C#: Implement View CFG query

csharp/ql/lib/printCfg.ql

@@ -0,0 +1,50 @@
+/**
+ * @name Print CFG
+ * @description Produces a representation of a file's Control Flow Graph.
+ *              This query is used by the VS Code extension.
+ * @id cs/print-cfg
+ * @kind graph
+ * @tags ide-contextual-queries/print-cfg
+ */
+
+private import semmle.code.csharp.controlflow.internal.ControlFlowGraphImpl
+
+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(
+    CfgScope scope, File file, int startLine, int startColumn, int endLine, int endColumn
+  ) {
+    file = scope.getFile() and
+    scope.getLocation().getStartLine() = startLine and
+    scope.getLocation().getStartColumn() = startColumn and
+    exists(Location loc |
+      loc.getEndLine() = endLine and
+      loc.getEndColumn() = endColumn
+    |
+      loc = scope.(Callable).getBody().getLocation()
+      or
+      loc = scope.(Field).getInitializer().getLocation()
+      or
+      loc = scope.(Property).getInitializer().getLocation()
+    )
+  }
+}
+
+import ViewCfgQuery<File, ViewCfgQueryInput>