Dartest CL - Please review

compiler/java/com/google/dart/compiler/ast/CoverageInstrumenter.java

+package com.google.dart.compiler.ast;
+
+import java.math.BigInteger;
+import java.net.URI;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import com.google.dart.compiler.common.SourceInfo;
+import com.google.dart.compiler.CommandLineOptions.CompilerOptions;
+import com.google.dart.compiler.CompilerConfiguration;
+
+/**
+ * CoverageInstrumenter contains specialized instrumenters to perform specific
+ * instrumentation for obtaining coverage of different program entities
+ */
+public class CoverageInstrumenter {
+  private List<BaseInstrumenter> instrumenters;
+  private static final String[] ignoredLibs = { "corelib", "corelib_impl",
+      "dom", "html", "htmlimpl", "base", "touch", "view", "utilslib",
+      "observable", "layout.dart", "unittest", "dartest" };
+
+  // Only createInstance should be used to instantiate this class
+  private CoverageInstrumenter() {
+  }
+
+  /**
+   * Method to instantiate a CoverageInstrumenter containing multiple
+   * instrumenters created based on command line flags.
+   * 
+   * @param config
+   * @return instance of this class
+   */
+  public static CoverageInstrumenter createInstance(
+      CompilerConfiguration config) {
+
+    CompilerOptions compilerOptions = config.getCompilerOptions();
+    String coverageTypes = compilerOptions.getCoverageType();
+
+    CoverageInstrumenter instr = new CoverageInstrumenter();
+    if (!"".equals(coverageTypes)) {
+      String outDir = compilerOptions.getWorkDirectory()
+          .getAbsolutePath();
+      instr.createInstrumenters(coverageTypes, outDir);
+    }
+    return instr;
+  }
+
+  /**
+   * Performs instrumentation of all classes
+   * 
+   * @param libraries
+   */
+  public void process(Map<URI, LibraryUnit> libraries) {
+
+    if (instrumenters == null) {
+      return;
+    }
+
+    // Instrument all dart units
+    for (LibraryUnit lib : libraries.values()) {
+      for (DartUnit unit : lib.getUnits()) {
+        exec(unit);
+      }
+    }
+
+    // Populate totals and initialize coverage
+    for (LibraryUnit lib : libraries.values()) {
+      for (DartUnit unit : lib.getUnits()) {
+        init(unit);
+      }
+    }
+  }
+
+  /**
+   * Runs all instrumenters on a particular Dart unit
+   * 
+   * @param unit
+   */
+  private void exec(DartUnit unit) {
+    if (isIgnored(unit)) {
+      return;
+    }
+    System.out.println("Instrumenting " + unit.getSourceName() + ", lib:"

[zundel, 2011/12/16 20:49:05]

this looks like debugging...  for a real dart program you going to get a lot of
output here. 

+        + unit.getLibrary().getName());
+    for (BaseInstrumenter instrumenter : instrumenters) {
+      instrumenter.accept(unit);
+    }
+  }
+
+  /**
+   * Ignores a Dart unit based on the library it belongs to
+   * 
+   * @param unit
+   * @return true is the unit should be ignored
+   */
+  private boolean isIgnored(DartUnit unit) {
+    LibraryUnit lu = unit.getLibrary();
+    if (lu != null) {
+      String libName = lu.getName();
+      for (String ignoredLib : ignoredLibs) {
+        if (ignoredLib.equals(libName)) {
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
+  /**
+   * Runs the TotalSettingInstrumenter on the supplied Dart unit, which adds
+   * totals of all coverable program entities
+   * 
+   * @param unit
+   */
+  private void init(DartUnit unit) {
+    if (isIgnored(unit)) {
+      return;
+    }
+    new TotalSettingInstrumenter().accept(unit);
+  }
+
+  /**
+   * Factory method to create instrumenters based on supplied command line
+   * configuration
+   * 
+   * @param coverageTypes
+   * @param outDir
+   */
+  private void createInstrumenters(String coverageTypes, String outDir) {
+    BaseInstrumenter.setOutDir(outDir);
+    instrumenters = new ArrayList<BaseInstrumenter>();
+    if (coverageTypes.length() > 0) {
+      for (String covType : coverageTypes.split(",")) {
+        if ("all".equals(covType)) {

[zundel, 2011/12/16 20:49:05]

instead of inlined strings, I'd make constants out of these values.

+          instrumenters.add(new StatementInstrumenter());
+          instrumenters.add(new FunctionInstrumenter());
+          instrumenters.add(new BranchInstrumenter());
+        }
+        if ("statement".equals(covType)) {
+          instrumenters.add(new StatementInstrumenter());

[zundel, 2011/12/16 20:49:05]

is it going to cause problems if you add the same instrumenter more than once? 
Maybe instrumenters should be a Set?

+        }
+        if ("function".equals(covType)) {
+          instrumenters.add(new FunctionInstrumenter());
+        }
+        if ("branch".equals(covType)) {
+          instrumenters.add(new BranchInstrumenter());
+        }
+      }
+    }
+  }
+
+  /**
+   * The Base Instrumenter class that provides some common functionalities to
+   * all Instrumenters
+   */
+  private static class BaseInstrumenter extends DartModVisitor {

[zundel, 2011/12/16 20:49:05]

FYI, we've been trying to replace instances of DartModVisitor with
DartNodeTraverser.  You probably don't have time to fix it, add a TODO

+    private static String outputDir;
+    protected DartUnit currentUnit;
+    protected static Set<String> unitsVisited = new HashSet<String>();
+    protected static Map<String, Integer> numFunctionsMap = 
+        new HashMap<String, Integer>(),

[zundel, 2011/12/16 20:49:05]

style nit: don't use the comma for followon declarations like this, use a
separate statement for each one.

+        numStatementsMap = new HashMap<String, Integer>(),
+        numBranchesMap = new HashMap<String, Integer>();
+
+    public static void setOutDir(String outDir) {
+      outputDir = outDir;
+    }
+
+    @Override
+    public boolean visit(DartUnit x, DartContext ctx) {
+      currentUnit = x;
+      unitsVisited.add(x.getSourceName());
+      return super.visit(x, ctx);
+    }
+
+    /**
+     * Prepend a function call to a Dart block, which is a body of a
+     * function.
+     * 
+     * @param oldBody
+     * @param functionStmt
+     * @return
+     */
+    protected DartBlock prependToFnBody(DartBlock oldBody,
+        DartExprStmt functionStmt) {
+      List<DartStatement> blockStmts = new ArrayList<DartStatement>();
+      blockStmts.add(functionStmt);
+      if (oldBody != null) {
+        List<DartStatement> stmts = oldBody.getStatements();
+        if (stmts != null) {
+          blockStmts.addAll(stmts);
+        }
+      }
+      DartBlock newDB = new DartBlock(blockStmts);
+      if (oldBody != null) {
+        newDB.setSourceInfo(oldBody.getSourceInfo());
+      }
+      return newDB;
+    }
+
+    protected void replaceFunction(DartContext ctx, DartFunction x,
+        DartBlock newFnBody) {
+      DartFunction newFn = new DartFunction(x.getParams(), newFnBody,
+          x.getReturnTypeNode());
+      newFn.setSourceInfo(x.getSourceInfo());
+      ctx.replaceMe(newFn);
+    }
+
+    protected DartExprStmt createFunctionCall(String functionName,
+        List<DartExpression> args, DartNode oldNode) {
+      DartIdentifier funcName = new DartIdentifier(functionName);
+      DartUnqualifiedInvocation funcInvocation = new DartUnqualifiedInvocation(
+          funcName, args);
+      DartExprStmt functionStmt = new DartExprStmt(funcInvocation);
+      if (oldNode != null) {
+        SourceInfo sourceInfo = oldNode.getSourceInfo();
+        setInstrumentedSourceInfo(functionStmt, sourceInfo);
+        setInstrumentedSourceInfo(funcInvocation, sourceInfo);
+        setInstrumentedSourceInfo(funcName, sourceInfo);
+        for (DartExpression arg : args) {
+          setInstrumentedSourceInfo(arg, sourceInfo);
+        }
+      }
+      return functionStmt;
+    }
+
+    void setInstrumentedSourceInfo(DartNode node, SourceInfo info) {
+      node.setInstrumentedNode(true);
+      node.setSourceInfo(info);
+    }
+  }
+
+  /**
+   * TotalSettingInstrumenter instruments the main function to initialize
+   * coverage variables and set totals for covered entities
+   */
+  private class TotalSettingInstrumenter extends BaseInstrumenter {
+
+    @Override
+    public boolean visit(DartFunction x, DartContext ctx) {
+      DartNode parent = x.getParent();
+      if (parent instanceof DartMethodDefinition) {
+        String funcName = ((DartMethodDefinition) parent).getName()
+            .toString();
+        if ("main".equals(funcName)) {
+          DartBlock newFnBody = x.getBody();
+
+          for (String unitName : unitsVisited) {
+            int numFunctions = nullCheckingUnBox(numFunctionsMap
+                .get(unitName));
+            int numStatements = nullCheckingUnBox(numStatementsMap
+                .get(unitName));
+            int numBranches = nullCheckingUnBox(numBranchesMap
+                .get(unitName));
+            List<DartExpression> args = new ArrayList<DartExpression>();
+            args.add(DartStringLiteral.get(unitName));
+            args.add(DartIntegerLiteral.get(BigInteger
+                .valueOf(numFunctions)));
+            args.add(DartIntegerLiteral.get(BigInteger
+                .valueOf(numStatements)));
+            args.add(DartIntegerLiteral.get(BigInteger
+                .valueOf(numBranches)));
+            DartExprStmt callCovTotals = createFunctionCall(
+                "setCoverageTotals", args, newFnBody);
+            callCovTotals.setInstrumentedNode(true);
+            newFnBody = prependToFnBody(newFnBody, callCovTotals);
+          }
+
+          replaceFunction(ctx, x, newFnBody);
+        }
+      }
+      return super.visit(x, ctx);
+    }
+
+    int nullCheckingUnBox(Integer value) {
+      int ret = 0;
+      if (value != null) {
+        ret = value.intValue();
+      }
+      return ret;
+    }
+  }
+
+  /**
+   * FunctionInstrumenter adds instrumentation to track function coverage
+   */
+  private class FunctionInstrumenter extends BaseInstrumenter {
+
+    private int numFunctions;
+
+    /**
+     * This visitor method transforms:
+     * 
+     * myFunction(){ stmts; ... }
+     * 
+     * to:
+     * 
+     * myFunction(){ coverFunction('unit.dart', 'myFunction'); stmts; ... }

[zundel, 2011/12/16 20:49:05]

You aren't covering closures here. Is that intentional?  I would think they
might be useful. You might create a name out of the unit name and line number
since naming closure expressions is optional.

+     */
+    @Override
+    public boolean visit(DartFunction x, DartContext ctx) {
+      DartNode parent = x.getParent();
+      if (parent instanceof DartMethodDefinition) {
+        String funcName = ((DartMethodDefinition) parent).getName()
+            .toString();
+        DartBlock oldBody = x.getBody();
+        List<DartExpression> covArgs = new ArrayList<DartExpression>();
+        covArgs.add(DartStringLiteral.get(currentUnit.getSourceName()));
+        covArgs.add(DartStringLiteral.get(funcName));
+        DartExprStmt callCovFunc = createFunctionCall("coverFunction",
+            covArgs, oldBody);
+        DartBlock newFnBody = prependToFnBody(oldBody, callCovFunc);
+        replaceFunction(ctx, x, newFnBody);
+        numFunctions++;
+      }
+      return super.visit(x, ctx);
+    }
+
+    /**
+     * Initialize function counter
+     */
+    @Override
+    public boolean visit(DartUnit x, DartContext ctx) {
+      numFunctions = 0;
+      return super.visit(x, ctx);
+    }
+
+    /**
+     * Populate number of functions for current unit
+     */
+    @Override
+    public void endVisit(DartUnit x, DartContext ctx) {
+      numFunctionsMap.put(currentUnit.getSourceName(), numFunctions);
+      super.endVisit(x, ctx);
+    }
+
+  }
+
+  /**
+   * StatementInstrumenter adds instrumentation before each statement to
+   * capture runtime coverage of that statement
+   */
+  private class StatementInstrumenter extends BaseInstrumenter {
+    private int numStatements;
+
+    /**
+     * Initialize statement counter
+     */
+    @Override
+    public boolean visit(DartUnit x, DartContext ctx) {
+      numStatements = 0;
+      return super.visit(x, ctx);
+    }
+
+    /**
+     * Populate number of statements for current unit
+     */
+    @Override
+    public void endVisit(DartUnit x, DartContext ctx) {
+      numStatementsMap.put(currentUnit.getSourceName(), numStatements);
+      super.endVisit(x, ctx);
+    }
+
+    @Override
+    public boolean visit(DartBlock x, DartContext ctx) {

[zundel, 2011/12/16 20:49:05]

it would be nice to add a big fat comment like you did for visitDartFunction
above about what gets added to the statement.

+      List<DartStatement> newStmts = new ArrayList<DartStatement>();
+      for (DartStatement stmt : x.getStatements()) {
+        if (!stmt.isInstrumentedNode()) {
+          List<DartExpression> covArgs = new ArrayList<DartExpression>();
+          covArgs.add(DartStringLiteral.get(currentUnit
+              .getSourceName()));
+          covArgs.add(DartIntegerLiteral.get(BigInteger.valueOf(stmt
+              .getSourceLine())));
+          DartExprStmt callCoverStmt = createFunctionCall(
+              "coverStatement", covArgs, stmt);
+          newStmts.add(callCoverStmt);
+        }
+        newStmts.add(stmt);
+        numStatements++;
+      }
+      DartBlock newBlock = new DartBlock(newStmts);
+      ctx.replaceMe(newBlock);
+      return super.visit(x, ctx);
+    }
+
+  }
+
+  /**
+   * BranchInstrumenter captures runtime execution of each branch in the
+   * program by adding instrumentation at each branch point
+   */
+  private class BranchInstrumenter extends BaseInstrumenter {
+    private int numBranches;
+
+    @Override
+    public boolean visit(DartUnit x, DartContext ctx) {
+      numBranches = 0;
+      return super.visit(x, ctx);
+    }
+
+    @Override
+    public void endVisit(DartUnit x, DartContext ctx) {
+      numBranchesMap.put(currentUnit.getSourceName(), numBranches);
+      super.endVisit(x, ctx);
+    }
+
+    /**
+     * Post-order instrumentation is needed to handle nested ifs and
+     * synthetic else
+     */
+    @Override
+    public void endVisit(DartIfStatement x, DartContext ctx) {

[zundel, 2011/12/16 20:49:05]

same comment as above - I'd appreciate seeing how the statmement is
instrumented.

+      DartIfStatement newIfStmt;
+      DartStatement thenStmt = x.getThenStatement();
+      DartStatement elseStmt = x.getElseStatement();
+
+      List<DartStatement> newThen = doCallCoverBranch(thenStmt);
+      numBranches++;
+      if (thenStmt instanceof DartBlock) {
+        List<DartStatement> stmts = ((DartBlock) thenStmt)
+            .getStatements();
+        if (stmts != null) {
+          newThen.addAll(stmts);
+        }
+      } else {
+        newThen.add(thenStmt);
+      }
+
+      if (elseStmt instanceof DartIfStatement) {
+        newIfStmt = new DartIfStatement(x.getCondition(),
+            new DartBlock(newThen), elseStmt);
+      } else {
+        List<DartStatement> newElse;
+        if (elseStmt != null) {
+          newElse = doCallCoverBranch(elseStmt);
+          if (elseStmt instanceof DartBlock) {
+            List<DartStatement> stmts = ((DartBlock) elseStmt)
+                .getStatements();
+            if (stmts != null) {
+              newElse.addAll(stmts);
+            }
+          } else {
+            newElse.add(elseStmt);
+          }
+        } else {
+          // Although else block is missing, there is a branch which
+          // doesn't cover the IfStatement
+          // So, we need to add a synthetic else block to track that
+          newElse = doCallCoverBranch(x);
+        }
+        newIfStmt = new DartIfStatement(x.getCondition(),
+            new DartBlock(newThen), new DartBlock(newElse));
+        numBranches++;
+      }
+      newIfStmt.setSourceInfo(x.getSourceInfo());
+      ctx.replaceMe(newIfStmt);
+      super.endVisit(x, ctx);
+    }
+
+    /**
+     * This method instruments all non-empty switch case blocks and the
+     * default block. It inserts a synthetic default statement if one
+     * doesn't exist.
+     * 
+     * For tracking branch on empty cases, this logic won't work directly
+     * since instrumenting empty cases will throw a FallThroughError at
+     * runtime. For achieving this, the switch needs to be transformed into
+     * an if. Its slightly complicated but here is what I think the
+     * transformation should be:
+     * 
+     * switch(expr) {
+     *   case 'a': // empty switch case 
+     *   case 'b': do1(); break;

[zundel, 2011/12/16 20:49:05]

I didn't think you needed a break stmt in dart.

+     *   case 'c': do2(); break;
+     *   default: doDefault();
+     * }
+     * 
+     * should be transformed to:
+     * 
+     * var tmp = expr;
+     * if( (tmp == 'a' && coverBranch(..)) || (tmp == 'b' &&
+     *   coverBranch(..))) {
+     *   do1(); 
+     * } else if (tmp == 'a' && coverBranch(..)) {
+     *   do2();
+     * } else {
+     *   coverBranch(..); 
+     *   doDefault();
+     * }
+     * 
+     */
+    @Override
+    public void endVisit(DartSwitchStatement x, DartContext ctx) {
+      List<DartSwitchMember> newSwitchMembers = 
+        new ArrayList<DartSwitchMember>();
+      boolean hasDefault = false;
+      for (DartSwitchMember swMember : x.getMembers()) {
+        List<DartStatement> stmts = doCallCoverBranch(swMember);
+        List<DartStatement> oldStmts = swMember.getStatements();
+        if (oldStmts == null || oldStmts.size() == 0) {
+          newSwitchMembers.add(swMember);
+          continue; // Ignore empty cases
+        } else {
+          stmts.addAll(oldStmts);
+        }
+
+        assert (swMember instanceof DartCase || 
+          swMember instanceof DartDefault);
+
+        DartSwitchMember newMember;
+        if (swMember instanceof DartCase) {
+          newMember = new DartCase(((DartCase) swMember).getExpr(),
+              swMember.getLabel(), stmts);
+        } else {
+          hasDefault = true;
+          newMember = new DartDefault(swMember.getLabel(), stmts);
+        }
+        setInstrumentedSourceInfo(newMember, swMember);
+        newSwitchMembers.add(newMember);
+        numBranches++;
+      }
+
+      if (!hasDefault) {
+        List<DartStatement> statements = doCallCoverBranch(x);
+        DartSwitchMember defaultMember = new DartDefault(null,
+            statements);
+        newSwitchMembers.add(defaultMember);
+        numBranches++;
+      }
+
+      DartSwitchStatement newSwitch = new DartSwitchStatement(
+          x.getExpression(), newSwitchMembers);
+      newSwitch.setSourceInfo(x.getSourceInfo());
+
+      ctx.replaceMe(newSwitch);
+      super.visit(x, ctx);
+    }
+
+    @Override
+    public void endVisit(DartTryStatement x, DartContext ctx) {
+      DartBlock tryBlock = x.getTryBlock(), finallyBlock = x
+          .getFinallyBlock();
+      List<DartCatchBlock> catchBlocks = x.getCatchBlocks();
+
+      List<DartStatement> tryStmts = doCallCoverBranch(tryBlock);
+      if (tryBlock != null && tryBlock.getStatements() != null) {
+        tryStmts.addAll(tryBlock.getStatements());
+      }
+      DartBlock newTryBlock = new DartBlock(tryStmts);
+      setInstrumentedSourceInfo(newTryBlock, tryBlock.getSourceInfo());
+      numBranches++;
+
+      List<DartCatchBlock> newCatchBlocks = null;
+      if (catchBlocks != null) {
+        newCatchBlocks = new ArrayList<DartCatchBlock>();
+        for (DartCatchBlock cBlock : catchBlocks) {
+          DartBlock oldBlock = cBlock.getBlock();
+
+          List<DartStatement> cBlockStmts = doCallCoverBranch(cBlock);
+          if (oldBlock != null && oldBlock.getStatements() != null) {
+            cBlockStmts.addAll(oldBlock.getStatements());
+          }
+          DartBlock newBlock = new DartBlock(cBlockStmts);
+          setInstrumentedSourceInfo(newBlock,
+              oldBlock.getSourceInfo());
+
+          DartCatchBlock newCatchBlock = new DartCatchBlock(newBlock,
+              cBlock.getException(), cBlock.getStackTrace());
+          setInstrumentedSourceInfo(newCatchBlock,
+              cBlock.getSourceInfo());
+
+          newCatchBlocks.add(newCatchBlock);
+          numBranches++;
+        }
+      }
+      
+      DartBlock newFinallyBlock = null;
+      if(finallyBlock != null){
+        List<DartStatement> finallyStmts = doCallCoverBranch(finallyBlock);
+        if(finallyBlock.getStatements() != null){
+          finallyStmts.addAll(finallyBlock.getStatements());
+        }
+        newFinallyBlock = new DartBlock(finallyStmts);
+        setInstrumentedSourceInfo(newFinallyBlock, 
+            finallyBlock.getSourceInfo());
+      } else {
+        List<DartStatement> finallyStmts = doCallCoverBranch(x);
+        newFinallyBlock = new DartBlock(finallyStmts);
+        setInstrumentedSourceInfo(newFinallyBlock, x.getSourceInfo());
+      }
+      numBranches++;
+      
+      DartTryStatement newTry = new DartTryStatement(tryBlock,
+          newCatchBlocks, newFinallyBlock);
+      ctx.replaceMe(newTry);
+      super.endVisit(x, ctx);
+    }
+
+    /**
+     * Rewrite all loops in this block
+     */
+    @Override
+    public void endVisit(DartBlock x, DartContext ctx) {
+      List<DartStatement> blockStmts = new ArrayList<DartStatement>(); 
+      for(DartStatement stmt : x.getStatements()) {
+        if(stmt instanceof DartForInStatement) {
+          doLoopBefore(stmt, blockStmts);
+          
+          DartForInStatement oldForIn = (DartForInStatement) stmt;
+          DartStatement setup = null;
+          if(oldForIn.introducesVariable()){
+            setup = oldForIn.getVariableStatement();
+          } else {
+            setup = new DartExprStmt(oldForIn.getIdentifier());
+          }
+          DartBlock body = doLoopInside(stmt, oldForIn.getBody());
+          DartForInStatement newForIn = 
+              new DartForInStatement(setup, oldForIn.getIterable(), body);
+          setInstrumentedSourceInfo(newForIn, oldForIn.getSourceInfo());
+          
+          doLoopAfter(stmt, blockStmts);
+          numBranches+=2;
+        } else if (stmt instanceof DartForStatement) {
+          doLoopBefore(stmt, blockStmts);
+          
+          DartForStatement oldFor = (DartForStatement) stmt;
+          DartBlock body = doLoopInside(stmt, oldFor.getBody());
+          DartForStatement newFor = new DartForStatement(oldFor.getInit(), 
+              oldFor.getCondition(), oldFor.getIncrement(), body);
+          setInstrumentedSourceInfo(newFor, oldFor.getSourceInfo());
+          
+          doLoopAfter(stmt, blockStmts);
+          numBranches+=2;
+        } else if (stmt instanceof DartWhileStatement) {
+          doLoopBefore(stmt, blockStmts);
+          
+          DartWhileStatement oldWhile = (DartWhileStatement) stmt;
+          DartBlock body = doLoopInside(stmt, oldWhile.getBody());
+          DartWhileStatement newWhile = 
+              new DartWhileStatement(oldWhile.getCondition(), body);
+          setInstrumentedSourceInfo(newWhile, oldWhile.getSourceInfo());
+          
+          doLoopAfter(stmt, blockStmts);
+          numBranches+=2;
+        } else if (stmt instanceof DartDoWhileStatement) {
+          doLoopBefore(stmt, blockStmts);
+          
+          DartDoWhileStatement oldDoWhile = (DartDoWhileStatement) stmt;
+          DartBlock body = doLoopInside(stmt, oldDoWhile.getBody());
+          DartDoWhileStatement newDoWhile = 
+              new DartDoWhileStatement(oldDoWhile.getCondition(), body);
+          setInstrumentedSourceInfo(newDoWhile, oldDoWhile.getSourceInfo());
+          
+          doLoopAfter(stmt, blockStmts);
+          numBranches+=2;
+        } else {
+          blockStmts.add(stmt);
+        }
+      }
+      
+      super.visit(x, ctx);
+    }
+
+    /**
+     * Adds function call to track coverage of a branch represented by
+     * blockNode
+     * 
+     * @param blockNode
+     * @return
+     */
+    private List<DartStatement> doCallCoverBranch(DartNode blockNode) {
+      List<DartStatement> newBlockStmts = new ArrayList<DartStatement>();
+      List<DartExpression> covArgs = makeCoverageArgs(blockNode);
+      DartExprStmt callCoverBranch = createFunctionCall("coverBranch",
+          covArgs, blockNode);
+      newBlockStmts.add(callCoverBranch);
+      setInstrumentedSourceInfo(callCoverBranch,
+          blockNode.getSourceInfo());
+      return newBlockStmts;
+    }
+    
+    private void doLoopBefore(DartNode loopNode, List<DartStatement> stmts) {
+      List<DartExpression> args = makeCoverageArgs(loopNode);
+      DartExprStmt callLoopBefore = 
+          createFunctionCall("loopBranchBefore", args, loopNode);
+      stmts.add(callLoopBefore);
+    }
+    
+    private void doLoopAfter(DartNode loopNode, List<DartStatement> stmts) {
+      List<DartExpression> args = makeCoverageArgs(loopNode);
+      args.add(DartIntegerLiteral.get(BigInteger.valueOf(
+          loopNode.getSourceStart() + loopNode.getSourceLength())));
+      DartExprStmt callLoopAfter = 
+          createFunctionCall("coverLoopBranch", args, loopNode);
+      stmts.add(callLoopAfter);
+    }
+    
+    private DartBlock doLoopInside(DartNode loopNode, DartStatement body) {
+      List<DartStatement> newBlockStmts = new ArrayList<DartStatement>();
+      List<DartExpression> covArgs = makeCoverageArgs(loopNode);
+      DartExprStmt callCoverBranch = createFunctionCall("loopBranchInside",
+          covArgs, loopNode);
+      newBlockStmts.add(callCoverBranch);
+      setInstrumentedSourceInfo(callCoverBranch,
+          loopNode.getSourceInfo());
+      
+      if(body instanceof DartBlock) {
+        newBlockStmts.addAll(((DartBlock) body).getStatements());
+      } else {
+        newBlockStmts.add(body);
+      }
+      
+      return new DartBlock(newBlockStmts);
+    }
+    private List<DartExpression> makeCoverageArgs(DartNode blockNode) {
+      List<DartExpression> covArgs = new ArrayList<DartExpression>();
+      covArgs.add(DartStringLiteral.get(currentUnit.getSourceName()));
+      covArgs.add(DartIntegerLiteral.get(BigInteger.valueOf(blockNode
+          .getSourceLine())));
+      covArgs.add(DartIntegerLiteral.get(BigInteger.valueOf(blockNode
+          .getSourceStart())));
+      return covArgs;
+    }
+  }
+
+}