Create ConstantExpr class

A ConstantExpr class represents a full expression that's in a context where a
constant expression is required. This class reflects the path the evaluator
took to reach the expression rather than the syntactic context in which the
expression occurs.

In the future, the class will be expanded to cache the result of the evaluated
expression so that it's not needlessly re-evaluated

Reviewed By: rsmith

Differential Revision: https://reviews.llvm.org/D53475


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@345692 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 58 insertions, 0 deletions

diff --git a/include/clang/AST/Expr.h b/include/clang/AST/Expr.h
index a835c01623..8b94be3be7 100644
--- a/include/clang/AST/Expr.h
+++ b/include/clang/AST/Expr.h
@@ -869,6 +869,64 @@ public:
 };
 
 //===----------------------------------------------------------------------===//
+// Wrapper Expressions.
+//===----------------------------------------------------------------------===//
+
+/// FullExpr - Represents a "full-expression" node.
+class FullExpr : public Expr {
+protected:
+ Stmt *SubExpr;
+
+ FullExpr(StmtClass SC, Expr *subexpr)
+    : Expr(SC, subexpr->getType(),
+           subexpr->getValueKind(), subexpr->getObjectKind(),
+           subexpr->isTypeDependent(), subexpr->isValueDependent(),
+           subexpr->isInstantiationDependent(),
+           subexpr->containsUnexpandedParameterPack()), SubExpr(subexpr) {}
+  FullExpr(StmtClass SC, EmptyShell Empty)
+    : Expr(SC, Empty) {}
+public:
+  const Expr *getSubExpr() const { return cast<Expr>(SubExpr); }
+  Expr *getSubExpr() { return cast<Expr>(SubExpr); }
+
+  /// As with any mutator of the AST, be very careful when modifying an
+  /// existing AST to preserve its invariants.
+  void setSubExpr(Expr *E) { SubExpr = E; }
+
+  static bool classof(const Stmt *T) {
+    return T->getStmtClass() >= firstFullExprConstant &&
+           T->getStmtClass() <= lastFullExprConstant;
+  }
+};
+
+/// ConstantExpr - An expression that occurs in a constant context.
+struct ConstantExpr : public FullExpr {
+  ConstantExpr(Expr *subexpr)
+    : FullExpr(ConstantExprClass, subexpr) {}
+
+  /// Build an empty constant expression wrapper.
+  explicit ConstantExpr(EmptyShell Empty)
+    : FullExpr(ConstantExprClass, Empty) {}
+
+  SourceLocation getBeginLoc() const LLVM_READONLY {
+    return SubExpr->getBeginLoc();
+  }
+  SourceLocation getEndLoc() const LLVM_READONLY {
+    return SubExpr->getEndLoc();
+  }
+
+  static bool classof(const Stmt *T) {
+    return T->getStmtClass() == ConstantExprClass;
+  }
+
+  // Iterators
+  child_range children() { return child_range(&SubExpr, &SubExpr+1); }
+  const_child_range children() const {
+    return const_child_range(&SubExpr, &SubExpr + 1);
+  }
+};
+
+//===----------------------------------------------------------------------===//
 // Primary Expressions.
 //===----------------------------------------------------------------------===//