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Problems with unary ++, -- [message #645550]

Fri, 17 December 2010 19:55

drew frantz

Messages: 340
Registered: July 2009

Senior Member

I am trying to build some rules for the java/C++ like ++,-- operators. That
I based loosely on the java 1.6 anltl grammar.

This works
int x=2;
x=++x;
x=--x;
x=x++;
x=x--;

but these do not
int x=2;
++x;
--x;
x++;
x--;

Has anyone built these kind of rules in their DSl's?
UnaryExpression ({ExpressionTree.leftExpr=current} operator=PowerOperator
rightExpr=UnaryExpression)*;

UnaryExpression returns Expression

: operator=AddOperator rightExpr=UnaryExpression

| operator=IncDecOperator rightExpr=UnaryExpression

| UnaryExpressionNotPlusMinus;

UnaryExpressionNotPlusMinus returns Expression

: operator=NotOperator rightExpr=UnaryExpression

| SimpleExpression ({ExpressionTree.leftExpr=current}
operator=IncDecOperator)?

;

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Re: Problems with unary ++, -- [message #645556 is a reply to message #645550]

Fri, 17 December 2010 23:27

No real name

Messages: 25
Registered: April 2010

Junior Member

in the First example you provide:

int x=2;
x=++x;
x=--x;
x=x++;
x=x--;

The unary operators are parsed as expressions.

In the second, the parser probably expects (depends on the rest of the grammar which you havent shown) a statement. Did you make the unuary expressions a statement as well?

e.g.

Statement:
.... //your statements here
| UnaryExpression SEMI;

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Re: Problems with unary ++, -- [message #645570 is a reply to message #645550]

Sat, 18 December 2010 01:57

Henrik Lindberg

Messages: 2509
Registered: July 2009

Senior Member

Hi, here is the relevant part from the b3 grammar. The InfixExpression
is the next expression up the precedence chain...

UnaryOrInfixExpression returns be::BExpression
: PostopExpression
| UnaryExpression
| PreopExpression
;

UnaryExpression returns be::BExpression : {be::BUnaryOpExpression}
functionName=("!" | "-") expr=InfixExpression
;

PreopExpression returns be::BExpression : {be::BUnaryPreOpExpression}
functionName=("++" | "--") expr=InfixExpression
;

PostopExpression returns be::BExpression :
InfixExpression ({be::BUnaryPostOpExpression.expr=current} functionName
= ("--" | "++"))?
;

Regards
- henrik

On 12/17/10 8:55 PM, Drew wrote:
> I am trying to build some rules for the java/C++ like ++,-- operators. That
> I based loosely on the java 1.6 anltl grammar.
>
> This works
> int x=2;
> x=++x;
> x=--x;
> x=x++;
> x=x--;
>
> but these do not
> int x=2;
> ++x;
> --x;
> x++;
> x--;
>
> Has anyone built these kind of rules in their DSl's?
> UnaryExpression ({ExpressionTree.leftExpr=current} operator=PowerOperator
> rightExpr=UnaryExpression)*;
>
>
> UnaryExpression returns Expression
>
> : operator=AddOperator rightExpr=UnaryExpression
>
> | operator=IncDecOperator rightExpr=UnaryExpression
>
> | UnaryExpressionNotPlusMinus;
>
>
>
> UnaryExpressionNotPlusMinus returns Expression
>
> : operator=NotOperator rightExpr=UnaryExpression
>
> | SimpleExpression ({ExpressionTree.leftExpr=current}
> operator=IncDecOperator)?
>
> ;
>
>

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Re: Problems with unary ++, -- [message #645606 is a reply to message #645556]

Sat, 18 December 2010 17:25

drew frantz

Messages: 340
Registered: July 2009

Senior Member

Yes that was the issue. Thanks for the help.

<Wattos@gmail.com> wrote in message news:iegrca$qe3$1@news.eclipse.org...
> in the First example you provide:
>
> int x=2;
> x=++x;
> x=--x;
> x=x++;
> x=x--;
>
>
> The unary operators are parsed as expressions.
> In the second, the parser probably expects (depends on the rest of the
> grammar which you havent shown) a statement. Did you make the unuary
> expressions a statement as well?
> e.g.
>
> Statement:
> ... //your statements here
> | UnaryExpression SEMI;
>

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