hlvm/docs/status/2006-05-25.html

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<h1>Status As Of May 25, 2006</h1>
<p>HLVM is moving along nicely. We have accomplished much in our first
month:</p>
<ul>
  <li>A few new people became interested in HLVM (Hi laurence and Slant).</li>
  <li>Everyone participated in making some design documentation in the wiki 
  site. It was populated with some designs and a mind map.</li>
  <li>Implemented 43 node types for the 
  <a href="/apis/html/classhlvm_1_1AST.html">Abstract Syntax Tree (AST)</a>in 
  C++. These represent the various program constructs (
  <a href="/apis/html/classhlvm_1_1Bundle.html">Bundle</a>, 
  <a href="/apis/html/classhlvm_1_1Program.html">Program</a>,
  <a href="/apis/html/classhlvm_1_1Function.html">Function</a>,
  <a href="/apis/html/classhlvm_1_1Variable.html">Type</a>,
  <a href="/apis/html/classhlvm_1_1Variable.html">Value</a>,
  <a href="/apis/html/classhlvm_1_1Variable.html">Variable</a>,
  <a href="/apis/html/classhlvm_1_1Block.html">Block</a>,
  <a href="/apis/html/classhlvm_1_1Operator.html">Operator</a>, etc.) that can 
  be defined by a source language. There are also a few super-classes 
  (
  <a href="/apis/html/classhlvm_1_1Node.html">Node</a>, 
  <a href="/apis/html/classhlvm_1_1Documentable.html">Documentable</a>,
  <a href="/apis/html/classhlvm_1_1LinkageItem.html">LinkageItem</a>) to allow 
  identification of categories of the AST nodes. See the 
  <a href="/apis/html/hierarchy.html">class hierarchy</a> for more details.
  A simple model for AST construction was adopted, that of "setParent".
  To insert a node, you simply tell it which node is its parent. The parent
  node then "owns" that child node.</li>
  <li>Implemented an 
  <a href="/apis/html/classhlvm_1_1XMLReader.html">XMLReader</a> based on 
  libxml2 to convert XML into AST nodes. This library uses the 
  <a href="http://hlvm.org/src/hlvm/Reader/XML/HLVM.rng">HLVM grammar</a> to
  validate an XML document that corresponds to the structure of the Abstract
  Syntax Tree.
  This is how we populate the AST in memory.</li>
  <li>Implemented a 
  <a href="/apis/html/classhlvm_1_1Pass.html">Pass</a> and 
  <a href="/apis/html/classhlvm_1_1PassManager.html">PassManager</a> 
  infrastructure for traversals through the AST. Passes can ask for pre-order, 
  post-order and both-order calls as the PassManager traverses the tree. This 
  gives us a single location in which the logic for walking the HLVM AST is 
  implemented.</li>
  <li>Implemented an 
  <a href="/apis/html/classhlvm_1_1XMLWriter.html">XMLWriter</a> based on 
  libxml2 to convert AST nodes into XML. This is the converse of the reader. 
  It takes an in-memory AST and generates XML output. The XMLWriter uses an 
  HLVM Pass to walk the tree.</li>
  <li>Implemented the 
  <a href="/src/tools/hlvm-xml2xml/hlvm-xml2xml.cpp">hlvm-xml2xml</a> tool to 
  convert XML -&gt; AST -&gt; XML. This is simply a combination of the 
  XMLReader, AST, and XMLWriter. Its purpose is to provide the means for 
  testing AST construction and validation.</li>
  <li>Implemented the beginnings of a validation pass to validate the AST
  nodes. This pass is now invoked from the hlvm-xml2xml program to validate that
  what was read is a legal AST.</li>
  <li>Started an implementation of a type resolving pass to assist with forward
  references in the tree and resolve them to their actual types.</li>
  <li>Implemented 12 test cases via deja-gnu to exercise AST construction with 
  the hlvm-xml2xml program. These implement an identity test where the output
  must match the input exactly. All tests pass as of this date.</li>
  <li>David began preparing additional test cases, as XML documents, to explore
  the AST nodes that are needed in HLVM, based on a review of Ruby.</li>
  <li>Completely rewrote the build system to use scons. The Makefile system,
  although working, was difficult to maintain and modify. scons gives us much
  more flexibility and some new capabilities as well.</li>
  <li>Got the doxygen documentation to auto-build and generated it to the public
  web site.</li>
  <li>David started work on documenting the AST specification in the HLVM.rng
  grammar (Relax/NG grammar for the Abstract Syntax Tree). We'll use XSLT to 
  convert this to HTML so we have one source for specifying and documenting 
  the AST nodes.</li>
  <li>David got HLVM to build on Mac OS/X.</li>
  <li>Saem got HLVM to build on SuSE Linux.</li>
  <li>Reid got HLVM to build on Fedora Core 3</li>
</ul>
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