103 lines
3.0 KiB
Plaintext
103 lines
3.0 KiB
Plaintext
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DEFINITION MODULE Strings;
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(*
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Variable-length character strings handler.
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NOTE: For most of these string handling procedures,there is the
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possibility of the user not providing a variable large enough to
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contain the result of a string operation.
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Should this possibility arise truncation may result,as there
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will be no other error notification.
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The implementation of this module must not cause a range error,
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it should instead silently truncate.
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String variables have the following characteristics:
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They are ARRAY OF CHAR
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Lowest bound must be 0
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The size of the string is the size of the string
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variable unless the null character (0C) occurs in
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the string to indicate end of string.
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*)
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EXPORT QUALIFIED Assign, Insert, Delete,
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Pos, Copy, Concat, Length, CompareStr;
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PROCEDURE Assign (VAR source, dest: ARRAY OF CHAR);
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(*- Assign the contents of string variable source into string variable dest
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in: source
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out: dest
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*)
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PROCEDURE Insert (substr: ARRAY OF CHAR;
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VAR str: ARRAY OF CHAR;
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inx: CARDINAL);
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(*- Insert the string substr into str,starting at str[inx].
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in: substr
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str
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inx
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out: str
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If inx is equal or greater than Length(str) then substr is appended
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to end of dest.
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*)
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PROCEDURE Delete (VAR str: ARRAY OF CHAR;
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inx: CARDINAL;
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len: CARDINAL);
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(*- Delete len characters from str, starting at str[inx].
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in: str
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inx
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len
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out: str
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If inx >= Length(str) then nothing happens.
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If there are not len characters to delete, characters to
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the end of string are deleted.
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*)
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PROCEDURE Pos (substr, str: ARRAY OF CHAR): CARDINAL;
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(*- Return the index into str of the first occurrence of the substr.
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in: substr
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str
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Pos returns a value greater then HIGH(str) if no occurrence of the
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substring is found
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*)
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PROCEDURE Copy (str: ARRAY OF CHAR;
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inx: CARDINAL;
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len: CARDINAL;
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VAR result: ARRAY OF CHAR);
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(*- Copy at most len characters from str into result.
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in: str source string,
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inx starting position in 'str',
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len maximum number of characters to copy,
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out: result copied string
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*)
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PROCEDURE Concat (s1, s2: ARRAY OF CHAR;
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VAR result: ARRAY OF CHAR);
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(*- Concatenate two strings.
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in: s1 left string,
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s2 right string,
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out: result receives left string followed by right string.
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*)
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PROCEDURE Length (VAR str: ARRAY OF CHAR): CARDINAL;
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(*- Return the number of characters in a string.
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in: str
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*)
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PROCEDURE CompareStr (s1, s2: ARRAY OF CHAR): INTEGER;
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(*- Compare two strings.
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in: s1
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s2
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Returns an integer value indicating the comparison result:
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-1 if s1 is less than s2;
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0 if s1 equals s2;
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1 if s1 is greater than s2
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*)
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END Strings.
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