Introduction to Lexical Analysis

A TLex object is used to perform lexical analysis. The class is used to:

• store a string

• maintain an extraction mark to indicate the current lexical element being analysed

• maintain a pointer to indicate the next character to be examined.

Member functions provide facilities to allow analysis and extraction of lexical elements from a TLex object, and a variety of string-to-number conversions.

The TLex class provides general-purpose lexical analysis functions, using the locale-dependent functions of TChar to identify whether characters are digits, letters etc. The data for these locale-dependent functions is held in kernel-side locale tables. Thus, TLex functions which use them, require an executive call. If an application requires very fast lexical analysis of a language which is not locale-specific, then there may be some advantage in designing and implementing a special-purpose lexical analyser class.