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+// -*- mode: c++ -*-
+
+// Copyright (c) 2010 Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// postfix_evaluator-inl.h: Postfix (reverse Polish) notation expression
+// evaluator.
+//
+// Documentation in postfix_evaluator.h.
+//
+// Author: Mark Mentovai
+
+#ifndef PROCESSOR_POSTFIX_EVALUATOR_INL_H__
+#define PROCESSOR_POSTFIX_EVALUATOR_INL_H__
+
+#include "processor/postfix_evaluator.h"
+
+#include <stdio.h>
+
+#include <sstream>
+
+#include "google_breakpad/processor/memory_region.h"
+#include "processor/logging.h"
+
+namespace google_breakpad {
+
+using std::istringstream;
+using std::ostringstream;
+
+
+// A small class used in Evaluate to make sure to clean up the stack
+// before returning failure.
+class AutoStackClearer {
+ public:
+  explicit AutoStackClearer(vector<string> *stack) : stack_(stack) {}
+  ~AutoStackClearer() { stack_->clear(); }
+
+ private:
+  vector<string> *stack_;
+};
+
+
+template<typename ValueType>
+bool PostfixEvaluator<ValueType>::EvaluateToken(
+    const string &token,
+    const string &expression,
+    DictionaryValidityType *assigned) {
+  // There are enough binary operations that do exactly the same thing
+  // (other than the specific operation, of course) that it makes sense
+  // to share as much code as possible.
+  enum BinaryOperation {
+    BINARY_OP_NONE = 0,
+    BINARY_OP_ADD,
+    BINARY_OP_SUBTRACT,
+    BINARY_OP_MULTIPLY,
+    BINARY_OP_DIVIDE_QUOTIENT,
+    BINARY_OP_DIVIDE_MODULUS,
+    BINARY_OP_ALIGN
+  };
+
+  BinaryOperation operation = BINARY_OP_NONE;
+  if (token == "+")
+    operation = BINARY_OP_ADD;
+  else if (token == "-")
+    operation = BINARY_OP_SUBTRACT;
+  else if (token == "*")
+    operation = BINARY_OP_MULTIPLY;
+  else if (token == "/")
+    operation = BINARY_OP_DIVIDE_QUOTIENT;
+  else if (token == "%")
+    operation = BINARY_OP_DIVIDE_MODULUS;
+  else if (token == "@")
+    operation = BINARY_OP_ALIGN;
+
+  if (operation != BINARY_OP_NONE) {
+    // Get the operands.
+    ValueType operand1 = ValueType();
+    ValueType operand2 = ValueType();
+    if (!PopValues(&operand1, &operand2)) {
+      BPLOG(ERROR) << "Could not PopValues to get two values for binary "
+                      "operation " << token << ": " << expression;
+      return false;
+    }
+
+    // Perform the operation.
+    ValueType result;
+    switch (operation) {
+      case BINARY_OP_ADD:
+        result = operand1 + operand2;
+        break;
+      case BINARY_OP_SUBTRACT:
+        result = operand1 - operand2;
+        break;
+      case BINARY_OP_MULTIPLY:
+        result = operand1 * operand2;
+        break;
+      case BINARY_OP_DIVIDE_QUOTIENT:
+        result = operand1 / operand2;
+        break;
+      case BINARY_OP_DIVIDE_MODULUS:
+        result = operand1 % operand2;
+        break;
+      case BINARY_OP_ALIGN:
+	result =
+	  operand1 & (static_cast<ValueType>(-1) ^ (operand2 - 1));
+        break;
+      case BINARY_OP_NONE:
+        // This will not happen, but compilers will want a default or
+        // BINARY_OP_NONE case.
+        BPLOG(ERROR) << "Not reached!";
+        return false;
+        break;
+    }
+
+    // Save the result.
+    PushValue(result);
+  } else if (token == "^") {
+    // ^ for unary dereference.  Can't dereference without memory.
+    if (!memory_) {
+      BPLOG(ERROR) << "Attempt to dereference without memory: " <<
+                      expression;
+      return false;
+    }
+
+    ValueType address;
+    if (!PopValue(&address)) {
+      BPLOG(ERROR) << "Could not PopValue to get value to derefence: " <<
+                      expression;
+      return false;
+    }
+
+    ValueType value;
+    if (!memory_->GetMemoryAtAddress(address, &value)) {
+      BPLOG(ERROR) << "Could not dereference memory at address " <<
+                      HexString(address) << ": " << expression;
+      return false;
+    }
+
+    PushValue(value);
+  } else if (token == "=") {
+    // = for assignment.
+    ValueType value;
+    if (!PopValue(&value)) {
+      BPLOG(INFO) << "Could not PopValue to get value to assign: " <<
+                     expression;
+      return false;
+    }
+
+    // Assignment is only meaningful when assigning into an identifier.
+    // The identifier must name a variable, not a constant.  Variables
+    // begin with '$'.
+    string identifier;
+    if (PopValueOrIdentifier(NULL, &identifier) != POP_RESULT_IDENTIFIER) {
+      BPLOG(ERROR) << "PopValueOrIdentifier returned a value, but an "
+                      "identifier is needed to assign " <<
+                      HexString(value) << ": " << expression;
+      return false;
+    }
+    if (identifier.empty() || identifier[0] != '$') {
+      BPLOG(ERROR) << "Can't assign " << HexString(value) << " to " <<
+                      identifier << ": " << expression;
+      return false;
+    }
+
+    (*dictionary_)[identifier] = value;
+    if (assigned)
+      (*assigned)[identifier] = true;
+  } else {
+    // The token is not an operator, it's a literal value or an identifier.
+    // Push it onto the stack as-is.  Use push_back instead of PushValue
+    // because PushValue pushes ValueType as a string, but token is already
+    // a string.
+    stack_.push_back(token);
+  }
+  return true;
+}
+
+template<typename ValueType>
+bool PostfixEvaluator<ValueType>::EvaluateInternal(
+    const string &expression,
+    DictionaryValidityType *assigned) {
+  // Tokenize, splitting on whitespace.
+  istringstream stream(expression);
+  string token;
+  while (stream >> token) {
+    // Normally, tokens are whitespace-separated, but occasionally, the
+    // assignment operator is smashed up against the next token, i.e.
+    // $T0 $ebp 128 + =$eip $T0 4 + ^ =$ebp $T0 ^ =
+    // This has been observed in program strings produced by MSVS 2010 in LTO
+    // mode.
+    if (token.size() > 1 && token[0] == '=') {
+      if (!EvaluateToken("=", expression, assigned)) {
+        return false;
+      }
+
+      if (!EvaluateToken(token.substr(1), expression, assigned)) {
+        return false;
+      }
+    } else if (!EvaluateToken(token, expression, assigned)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+template<typename ValueType>
+bool PostfixEvaluator<ValueType>::Evaluate(const string &expression,
+                                           DictionaryValidityType *assigned) {
+  // Ensure that the stack is cleared before returning.
+  AutoStackClearer clearer(&stack_);
+
+  if (!EvaluateInternal(expression, assigned))
+    return false;
+
+  // If there's anything left on the stack, it indicates incomplete execution.
+  // This is a failure case.  If the stack is empty, evalution was complete
+  // and successful.
+  if (stack_.empty())
+    return true;
+
+  BPLOG(ERROR) << "Incomplete execution: " << expression;
+  return false;
+}
+
+template<typename ValueType>
+bool PostfixEvaluator<ValueType>::EvaluateForValue(const string &expression,
+                                                   ValueType *result) {
+  // Ensure that the stack is cleared before returning.
+  AutoStackClearer clearer(&stack_);
+
+  if (!EvaluateInternal(expression, NULL))
+    return false;
+
+  // A successful execution should leave exactly one value on the stack.
+  if (stack_.size() != 1) {
+    BPLOG(ERROR) << "Expression yielded bad number of results: "
+                 << "'" << expression << "'";
+    return false;
+  }
+
+  return PopValue(result);
+}
+
+template<typename ValueType>
+typename PostfixEvaluator<ValueType>::PopResult
+PostfixEvaluator<ValueType>::PopValueOrIdentifier(
+    ValueType *value, string *identifier) {
+  // There needs to be at least one element on the stack to pop.
+  if (!stack_.size())
+    return POP_RESULT_FAIL;
+
+  string token = stack_.back();
+  stack_.pop_back();
+
+  // First, try to treat the value as a literal. Literals may have leading
+  // '-' sign, and the entire remaining string must be parseable as
+  // ValueType. If this isn't possible, it can't be a literal, so treat it
+  // as an identifier instead.
+  //
+  // Some versions of the libstdc++, the GNU standard C++ library, have
+  // stream extractors for unsigned integer values that permit a leading
+  // '-' sign (6.0.13); others do not (6.0.9). Since we require it, we
+  // handle it explicitly here.
+  istringstream token_stream(token);
+  ValueType literal = ValueType();
+  bool negative;
+  if (token_stream.peek() == '-') {
+    negative = true;
+    token_stream.get();
+  } else {
+    negative = false;
+  }
+  if (token_stream >> literal && token_stream.peek() == EOF) {
+    if (value) {
+      *value = literal;
+    }
+    if (negative)
+      *value = -*value;
+    return POP_RESULT_VALUE;
+  } else {
+    if (identifier) {
+      *identifier = token;
+    }
+    return POP_RESULT_IDENTIFIER;
+  }
+}
+
+
+template<typename ValueType>
+bool PostfixEvaluator<ValueType>::PopValue(ValueType *value) {
+  ValueType literal = ValueType();
+  string token;
+  PopResult result;
+  if ((result = PopValueOrIdentifier(&literal, &token)) == POP_RESULT_FAIL) {
+    return false;
+  } else if (result == POP_RESULT_VALUE) {
+    // This is the easy case.
+    *value = literal;
+  } else {  // result == POP_RESULT_IDENTIFIER
+    // There was an identifier at the top of the stack.  Resolve it to a
+    // value by looking it up in the dictionary.
+    typename DictionaryType::const_iterator iterator =
+        dictionary_->find(token);
+    if (iterator == dictionary_->end()) {
+      // The identifier wasn't found in the dictionary.  Don't imply any
+      // default value, just fail.
+      BPLOG(INFO) << "Identifier " << token << " not in dictionary";
+      return false;
+    }
+
+    *value = iterator->second;
+  }
+
+  return true;
+}
+
+
+template<typename ValueType>
+bool PostfixEvaluator<ValueType>::PopValues(ValueType *value1,
+                                            ValueType *value2) {
+  return PopValue(value2) && PopValue(value1);
+}
+
+
+template<typename ValueType>
+void PostfixEvaluator<ValueType>::PushValue(const ValueType &value) {
+  ostringstream token_stream;
+  token_stream << value;
+  stack_.push_back(token_stream.str());
+}
+
+
+}  // namespace google_breakpad
+
+
+#endif  // PROCESSOR_POSTFIX_EVALUATOR_INL_H__