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POConverting Antlr syntax tree into useful objects
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copied!<p>I'm currently pondering how best to take an AST generated using Antlr and convert it into useful objects which I can use in my program. </p> <p>The purpose of my grammar (apart from learning) is to create an executable (runtime interpretted) language. </p> <p>For example, how would I take an attribute sub-tree and have a specific Attribute class instanciated. E.g. </p> <p>The following code in my language:</p> <pre><code>Print(message:"Hello stackoverflow") </code></pre> <p>would product the following AST:</p> <p><a href="http://img36.imageshack.us/img36/1672/simpleast.png" rel="nofollow noreferrer">alt text http://img36.imageshack.us/img36/1672/simpleast.png</a></p> <p>My current line of thinking is that a factory class could read the tree, pull out the name (<code>message</code>), and type(<code>STRING</code>) value("<code>Hello stackoverflow</code>"). Now, knowing the type I could instanciate the correct class (e.g. A StringAttribute class) and pass in the required attribute data - the <code>name</code> and <code>value</code>.</p> <p>The same approach could be used for a definition factory, pulling out the definition name (<code>Print</code>), instanciating the Print class, and then passing in the attributes generated from the attribute factory.</p> <p>Things do get a bit more complicated with a more complicated program:</p> <pre><code>Program(args:[1,2,3,4,5]) { If(isTrue:IsInArray(array:{Program.args} value:5)) { Then { Print(message:"5 is in the array") } Else { Print(message:"More complex " + "message") } } } </code></pre> <p><a href="http://img205.imageshack.us/img205/3452/complexast.png" rel="nofollow noreferrer">alt text http://img205.imageshack.us/img205/3452/complexast.png</a></p> <p>ANY/ALL help or thoughts are very welcome. Many thanks.</p> <p>Previous related questions by me (Could be useful):</p> <ol> <li><a href="https://stackoverflow.com/questions/2061166/how-do-i-make-a-treeparser-in-antrl3/2061277#2061277">How do I make a tree parser</a> </li> <li><a href="https://stackoverflow.com/questions/2113703/antlr-left-recursive-problem/2117334#2117334">Solving LL recursion problem</a></li> <li><a href="https://stackoverflow.com/questions/2129569/antrl3-conditional-tree-rewrites/2136770#2136770">Antrl3 conditional tree rewrites</a></li> </ol>

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