Python remove a couple of small AST related modules, moving contents to more appropriate modules.

Author: markshannon

python/ql/src/python.qll

@@ -3,7 +3,6 @@ import semmle.python.Operations
 import semmle.python.Variables
 import semmle.python.AstGenerated
 import semmle.python.AstExtended
-import semmle.python.AST
 import semmle.python.Function
 import semmle.python.Module
 import semmle.python.Class
@@ -28,7 +27,6 @@ import semmle.python.types.Version
 import semmle.python.types.Descriptors
 import semmle.python.protocols
 import semmle.python.SSA
-import semmle.python.Assigns
 import semmle.python.SelfAttribute
 import semmle.python.types.Properties
 import semmle.python.xml.XML

python/ql/src/semmle/python/AST.qll

@@ -1,5 +1,61 @@
 import python
 
+/** Syntactic node (Class, Function, Module, Expr, Stmt or Comprehension) corresponding to a flow node */
+abstract class AstNode extends AstNode_ {
+
+    /** Gets the scope that this node occurs in */
+    abstract Scope getScope();
+
+    /** Gets a flow node corresponding directly to this node.
+     * NOTE: For some statements and other purely syntactic elements,
+     * there may not be a `ControlFlowNode` */
+    ControlFlowNode getAFlowNode() {
+        py_flow_bb_node(result, this, _, _)
+    }
+
+    /** Gets the location for this AST node */
+    Location getLocation() {
+        none()
+    }
+
+    /** Whether this syntactic element is artificial, that is it is generated 
+     *  by the compiler and is not present in the source */
+    predicate isArtificial() {
+        none()
+    }
+
+    /** Gets a child node of this node in the AST. This predicate exists to aid exploration of the AST
+      * and other experiments. The child-parent relation may not be meaningful. 
+      * For a more meaningful relation in terms of dependency use 
+      * Expr.getASubExpression(), Stmt.getASubStatement(), Stmt.getASubExpression() or
+      * Scope.getAStmt().
+      */
+    abstract AstNode getAChildNode();
+
+    /** Gets the parent node of this node in the AST. This predicate exists to aid exploration of the AST
+      * and other experiments. The child-parent relation may not be meaningful. 
+      * For a more meaningful relation in terms of dependency use 
+      * Expr.getASubExpression(), Stmt.getASubStatement(), Stmt.getASubExpression() or
+      * Scope.getAStmt() applied to the parent.
+      */
+    AstNode getParentNode() {
+        result.getAChildNode() = this
+    }
+
+    /** Whether this contains `inner` syntactically */
+    predicate contains(AstNode inner) {
+        this.getAChildNode+() = inner
+    }
+
+    /** Whether this contains `inner` syntactically and `inner` has the same scope as `this` */
+    predicate containsInScope(AstNode inner) {
+        this.contains(inner) and
+        this.getScope() = inner.getScope() and
+        not inner instanceof Scope
+    }
+
+}
+
 /* Parents */
 
 /** Internal implementation class */

python/ql/src/semmle/python/Assigns.qll

@@ -95,6 +95,18 @@ class Assign extends Assign_ {
     }
 }
 
+/** An assignment statement */
+class AssignStmt extends Assign {
+
+    AssignStmt() {
+        not this instanceof FunctionDef and not this instanceof ClassDef
+    }
+
+    override string toString() {
+        result = "AssignStmt"
+    }
+}
+
 /** An augmented assignment statement, such as `x += y` */
 class AugAssign extends AugAssign_ {