feat(controlflow): Add classes for control flow graph nodes

Author: GeekMasher

ql/lib/codeql/bicep/controlflow/CfgNodes.qll

@@ -0,0 +1,52 @@
+/** Provides classes representing nodes in a control flow graph. */
+
+private import bicep
+private import BasicBlocks
+private import ControlFlowGraph
+private import internal.ControlFlowGraphImpl as CfgImpl
+
+/** A control-flow node that wraps an AST expression. */
+class ExprCfgNode extends CfgImpl::AstCfgNode {
+  string getAPrimaryQlClass() { result = "ExprCfgNode" }
+
+  Expr e;
+
+  ExprCfgNode() { e = this.getAstNode() }
+
+  /** Gets the underlying expression. */
+  Expr getExpr() { result = e }
+}
+
+/** A control-flow node that wraps an AST statement. */
+class StmtsCfgNode extends CfgImpl::AstCfgNode {
+  string getAPrimaryQlClass() { result = "StmtsCfgNode" }
+
+  Stmts s;
+
+  StmtsCfgNode() { s = this.getAstNode() }
+
+  /** Gets the underlying expression. */
+  Stmts getStmt() { result = s }
+}
+
+/** Provides classes for control-flow nodes that wrap AST expressions. */
+module ExprNodes { 
+  class CallCfgNode extends ExprCfgNode {
+    override string getAPrimaryQlClass() { result = "CallCfgNode" }
+
+    override CallExpression e;
+
+    override CallExpression getExpr() { result = super.getExpr() }
+  }
+}
+
+module StmtNodes {
+  /** A control-flow node that wraps a `Cmd` AST expression. */
+  class CallCfgNode extends StmtsCfgNode {
+    override string getAPrimaryQlClass() { result = "CallCfgNode" }
+
+    override UserDefinedFunction s;
+
+    override UserDefinedFunction getStmt() { result = super.getStmt() }
+  }
+}