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Section 8.16.1.6: |
This page defines two generic abstract classes named $FTEXT_STRING which have different numbers of class arguments
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This abstract class defines a state component which is a set of all instantiations of objects of any class sub-typing from this class in addition to the vdm model types used wherever this class name is used. Note that SAME has to be an instantiated class, not an abstract one.
NOTE | See the important note about vdm state in the notes on vdm-sl usage in this specification. |
This abstract class characterises the concept of a mutable text string as sequences of the argument class (elements) which must sub-type from $IS_EQ.
This feature is the cultural description and coding which is associated with the string. It need not be the default culture and coding for the environment in which the program is executing, since a program may manipulate culture objects independently of local textual representations.
Since the string has to exist then so does this component. The pre-condition, therefore, is vacuously true.
Thie is also vacuously true, since it is a component of every string of text.
This feature provides access to all of the cultural and environment dependencies relating to this character string.
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This abstract class defines a state component which is a set of all instantiations of objects of any class sub-typing from this class in addition to the vdm model types used wherever this class name is used. Note that SAME has to be an instantiated class, not an abstract one.
NOTE | See the important note about vdm state in the notes on vdm-sl usage in this specification. |
This abstract class characterises the concept of a mutable text string as a sequence of the argument class (elements) which must sub-type from $IS_EQ. The second and third class arguments are the 'corresponding' mutable ($FTEXT_STRING{ELT}) and immutable (sub-typing from $TEXT_STRING{ELT}) string classes.
build( cursor : BIN_CURSOR, lib : LIBCHARS ) : SAME ; -- This routine builds the string from the binary string indicated using -- the encoding and repertoire defined by lib. If there is not an exact -- number of character codes in the string then void is returned and the -- cursor has not been moved.![]() |
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Keith
Hopper. Page last modified: Monday, 22 May 2000. |
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