dolphin/Source/Core/InputCommon/ControlReference/ExpressionParser.cpp

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// Copyright 2013 Dolphin Emulator Project
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// 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 "Common/StringUtil.h"
#include "InputCommon/ControlReference/ExpressionParser.h"
namespace ciface::ExpressionParser
{
using namespace ciface::Core;
enum TokenType
{
TOK_DISCARD,
TOK_INVALID,
TOK_EOF,
TOK_LPAREN,
TOK_RPAREN,
TOK_AND,
TOK_OR,
TOK_NOT,
TOK_ADD,
TOK_MUL,
TOK_DIV,
TOK_CONTROL,
TOK_LITERAL,
};
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";
case TOK_MUL:
return "Mul";
case TOK_DIV:
return "Div";
default:
assert(false);
return "";
}
}
class Token
{
public:
TokenType type;
std::string data;
Token(TokenType type_) : type(type_) {}
Token(TokenType type_, std::string data_) : type(type_), data(std::move(data_)) {}
operator std::string() const
{
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_MUL:
return "*";
case TOK_DIV:
return "/";
case TOK_CONTROL:
return "Device(" + data + ")";
case TOK_LITERAL:
return '\'' + data + '\'';
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 FetchDelimString(std::string& value, char delim)
{
value = "";
while (it != expr.end())
{
char c = *it;
++it;
if (c == delim)
return true;
value += c;
}
return false;
}
Token GetLiteral()
{
std::string value;
FetchDelimString(value, '\'');
return Token(TOK_LITERAL, value);
}
Token GetFullyQualifiedControl()
{
std::string value;
FetchDelimString(value, '`');
return Token(TOK_CONTROL, value);
}
Token GetBarewordsControl(char c)
{
std::string name;
name += c;
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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 Token(TOK_MUL);
case '/':
return Token(TOK_DIV);
case '\'':
return GetLiteral();
case '`':
return GetFullyQualifiedControl();
default:
if (isalpha(c))
return GetBarewordsControl(c);
else
return Token(TOK_INVALID);
}
}
ParseStatus Tokenize(std::vector<Token>& tokens)
{
while (true)
{
Token tok = NextToken();
if (tok.type == TOK_DISCARD)
continue;
if (tok.type == TOK_INVALID)
{
tokens.clear();
return ParseStatus::SyntaxError;
}
tokens.push_back(tok);
if (tok.type == TOK_EOF)
break;
}
return ParseStatus::Successful;
}
};
class ControlExpression : public Expression
{
public:
ControlQualifier qualifier;
Device::Control* control = nullptr;
// Keep a shared_ptr to the device so the control pointer doesn't become invalid
std::shared_ptr<Device> m_device;
explicit ControlExpression(ControlQualifier qualifier_) : qualifier(qualifier_) {}
ControlState GetValue() const override
{
if (!control)
return 0.0;
// Note: Inputs may return negative values in situations where opposing directions are
// activated. We clamp off the negative values here.
// FYI: Clamping values greater than 1.0 is purposely not done to support unbounded values in
// the future. (e.g. raw accelerometer/gyro data)
return std::max(0.0, control->ToInput()->GetState());
}
void SetValue(ControlState value) override
{
if (control)
control->ToOutput()->SetState(value);
}
int CountNumControls() const override { return control ? 1 : 0; }
void UpdateReferences(ControlFinder& finder) override
{
m_device = finder.FindDevice(qualifier);
control = finder.FindControl(qualifier);
}
operator std::string() const override { return "`" + static_cast<std::string>(qualifier) + "`"; }
};
class BinaryExpression : public Expression
{
public:
TokenType op;
std::unique_ptr<Expression> lhs;
std::unique_ptr<Expression> rhs;
BinaryExpression(TokenType op_, std::unique_ptr<Expression>&& lhs_,
std::unique_ptr<Expression>&& rhs_)
: op(op_), lhs(std::move(lhs_)), rhs(std::move(rhs_))
{
}
ControlState GetValue() const 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 lhsValue + rhsValue;
case TOK_MUL:
return lhsValue * rhsValue;
case TOK_DIV:
{
const ControlState result = lhsValue / rhsValue;
return std::isinf(result) ? 0.0 : result;
}
default:
assert(false);
return 0;
}
}
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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() const override
{
return lhs->CountNumControls() + rhs->CountNumControls();
}
void UpdateReferences(ControlFinder& finder) override
{
lhs->UpdateReferences(finder);
rhs->UpdateReferences(finder);
}
operator std::string() const override
{
return OpName(op) + "(" + (std::string)(*lhs) + ", " + (std::string)(*rhs) + ")";
}
};
class UnaryExpression : public Expression
{
public:
TokenType op;
std::unique_ptr<Expression> inner;
UnaryExpression(TokenType op_, std::unique_ptr<Expression>&& inner_)
: op(op_), inner(std::move(inner_))
{
}
ControlState GetValue() const override
{
ControlState value = inner->GetValue();
switch (op)
{
case TOK_NOT:
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return 1.0 - value;
default:
assert(false);
return 0;
}
}
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void SetValue(ControlState value) override
{
switch (op)
{
case TOK_NOT:
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inner->SetValue(1.0 - value);
break;
default:
assert(false);
}
}
int CountNumControls() const override { return inner->CountNumControls(); }
void UpdateReferences(ControlFinder& finder) override { inner->UpdateReferences(finder); }
operator std::string() const override { return OpName(op) + "(" + (std::string)(*inner) + ")"; }
};
class LiteralExpression : public Expression
{
public:
explicit LiteralExpression(const std::string& str)
{
// If it fails to parse it will just be the default: 0.0
TryParse(str, &m_value);
}
ControlState GetValue() const override { return m_value; }
void SetValue(ControlState value) override
{
// Do nothing.
}
int CountNumControls() const override { return 1; }
void UpdateReferences(ControlFinder&) override
{
// Nothing needed.
}
operator std::string() const override { return '\'' + ValueToString(m_value) + '\''; }
private:
ControlState m_value{};
};
// This class proxies all methods to its either left-hand child if it has bound controls, or its
// right-hand child. Its intended use is for supporting old-style barewords expressions.
class CoalesceExpression : public Expression
{
public:
CoalesceExpression(std::unique_ptr<Expression>&& lhs, std::unique_ptr<Expression>&& rhs)
: m_lhs(std::move(lhs)), m_rhs(std::move(rhs))
{
}
ControlState GetValue() const override { return GetActiveChild()->GetValue(); }
void SetValue(ControlState value) override { GetActiveChild()->SetValue(value); }
int CountNumControls() const override { return GetActiveChild()->CountNumControls(); }
operator std::string() const override
{
return "Coalesce(" + static_cast<std::string>(*m_lhs) + ", " +
static_cast<std::string>(*m_rhs) + ')';
}
void UpdateReferences(ControlFinder& finder) override
{
m_lhs->UpdateReferences(finder);
m_rhs->UpdateReferences(finder);
}
private:
const std::unique_ptr<Expression>& GetActiveChild() const
{
return m_lhs->CountNumControls() > 0 ? m_lhs : m_rhs;
}
std::unique_ptr<Expression> m_lhs;
std::unique_ptr<Expression> m_rhs;
};
std::shared_ptr<Device> ControlFinder::FindDevice(ControlQualifier qualifier) const
{
if (qualifier.has_device)
return container.FindDevice(qualifier.device_qualifier);
else
return container.FindDevice(default_device);
}
Device::Control* ControlFinder::FindControl(ControlQualifier qualifier) const
{
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);
}
struct ParseResult
{
ParseResult(ParseStatus status_, std::unique_ptr<Expression>&& expr_ = {})
: status(status_), expr(std::move(expr_))
{
}
ParseStatus status;
std::unique_ptr<Expression> expr;
};
class Parser
{
public:
explicit Parser(std::vector<Token> tokens_) : tokens(tokens_) { m_it = tokens.begin(); }
ParseResult Parse() { return Toplevel(); }
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private:
std::vector<Token> tokens;
std::vector<Token>::iterator m_it;
Token Chew() { return *m_it++; }
Token Peek() { return *m_it; }
bool Expects(TokenType type)
{
Token tok = Chew();
return tok.type == type;
}
ParseResult Atom()
{
Token tok = Chew();
switch (tok.type)
{
case TOK_CONTROL:
{
ControlQualifier cq;
cq.FromString(tok.data);
return {ParseStatus::Successful, std::make_unique<ControlExpression>(cq)};
}
case TOK_LITERAL:
{
return {ParseStatus::Successful, std::make_unique<LiteralExpression>(tok.data)};
}
case TOK_LPAREN:
return Paren();
default:
return {ParseStatus::SyntaxError};
}
}
bool IsUnaryExpression(TokenType type)
{
switch (type)
{
case TOK_NOT:
return true;
default:
return false;
}
}
ParseResult Unary()
{
if (IsUnaryExpression(Peek().type))
{
Token tok = Chew();
ParseResult result = Atom();
if (result.status == ParseStatus::SyntaxError)
return result;
return {ParseStatus::Successful,
std::make_unique<UnaryExpression>(tok.type, std::move(result.expr))};
}
return Atom();
}
bool IsBinaryToken(TokenType type)
{
switch (type)
{
case TOK_AND:
case TOK_OR:
case TOK_ADD:
case TOK_MUL:
case TOK_DIV:
return true;
default:
return false;
}
}
ParseResult Binary()
{
ParseResult result = Unary();
if (result.status == ParseStatus::SyntaxError)
return result;
std::unique_ptr<Expression> expr = std::move(result.expr);
while (IsBinaryToken(Peek().type))
{
Token tok = Chew();
ParseResult unary_result = Unary();
if (unary_result.status == ParseStatus::SyntaxError)
{
return unary_result;
}
expr = std::make_unique<BinaryExpression>(tok.type, std::move(expr),
std::move(unary_result.expr));
}
return {ParseStatus::Successful, std::move(expr)};
}
ParseResult Paren()
{
// lparen already chewed
ParseResult result = Toplevel();
if (result.status != ParseStatus::Successful)
return result;
if (!Expects(TOK_RPAREN))
{
return {ParseStatus::SyntaxError};
}
return result;
}
ParseResult Toplevel() { return Binary(); }
};
static ParseResult ParseComplexExpression(const std::string& str)
{
Lexer l(str);
std::vector<Token> tokens;
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ParseStatus tokenize_status = l.Tokenize(tokens);
if (tokenize_status != ParseStatus::Successful)
return {tokenize_status};
return Parser(std::move(tokens)).Parse();
}
static std::unique_ptr<Expression> ParseBarewordExpression(const std::string& str)
{
ControlQualifier qualifier;
qualifier.control_name = str;
qualifier.has_device = false;
return std::make_unique<ControlExpression>(qualifier);
}
std::pair<ParseStatus, std::unique_ptr<Expression>> ParseExpression(const std::string& str)
{
if (StripSpaces(str).empty())
return std::make_pair(ParseStatus::EmptyExpression, nullptr);
auto bareword_expr = ParseBarewordExpression(str);
ParseResult complex_result = ParseComplexExpression(str);
if (complex_result.status != ParseStatus::Successful)
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{
return std::make_pair(complex_result.status, std::move(bareword_expr));
}
auto combined_expr = std::make_unique<CoalesceExpression>(std::move(bareword_expr),
std::move(complex_result.expr));
return std::make_pair(complex_result.status, std::move(combined_expr));
}
} // namespace ciface::ExpressionParser