RQL grammar for Xtext

gistfile1.xtend

grammar org.xtext.rql.RQL //with org.eclipse.xtext.common.Terminals

import "http://www.eclipse.org/emf/2002/Ecore" as ecore

generate rQL "http://www.xtext.org/rql/RQL"

//Model:
//	greetings+=Greeting*;
//	
//Greeting:
//	'Hello' name=ALPHA '!';
	
Model:
	operands+=Ho_operand ( (','|'&')* Ho_operand )
;
	
And: Ho_operand ( '&' Ho_operand )+;
Or: Ho_operand ( (';'|'|') Ho_operand )+;

Ho_operand:
	WSP* ( Higher_order_call | Call_operator | Predicate | Comparison | ( "(" (And | Or) ")" ) ) WSP*
;
	
Logical_op_aliases: ("or"|"and"|"not");
Higher_order_call:
	Logical_op_aliases WSP* '(' ( Ho_operand ( "," Ho_operand )* ) ')'
;
	
Binary_op_aliases: ("ne"|"eq"|"lt"|"le"|"gt"|"ge"|"like");
Comp_ops : ("!="|"="|"<"|"<="|">"|">=");
Comparison : Strval WSP* ( ( '=' Binary_op_aliases '=' ) | Comp_ops ) Primary_expr;

Call_operator:
	( Binary_op_aliases | Functions_tbl ) WSP* '(' ( Primary_expr ( "," Primary_expr )* )? ')'
;

Pred_tbl: ("select"|"sort"|"limit"|"implementing"|"composing");
Predicate: Pred_tbl WSP* '(' ( Primary_expr ( ',' Primary_expr )* )? ')';
	
Primary_expr:
	WSP* ( ( Const_func_tbl WSP* '(' WSP* ')' ) | Array | Strval ) WSP*
;

Functions_tbl: ("isnull"|"in"|"out");
Const_func_tbl : ("true"|"false"|"empty"|"null");
	
Array: '(' WSP* Strval WSP* ("," WSP* Strval WSP* )* ')';

Nchar: (ALPHA|DIGIT|'-'|'.'|'_'|'~'|'$'|':'|'*'|'+'|'?'|'/'|'@');
Pct_encoded: '%' XDIGIT XDIGIT;	
Strval:	(Nchar|Pct_encoded)*;
	
terminal ALPHA:	('A'..'Z'|'a'..'z');
terminal DIGIT:	('0'..'9');
terminal XDIGIT: (DIGIT|'A'..'F');
//terminal SP: ' ';
//terminal HTAB: '\t';
terminal WSP: (' '|'\t');
//DIGIT          =  %x30-39;
//XDIGIT         =  DIGIT / "A" / "B" / "C" / "D" / "E" / "F";
//SP             =  %x20;
//HTAB           =  %x09;
//WSP            =  SP / HTAB;