[antlr-interest] Newbie with a simple problem

[Martijn Reuvers]

Hello Tom,

First: don't use literals (the strings) in parser rules, this always
gives problems sooner or later and makes error reporting bad - use
real tokens instead.

To skip whitespace between tokens (you can also write it to a hidden
channel if you need it later):

WS
	: (' ' | '\t' | '\n' | '\r')+
		{ skip(); }
  ;

Regards,
Martijn


On Mon, Feb 27, 2012 at 7:37 PM, Tom Hicks <headhunter3 at gmail.com> wrote:
> I need to implement a fairly simple scripting language for a project
> I'm working on and I'm trying to use antlr to help.
>
> I'm not sure if antlr is the right tool for this so I'm going to start
> by explaining how I'm trying to use the script.
> Each line is either whitespace, a directive, or an action.
> Whitespace is only for readability and when I load the script should be ignored.
> Actions are things like show a message box, play a bgm, or change the
> current character and background images.  There are more but they are
> all implemented the same way.
> Directives are used to set options on groups of actions.  Each action
> has a play condition so if I put a message box action after an "#if
> HasHadConversation dlg_darren_photos" directive and before the
> corresponding "#endif" directive, then the action should have it's
> playcondition set to "HasHadConversation dlg_darren_photos" Which is
> another data model object.
> I can explain that in more detail if necessarry, but I don't want to
> make this too long.
>
> When I load the script file I want to generate a list of the
> appropriate actions.  I have this working except for the directives
> just using regular expressions, unfortunately the logical expressions
> in the directives can't be matched to regular expressions.
> So I started looking at parser generators but everything else I've
> found expects that I'm familiar with bison/lex and I'm not.  Antlr
> looks far more friendly and supports C# which is what I need.
>
> I tried writing a grammar for the script other than an extremely
> trivial example I'm completely stumped.
>
> When I use the following grammar with the input "_SC play test 01"
> (without the quotes). I get a NoViableAltException.  "_SC stop" works
> though
> grammar PBScript;
> options {
> output = AST;
> }
>
> line    :       '_SC stop'
>        |       '_SC play ' ASSETNAME
>        ;
> ASSETNAME
>        :       (~('\n'|'\r'))+ ;
>
> If instead I use this grammar it works but captures the space as part
> of ASSETNAME
> grammar PBScript;
> options {
> output = AST;
> }
>
> line    :       '_SC stop'
>        |       '_SC play' ASSETNAME
>        ;
> ASSETNAME
>        :       ' '(~('\n'|'\r'))+ ;
>
> ~Tom
>
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