1 files changed, 82 insertions, 0 deletions
diff --git a/lldb/source/Symbol/PostfixExpression.cpp b/lldb/source/Symbol/PostfixExpression.cpp
new file mode 100644
index 00000000000..627c17b47fc
--- /dev/null
+++ b/lldb/source/Symbol/PostfixExpression.cpp
@@ -0,0 +1,82 @@
+//===-- PostfixExpression.cpp -----------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file implements support for postfix expressions found in several symbol
+//  file formats, and their conversion to DWARF.
+//
+//===----------------------------------------------------------------------===//
+
+#include "lldb/Symbol/PostfixExpression.h"
+#include "llvm/ADT/StringExtras.h"
+
+using namespace lldb_private;
+using namespace lldb_private::postfix;
+
+static llvm::Optional<BinaryOpNode::OpType>
+GetBinaryOpType(llvm::StringRef token) {
+  if (token.size() != 1)
+    return llvm::None;
+  switch (token[0]) {
+  case '@':
+    return BinaryOpNode::Align;
+  case '-':
+    return BinaryOpNode::Minus;
+  case '+':
+    return BinaryOpNode::Plus;
+  }
+  return llvm::None;
+}
+
+static llvm::Optional<UnaryOpNode::OpType>
+GetUnaryOpType(llvm::StringRef token) {
+  if (token == "^")
+    return UnaryOpNode::Deref;
+  return llvm::None;
+}
+
+Node *postfix::Parse(llvm::StringRef expr, llvm::BumpPtrAllocator &alloc) {
+  llvm::SmallVector<Node *, 4> stack;
+
+  llvm::StringRef token;
+  while (std::tie(token, expr) = getToken(expr), !token.empty()) {
+    if (auto op_type = GetBinaryOpType(token)) {
+      // token is binary operator
+      if (stack.size() < 2)
+        return nullptr;
+
+      Node *right = stack.pop_back_val();
+      Node *left = stack.pop_back_val();
+      stack.push_back(MakeNode<BinaryOpNode>(alloc, *op_type, *left, *right));
+      continue;
+    }
+
+    if (auto op_type = GetUnaryOpType(token)) {
+      // token is unary operator
+      if (stack.empty())
+        return nullptr;
+
+      Node *operand = stack.pop_back_val();
+      stack.push_back(MakeNode<UnaryOpNode>(alloc, *op_type, *operand));
+      continue;
+    }
+
+    uint32_t value;
+    if (to_integer(token, value, 10)) {
+      // token is integer literal
+      stack.push_back(MakeNode<IntegerNode>(alloc, value));
+      continue;
+    }
+
+    stack.push_back(MakeNode<SymbolNode>(alloc, token));
+  }
+
+  if (stack.size() != 1)
+    return nullptr;
+
+  return stack.back();
+}