Java: Add support for "View CFG".

Author: aschackmull

java/ql/lib/printCfg.ql

@@ -0,0 +1,45 @@
+/**
+ * @name Print CFG
+ * @description Produces a representation of a file's Control Flow Graph.
+ *              This query is used by the VS Code extension.
+ * @id java/print-cfg
+ * @kind graph
+ * @tags ide-contextual-queries/print-cfg
+ */
+
+import java
+
+external string selectedSourceFile();
+
+private predicate selectedSourceFileAlias = selectedSourceFile/0;
+
+external int selectedSourceLine();
+
+private predicate selectedSourceLineAlias = selectedSourceLine/0;
+
+external int selectedSourceColumn();
+
+private predicate selectedSourceColumnAlias = selectedSourceColumn/0;
+
+module ViewCfgQueryInput implements ViewCfgQueryInputSig<File> {
+  predicate selectedSourceFile = selectedSourceFileAlias/0;
+
+  predicate selectedSourceLine = selectedSourceLineAlias/0;
+
+  predicate selectedSourceColumn = selectedSourceColumnAlias/0;
+
+  predicate cfgScopeSpan(
+    Callable callable, File file, int startLine, int startColumn, int endLine, int endColumn
+  ) {
+    file = callable.getFile() and
+    callable.getLocation().getStartLine() = startLine and
+    callable.getLocation().getStartColumn() = startColumn and
+    exists(Location loc |
+      loc.getEndLine() = endLine and
+      loc.getEndColumn() = endColumn and
+      loc = callable.getBody().getLocation()
+    )
+  }
+}
+
+import ViewCfgQuery<File, ViewCfgQueryInput>

java/ql/lib/semmle/code/java/ControlFlowGraph.qll

@@ -1775,3 +1775,17 @@ class ConditionNode extends ControlFlow::Node {
   /** Gets the condition of this `ConditionNode`. */
   ExprParent getCondition() { result = this.asExpr() or result = this.asStmt() }
 }
+
+private import codeql.controlflow.PrintGraph as PrintGraph
+
+private module PrintGraphInput implements PrintGraph::InputSig<Location> {
+  private import java as J
+
+  class Callable = J::Callable;
+
+  class ControlFlowNode = J::ControlFlowNode;
+
+  ControlFlowNode getASuccessor(ControlFlowNode n, SuccessorType t) { result = n.getASuccessor(t) }
+}
+
+import PrintGraph::PrintGraph<Location, PrintGraphInput>