Method of determining the syntactic correctness of expressions
First Claim
1. A method of determining the syntactic correctness of an expression for use in a computing environment, said method comprising the steps of:
- (a) creating a string of characters from said expression;
(b) iteratively substituting occurrences of said characters also occurring in a first predetermined list with characters from a second predetermined list; and
(c) determining said expression to be syntactically correct only if said string reduces to a single predetermined character.
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Abstract
The present invention is a method (100) of determining the syntactic correctness of an expression for use in a computing environment. After creating (30) a string of characters from said expression, it looks for substrings (character sequences), which are legitimate and replaces (54) them with a shorter but semantically equivalent substring. It also looks for character sequences which are illegitimate, and replaces (54) them with a substring (i.e. “?”) to indicate that it has met with an illegal sequence. It does these operations repeatedly, and in predetermined sequences, till no further changes in the string can be made; that is, the string achieves a constant length. An expression is determined to be syntactically correct only if said string reduces to a single predetermined character.
10 Citations
16 Claims
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1. A method of determining the syntactic correctness of an expression for use in a computing environment, said method comprising the steps of:
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(a) creating a string of characters from said expression;
(b) iteratively substituting occurrences of said characters also occurring in a first predetermined list with characters from a second predetermined list; and
(c) determining said expression to be syntactically correct only if said string reduces to a single predetermined character. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A computer readable memory medium for storing a program for apparatus which determines the syntactic correctness of an expression for use in a computing environment, said program comprising:
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code for a creation step for creating a string of characters from said expression;
code for a substitution step for iteratively substituting occurrences of said characters also occurring in a first predetermined list with characters from a second predetermined list; and
code for a determination step for determining said expression to be syntactically correct only if said string reduces to a single predetermined character. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification