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POtraversing an ast having complex conditional expression to generate linq expression
 

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  1. POtraversing an ast having complex conditional expression to generate linq expression
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    <p>I'm using Irony.net for generating a parse tree out of the source. Essentially I'm using ExpressionEvaluatorGrammer like grammer for binary expressions (arithmetic, relational and logical/conditional). I want to convert the resultant parse tree into Linq expression by traversing it. However, the tree does not seem to have a formation directly convertable to linq conditional expression. Hypothetical example of such an expression:</p> <pre><code>1 == 1 &amp;&amp; 4 - 1 == 3 </code></pre> <p>generates (pseudo xml tree for brevity):</p> <pre><code>&lt;binary&gt; &lt;binary&gt; &lt;binary&gt; &lt;literal&gt;1&lt;/literal&gt; &lt;op&gt;==&lt;/op&gt; &lt;literal&gt;1&lt;/literal&gt; &lt;/binary&gt; &lt;op&gt;&amp;&amp;&lt;/op&gt; &lt;binary&gt; &lt;literal&gt;4&lt;/literal&gt; &lt;op&gt;-&lt;/op&gt; &lt;literal&gt;1&lt;/literal&gt; &lt;/binary&gt; &lt;/binary&gt; &lt;op&gt;==&lt;/op&gt; &lt;literal&gt;3&lt;/literal&gt; &lt;/binary&gt; </code></pre> <p>In the tree above, the arithmetic expression (4 - 1) becomes the right expression to the &amp;&amp; logical operation as the parent node closes after it. In the ideal world, it should have been a left expression of the nodes representing "== 3".</p> <p>How do you traverse such a tree to generate a proper and operation? Or, is there a way to generate the tree in the form I desire?</p> <p>Edit: here's the grammer (partial) definition. I have taken it from ExpressionEvaluatorGrammer that comes with Irony.interpreter.</p> <pre><code>RegisterOperators(15, "&amp;", "&amp;&amp;", "|", "||"); RegisterOperators(20, "==", "&lt;", "&lt;=", "&gt;", "&gt;=", "!="); RegisterOperators(30, "+", "-"); RegisterOperators(40, "*", "/"); Expr.Rule = Term Term.Rule = number | ParExpr | stringLit | FunctionCall | identifier | MemberAccess | IndexedAccess; ParExpr.Rule = "(" + Expr + ")"; BinExpr.Rule = Expr + BinOp + Expr; BinOp.Rule = ToTerm("+") | "-" | "*" | "/" | "**" | "==" | "&lt;" | "&lt;=" | "&gt;" | "&gt;=" | "!=" | "&amp;&amp;" | "||" | "&amp;" | "|"; </code></pre>
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    1. USVarun K
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    1. COI don't know Irony.Net but the xml it generates corresponds to ((1==1)&&(4*1))==3. Either it is the case that && and == has equal precedence while * has a higher precedence or it is a bug. You might try to add paranthesis before parsing, or use another tool. If the actual grammar is not much more complicated it should not be difficult to write a parser (that directly generates an expression) by hand.
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      1. USAli Ferhat
    2. COWhat do your calls to `RegisterOperators` look like and how do you set up the associativity?
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    3. CO@sixlettervariables please see the grammer with precedence
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