Erlang Plugin for NetBeans in Scala#7: Occurrences Finder

During the AST node visiting (AstNodeVisitor.scala), I’ve gathered a lot of variable definitions and their references, we can now try to get editor to mark these occurrences. There are preliminary functions in AstScope.scala, such as findOccurrences(AstItem). You can override AstDfn#isReferredBy(AstRef) and AstRef#isOccurence(AstRef) to get accurate reference relations. As the first step, I just simply judge the reference relation by the equation of names.

We’ll extends org.netbeans.modules.csl.api.OccurrencesFinder and implement:

run(pResult:ErlangParserResult, event:SchedulerEvent) :Unit

First, we try to get the AstItem which is at the caretPosition by rootScope.findItemAt(th, caretPosition), and verify if it’s a valid token.

Then, by calling rootScope.findOccurrences(item), we collect all occurrences of this item, and put a ColoringAttributes.MARK_OCCURRENCES with its OffsetRange.

The code of ErlangOccurrencesFinder.scala:

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package org.netbeans.modules.erlang.editor import _root_.java.util.{HashMap,List,Map}
import javax.swing.text.Document
import org.netbeans.api.lexer.{Token,TokenId,TokenHierarchy}
import _root_.org.netbeans.modules.csl.api.{ColoringAttributes,OccurrencesFinder,OffsetRange}
import org.netbeans.modules.parsing.spi.Parser
import org.netbeans.modules.parsing.spi.{Scheduler,SchedulerEvent}
import org.netbeans.modules.erlang.editor.ast.{AstDfn,AstItem,AstRef,AstRootScope}
import org.netbeans.modules.erlang.editor.lexer.{ErlangTokenId,LexUtil}
import org.openide.filesystems.FileObject /** * * @author Caoyuan Deng */
class ErlangOccurrencesFinder extends OccurrencesFinder[ErlangParserResult] { protected var cancelled = false private var caretPosition = 0 private var occurrences :Map[OffsetRange, ColoringAttributes] = _ private var file :FileObject = _ protected def isCancelled = synchronized {cancelled} protected def resume :Unit = synchronized {cancelled = false} override def getPriority = 0 override def getSchedulerClass = Scheduler.CURSOR_SENSITIVE_TASK_SCHEDULER override def getOccurrences :Map[OffsetRange, ColoringAttributes] = occurrences override def cancel :Unit = synchronized {cancelled = true} override def setCaretPosition(position:Int) :Unit = {this.caretPosition = position} def run(pResult:ErlangParserResult, event:SchedulerEvent) :Unit = { resume if (pResult == null || isCancelled) { return } val currentFile = pResult.getSnapshot.getSource.getFileObject if (currentFile != file) { // Ensure that we don't reuse results from a different file occurrences = null file = currentFile } for (rootScope <- pResult.rootScope; th <- LexUtil.tokenHierarchy(pResult); doc <- LexUtil.document(pResult, true); // * we'll find item by offset of item's idToken, so, use caretPosition directly item <- rootScope.findItemAt(th, caretPosition); idToken <- item.idToken ) { var highlights = new HashMap[OffsetRange, ColoringAttributes](100) val astOffset = LexUtil.astOffset(pResult, caretPosition) if (astOffset == -1) { return } // * When we sanitize the line around the caret, occurrences // * highlighting can get really ugly val blankRange = pResult.sanitizedRange if (blankRange.containsInclusive(astOffset)) { return } // * test if document was just closed? LexUtil.document(pResult, true) match { case None => return case _ => } try { doc.readLock val length = doc.getLength val astRange = LexUtil.rangeOfToken(th.asInstanceOf[TokenHierarchy[TokenId]], idToken.asInstanceOf[Token[TokenId]]) val lexRange = LexUtil.lexerOffsets(pResult, astRange) var lexStartPos = lexRange.getStart var lexEndPos = lexRange.getEnd // If the buffer was just modified where a lot of text was deleted, // the parse tree positions could be pointing outside the valid range if (lexStartPos > length) { lexStartPos = length } if (lexEndPos > length) { lexEndPos = length } LexUtil.token(doc, caretPosition) match { case None => return case token => // valid token, go on } } finally { doc.readUnlock } val _occurrences = rootScope.findOccurrences(item) for (_item <- _occurrences; _idToken <- _item.idToken ) { highlights.put(LexUtil.rangeOfToken(th.asInstanceOf[TokenHierarchy[TokenId]], _idToken.asInstanceOf[Token[TokenId]]), ColoringAttributes.MARK_OCCURRENCES) } if (isCancelled) { return } if (highlights.size > 0) { val translated = new HashMap[OffsetRange, ColoringAttributes](2 * highlights.size) val entries = highlights.entrySet.iterator while (entries.hasNext) { val entry = entries.next LexUtil.lexerOffsets(pResult, entry.getKey) match { case OffsetRange.NONE => case range => translated.put(range, entry.getValue) } } highlights = translated this.occurrences = highlights } else { this.occurrences = null } } }
}

Finally, again, register it in ErlangLanguage.scala

override def hasOccurrencesFinder = true
override def getOccurrencesFinder = new ErlangOccurrencesFinder

And add mark-occurrences effect setting in fontsColors.xml:

<fontcolor name="mark-occurrences" bgColor="ECEBA3"/>

That’s all. Run it, you got:

Var LogPid’s definition and references were highlighted now.

The correctness of occurrences marking depends on the correctness of scopes of variables when you visit AST node, I did not finish all of such work yet, but, enabling occurrences marking feature is very helpful for further work.

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