lex for Not Yet Techies

lex is a Unix software tool, often used in conjunction with yacc and compiler writing, that generates programs for simple lexical tasks. Yet lex may be used as a standalone utility generating code automatically and more reliably than a programmer might do.

lex source files are short and easier to read than the equivalent C code and thus produce more maintainable products.

It is very similar to awk, so we can sometimes replace awk-based solutions which normally involve shell scripts and multiple tools with a single based process.

It is a compiler writing tool and is also well suited to scanning an input stream of characters for transformation or analysis. Like awk, a source file of patterns and their associated actions is provided as an input script. Each time a pattern (using regular expressions and literals) maps to the input data it triggers an action(s). Unlike awk it does not perform the action immediately but instead generates a C source file containing a C function called yylex().

1. The standard documentation can be a barrier
2. It is usually in the shadow of yacc and therefore often overlooked as a standalone software tool
3. Simple problems can be solved simply in conventional programming language

Yet it can be used to implement even simple programs more quickly than a conventional programming language.

A script is usually much more readable than a conventional programming language.

lex is easy to learn, especially if one is familiar with the syntax of C and regular expressions.

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