C++: Provide the predicates that can be used to traverse the AST as metadata.

cpp/ql/src/semmle/code/cpp/PrintAST.qll

@@ -182,6 +182,8 @@ class PrintASTNode extends TPrintASTNode {
     result = childIndex.toString()
   }
 
+  abstract string getChildAccessorPredicate(int childIndex);
+
   /**
    * Gets the label for the edge from this node to the specified child,
    * including labels for edges to nodes that represent conversions.
@@ -261,6 +263,10 @@ class ExprNode extends ASTNode {
     result = expr.getValueCategoryString()
   }
 
+  override string getChildAccessorPredicate(int childIndex) {
+  result = getChildAccessor(ast, getChildInternal(childIndex).getAST())
+  }
+
   /**
    * Gets the value of this expression, if it is a constant.
    */
@@ -322,6 +328,8 @@ class DeclarationEntryNode extends BaseASTNode, TDeclarationEntryNode {
 
   override PrintASTNode getChildInternal(int childIndex) { none() }
 
+  override string getChildAccessorPredicate(int childIndex) { none() }
+
   override string getProperty(string key) {
     result = BaseASTNode.super.getProperty(key)
     or
@@ -341,6 +349,11 @@ class VariableDeclarationEntryNode extends DeclarationEntryNode {
     result.getAST() = ast.getVariable().getInitializer()
   }
 
+  override string getChildAccessorPredicate(int childIndex) {
+    childIndex = 0 and
+    result = "getVariable().getInitializer()"
+  }
+
   override string getChildEdgeLabelInternal(int childIndex) { childIndex = 0 and result = "init" }
 }
 
@@ -361,6 +374,10 @@ class StmtNode extends ASTNode {
       )
     )
   }
+
+  override string getChildAccessorPredicate(int childIndex) {
+    result = getChildAccessor(ast, getChildInternal(childIndex).getAST())
+  }
 }
 
 /**
@@ -389,6 +406,8 @@ class ParameterNode extends ASTNode {
 
   final override PrintASTNode getChildInternal(int childIndex) { none() }
 
+  final override string getChildAccessorPredicate(int childIndex) { none() }
+
   final override string getProperty(string key) {
     result = super.getProperty(key)
     or
@@ -410,6 +429,11 @@ class InitializerNode extends ASTNode {
     result.getAST() = init.getExpr()
   }
 
+  override string getChildAccessorPredicate(int childIndex) {
+    childIndex = 0 and
+    result = "getExpr()"
+  }
+
   override string getChildEdgeLabelInternal(int childIndex) {
     childIndex = 0 and
     result = "expr"
@@ -432,6 +456,11 @@ class ParametersNode extends PrintASTNode, TParametersNode {
     result.getAST() = func.getParameter(childIndex)
   }
 
+  override string getChildAccessorPredicate(int childIndex) {
+    exists(getChild(childIndex)) and
+    result = "getParameter(" + childIndex.toString() + ")"
+  }
+
   /**
    * Gets the `Function` for which this node represents the parameters.
    */
@@ -454,6 +483,11 @@ class ConstructorInitializersNode extends PrintASTNode, TConstructorInitializers
     result.getAST() = ctor.getInitializer(childIndex)
   }
 
+  final override string getChildAccessorPredicate(int childIndex) {
+    exists(getChild(childIndex)) and
+    result = "getInitializer(" + childIndex.toString() + ")"
+  }
+
   /**
    * Gets the `Constructor` for which this node represents the initializer list.
    */
@@ -476,6 +510,11 @@ class DestructorDestructionsNode extends PrintASTNode, TDestructorDestructionsNo
     result.getAST() = dtor.getDestruction(childIndex)
   }
 
+  final override string getChildAccessorPredicate(int childIndex) {
+    exists(getChild(childIndex)) and
+    result = "getDestruction(" + childIndex.toString() + ")"
+  }
+
   /**
    * Gets the `Destructor` for which this node represents the destruction list.
    */
@@ -506,6 +545,20 @@ class FunctionNode extends ASTNode {
     result.(DestructorDestructionsNode).getDestructor() = func
   }
 
+  override string getChildAccessorPredicate(int childIndex) {
+    childIndex = 0 and
+    result = "..."
+    or
+    childIndex = 1 and
+    result = "..."
+    or
+    childIndex = 2 and
+    result = "getEntryPoint()"
+    or
+    childIndex = 3 and
+    result = "..."
+  }
+
   override string getChildEdgeLabelInternal(int childIndex) {
     childIndex = 0 and result = "params"
     or
@@ -570,6 +623,239 @@ class ArrayAggregateLiteralNode extends ExprNode {
   }
 }
 
+string getChildAccessor(Locatable parent, Element child) {
+  shouldPrintFunction(getEnclosingFunction(parent)) and
+  (
+    exists(Stmt s | s = parent.(Stmt) |
+      namedStmtChildPredicates(s, child, result)
+      or
+      not exists(string p | namedStmtChildPredicates(s, child, p)) and
+      exists(int n | s.getChild(n) = child and result = "getChild(" + n + ")")
+    )
+    or
+    exists(Expr expr | expr = parent.(Expr) |
+      namedExprChildPredicates(expr, child, result)
+      or
+      not exists(string p | namedExprChildPredicates(expr, child, p)) and
+      exists(int n | expr.getChild(n) = child and result = "getChild(" + n + ")")
+    )
+  )
+}
+
+predicate namedStmtChildPredicates(Locatable s, Element e, string pred) {
+  shouldPrintFunction(getEnclosingFunction(s)) and
+  (
+    exists(int n | s.(BlockStmt).getStmt(n) = e and pred = "getStmt(" + n + ")")
+    or
+    s.(ComputedGotoStmt).getExpr() = e and pred = "getExpr()"
+    or
+    s.(ConstexprIfStmt).getCondition() = e and pred = "getCondition()"
+    or
+    s.(ConstexprIfStmt).getThen() = e and pred = "getThen()"
+    or
+    s.(ConstexprIfStmt).getElse() = e and pred = "getElse()"
+    or
+    s.(IfStmt).getCondition() = e and pred = "getCondition()"
+    or
+    s.(IfStmt).getThen() = e and pred = "getThen()"
+    or
+    s.(IfStmt).getElse() = e and pred = "getElse()"
+    or
+    s.(SwitchStmt).getExpr() = e and pred = "getExpr()"
+    or
+    s.(SwitchStmt).getStmt() = e and pred = "getStmt()"
+    or
+    s.(DoStmt).getCondition() = e and pred = "getCondition()"
+    or
+    s.(DoStmt).getStmt() = e and pred = "getStmt()"
+    or
+    s.(ForStmt).getInitialization() = e and pred = "getInitialization()"
+    or
+    s.(ForStmt).getCondition() = e and pred = "getCondition()"
+    or
+    s.(ForStmt).getUpdate() = e and pred = "getUpdate()"
+    or
+    s.(ForStmt).getStmt() = e and pred = "getStmt()"
+    or
+    s.(RangeBasedForStmt).getChild(0) = e and pred = "getChild(0)" // TODO: could be omitted
+    or
+    s.(RangeBasedForStmt).getBeginEndDeclaration() = e and pred = "getBeginEndDeclaration()"
+    or
+    s.(RangeBasedForStmt).getCondition() = e and pred = "getCondition()"
+    or
+    s.(RangeBasedForStmt).getUpdate() = e and pred = "getUpdate()"
+    or
+    s.(RangeBasedForStmt).getChild(4) = e and pred = "getChild(4)" // TODO: could be omitted
+    or
+    s.(RangeBasedForStmt).getStmt() = e and pred = "getStmt()"
+    or
+    s.(WhileStmt).getCondition() = e and pred = "getCondition()"
+    or
+    s.(WhileStmt).getStmt() = e and pred = "getStmt()"
+    or
+    exists(int n |
+      s.(DeclStmt).getDeclarationEntry(n) = e and pred = "getDeclarationEntry(" + n.toString() + ")"
+    )
+    or
+    // EmptyStmt does not have children
+    s.(ExprStmt).getExpr() = e and pred = "getExpr()"
+    or
+    s.(Handler).getBlock() = e and pred = "getBlock()"
+    or
+    s.(JumpStmt).getTarget() = e and pred = "getTarget()"
+    or
+    s.(MicrosoftTryStmt).getStmt() = e and pred = "getStmt()"
+    or
+    s.(MicrosoftTryExceptStmt).getCondition() = e and pred = "getCondition()"
+    or
+    s.(MicrosoftTryExceptStmt).getExcept() = e and pred = "getExcept()"
+    or
+    s.(MicrosoftTryFinallyStmt).getFinally() = e and pred = "getFinally()"
+    or
+    s.(ReturnStmt).getExpr() = e and pred = "getExpr()"
+    or
+    s.(SwitchCase).getExpr() = e and pred = "getExpr()"
+    or
+    s.(SwitchCase).getEndExpr() = e and pred = "getEndExpr()"
+    or
+    s.(TryStmt).getStmt() = e and pred = "getStmt()"
+    or
+    s.(VlaDimensionStmt).getDimensionExpr() = e and pred = "getDimensionExpr()"
+  )
+}
+
+predicate namedExprChildPredicates(Expr expr, Element ele, string pred) {
+  shouldPrintFunction(expr.getEnclosingFunction()) and
+  (
+    expr.(Access).getTarget() = ele and pred = "getTarget()"
+    or
+    expr.(VariableAccess).getQualifier() = ele and pred = "getQualifier()"
+    or
+    exists(Field f |
+      expr.(ClassAggregateLiteral).getFieldExpr(f) = ele and
+      pred = "getFieldExpr(" + f.toString() + ")"
+    )
+    or
+    exists(int n |
+      expr.(ArrayOrVectorAggregateLiteral).getElementExpr(n) = ele and
+      pred = "getElementExpr(" + n.toString() + ")"
+    )
+    or
+    expr.(AlignofExprOperator).getExprOperand() = ele and pred = "getExprOperand()"
+    or
+    expr.(ArrayExpr).getArrayBase() = ele and pred = "getArrayBase()"
+    or
+    expr.(ArrayExpr).getArrayOffset() = ele and pred = "getArrayOffset()"
+    or
+    expr.(AssumeExpr).getOperand() = ele and pred = "getOperand()"
+    or
+    expr.(BuiltInComplexOperation).getRealOperand() = ele and pred = "getRealOperand()"
+    or
+    expr.(BuiltInComplexOperation).getImaginaryOperand() = ele and pred = "getImaginaryOperand()"
+    or
+    expr.(BuiltInVarArg).getVAList() = ele and pred = "getVAList()"
+    or
+    expr.(BuiltInVarArgCopy).getDestinationVAList() = ele and pred = "getDestinationVAList()"
+    or
+    expr.(BuiltInVarArgCopy).getSourceVAList() = ele and pred = "getSourceVAList()"
+    or
+    expr.(BuiltInVarArgsEnd).getVAList() = ele and pred = "getVAList()"
+    or
+    expr.(BuiltInVarArgsStart).getVAList() = ele and pred = "getVAList()"
+    or
+    expr.(BuiltInVarArgsStart).getLastNamedParameter() = ele and pred = "getLastNamedParameter()"
+    or
+    expr.(Call).getQualifier() = ele and pred = "getQualifier()"
+    or
+    exists(int n | expr.(Call).getArgument(n) = ele and pred = "getArgument(" + n.toString() + ")")
+    or
+    expr.(ExprCall).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(OverloadedArrayExpr).getArrayBase() = ele and pred = "getArrayBase()"
+    or
+    expr.(OverloadedArrayExpr).getArrayOffset() = ele and pred = "getArrayOffset()"
+    or
+    expr.(OverloadedPointerDereferenceExpr).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(CommaExpr).getLeftOperand() = ele and pred = "getLeftOperand()"
+    or
+    expr.(CommaExpr).getRightOperand() = ele and pred = "getRightOperand()"
+    or
+    expr.(ConditionDeclExpr).getVariableAccess() = ele and pred = "getVariableAccess()"
+    or
+    expr.(ConstructorFieldInit).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(Conversion).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(DeleteArrayExpr).getAllocatorCall() = ele and pred = "getAllocatorCall()"
+    or
+    expr.(DeleteArrayExpr).getDestructorCall() = ele and pred = "getDestructorCall()"
+    or
+    expr.(DeleteArrayExpr).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(DeleteExpr).getAllocatorCall() = ele and pred = "getAllocatorCall()"
+    or
+    expr.(DeleteExpr).getDestructorCall() = ele and pred = "getDestructorCall()"
+    or
+    expr.(DeleteExpr).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(DestructorFieldDestruction).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(FoldExpr).getInitExpr() = ele and pred = "getInitExpr()"
+    or
+    expr.(FoldExpr).getPackExpr() = ele and pred = "getPackExpr()"
+    or
+    expr.(LambdaExpression).getInitializer() = ele and pred = "getInitializer()"
+    or
+    expr.(NewOrNewArrayExpr).getAllocatorCall() = ele and pred = "getAllocatorCall()"
+    or
+    expr.(NewOrNewArrayExpr).getAlignmentArgument() = ele and pred = "getAlignmentArgument()"
+    or
+    expr.(NewArrayExpr).getInitializer() = ele and pred = "getInitializer()"
+    or
+    expr.(NewArrayExpr).getExtent() = ele and pred = "getExtent()"
+    or
+    expr.(NewExpr).getInitializer() = ele and pred = "getInitializer()"
+    or
+    expr.(NoExceptExpr).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(Assignment).getLValue() = ele and pred = "getLValue()"
+    or
+    expr.(Assignment).getRValue() = ele and pred = "getRValue()"
+    or
+    not expr instanceof RelationalOperation and
+    expr.(BinaryOperation).getLeftOperand() = ele and
+    pred = "getLeftOperand()"
+    or
+    not expr instanceof RelationalOperation and
+    expr.(BinaryOperation).getRightOperand() = ele and
+    pred = "getRightOperand()"
+    or
+    expr.(RelationalOperation).getGreaterOperand() = ele and pred = "getGreaterOperand()"
+    or
+    expr.(RelationalOperation).getLesserOperand() = ele and pred = "getLesserOperand()"
+    or
+    expr.(ConditionalExpr).getCondition() = ele and pred = "getCondition()"
+    or
+    // If ConditionalExpr is in two-operand form, getThen() = getCondition() holds
+    not expr.(ConditionalExpr).isTwoOperand() and
+    expr.(ConditionalExpr).getThen() = ele and
+    pred = "getThen()"
+    or
+    expr.(ConditionalExpr).getElse() = ele and pred = "getElse()"
+    or
+    expr.(UnaryOperation).getOperand() = ele and pred = "getOperand()"
+    or
+    expr.(SizeofExprOperator).getExprOperand() = ele and pred = "getExprOperand()"
+    or
+    //expr.(StmtExpr).getStmt() = ele and pred = "getStmt()" // TODO confirm via test that this is a/the child
+    //or
+    expr.(ThrowExpr).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(TypeidOperator).getExpr() = ele and pred = "getExpr()"
+  )
+}
+
 /** Holds if `node` belongs to the output tree, and its property `key` has the given `value`. */
 query predicate nodes(PrintASTNode node, string key, string value) {
   node.shouldPrint() and
@@ -586,9 +872,12 @@ query predicate edges(PrintASTNode source, PrintASTNode target, string key, stri
     target.shouldPrint() and
     target = source.getChild(childIndex) and
     (
-      key = "semmle.label" and value = source.getChildEdgeLabel(childIndex)
+      key = "semmle.label" and value = source.getChildAccessorPredicate(childIndex) //source.getChildEdgeLabel(childIndex)
       or
       key = "semmle.order" and value = childIndex.toString()
+      or
+      key = "semmle.predicate" and
+      value = source.getChildAccessorPredicate(childIndex)
     )
   )
 }