operations of this type.

3.4. Expressions

3.4.1. Arithmetical expressions

arithm-expression :

[ { +, - } ] term { arithm-operation term }*

term :

arihm-constant

call-function

name-index

name-domain-parameter

name-scalar

variable-on-domain

(arithm-expression)

variable-on-domain :

name-variable-on-domain [ [ list-index-expression ] ]

const-expression :

[ { +,- } ] const-expression-without-sign

const-expression-without-sign :

integer-term { arithm-operation integer-term }*

integer-term :

int-constant

name-domain-parameter

( const-expression )

index-expression :

name-index [ [ { +,- } ] const-expression-without-sign ]

name-index = const-expression-without-sign

name-index = name-index [ [ { +,- } ] const-expression-without-sign ]

The result of the index expression computation in a fixed point T of the domain (5.1.1.) is coordinates of the point T’. These coordinates can be defined according to the rules :

indexes are substituted to the constant expressions, values of T coordinates (taking into account index displacement if it is given) or values of the other given indexes in the point T.

For example, the list of index expressions [i-1,j,k=7,l=i+4] for the point T with i=9, j=15, k=3, l=37 gives us the value of the point T’ from index domain with i=8, j=15, k=7, l=13 coordinates.

The order of arithmetical expression computation is :

(1) index expressions computation;

(2) finding arguments (actual parameters) of the functions ( including determination of reduction functions operation domain [5.2.3];

(3) carrying-out in-brackets ( and ) operations: if there are several brackets of the one level, they are examined from the left to the right;

(4) carrying-out raising to the ** power operations: if there are several operations of the one level, they are examined from the right to the left;

(5) carrying-out of multiplication and division * and / operations; if there are several operations of the one level, they are examined from the left to the right;

(6) carrying-out of sum and difference + and - operations; if there are several operations of the one level, they are examined from the left to the right.

The type of arithmetical expression result is defined by the types of operation results. The type of operation result can be :

(1) integer, if both operands are integer ;

(2) double, if even one operand is double ;

(3) real in any other cases.

Constant expression is a particular case of arithmetical expression. The examples of arithmetical expressions :

AL12[J=2_*M-1]+STEPLP_*JJ

Q+1.0D5/((R[Q-1]-R)_*(R[Q-1]-R[Q+1]))

CN_*TRAP(STEP, 2_*MV+1, MMR ON POLL)

3.4.2. Conditional expressions

log-expression :

[ NOT ] logic-term { log-operation logic-term }*

logic-term :

comparison

( log-expression )

comparison :

arithm-expression comp-operation arithm-expression

condition-on-domain :

log-expression

condition-on-index :

name-index rel-except-not-equal-operation

name-index [ { +,- } const-expression-without-sign ]

name-index rel-except-not-equal-operation const-expression-without-sign

The order of operations for logical expression computation :

(1) carrying out of arithmetical expressions computation;

(2) carrying out of in-brackets ( and ) operations; if there are several brackets of the one level, they are examined from the left to the right.

(3) carrying out of comparisons =,>,<,>=,<=,<>,>< ; if there are several operations of the one level, they are examined from the left to the right.

(4) carrying out of logical negation NOT operations; if there are several operations of the one level, they are examined from the left to the right.

(5) carrying out of logical multiplication AND operations; if there are several operations of the one level, they are examined from the left to the right.

(6) carrying out of logical sum OR operations; if there are several operations of the one level, they are examined from the left to the right.

There are examples of logical expressions:

ABS(MOD-X1+Y1)<=1.0D-20

NOT (II=(2_*N+1)_*(2_*NV+1) AND NU=0)

I=J+1

4. Program structure

program :

{ part }⁺

part :

main-part

simple-part

part-function

main-part :

MAIN PART name-part . declaration-of-part

simple-part :

PART name-simple-part . declaration-of-part

part-function :

FUNCTION name-function [type-function] . declaration-of-function

declaration-of-part :

formal-parameters-of-part BEGIN body-of-part END PART

formal-parameters-of-part :

[ list-name ] [RESULT list-name]

declaration-of-function :

formal-parameters-of-function BEGIN body-of-part END PART

formal-parameters-of-function :

list-name

body-of-part :

{ element-of-part }*

element-of-part :

Характеристики

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