| | |
| | /** |
| | - * Parses the expression into an abstract tree. |
| | + * Parses the Relational eXpression Map (<b>rxm</b>) into a tree. |
| | */ |
| | public class Parser extends QueryBaseListener { |
| | private static int INDENT = 2; |
| | |
| | + /** Map for containing modules. */ |
| | private RXM rxm; |
| | - |
| | - /** Used to convert linear map to hierarchical form. */ |
| | - private List<String> statements = new ArrayList<String>(); |
| | - |
| | - /** The tree constructed while walking the <b>rxm</b>. */ |
| | - private Tree<ParserRuleContext> queryTree; |
| | |
| | - /** Current context within queryTree. */ |
| | + /** Current context. */ |
| | private Tree<ParserRuleContext> contextTree; |
| | |
 |
| | } |
| | |
| | + /** |
| | + * Parses the given <b>rxm</b> text. This creates a tree that is used |
| | + * for context when building the query. |
| | + * |
| | + * @param rxm The <b>rxm</b> string to parse. |
| | + */ |
| | public void parse( String rxm ) { |
| | QueryLexer lexer = new QueryLexer( new ANTLRInputStream( rxm ) ); |
| | CommonTokenStream tokens = new CommonTokenStream( lexer ); |
| | |
| | QueryParser parser = new QueryParser( tokens ); |
| | QueryParser.QueryContext ctx = parser.query(); |
| | |
| | ParseTreeWalker walker = new ParseTreeWalker(); |
| | walker.walk( this, ctx ); |
| | - } |
| | - |
| | - @Override |
| | - public synchronized void enterQuery( QueryParser.QueryContext ctx ) { |
| | - setQueryTree( createTree( ctx ) ); |
| | } |
| | |
| | + /** |
| | + * Adds the root context node to the top-most part of the tree. This |
| | + * sets the context tree to the root context node. |
| | + * |
| | + * @param ctx The root context node. |
| | + */ |
| | @Override |
| | public synchronized void enterRoot( QueryParser.RootContext ctx ) { |
| | - setContextTree( getQueryTree().addLeaf( ctx ) ); |
| | + setContextTree( createTree( ctx ) ); |
| | } |
| | |
| | + /** |
| | + * Invoked when parsing <code>table > node</code>. Adds a new leaf to |
| | + * the context tree, then changes the context tree to the newly added leaf. |
| | + */ |
| | @Override |
| | public synchronized void enterTableMap( QueryParser.TableMapContext ctx ) { |
| | setContextTree( getContextTree().addLeaf( ctx ) ); |
| | } |
| | |
| | + /** |
| | + * Invoked when parsing <code>column > node</code>. Adds a new leaf to |
| | + * the context tree. |
| | + */ |
| | @Override |
| | public synchronized void enterColumnMap( QueryParser.ColumnMapContext ctx ) { |
| | getContextTree().addLeaf( ctx ); |
| | } |
| | |
| | + /** |
| | + * Invoked when parsing <code>^</code>. Changes context tree to its parent. |
| | + * If the parent doesn't exist, this will fail silently. |
| | + */ |
| | @Override |
| | public synchronized void enterPop( QueryParser.PopContext ctx ) { |
| | - setContextTree( getContextTree().getParent() ); |
| | + Tree<ParserRuleContext> parent = getContextTree().getParent(); |
| | + |
| | + if( parent != null ) { |
| | + setContextTree( getContextTree().getParent() ); |
| | + } |
| | } |
| | |
| | + /** |
| | + * Invoked when there are no more <b>rxm</b> tokens to parse. |
| | + */ |
| | @Override |
| | public synchronized void exitQuery( QueryParser.QueryContext ctx ) { |
|
| | @Override |
| | public String toString() { |
| | - return toString( getQueryTree().getLeaves().get(0), INDENT ); |
| | + return toString( getContextTree().getRoot(), INDENT ); |
| | } |
| | |
|
| | } |
| | |
| | + /** |
| | + * Creates a string of spaces that is spaces spaces long. |
| | + * |
| | + * @param spaces The number of spaces to add to the string. |
| | + */ |
| | private String indent( int spaces ) { |
| | String empty = CharBuffer.allocate( spaces ).toString(); |
|
| | private RXM getRXM() { |
| | return this.rxm; |
| | - } |
| | - |
| | - private List<String> getStatements() { |
| | - return this.statements; |
| | } |
| | |
| | + /** |
| | + * Changes where the next mapped items will be attached. |
| | + */ |
| | private void setContextTree( Tree<ParserRuleContext> contextTree ) { |
| | this.contextTree = contextTree; |
| | } |
| | |
| | + /** |
| | + * Returns where to attach upcoming map items. |
| | + */ |
| | private Tree<ParserRuleContext> getContextTree() { |
| | return this.contextTree; |
| | - } |
| | - |
| | - private void setQueryTree( Tree<ParserRuleContext> queryTree ) { |
| | - this.queryTree = queryTree; |
| | - } |
| | - |
| | - private Tree<ParserRuleContext> getQueryTree() { |
| | - return this.queryTree; |
| | } |
| | |