InputCommon: Extract ControlReference from ControllerInterface

Better separation of concerns. Relegates `ControllerInterface` to
enumerating input controls, and the new `ControlReference` deals with
combining inputs and configuration expression parsing.

4 files changed, 866 insertions, 0 deletions

diff --git a/Source/Core/InputCommon/ControlReference/ControlReference.cpp b/Source/Core/InputCommon/ControlReference/ControlReference.cpp
new file mode 100644
index 0000000000..4268531668
--- /dev/null
+++ b/Source/Core/InputCommon/ControlReference/ControlReference.cpp
@@ -0,0 +1,148 @@
+// Copyright 2016 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include "Common/Thread.h"
+// For InputGateOn()
+// This is a bad layering violation, but it's the cleanest
+// place I could find to put it.
+#include "Core/ConfigManager.h"
+#include "Core/Host.h"
+
+#include "InputCommon/ControlReference/ControlReference.h"
+
+using namespace ciface::ExpressionParser;
+
+constexpr ControlState INPUT_DETECT_THRESHOLD = 0.55;
+
+bool ControlReference::InputGateOn()
+{
+  return SConfig::GetInstance().m_BackgroundInput || Host_RendererHasFocus() || Host_UIHasFocus();
+}
+
+//
+// UpdateReference
+//
+// Updates a controlreference's binded devices/controls
+// need to call this to re-parse a control reference's expression after changing it
+//
+void ControlReference::UpdateReference(ciface::Core::DeviceContainer& devices,
+                                       const ciface::Core::DeviceQualifier& default_device)
+{
+  delete parsed_expression;
+  parsed_expression = nullptr;
+
+  ControlFinder finder(devices, default_device, is_input);
+  parse_error = ParseExpression(expression, finder, &parsed_expression);
+}
+
+//
+// InputReference :: State
+//
+// Gets the state of an input reference
+// override function for ControlReference::State ...
+//
+ControlState InputReference::State(const ControlState ignore)
+{
+  if (parsed_expression && InputGateOn())
+    return parsed_expression->GetValue() * range;
+  return 0.0;
+}
+
+//
+// OutputReference :: State
+//
+// Set the state of all binded outputs
+// overrides ControlReference::State .. combined them so I could make the GUI simple / inputs ==
+// same as outputs one list
+// I was lazy and it works so watever
+//
+ControlState OutputReference::State(const ControlState state)
+{
+  if (parsed_expression && InputGateOn())
+    parsed_expression->SetValue(state);
+  return 0.0;
+}
+
+//
+// InputReference :: Detect
+//
+// Wait for input on all binded devices
+// supports not detecting inputs that were held down at the time of Detect start,
+// which is useful for those crazy flightsticks that have certain buttons that are always held down
+// or some crazy axes or something
+// upon input, return pointer to detected Control
+// else return nullptr
+//
+ciface::Core::Device::Control* InputReference::Detect(const unsigned int ms,
+                                                      ciface::Core::Device* const device)
+{
+  unsigned int time = 0;
+  std::vector<bool> states(device->Inputs().size());
+
+  if (device->Inputs().size() == 0)
+    return nullptr;
+
+  // get starting state of all inputs,
+  // so we can ignore those that were activated at time of Detect start
+  std::vector<ciface::Core::Device::Input *>::const_iterator i = device->Inputs().begin(),
+                                                             e = device->Inputs().end();
+  for (std::vector<bool>::iterator state = states.begin(); i != e; ++i)
+    *state++ = ((*i)->GetState() > (1 - INPUT_DETECT_THRESHOLD));
+
+  while (time < ms)
+  {
+    device->UpdateInput();
+    i = device->Inputs().begin();
+    for (std::vector<bool>::iterator state = states.begin(); i != e; ++i, ++state)
+    {
+      // detected an input
+      if ((*i)->IsDetectable() && (*i)->GetState() > INPUT_DETECT_THRESHOLD)
+      {
+        // input was released at some point during Detect call
+        // return the detected input
+        if (false == *state)
+          return *i;
+      }
+      else if ((*i)->GetState() < (1 - INPUT_DETECT_THRESHOLD))
+      {
+        *state = false;
+      }
+    }
+    Common::SleepCurrentThread(10);
+    time += 10;
+  }
+
+  // no input was detected
+  return nullptr;
+}
+
+//
+// OutputReference :: Detect
+//
+// Totally different from the inputReference detect / I have them combined so it was simpler to make
+// the GUI.
+// The GUI doesn't know the difference between an input and an output / it's odd but I was lazy and
+// it was easy
+//
+// set all binded outputs to <range> power for x milliseconds return false
+//
+ciface::Core::Device::Control* OutputReference::Detect(const unsigned int ms,
+                                                       ciface::Core::Device* const device)
+{
+  // ignore device
+
+  // don't hang if we don't even have any controls mapped
+  if (BoundCount() > 0)
+  {
+    State(1);
+    unsigned int slept = 0;
+
+    // this loop is to make stuff like flashing keyboard LEDs work
+    while (ms > (slept += 10))
+      Common::SleepCurrentThread(10);
+
+    State(0);
+  }
+  return nullptr;
+}
diff --git a/Source/Core/InputCommon/ControlReference/ControlReference.h b/Source/Core/InputCommon/ControlReference/ControlReference.h
new file mode 100644
index 0000000000..335675e5eb
--- /dev/null
+++ b/Source/Core/InputCommon/ControlReference/ControlReference.h
@@ -0,0 +1,79 @@
+// Copyright 2016 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "InputCommon/ControlReference/ExpressionParser.h"
+#include "InputCommon/ControllerInterface/Device.h"
+
+// ControlReference
+//
+// These are what you create to actually use the inputs, InputReference or OutputReference.
+//
+// After being bound to devices and controls with UpdateReference,
+// each one can link to multiple devices and controls
+// when you change a ControlReference's expression,
+// you must use UpdateReference on it to rebind controls
+//
+
+class ControlReference
+{
+public:
+  static bool InputGateOn();
+
+  virtual ControlState State(const ControlState state = 0) = 0;
+  virtual ciface::Core::Device::Control* Detect(const unsigned int ms,
+                                                ciface::Core::Device* const device) = 0;
+
+  void UpdateReference(ciface::Core::DeviceContainer& devices,
+                       const ciface::Core::DeviceQualifier& default_device);
+
+  ControlState range;
+  std::string expression;
+  const bool is_input;
+  ciface::ExpressionParser::ExpressionParseStatus parse_error;
+
+  virtual ~ControlReference() { delete parsed_expression; }
+  int BoundCount()
+  {
+    if (parsed_expression)
+      return parsed_expression->num_controls;
+    else
+      return 0;
+  }
+
+protected:
+  ControlReference(const bool _is_input) : range(1), is_input(_is_input), parsed_expression(nullptr)
+  {
+  }
+  ciface::ExpressionParser::Expression* parsed_expression;
+};
+
+//
+// InputReference
+//
+// Control reference for inputs
+//
+class InputReference : public ControlReference
+{
+public:
+  InputReference() : ControlReference(true) {}
+  ControlState State(const ControlState state) override;
+  ciface::Core::Device::Control* Detect(const unsigned int ms,
+                                        ciface::Core::Device* const device) override;
+};
+
+//
+// OutputReference
+//
+// Control reference for outputs
+//
+class OutputReference : public ControlReference
+{
+public:
+  OutputReference() : ControlReference(false) {}
+  ControlState State(const ControlState state) override;
+  ciface::Core::Device::Control* Detect(const unsigned int ms,
+                                        ciface::Core::Device* const device) override;
+};
diff --git a/Source/Core/InputCommon/ControlReference/ExpressionParser.cpp b/Source/Core/InputCommon/ControlReference/ExpressionParser.cpp
new file mode 100644
index 0000000000..47fbd001a6
--- /dev/null
+++ b/Source/Core/InputCommon/ControlReference/ExpressionParser.cpp
@@ -0,0 +1,567 @@
+// Copyright 2013 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include <algorithm>
+#include <cassert>
+#include <iostream>
+#include <map>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "InputCommon/ControlReference/ExpressionParser.h"
+
+using namespace ciface::Core;
+
+namespace ciface
+{
+namespace ExpressionParser
+{
+enum TokenType
+{
+  TOK_DISCARD,
+  TOK_INVALID,
+  TOK_EOF,
+  TOK_LPAREN,
+  TOK_RPAREN,
+  TOK_AND,
+  TOK_OR,
+  TOK_NOT,
+  TOK_ADD,
+  TOK_CONTROL,
+};
+
+inline std::string OpName(TokenType op)
+{
+  switch (op)
+  {
+  case TOK_AND:
+    return "And";
+  case TOK_OR:
+    return "Or";
+  case TOK_NOT:
+    return "Not";
+  case TOK_ADD:
+    return "Add";
+  default:
+    assert(false);
+    return "";
+  }
+}
+
+class Token
+{
+public:
+  TokenType type;
+  ControlQualifier qualifier;
+
+  Token(TokenType type_) : type(type_) {}
+  Token(TokenType type_, ControlQualifier qualifier_) : type(type_), qualifier(qualifier_) {}
+  operator std::string()
+  {
+    switch (type)
+    {
+    case TOK_DISCARD:
+      return "Discard";
+    case TOK_EOF:
+      return "EOF";
+    case TOK_LPAREN:
+      return "(";
+    case TOK_RPAREN:
+      return ")";
+    case TOK_AND:
+      return "&";
+    case TOK_OR:
+      return "|";
+    case TOK_NOT:
+      return "!";
+    case TOK_ADD:
+      return "+";
+    case TOK_CONTROL:
+      return "Device(" + (std::string)qualifier + ")";
+    case TOK_INVALID:
+      break;
+    }
+
+    return "Invalid";
+  }
+};
+
+class Lexer
+{
+public:
+  std::string expr;
+  std::string::iterator it;
+
+  Lexer(const std::string& expr_) : expr(expr_) { it = expr.begin(); }
+  bool FetchBacktickString(std::string& value, char otherDelim = 0)
+  {
+    value = "";
+    while (it != expr.end())
+    {
+      char c = *it;
+      ++it;
+      if (c == '`')
+        return false;
+      if (c > 0 && c == otherDelim)
+        return true;
+      value += c;
+    }
+    return false;
+  }
+
+  Token GetFullyQualifiedControl()
+  {
+    ControlQualifier qualifier;
+    std::string value;
+
+    if (FetchBacktickString(value, ':'))
+    {
+      // Found colon, this is the device name
+      qualifier.has_device = true;
+      qualifier.device_qualifier.FromString(value);
+      FetchBacktickString(value);
+    }
+
+    qualifier.control_name = value;
+
+    return Token(TOK_CONTROL, qualifier);
+  }
+
+  Token GetBarewordsControl(char c)
+  {
+    std::string name;
+    name += c;
+
+    while (it != expr.end())
+    {
+      c = *it;
+      if (!isalpha(c))
+        break;
+      name += c;
+      ++it;
+    }
+
+    ControlQualifier qualifier;
+    qualifier.control_name = name;
+    return Token(TOK_CONTROL, qualifier);
+  }
+
+  Token NextToken()
+  {
+    if (it == expr.end())
+      return Token(TOK_EOF);
+
+    char c = *it++;
+    switch (c)
+    {
+    case ' ':
+    case '\t':
+    case '\n':
+    case '\r':
+      return Token(TOK_DISCARD);
+    case '(':
+      return Token(TOK_LPAREN);
+    case ')':
+      return Token(TOK_RPAREN);
+    case '&':
+      return Token(TOK_AND);
+    case '|':
+      return Token(TOK_OR);
+    case '!':
+      return Token(TOK_NOT);
+    case '+':
+      return Token(TOK_ADD);
+    case '`':
+      return GetFullyQualifiedControl();
+    default:
+      if (isalpha(c))
+        return GetBarewordsControl(c);
+      else
+        return Token(TOK_INVALID);
+    }
+  }
+
+  ExpressionParseStatus Tokenize(std::vector<Token>& tokens)
+  {
+    while (true)
+    {
+      Token tok = NextToken();
+
+      if (tok.type == TOK_DISCARD)
+        continue;
+
+      if (tok.type == TOK_INVALID)
+      {
+        tokens.clear();
+        return EXPRESSION_PARSE_SYNTAX_ERROR;
+      }
+
+      tokens.push_back(tok);
+
+      if (tok.type == TOK_EOF)
+        break;
+    }
+    return EXPRESSION_PARSE_SUCCESS;
+  }
+};
+
+class ExpressionNode
+{
+public:
+  virtual ~ExpressionNode() {}
+  virtual ControlState GetValue() { return 0; }
+  virtual void SetValue(ControlState state) {}
+  virtual int CountNumControls() { return 0; }
+  virtual operator std::string() { return ""; }
+};
+
+class DummyExpression : public ExpressionNode
+{
+public:
+  std::string name;
+
+  DummyExpression(const std::string& name_) : name(name_) {}
+  ControlState GetValue() override { return 0.0; }
+  void SetValue(ControlState value) override {}
+  int CountNumControls() override { return 0; }
+  operator std::string() override { return "`" + name + "`"; }
+};
+
+class ControlExpression : public ExpressionNode
+{
+public:
+  ControlQualifier qualifier;
+  Device::Control* control;
+
+  ControlExpression(ControlQualifier qualifier_, std::shared_ptr<Device> device,
+                    Device::Control* control_)
+      : qualifier(qualifier_), control(control_), m_device(device)
+  {
+  }
+
+  ControlState GetValue() override { return control->ToInput()->GetState(); }
+  void SetValue(ControlState value) override { control->ToOutput()->SetState(value); }
+  int CountNumControls() override { return 1; }
+  operator std::string() override { return "`" + (std::string)qualifier + "`"; }
+private:
+  std::shared_ptr<Device> m_device;
+};
+
+class BinaryExpression : public ExpressionNode
+{
+public:
+  TokenType op;
+  ExpressionNode* lhs;
+  ExpressionNode* rhs;
+
+  BinaryExpression(TokenType op_, ExpressionNode* lhs_, ExpressionNode* rhs_)
+      : op(op_), lhs(lhs_), rhs(rhs_)
+  {
+  }
+  virtual ~BinaryExpression()
+  {
+    delete lhs;
+    delete rhs;
+  }
+
+  ControlState GetValue() override
+  {
+    ControlState lhsValue = lhs->GetValue();
+    ControlState rhsValue = rhs->GetValue();
+    switch (op)
+    {
+    case TOK_AND:
+      return std::min(lhsValue, rhsValue);
+    case TOK_OR:
+      return std::max(lhsValue, rhsValue);
+    case TOK_ADD:
+      return std::min(lhsValue + rhsValue, 1.0);
+    default:
+      assert(false);
+      return 0;
+    }
+  }
+
+  void SetValue(ControlState value) override
+  {
+    // Don't do anything special with the op we have.
+    // Treat "A & B" the same as "A | B".
+    lhs->SetValue(value);
+    rhs->SetValue(value);
+  }
+
+  int CountNumControls() override { return lhs->CountNumControls() + rhs->CountNumControls(); }
+  operator std::string() override
+  {
+    return OpName(op) + "(" + (std::string)(*lhs) + ", " + (std::string)(*rhs) + ")";
+  }
+};
+
+class UnaryExpression : public ExpressionNode
+{
+public:
+  TokenType op;
+  ExpressionNode* inner;
+
+  UnaryExpression(TokenType op_, ExpressionNode* inner_) : op(op_), inner(inner_) {}
+  virtual ~UnaryExpression() { delete inner; }
+  ControlState GetValue() override
+  {
+    ControlState value = inner->GetValue();
+    switch (op)
+    {
+    case TOK_NOT:
+      return 1.0 - value;
+    default:
+      assert(false);
+      return 0;
+    }
+  }
+
+  void SetValue(ControlState value) override
+  {
+    switch (op)
+    {
+    case TOK_NOT:
+      inner->SetValue(1.0 - value);
+      break;
+
+    default:
+      assert(false);
+    }
+  }
+
+  int CountNumControls() override { return inner->CountNumControls(); }
+  operator std::string() override { return OpName(op) + "(" + (std::string)(*inner) + ")"; }
+};
+
+std::shared_ptr<Device> ControlFinder::FindDevice(ControlQualifier qualifier)
+{
+  if (qualifier.has_device)
+    return container.FindDevice(qualifier.device_qualifier);
+  else
+    return container.FindDevice(default_device);
+}
+
+Device::Control* ControlFinder::FindControl(ControlQualifier qualifier)
+{
+  const std::shared_ptr<Device> device = FindDevice(qualifier);
+  if (!device)
+    return nullptr;
+
+  if (is_input)
+    return device->FindInput(qualifier.control_name);
+  else
+    return device->FindOutput(qualifier.control_name);
+}
+
+class Parser
+{
+public:
+  Parser(std::vector<Token> tokens_, ControlFinder& finder_) : tokens(tokens_), finder(finder_)
+  {
+    m_it = tokens.begin();
+  }
+
+  ExpressionParseStatus Parse(Expression** expr_out)
+  {
+    ExpressionNode* node;
+    ExpressionParseStatus status = Toplevel(&node);
+    if (status != EXPRESSION_PARSE_SUCCESS)
+      return status;
+
+    *expr_out = new Expression(node);
+    return EXPRESSION_PARSE_SUCCESS;
+  }
+
+private:
+  std::vector<Token> tokens;
+  std::vector<Token>::iterator m_it;
+  ControlFinder& finder;
+
+  Token Chew() { return *m_it++; }
+  Token Peek() { return *m_it; }
+  bool Expects(TokenType type)
+  {
+    Token tok = Chew();
+    return tok.type == type;
+  }
+
+  ExpressionParseStatus Atom(ExpressionNode** expr_out)
+  {
+    Token tok = Chew();
+    switch (tok.type)
+    {
+    case TOK_CONTROL:
+    {
+      std::shared_ptr<Device> device = finder.FindDevice(tok.qualifier);
+      Device::Control* control = finder.FindControl(tok.qualifier);
+      if (control == nullptr)
+      {
+        *expr_out = new DummyExpression(tok.qualifier);
+        return EXPRESSION_PARSE_NO_DEVICE;
+      }
+
+      *expr_out = new ControlExpression(tok.qualifier, device, control);
+      return EXPRESSION_PARSE_SUCCESS;
+    }
+    case TOK_LPAREN:
+      return Paren(expr_out);
+    default:
+      return EXPRESSION_PARSE_SYNTAX_ERROR;
+    }
+  }
+
+  bool IsUnaryExpression(TokenType type)
+  {
+    switch (type)
+    {
+    case TOK_NOT:
+      return true;
+    default:
+      return false;
+    }
+  }
+
+  ExpressionParseStatus Unary(ExpressionNode** expr_out)
+  {
+    if (IsUnaryExpression(Peek().type))
+    {
+      Token tok = Chew();
+      ExpressionNode* atom_expr;
+      ExpressionParseStatus status = Atom(&atom_expr);
+      if (status == EXPRESSION_PARSE_SYNTAX_ERROR)
+        return status;
+      *expr_out = new UnaryExpression(tok.type, atom_expr);
+      return EXPRESSION_PARSE_SUCCESS;
+    }
+
+    return Atom(expr_out);
+  }
+
+  bool IsBinaryToken(TokenType type)
+  {
+    switch (type)
+    {
+    case TOK_AND:
+    case TOK_OR:
+    case TOK_ADD:
+      return true;
+    default:
+      return false;
+    }
+  }
+
+  ExpressionParseStatus Binary(ExpressionNode** expr_out)
+  {
+    ExpressionParseStatus status = Unary(expr_out);
+    if (status == EXPRESSION_PARSE_SYNTAX_ERROR)
+      return status;
+
+    while (IsBinaryToken(Peek().type))
+    {
+      Token tok = Chew();
+      ExpressionNode* unary_expr;
+      status = Unary(&unary_expr);
+      if (status == EXPRESSION_PARSE_SYNTAX_ERROR)
+      {
+        delete *expr_out;
+        return status;
+      }
+
+      *expr_out = new BinaryExpression(tok.type, *expr_out, unary_expr);
+    }
+
+    return EXPRESSION_PARSE_SUCCESS;
+  }
+
+  ExpressionParseStatus Paren(ExpressionNode** expr_out)
+  {
+    ExpressionParseStatus status;
+
+    // lparen already chewed
+    if ((status = Toplevel(expr_out)) != EXPRESSION_PARSE_SUCCESS)
+      return status;
+
+    if (!Expects(TOK_RPAREN))
+    {
+      delete *expr_out;
+      return EXPRESSION_PARSE_SYNTAX_ERROR;
+    }
+
+    return EXPRESSION_PARSE_SUCCESS;
+  }
+
+  ExpressionParseStatus Toplevel(ExpressionNode** expr_out) { return Binary(expr_out); }
+};
+
+ControlState Expression::GetValue()
+{
+  return node->GetValue();
+}
+
+void Expression::SetValue(ControlState value)
+{
+  node->SetValue(value);
+}
+
+Expression::Expression(ExpressionNode* node_)
+{
+  node = node_;
+  num_controls = node->CountNumControls();
+}
+
+Expression::~Expression()
+{
+  delete node;
+}
+
+static ExpressionParseStatus ParseExpressionInner(const std::string& str, ControlFinder& finder,
+                                                  Expression** expr_out)
+{
+  ExpressionParseStatus status;
+  Expression* expr;
+  *expr_out = nullptr;
+
+  if (str == "")
+    return EXPRESSION_PARSE_SUCCESS;
+
+  Lexer l(str);
+  std::vector<Token> tokens;
+  status = l.Tokenize(tokens);
+  if (status != EXPRESSION_PARSE_SUCCESS)
+    return status;
+
+  Parser p(tokens, finder);
+  status = p.Parse(&expr);
+  if (status != EXPRESSION_PARSE_SUCCESS)
+    return status;
+
+  *expr_out = expr;
+  return EXPRESSION_PARSE_SUCCESS;
+}
+
+ExpressionParseStatus ParseExpression(const std::string& str, ControlFinder& finder,
+                                      Expression** expr_out)
+{
+  // Add compatibility with old simple expressions, which are simple
+  // barewords control names.
+
+  ControlQualifier qualifier;
+  qualifier.control_name = str;
+  qualifier.has_device = false;
+
+  std::shared_ptr<Device> device = finder.FindDevice(qualifier);
+  Device::Control* control = finder.FindControl(qualifier);
+  if (control)
+  {
+    *expr_out = new Expression(new ControlExpression(qualifier, device, control));
+    return EXPRESSION_PARSE_SUCCESS;
+  }
+
+  return ParseExpressionInner(str, finder, expr_out);
+}
+}
+}
diff --git a/Source/Core/InputCommon/ControlReference/ExpressionParser.h b/Source/Core/InputCommon/ControlReference/ExpressionParser.h
new file mode 100644
index 0000000000..2c8f5a793f
--- /dev/null
+++ b/Source/Core/InputCommon/ControlReference/ExpressionParser.h
@@ -0,0 +1,72 @@
+// Copyright 2013 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <memory>
+#include <string>
+#include "InputCommon/ControllerInterface/Device.h"
+
+namespace ciface
+{
+namespace ExpressionParser
+{
+class ControlQualifier
+{
+public:
+  bool has_device;
+  Core::DeviceQualifier device_qualifier;
+  std::string control_name;
+
+  ControlQualifier() : has_device(false) {}
+  operator std::string()
+  {
+    if (has_device)
+      return device_qualifier.ToString() + ":" + control_name;
+    else
+      return control_name;
+  }
+};
+
+class ControlFinder
+{
+public:
+  ControlFinder(const Core::DeviceContainer& container_, const Core::DeviceQualifier& default_,
+                const bool is_input_)
+      : container(container_), default_device(default_), is_input(is_input_)
+  {
+  }
+  std::shared_ptr<Core::Device> FindDevice(ControlQualifier qualifier);
+  Core::Device::Control* FindControl(ControlQualifier qualifier);
+
+private:
+  const Core::DeviceContainer& container;
+  const Core::DeviceQualifier& default_device;
+  bool is_input;
+};
+
+class ExpressionNode;
+class Expression
+{
+public:
+  Expression() : node(nullptr) {}
+  Expression(ExpressionNode* node);
+  ~Expression();
+  ControlState GetValue();
+  void SetValue(ControlState state);
+  int num_controls;
+  ExpressionNode* node;
+};
+
+enum ExpressionParseStatus
+{
+  EXPRESSION_PARSE_SUCCESS = 0,
+  EXPRESSION_PARSE_SYNTAX_ERROR,
+  EXPRESSION_PARSE_NO_DEVICE,
+};
+
+ExpressionParseStatus ParseExpression(const std::string& expr, ControlFinder& finder,
+                                      Expression** expr_out);
+}
+}