V-Gears/V-Gears-Installer/include/decompiler/decompiler_codegen.h

#pragma once

/* ScummVM Tools
 *
 * ScummVM Tools is the legal property of its developers, whose
 * names are too numerous to list here. Please refer to the
 * COPYRIGHT file distributed with this source distribution.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#include "graph.h"
#include "value.h"
#include "unknown_opcode_exception.h"

#include <ostream>
#include <utility>

#include <boost/intrusive_ptr.hpp>
#include <memory>


class Engine;

class Function;

const int kIndentAmount = 4; ///< How many spaces to use for each indent.

/**
 * Enumeration for the different argument/operand orderings.
 */
enum ArgOrder
{
    FIFO_ARGUMENT_ORDER, ///< First argument is pushed to stack first.
    LIFO_ARGUMENT_ORDER  ///< First argument is pushed to stack last.
};

class ITargetLanaguge
{
public:
    enum eContext
    {
        eToElseBlock,       // End of if/elseif block and about to start a final else
        eBeginElse,
        eEndOfIf,
        eEndOfWhile,
        eEndIfElseChain,
        eBeginWhile,
        eEndWhile
    };
    virtual ~ITargetLanaguge() = default;
    virtual std::string LoopBreak() = 0;
    virtual std::string LoopContinue() = 0;
    virtual std::string Goto(uint32 target) = 0;
    virtual std::string DoLoopHeader() = 0;
    virtual std::string DoLoopFooter(bool beforeExpr) = 0;
    virtual std::string If(bool beforeExpr) = 0;
    virtual std::string WhileHeader(bool beforeExpr) = 0;
    virtual std::string FunctionCallArgumentSeperator() = 0;
    virtual std::string FunctionCallBegin() = 0;
    virtual std::string FunctionCallEnd() = 0;
    virtual std::string Label(uint32 addr) = 0;
    virtual std::string Else() = 0;
    virtual std::string StartBlock(eContext) = 0;
    virtual std::string EndBlock(eContext) = 0;
    virtual std::string LineTerminator() = 0;
};

class CTargetLanguage : public ITargetLanaguge
{
public:
    virtual std::string LoopBreak() override
    {
        return "break;";
    }

    virtual std::string LoopContinue() override
    {
        return "continue;";
    }

    virtual std::string Goto(uint32 target) override
    {
        std::stringstream s;
        s << boost::format("goto label_0x%X;") % target;
        return s.str();
    }

    virtual std::string DoLoopHeader() override
    {
        return "do {";
    }

    virtual std::string DoLoopFooter(bool beforeExpr) override
    {
        if (beforeExpr)
        {
            return " } while (";
        }
        return ");";
    }

    virtual std::string If(bool beforeExpr) override
    {
        if (beforeExpr)
        {
            return "if (";
        }
        return ") {";
    }

    virtual std::string WhileHeader(bool beforeExpr) override
    {
        if (beforeExpr)
        {
            return "while (";
        }
        return ")";
    }

    virtual std::string FunctionCallArgumentSeperator() override
    {
        return ",";
    }
    
    virtual std::string FunctionCallBegin() override
    {
        return "(";
    }
    
    virtual std::string FunctionCallEnd() override
    {
        return ");";
    }

    virtual std::string Label(uint32 addr) override
    {
        std::stringstream s;
        s << boost::format("label_0x%X:") % addr;
        return s.str();
    }

    virtual std::string Else() override
    {
        return "else";
    }

    virtual std::string StartBlock(eContext) override
    {
        return "{";
    }

    virtual std::string EndBlock(eContext) override
    {
        return "}";
    }

    virtual std::string LineTerminator() override
    {
        return ";";
    }
};

class LuaTargetLanguage : public ITargetLanaguge
{
public:
    virtual std::string LoopBreak() override
    {
        return "break";
    }

    virtual std::string LoopContinue() override
    {
        // LUA has no continue keyword
        //throw InternalDecompilerError();
        return "-- TODO continue not supported in LUA!";
    }

    virtual std::string Goto(uint32 target) override
    {
        std::stringstream s;
        s << boost::format("goto label_0x%X") % target;
        return s.str();
    }

    virtual std::string DoLoopHeader() override
    {
        return "repeat";
    }

    virtual std::string DoLoopFooter(bool beforeExpr) override
    {
        if (beforeExpr)
        {
            return "until (";
        }
        return ")";
    }

    virtual std::string If(bool beforeExpr) override
    {
        if (beforeExpr)
        {
            return "if (";
        }
        return ") then";
    }

    virtual std::string WhileHeader(bool beforeExpr) override
    {
        if (beforeExpr)
        {
            return "while (";
        }
        return ") do";
    }

    virtual std::string FunctionCallArgumentSeperator() override
    {
        return ",";
    }

    virtual std::string FunctionCallBegin() override
    {
        return "(";
    }

    virtual std::string FunctionCallEnd() override
    {
        return ")";
    }

    virtual std::string Label(uint32 addr) override
    {
        std::stringstream s;
        s << boost::format("::label_0x%X::") % addr;
        return s.str();
    }

    virtual std::string Else() override
    {
        return "else";
    }

    virtual std::string StartBlock(eContext) override
    {
        return "";
    }

    virtual std::string EndBlock(eContext ctx) override
    {
        if (ctx == eToElseBlock)
        {
            // For the final else we don't need an end before it
            return "";
        }
        return "end";
    }

    virtual std::string LineTerminator() override
    {
        return "";
    }
};

/**
 * Base class for code generators.
 */
class CodeGenerator 
{
private:
    Graph _g;                  ///< The annotated graph of the script.

    /**
     * Processes a GraphVertex.
     *
     * @param v The vertex to process.
     */
    void process(Function& func, InstVec& insts, GraphVertex v);

protected:
    Engine *_engine;        ///< Pointer to the Engine used for the script.
    std::ostream &_output;  ///< The std::ostream to output the code to.
    ValueStack _stack;      ///< The stack currently being processed.
    uint _indentLevel;      ///< Indentation level.
    GraphVertex _curVertex; ///< Graph vertex currently being processed.
    std::unique_ptr<ITargetLanaguge> target_lang_;

    /**
     * Processes an instruction. Called by process() for each instruction.
     * Call the base class implementation for opcodes you cannot handle yourself,
     * or where the base class implementation is preferable.
     *
     * @param inst The instruction to process.
     */
    void ProcessInst(Function& func, InstVec& insts, const InstPtr inst);
    void processUncondJumpInst(Function& func, InstVec& insts, const InstPtr inst);
    void processCondJumpInst(const InstPtr inst);

    /**
     * Indents a string according to the current indentation level.
     *
     * @param s The string to indent.
     * @result The indented string.
     */
    std::string indentString(std::string s);

    /**
     * Construct the signature for a function.
     *
     * @param func Reference to the function to construct the signature for.
     */
    virtual std::string ConstructFuncSignature(const Function& func);
    virtual void OnBeforeStartFunction(const Function& func);
    virtual void OnEndFunction(const Function& func);
    virtual void OnStartFunction(const Function&) { }
    virtual bool OutputOnlyRequiredLabels() const { return false; }

    void generatePass(InstVec& insts, const Graph& g);
    bool mIsLabelPass = true;

public:
    ITargetLanaguge& TargetLang()
    {
        assert(target_lang_);
        return *target_lang_;
    }

    void writeFunctionCall(std::string functionName, std::string paramsFormat, const std::vector<ValuePtr>& params);

    const ArgOrder _binOrder;  ///< Order of operands for binary operations.
    const ArgOrder _callOrder; ///< Order of operands for call arguments.
    ValueList _argList;        ///< Storage for lists of arguments to be built when processing function calls.
    GroupPtr mCurGroup;     ///< Pointer to the group currently being processed.

    virtual ~CodeGenerator() { }

    /**
     * Constructor for CodeGenerator.
     *
     * @param engine Pointer to the Engine used for the script.
     * @param output The std::ostream to output the code to.
     * @param binOrder Order of arguments for binary operators.
     * @param callOrder Order of arguments for function calls.
     */
    CodeGenerator(Engine *engine, std::ostream &output, ArgOrder binOrder, ArgOrder callOrder);

    /**
     * Generates code from the provided graph and outputs it to stdout.
     *
     * @param g The annotated graph of the script.
     */
    virtual void Generate(InstVec& insts, const Graph &g);

    /**
     * Adds a line of code to the current group.
     *
     * @param s The line to add.
     * @param unindentBefore Whether or not to remove an indentation level before the line. Defaults to false.
     * @param indentAfter Whether or not to add an indentation level after the line. Defaults to false.
     */
    virtual void AddOutputLine(std::string s, bool unindentBefore = false, bool indentAfter = false);

    /**
     * Generate an assignment statement.
     *
     * @param dst The variable being assigned to.
     * @param src The value being assigned.
     */
    void writeAssignment(ValuePtr dst, ValuePtr src);

    /**
     * Add an argument to the argument list.
     *
     * @param p The argument to add.
     */
    void addArg(ValuePtr p);

    /**
     * Process a single character of metadata.
     *
     * @param inst The instruction being processed.
     * @param c The character signifying the action to be taken.
     * @param pos The position at which c occurred in the metadata.
     */
    virtual void processSpecialMetadata(const InstPtr inst, char c, int pos);
};