Integration options

If both lexer and parser are generated using Alpag, user has following options:

• define both lexer and parser in one common grammar file, and:
• generate single class which hosts combined lexer-parser
• generate separate classes for lexer and parser which must be integrated
• define lexer and parser in distinct files, process them separately and integrate later on

Choosing either of above approaches is matter of convenience. Separate lexers and parsers are often preferred during development. In release version combined lexer-parser may be a better solution. It is relatively easy to switch between above options.

When option LexerParser.Combined is set to true, a single class with both lexer and parser is generated. When this option is false lexer and parser are hosted in own separate classes.

Options describing generated classes are grouped in:

• LexerParser.Code for combined lexer-parser
• Lexer.Code for standalone lexer
• Parser.Code for standalone parser

Even if single Alpag input file contains definition of both lexer and, it is still possible to generate these components separately using switches:

Generates lexer only. Parser component, if present, is ignored

Generates parser only. lexer component, if present, is ignored.

Note that syntax of entire input file must be correct even if generation of either parser or lexer is to be skipped.