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need explanation regarding assignments [message #870552]

Tue, 08 May 2012 12:23

Eclipse User

I'm totaly new in Xtext and have a probably simple question.

Here is my code.
Several different types of lines will be present in my language, here you only see two of them (activity_line and command_line).

Model:
		lines+=line*
		;

line:		activity_line  |
		command_line
		;

activity_line:	'activity:' name=ID comment*
		;

command_line:	'command:' ID comment*
		;

comment:	'#' ID*
		;

Now the question:
What causes the assignment name=ID in rule activity_line. The generated editor recognizes equivalent the same at the command_line rule, when I only regard the Syntaxhighlighting, spell checking etc.

Can somebody tell me the difference of name=ID and ID?
Can I somehow use the 'name' as some kind of variable, where the explicit ID is stored? I can't understand that...

Thanks so far.

[Updated on: Tue, 08 May 2012 14:26] by Moderator

Re: need explanation regarding assignments [message #870565 is a reply to message #870552]

Tue, 08 May 2012 14:34

Eclipse User

Hi,

guess some basic reading on parsers will help you. Xtext does not only parse (this would be senseless) but it creates an Object Tree / Abstract Syntax Tree too. This tree can be used in a code Generator or Interpreter.

The tree is actually a Graph that consists of Nodes (EClass). There eclasses have attributes and can contain other Nodes (through a containment reference) and reference other Nodes (Cross References)

doing a Xtext tutorial and doing some basic reading on EMF Ecore will give you more information.

~Christian

Re: need explanation regarding assignments [message #870726 is a reply to message #870565]

Wed, 09 May 2012 09:22

Eclipse User

Thanks Christian,

that hadn't solved my problem directly, but it can never be wrong to read some basics again Wink

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