PS: Add continue completion and successor.

Author: MathiasVP

powershell/ql/lib/semmle/code/powershell/controlflow/ControlFlowGraph.qll

@@ -90,6 +90,10 @@ module SuccessorTypes {
     final override string toString() { result = "break" }
   }
 
+  class ContinueSuccessor extends SuccessorType, CfgImpl::TContinueSuccessor {
+    final override string toString() { result = "continue" }
+  }
+
   class RaiseSuccessor extends SuccessorType, CfgImpl::TRaiseSuccessor {
     final override string toString() { result = "raise" }
   }

powershell/ql/lib/semmle/code/powershell/controlflow/internal/Completion.qll

@@ -15,11 +15,18 @@ private newtype TCompletion =
   TBooleanCompletion(boolean b) { b in [false, true] } or
   TReturnCompletion() or
   TBreakCompletion() or
+  TContinueCompletion() or
   TRaiseCompletion() or
   TExitCompletion()
 
 pragma[noinline]
-private predicate completionIsValidForStmt(Ast n, Completion c) { none() }
+private predicate completionIsValidForStmt(Ast n, Completion c) {
+  n instanceof BreakStmt and
+  c instanceof BreakCompletion
+  or
+  n instanceof ContinueStmt and
+  c instanceof ContinueCompletion
+}
 
 /** A completion of a statement or an expression. */
 abstract class Completion extends TCompletion {
@@ -49,19 +56,10 @@ abstract class Completion extends TCompletion {
    * Holds if this completion will continue a loop when it is the completion
    * of a loop body.
    */
-  predicate continuesLoop() { this instanceof NormalCompletion }
-
-  /**
-   * Gets the inner completion. This is either the inner completion,
-   * when the completion is nested, or the completion itself.
-   */
-  Completion getInnerCompletion() { result = this }
-
-  /**
-   * Gets the outer completion. This is either the outer completion,
-   * when the completion is nested, or the completion itself.
-   */
-  Completion getOuterCompletion() { result = this }
+  predicate continuesLoop() {
+    this instanceof NormalCompletion or
+    this instanceof ContinueCompletion
+  }
 
   /** Gets a successor type that matches this completion. */
   abstract SuccessorType getAMatchingSuccessorType();
@@ -159,6 +157,16 @@ class BreakCompletion extends Completion, TBreakCompletion {
   override string toString() { result = "break" }
 }
 
+/**
+ * A completion that represents evaluation of a statement or an
+ * expression resulting in a continuation of a loop.
+ */
+class ContinueCompletion extends Completion, TContinueCompletion {
+  override ContinueSuccessor getAMatchingSuccessorType() { any() }
+
+  override string toString() { result = "continue" }
+}
+
 /**
  * A completion that represents evaluation of a statement or an
  * expression resulting in a thrown exception.

powershell/ql/lib/semmle/code/powershell/controlflow/internal/ControlFlowGraphImpl.qll

@@ -188,6 +188,7 @@ private module Cached {
     TBooleanSuccessor(boolean b) { b in [false, true] } or
     TReturnSuccessor() or
     TBreakSuccessor() or
+    TContinueSuccessor() or
     TRaiseSuccessor() or
     TExitSuccessor()
 }