vn/code/vn_config.cpp

static config_entry *Config_FindEntryByName(config *Config, string Name)
{
    config_entry *Result = 0;
    
    u32 BucketSlot = HashString(Name) % ArrayCount(Config->EntryBuckets);
    config_entry_bucket *Bucket = Config->EntryBuckets + BucketSlot;
    
    for(config_entry *Entry = Bucket->First;
        Entry != 0;
        Entry = Entry->Next)
    {
        if(AreEqual(Entry->Name, Name))
        {
            Result = Entry;
            break;
        }
    }
    
    return(Result);
}

static void Config_BindEntry(config *Config, string Name, config_entry_type Type, void *Target)
{
    config_entry *Entry = Config_FindEntryByName(Config, Name);
    if(!Entry)
    {
        Entry = PushStruct(&Config->Arena, config_entry);
        Entry->Name = PushString(&Config->Arena, Name);
        Entry->Type = Type;
        
        u32 BucketSlot = HashString(Name) % ArrayCount(Config->EntryBuckets);
        config_entry_bucket *Bucket = Config->EntryBuckets + BucketSlot;
        
        DLLInsertLast(Bucket->First, Bucket->Last, Entry);
        
        if(Config->LastInternal)
        {
            Config->LastInternal->NextInternal = Entry;
            Config->LastInternal = Entry;
        }
        else
        {
            Config->FirstInternal = Config->LastInternal = Entry;
        }
    }
    
    Assert(Entry->Type == Type);
    Entry->Target = Target;
}

inline void Config_BindS32(config *Config, string Name, s32 *Target, s32 Default)
{
    *Target = Default;
    Config_BindEntry(Config, Name, Config_Entry_S32, Target);
}

inline void Config_BindS64(config *Config, string Name, s64 *Target, s64 Default)
{
    *Target = Default;
    Config_BindEntry(Config, Name, Config_Entry_S64, Target);
}

inline void Config_BindB32(config *Config, string Name, b32 *Target, b32 Default)
{
    *Target = Default;
    Config_BindEntry(Config, Name, Config_Entry_B32, Target);
}

static void Config_ParseError(char *Message, memory_arena *Arena)
{
    string String = PushFormat(Arena, "An error occured during config parsing:\n\"%s\"", Message);
    Platform.ShowMessage(String, Platform_Message_Warning);
}

static void Config_ReadFile(config *Config, string Path)
{
    temporary_memory Scratch = GetScratch();
    
    tokenizer Tokenizer = Tokenizer_BeginTokenization(Platform_ReadEntireFile(Scratch.Arena, Path));
    if(Tokenizer.Input.Data)
    {
        token Token;
        for(;;)
        {
            Token = Tokenizer_GetNextToken(&Tokenizer);
            
            if(Token.Type == Token_Identifier)
            {
                string Dir = Token.String;
                
                if(Tokenizer_RequireToken(&Tokenizer, Token_CurlyOpen))
                {
                    for(;;)
                    {
                        Token = Tokenizer_GetNextToken(&Tokenizer);
                        
                        if(Token.Type == Token_Identifier)
                        {
                            string Name = Token.String;
                            
                            if(Tokenizer_RequireToken(&Tokenizer, Token_Equals))
                            {
                                Token = Tokenizer_GetNextToken(&Tokenizer);
                                
                                if(Token.Type == Token_IntegerValue)
                                {
                                    s64 Value = ConvertStringToS64(Token.String);
                                    
                                    string FullName = PushFormat(Scratch.Arena, "%S/%S", Dir, Name);
                                    config_entry *Entry = Config_FindEntryByName(Config, FullName);
                                    if(Entry)
                                    {
                                        if(Entry->Type == Config_Entry_S32)
                                        {
                                            *(s32 *)Entry->Target = (s32)Value;
                                        }
                                        else if(Entry->Type == Config_Entry_S64)
                                        {
                                            *(s64 *)Entry->Target = Value;
                                        }
                                        else
                                        {
                                            Config_ParseError("Entry has wrong data type.", Scratch.Arena);
                                            goto End;
                                        }
                                    }
                                    else
                                    {
                                        Config_ParseError("Cannot find entry.", Scratch.Arena);
                                        goto End;
                                    }
                                }
                                else if(Token.Type == Token_Identifier)
                                {
                                    string FullName = PushFormat(Scratch.Arena, "%S/%S", Dir, Name);
                                    config_entry *Entry = Config_FindEntryByName(Config, FullName);
                                    if(Entry)
                                    {
                                        if(AreEqual(Token.String, StrLit("true")))
                                        {
                                            *(b32 *)Entry->Target = true;
                                        }
                                        else if(AreEqual(Token.String, StrLit("false")))
                                        {
                                            *(b32 *)Entry->Target = false;
                                        }
                                        else
                                        {
                                            Config_ParseError("Entry has wrong data type.", Scratch.Arena);
                                            goto End;
                                        }
                                    }
                                    else
                                    {
                                        Config_ParseError("Cannot find entry.", Scratch.Arena);
                                        goto End;
                                    }
                                }
                                else
                                {
                                    Config_ParseError("Expected a value.", Scratch.Arena);
                                    goto End;
                                }
                                
                                if(!Tokenizer_RequireToken(&Tokenizer, Token_Semicolon))
                                {
                                    Config_ParseError("Expected a ';'.", Scratch.Arena);
                                    goto End;
                                }
                            }
                            else
                            {
                                Config_ParseError("Expected '='.", Scratch.Arena);
                                goto End;
                            }
                        }
                        else if(Token.Type == Token_CurlyClose)
                        {
                            break;
                        }
                        else
                        {
                            Config_ParseError("Expected '}' or identifier.", Scratch.Arena);
                            goto End;
                        }
                    }
                }
                else
                {
                    Config_ParseError("Expected '{'.", Scratch.Arena);
                    goto End;
                }
            }
            else if(Token.Type == Token_EndOfFile)
            {
                goto End;
            }
            else
            {
                Config_ParseError("Unexpected token.", Scratch.Arena);
                goto End;
            }
        }
    }
    
    End:
    ReleaseScratch(Scratch);
}

static void Config_WriteFile(config *Config)
{
    string_list Out = {};
    temporary_memory Scratch = GetScratch();
    
    string LastDir = MakeString(0, 0);
    for(config_entry *Entry = Config->FirstInternal;
        Entry != 0;
        Entry = Entry->NextInternal)
    {
        s64 LastSlash = LastIndexOf(Entry->Name, '/');
        Assert(LastSlash != -1);
        
        string Dir = Prefix(Entry->Name, LastSlash);
        string Name = Suffix(Entry->Name, Entry->Name.Count - LastSlash - 1);
        
        if(!AreEqual(Dir, LastDir))
        {
            if(!AreEqual(LastDir, MakeString(0, 0)))
            {
                AppendString(&Out, StrLit("}\n\n"), Scratch.Arena);
            }
            
            AppendString(&Out, Dir, Scratch.Arena);
            AppendString(&Out, StrLit("\n{\n"), Scratch.Arena);
            
            LastDir = Dir;
        }
        
        AppendString(&Out, StrLit("\t"), Scratch.Arena);
        AppendString(&Out, Name, Scratch.Arena);
        AppendString(&Out, StrLit(" = "), Scratch.Arena);
        
        // sixten: Output the value of the entry
        if(Entry->Type == Config_Entry_S32 || Entry->Type == Config_Entry_S64)
        {
            s64 IntegerValue;
            if(Entry->Type == Config_Entry_S32)
            {
                IntegerValue = *(s32 *)Entry->Target;
            }
            else
            {
                IntegerValue = *(s64 *)Entry->Target;
            }
            
            string Value = ConvertS64ToString(Scratch.Arena, IntegerValue);
            AppendString(&Out, Value, Scratch.Arena);
        }
        else if(Entry->Type == Config_Entry_B32)
        {
            string Value = (*(b32 *)Entry->Target)?StrLit("true"):StrLit("false");
            AppendString(&Out, Value, Scratch.Arena);
        }
        else
        {
            UnimplementedCodepath;
        }
        
        AppendString(&Out, StrLit(";\n"), Scratch.Arena);
    }
    
    if(!AreEqual(LastDir, MakeString(0, 0)))
    {
        AppendString(&Out, StrLit("}"), Scratch.Arena);
    }
    
    string FinalOut = JoinStringList(&Out, Scratch.Arena);
    
    platform_file_handle Handle = Platform.OpenFile(StrLit("config.vn"), PlatformAccess_Write);
    if(Handle.IsValid)
    {
        Platform.WriteFile(Handle, FinalOut.Data, 0, FinalOut.Count);
        Platform.CloseFile(Handle);
    }
    
    ReleaseScratch(Scratch);
}