/**
    STCompiler.m
    Bytecode compiler. Generates STExecutableCode from source code.
 
    Copyright (c) 2002 Free Software Foundation
 
    This file is part of the StepTalk project.
 
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.
 
    This library 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
    Lesser General Public License for more details.
 
    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#import "STCompiler.h"

#import "STMessage.h"
#import "STLiterals.h"
#import "STBytecodes.h"
#import "STCompiledScript.h"
#import "STCompiledCode.h"
#import "STCompiledMethod.h"
#import "STCompilerUtils.h"
#import "STSourceReader.h"
#import "Externs.h"

#import <StepTalk/STExterns.h>
#import <StepTalk/STObjectReference.h>
#import <StepTalk/STSelector.h>

#import <Foundation/NSArray.h>
#import <Foundation/NSAutoreleasePool.h>
#import <Foundation/NSData.h>
#import <Foundation/NSDebug.h>
#import <Foundation/NSDictionary.h>
#import <Foundation/NSException.h>
#import <Foundation/NSValue.h>

extern int STCparse(void *context);

/* FIXME: rewrite parser 

    We need three kinds of grammars:

    1. <source> = <statements> | <temp_variables> <statements>

    2. <source> = '[|' <method_list> ']'
       <method_list> = <method> | <method> '!' <method_list>
       <method> =  <statements> | <temp_variables> <statements>

    3. <source> = <method>
       <method> =  <statements> | <temp_variables> <statements>

    Parser 1. are 2. are for scripts. Parser 3. is for script object
    methods. Because majority of the grammar is reused in all three
    parsers we use only one grammar definition. There is no problem
    in haveng 1. and 2. in one file. To be able to have 3. in the same
    file we do a hack: we add a prefix '!!' for method source. Then
    we diferentiate it in grammar file by changin the rule:

        3. <source> = '!' '!' <method>

    See STGrammar.y
*/

@interface STCompiler(STCompilerPrivate)
- (void)compile;
- (void)initializeContext;
- (void)destroyCompilationContext;
- (unsigned)tempVariableIndex:(NSString *)varName;
- (unsigned)externalVariableIndex:(NSString *)varName;

- (void) initializeCompilationContext;

- (NSDictionary *)exceptionInfo;

- (unsigned)addSelectorLiteral:(NSString*)selector;
- (unsigned)addLiteral:literal;

- (void)compileMethod:(STCMethod *)method;
- (STCompiledCode *) compileStatements:(STCStatements *)statements;
- (void)compileStatements:(STCStatements *)statements blockFlag:(BOOL)blockFlag;
- (void)compilePrimary:(STCPrimary *)primary;
- (void)compileExpression:(STCExpression *)expr;

- (void)emitPushReceiverVariable:(unsigned)index;
- (void)emitPushSelf;
- (void)emitPopAndStoreReceiverVariable:(unsigned)index;
- (void)emitReturn;
- (void)emitReturnFromBlock;
- (void)emitPushTemporary:(unsigned)index;
- (void)emitPushLiteral:(unsigned)index;
- (void)emitPushVariable:(unsigned)index;
- (void)emitPopAndStoreTemporary:(unsigned)index;
- (void)emitPopAndStoreVariable:(unsigned)index ;
- (void)emitPopStack;
- (void)emitSendSelector:(unsigned)index argCount:(unsigned)argCount;
- (void)emitBlockCopy;
- (void)emitDuplicateStackTop;
- (void)emitJump:(short)offset;
- (void)emitLongJump:(short)offset;
- (void)emitPushNil;
- (void)emitPushTrue;
- (void)emitPushFalse;

- (void)fixupLongJumpAt:(unsigned)index with:(short)offset;
- (unsigned)currentBytecode;
@end

#define MAX(a,b) (((a)>(b))?(a):(b))

@implementation STCompiler
+ compilerWithEnvironment:(STEnvironment *)env
{
    return AUTORELEASE([[self alloc] initWithEnvironment:env]);
}
- initWithEnvironment:(STEnvironment *)env
{
    self = [self init];
    [self setEnvironment:env];
    return self;
}

- init
{
    [super init];
    
    arrayLiteralClass     = [NSMutableArray class];
    stringLiteralClass    = [NSMutableString class];
    /* bytesLiteralClass  = [NSMutableData class]; */
    intNumberLiteralClass  = [NSNumber class];
    realNumberLiteralClass = [NSNumber class];
    symbolLiteralClass    = [STSelector class];        
    characterLiteralClass = [NSString class];
    
    return self;
}
- (void)dealloc
{
    [super dealloc];
}

- (BOOL)beginScript
{
    if(isSingleMethod)
    {
        [NSException raise:@"STCompilerException"
                    format:@"Script source given for single method"];
        return NO;
    }
    else
    {
        return YES;
    }

}
/* ---------------------------------------------------------------------------
 * Compilation
 * ---------------------------------------------------------------------------
 */

- (void)setEnvironment:(STEnvironment *)env
{
    ASSIGN(environment,env);
}

- (STCompiledMethod *)compileMethodFromSource:(NSString *)aString
                                  forReceiver:(id)receiver
{
    STCompiledMethod *result;
    NSString         *hackedSource;
    NSString         *exceptionFmt = @"Syntax error at line %i near '%@', "
                                   @"reason: %@.";
    int               parsRetval = 0;


    NSDebugLLog(@"STCompiler", @"Compile method", aString);

    if(!environment)
    {
        [NSException  raise:STCompilerGenericException
                     format:@"Compilation environment is not initialized"];
        return nil;
    }
        
    hackedSource = [@"!!" stringByAppendingString:aString];
    reader = [[STSourceReader alloc] initWithString:hackedSource];
    receiverVars = [[NSArray alloc] 
                                initWithArray:[receiver instanceVariableNames]];

    isSingleMethod = YES;   
    STParserContextInit(&context,self,reader);
    
    NS_DURING
    {
        // extern int STCdebug;
        // STCdebug = 1;
        parsRetval = STCparse(&context);
    }
    NS_HANDLER
    {
        if ([[localException name] isEqualToString: STCompilerSyntaxException])
        {
            NSString *tokenString;
            int       line;
            
            tokenString = [reader tokenString];
            line = [reader currentLine];
            RELEASE(reader);
            RELEASE(receiverVars);

            receiverVars = nil;
            reader = nil;
            
            [NSException  raise:STCompilerSyntaxException
                         format:exceptionFmt,
                                line,
                                tokenString,
                                [localException reason]];
                         
        }
        [localException raise];
    }
    NS_ENDHANDLER

    RELEASE(receiverVars);
    RELEASE(reader);

    result = AUTORELEASE(resultMethod);
    resultMethod = nil;
    
    return result;
}

- (STCompiledScript *)compileString:(NSString *)aString
{
    STCompiledScript *result;
    NSString         *exceptionFmt = @"Syntax error at line %i near '%@', "
                                   @"reason: %@.";
    int               parsRetval = 0;


    NSDebugLLog(@"STCompiler", @"Compile string", aString);

    isSingleMethod = NO;

    if(!environment)
    {
        [NSException  raise:STCompilerGenericException
                     format:@"Compilation environment is not initialized"];
        return nil;
    }
    
    reader = [[STSourceReader alloc] initWithString:aString];
    receiverVars = [[NSMutableArray alloc] init];

    STParserContextInit(&context,self,reader);
    
    NS_DURING
    {
        // extern int STCdebug;
        // STCdebug = 1;
        parsRetval = STCparse(&context);
    }
    NS_HANDLER
    {
        if ([[localException name] isEqualToString: STCompilerSyntaxException])
        {
            NSString *tokenString;
            int       line;
            
            tokenString = [reader tokenString];
            line = [reader currentLine];
            RELEASE(reader);
            RELEASE(receiverVars);

            receiverVars = nil;
            reader = nil;
            
            [NSException  raise:STCompilerSyntaxException
                         format:exceptionFmt,
                                line,
                                tokenString,
                                [localException reason]];
                         
        }
        [localException raise];
    }
    NS_ENDHANDLER

    RELEASE(receiverVars);
    RELEASE(reader);

    result = AUTORELEASE(resultScript);
    resultScript = nil;
    
    return result;
}

- (void)compileMethod:(STCMethod *)method
{
    STCompiledMethod *compiledMethod;
    STCompiledCode   *code;
    STMessage        *messagePattern;
    
    /* FIXME: unite STCMessage and STMessage */
    messagePattern = (STMessage *)[method messagePattern];
    
    if(!messagePattern)
    {
        messagePattern = [STMessage messageWithSelector:@"_unnamed_method"
                                              arguments:nil];
    }
    
    NSDebugLLog(@"STCompiler", @"Compile method %@", [messagePattern selector]);

    tempVars = [NSMutableArray arrayWithArray:[messagePattern arguments]];

    code = [self compileStatements:[method statements]];
   
    compiledMethod = [STCompiledMethod methodWithCode:AUTORELEASE(code)
                                       messagePattern:messagePattern];
                                       
    if(!isSingleMethod)
    {

        if(resultMethod)
        {
            [NSException  raise:@"STCompilerException"
                         format:@"Method is present when compiling a script"];
            return;
        }
        if(!resultScript)
        {
            NSDebugLLog(@"STCompiler",
                        @"Creating script with %i variables",[receiverVars count]);

            resultScript = [[STCompiledScript alloc] initWithVariableCount:
                                                     [receiverVars count]];
        }
        [resultScript addMethod:compiledMethod];
    }
    else
    {
        if(resultMethod)
        {
            [NSException  raise:@"STCompilerException"
                         format:@"More than one method compiled for single method request"];
            return;
        }
        if(resultScript)
        {
            [NSException  raise:@"STCompilerException"
                         format:@"Compiled script is present when compiling single method"];
            return;
        }
        resultMethod = RETAIN(compiledMethod);
    }
}

- (STCompiledCode *)compileStatements:(STCStatements *)statements
{
    STCompiledCode  *compiledCode;
#ifdef DEBUG
    int              count;
    int              i;
#endif
    
    /* FIXME: create another class */
    [self initializeCompilationContext];
    
    NSDebugLLog(@"STCompiler", @"compiling statements");

    tempsSize = tempsCount = [tempVars count];

    [self compileStatements:statements blockFlag:NO];

    NSDebugLLog(@"STCompiler", @"  temporaries %i stack %i",
                 tempsSize,stackSize);

#ifdef DEBUG
    count = [literals count];

    NSDebugLLog(@"STCompiler", @"  literals count %i", count);

    for(i=0;i<count;i++)
    {
        NSDebugLLog(@"STCompiler",
                    @"    %2i %@", i, [literals objectAtIndex:i]);
    }

    count = [externVars count];
    NSDebugLLog(@"STCompiler",@"  extern vars count %i",count);
    for(i=0;i<count;i++)
    {
        NSDebugLLog(@"STCompiler",
                    @"    %i %@",i,[externVars objectAtIndex:i]);
    }
#endif
    
    compiledCode = [STCompiledCode alloc];

    [compiledCode initWithBytecodesData:byteCodes
                               literals:literals
                       temporariesCount:tempsSize
                              stackSize:stackSize
                       externReferences:externVars];

    [self destroyCompilationContext];
    
    return compiledCode;
}

- (STSourceReader *)sourceReader
{
    return reader;
}

/* ---------------------------------------------------------------------------
 * Variables
 * ---------------------------------------------------------------------------
 */

- (unsigned)tempVariableIndex:(NSString *)varName
{
    return [tempVars indexOfObject:varName];
}

- (void)setReceiverVariables:(NSArray *)array
{
    ASSIGN(receiverVars,array);
}

- (unsigned)receiverVariableIndex:(NSString *)varName
{
    return [receiverVars indexOfObject:varName];
}

- (void)addTempVariable:(NSString *)varName
{
    if([tempVars containsObject:varName])
    {
        [NSException raise:STCompilerGenericException
                    format:@"Multiple definition of temporary variable %@",
                           varName];
    }
    else
    {
        [tempVars addObject:varName];
    }
}

- (unsigned)addSelectorLiteral:(NSString*)selector
{
    return [self addLiteral:selector];
}

- (unsigned)addLiteral:literal
{
    [literals addObject:literal];
    return [literals count] - 1;
}

- (unsigned)externalVariableIndex:(NSString *)varName
{
    STObjectReferenceLiteral *ref;
    unsigned i;
    unsigned count;
    
    count = [externVars count];
    for(i=0;i<count;i++)
    {
        ref = [externVars objectAtIndex:i];
        if([[ref objectName] isEqualToString:varName])
        {
            return i;
        }
    }

    ref = [[STObjectReferenceLiteral alloc] initWithObjectName:varName
                                                      poolName:nil];
    [externVars addObject:AUTORELEASE(ref)];

    return count;
}


/* ---------------------------------------------------------------------------
 * Compiler internals (called from parser)
 * ---------------------------------------------------------------------------
 */

- (void) initializeCompilationContext
{
    RELEASE(byteCodes);
    RELEASE(externVars);
    RELEASE(literals);
    byteCodes  = [[NSMutableData  alloc] init];
    externVars = [[NSMutableArray alloc] init];
    literals   = [[NSMutableArray alloc] init];
    
    stackSize = stackPos = 0;
    tempsSize = tempsCount = 0;
    bcpos = 0;
}

- (void) destroyCompilationContext
{
    RELEASE(byteCodes);
    RELEASE(externVars);
    RELEASE(literals);
    byteCodes  = nil;
    externVars = nil;
    literals   = nil;
    
    stackSize = stackPos = 0;
    tempsSize = tempsCount = 0;
    bcpos = 0;
}

- (void)compileStatements:(STCStatements *)statements blockFlag:(BOOL)blockFlag
{
    NSEnumerator   *enumerator;
    STBlockLiteral *blockInfo = nil;
    STCExpression  *expr;
    NSArray        *array;
    unsigned        tempsSave;           /* stored count of temporaries */
    unsigned        stackPosSave  = 0;   /* stored previous stack value */  
    unsigned        stackSizeSave = 0;
    unsigned        jumpIP = 0; /* location of jump bytecode for later fixup */
    unsigned        index;
    unsigned        argCount=0;  /* argument count for block context */
        
    NSDebugLLog(@"STCompiler-misc",
                @"  compile statements; blockFlag=%i; tempCount=%i",
                 blockFlag,tempsCount);

    tempsSave = tempsCount; /* store value, so we can cleanup array later */
    
    array = [statements temporaries];

    NSDebugLLog(@"STCompiler-misc",@"  temporaries %@", array);

    if(array)
    {
        argCount = [array count];
        for(index=0;index<argCount;index++)
        {
            [self addTempVariable:[array objectAtIndex:index]];
        }

        tempsCount += argCount;
        tempsSize = MAX(tempsSize,tempsCount);
    }

    if(blockFlag)
    {
        
        blockInfo = [STBlockLiteral alloc];
        [blockInfo initWithArgumentCount:argCount];

        index = [self addLiteral:blockInfo];
        [self emitPushLiteral:index];
        [self emitBlockCopy];

        jumpIP = [self currentBytecode];

        /* block has its own stack */
        stackPosSave = stackPos;
        stackSizeSave = stackSize;
        stackSize = argCount;
        stackPos = argCount;

        [self emitLongJump:0];
        
        for(index = argCount; index > 0; index--)
        {
            [self emitPopAndStoreTemporary:tempsSave + index - 1];
        }
    }
    
    array = [statements expressions];
    
    if(array)
    {
        enumerator = [array objectEnumerator];
        while((expr = [enumerator nextObject]))
        {
            [self compileExpression:expr];
        }
    }

    expr = [statements returnExpression];
    if(expr)
    {
        [self compileExpression:expr];
    }

    if(blockFlag)
    {
        [blockInfo setStackSize:stackSize];
        AUTORELEASE(blockInfo);

        stackSize = stackSizeSave;
        stackPos = stackPosSave;

        [self emitReturnFromBlock];
    }
    else
    {
        [self emitReturn];
    }

    /* fixup jump (if block) */
    if(blockFlag)
    {
        [self fixupLongJumpAt:jumpIP with:[self currentBytecode] - jumpIP];
    }

    /* cleanup unneeded temp variables */
    [tempVars removeObjectsInRange:NSMakeRange(tempsSave,
                                               [tempVars count]-tempsSave)];
    tempsCount = tempsSave;
}

- (void)compilePrimary:(STCPrimary *)primary
{
    id object = [primary object];
    int index;

    NSDebugLLog(@"STCompiler-misc",@"  compile primary");

    switch([primary type])
    {
    case STCVariablePrimaryType:

            if([object isEqualToString:@"YES"]
                || [object isEqualToString:@"true"])
            {
                [self emitPushTrue];
            }
            else if([object isEqualToString:@"NO"]
                || [object isEqualToString:@"false"])
            {
                [self emitPushFalse];
            }
            else if([object isEqualToString:@"nil"])
            {
                [self emitPushNil];
            }
            else
            {
                index = [self tempVariableIndex:object];
                if(index != NSNotFound)
                {
                    [self emitPushTemporary:index];
                    break;
                }
                else if( (index = [self receiverVariableIndex:object])!= NSNotFound)
                {
                    [self emitPushReceiverVariable:index];
                    break;
                }
                else if( [object isEqual:@"self"] )
                {
                    [self emitPushSelf];
                    break;
                }

                index = [self externalVariableIndex:object];
                [self emitPushVariable:index];
            }
            break;

    case STCLiteralPrimaryType:

            index = [self addLiteral:object];
            [self emitPushLiteral:index];
            break;

    case STCBlockPrimaryType:

            [self compileStatements:object blockFlag:YES];
            break;

    case STCExpressionPrimaryType:

            [self compileExpression:object];
            break;

    default:

            [NSException raise:STCompilerInconsistencyException
                        format:@"Unknown primary type %i", 
                               [primary type]];
            break;
    }
}

- (void)compileMessage:(STCMessage *)message
{
    NSEnumerator *enumerator;
    NSArray      *args;
    id            obj;
    int           index;
    
    args = [message arguments];
    if(args && ([args count]>0))
    {
        enumerator = [args objectEnumerator];
        while((obj = [enumerator nextObject]))
        {
            if([obj isKindOfClass:[STCPrimary class]])
                [self compilePrimary:obj];
            else
                [self compileExpression:obj];
        }
    }

    index = [self addSelectorLiteral:[message selector]];
    [self emitSendSelector:index argCount:[args count]];
}

- (void)compileExpression:(STCExpression *)expr
{
    NSEnumerator  *enumerator;
    NSArray       *cascade;
    NSString      *varName;
    NSArray       *array;
    unsigned       count;
    unsigned       index,i;
    id             obj;
    
    NSDebugLLog(@"STCompiler-misc",@"  compile expression");
    
    if([expr isPrimary])
    {
        [self compilePrimary:[expr object]];
    }
    else /* message expression */
    {
        obj = [expr target];

        /* target */
        if([obj isKindOfClass:[STCPrimary class]])
            [self compilePrimary:obj];
        else
            [self compileExpression:obj];
        
        cascade = [expr cascade];
        if(cascade)
        {
            count = [cascade count];
            for(i=0;i<count;i++)
                [self emitDuplicateStackTop];
        }
        
        [self compileMessage:[expr message]];

        /* cascade expression */
        if(cascade)
        {
            enumerator = [cascade objectEnumerator];
            while( (obj = [enumerator nextObject]) )
            {
                /* ignore previous return value */
                [self emitPopStack];
                [self compileMessage:obj];
            }
        }        
    }

    array = [expr assignments];
    count = [array count];
    if(array && count>0)
    {
        for(i = 0; i<count; i++)
        {
            [self emitDuplicateStackTop];
        }
        
        for(i = 0; i<count; i++)
        {
            varName = [array objectAtIndex:i];

            index = [self tempVariableIndex:varName];
            if(index != NSNotFound)
            {
                [self emitPopAndStoreTemporary:index];
                continue;
            }
            else if( (index = [self receiverVariableIndex:varName])!= NSNotFound)
            {
                [self emitPopAndStoreReceiverVariable:index];
                continue;
            }
            if( [varName isEqual:@"self"] )
            {
                NSLog(@"Warning: trying to store to self (ignoring)");
                [self emitPopStack];
                continue;
            }
            
            index = [self externalVariableIndex:varName];
            [self emitPopAndStoreVariable:index];
        }
    }
}


/* ---------------------------------------------------------------------------
 * Literal classes
 * ---------------------------------------------------------------------------
 */

- (Class)stringLiteralClass
{
    return stringLiteralClass;
}
- (Class)arrayLiteralClass
{
    return arrayLiteralClass;
}
- (Class)intNumberLiteralClass
{
    return intNumberLiteralClass;
}
- (Class)realNumberLiteralClass
{
    return realNumberLiteralClass;
}
- (Class)symbolLiteralClass
{
    return symbolLiteralClass;
}
- (Class)characterLiteralClass
{
    return characterLiteralClass;
}
- (void)setStringLiteralClass:(Class)aClass
{
    stringLiteralClass = aClass;
}
- (void)setArrayLiteralClass:(Class)aClass
{
    arrayLiteralClass = aClass;
}
- (void)setIntNumberLiteralClass:(Class)aClass
{
    intNumberLiteralClass = aClass;
}
- (void)setRealNumberLiteralClass:(Class)aClass
{
    realNumberLiteralClass = aClass;
}
- (void)setSymbolLiteralClass:(Class)aClass
{
    symbolLiteralClass = aClass;
}
- (void)setCharacterLiteralClass:(Class)aClass
{
    characterLiteralClass = aClass;
}

- (id)createIntNumberLiteralFrom:(NSString *)aString
{
    return [intNumberLiteralClass intNumberFromString:aString];
}
- (id)createRealNumberLiteralFrom:(NSString *)aString
{
    return [realNumberLiteralClass realNumberFromString:aString];
}
- (id)createSymbolLiteralFrom:(NSString *)aString
{
    return [symbolLiteralClass symbolFromString:aString];
}
- (id)createStringLiteralFrom:(NSString *)aString
{
    return [stringLiteralClass stringFromString:aString];
}
- (id)createCharacterLiteralFrom:(NSString *)aString
{
    return [characterLiteralClass characterFromString:aString];
}
- (id)createArrayLiteralFrom:(NSArray *)anArray
{
   return [arrayLiteralClass arrayFromArray:anArray];
}

- (NSDictionary *)exceptionInfo
{
    NSDictionary *dict;
    
    dict = [NSDictionary dictionaryWithObjectsAndKeys:
                            [NSNumber numberWithInt:[reader currentLine]], 
                                @"LineNumber", 
                            [reader tokenString], 
                                @"Token",      
                            [NSValue valueWithRange:[reader tokenRange]],
                                @"TokenRange",
                            nil,nil];
    return nil;
}
/* ---------------------------------------------------------------------------
 * Emit bytecodes
 * ---------------------------------------------------------------------------
 */
#define STDebugEmit(bc) \
                NSDebugLLog(@"STCompiler-emit", \
                            @"#%04x %@", \
                            (bc).pointer, \
                            STDissasembleBytecode(bc))

#define STDebugEmitWith(bc,object) \
                NSDebugLLog(@"STCompiler-emit", \
                            @"#%04x %@ (%@)", \
                            (bc).pointer, \
                            STDissasembleBytecode(bc), \
                            (object))

#define EMIT_SINGLE(bytecode) \
            do { \
                char bc = bytecode; \
                [byteCodes appendBytes:&bc length:1];\
                bcpos++;\
            } while(0)
#define EMIT_DOUBLE(bc1,bc2) \
            do { \
                char bc[2] = {bc1,bc2}; \
                [byteCodes appendBytes:bc length:2];\
                bcpos+=2;\
            } while(0)
#define EMIT_TRIPPLE(bc1,bc2,bc3) \
            do { \
                char bc[3] = {bc1,bc2,bc3}; \
                [byteCodes appendBytes:bc length:3];\
                bcpos+=3;\
            } while(0)

#define STACK_PUSH \
            do {\
                stackPos++; \
                stackSize = MAX(stackPos,stackSize);\
                /* NSDebugLLog(@"STCompiler",@"stack pointer %i/%i",stackPos,stackSize); */\
            } while(0)
#define STACK_PUSH_COUNT(count) \
            do {\
                stackPos+=count; \
                stackSize = MAX(stackPos,stackSize);\
                /* NSDebugLLog(@"STCompiler",@"stack pointer %i/%i",stackPos,stackSize);*/ \
            } while(0)

#define STACK_POP \
            stackPos--; \
            /* NSDebugLLog(@"STCompiler",@"stack pointer %i/%i",stackPos,stackSize) */;
#define STACK_POP_COUNT(count) \
            stackPos-=count; \
            /* NSDebugLLog(@"STCompiler",@"stack pointer %i/%i",stackPos,stackSize) */;
            
- (void)emitPushSelf
{
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x push self", bcpos);
                
    EMIT_SINGLE(STPushReceiverBytecode);
    STACK_PUSH;
}
- (void)emitPushNil
{
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x push nil", bcpos);
                
    EMIT_SINGLE(STPushNilBytecode);
    STACK_PUSH;
}
- (void)emitPushTrue
{
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x push true", bcpos);
                
    EMIT_SINGLE(STPushTrueBytecode);
    STACK_PUSH;
}
- (void)emitPushFalse
{
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x push false", bcpos);
                
    EMIT_SINGLE(STPushFalseBytecode);
    STACK_PUSH;
}
- (void)emitPushReceiverVariable:(unsigned)index
{
                
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x push receiver variable %i (%@)",
                bcpos,index,[receiverVars objectAtIndex:index]);

    EMIT_DOUBLE(STPushRecVarBytecode,index);
    STACK_PUSH;
}

- (void)emitPushTemporary:(unsigned)index
{
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x push temporary %i (%@)",
                bcpos,index,[tempVars objectAtIndex:index]);
                
    EMIT_DOUBLE(STPushTemporaryBytecode,index);
    STACK_PUSH;
    
}

- (void)emitPushLiteral:(unsigned)index
{
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x push literal %i (%@)",
                bcpos,index,[literals objectAtIndex:index]);
                
    EMIT_DOUBLE(STPushLiteralBytecode,index);
    STACK_PUSH;
    stackSize++;
}
- (void)emitPushVariable:(unsigned)index
{
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x push external variable %i (%@)",
                bcpos,index,[externVars objectAtIndex:index]);
                
    EMIT_DOUBLE(STPushExternBytecode,index);
    STACK_PUSH;
}
- (void)emitPopAndStoreTemporary:(unsigned)index
{
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x pop and store temp %i (%@)",
                bcpos,index,[tempVars objectAtIndex:index]);
                
    EMIT_DOUBLE(STPopAndStoreTempBytecode,index);
    STACK_POP;
}
- (void)emitPopAndStoreVariable:(unsigned)index
{
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x pop and store ext variable %i (%@)",
                bcpos,index,[externVars objectAtIndex:index]);
                
    EMIT_DOUBLE(STPopAndStoreExternBytecode,index);
    STACK_POP;
}
- (void)emitPopAndStoreReceiverVariable:(unsigned)index
{
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x pop and store rec variable %i (%@)",
                bcpos,index,[receiverVars objectAtIndex:index]);
                
    EMIT_DOUBLE(STPopAndStoreRecVarBytecode,index);
    STACK_POP;
}

- (void)emitSendSelector:(unsigned)index argCount:(unsigned)argCount
{
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x send selector %i (%@) with %i args",
                bcpos,index,[literals objectAtIndex:index],argCount);
            
    EMIT_TRIPPLE(STSendSelectorBytecode,index,argCount);
    STACK_PUSH_COUNT(argCount);
    STACK_POP_COUNT(argCount);
}
- (void)emitDuplicateStackTop
{
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x dup",bcpos);
                
    EMIT_SINGLE(STDupBytecode);
    STACK_PUSH;
}
- (void)emitPopStack
{
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x pop stack",bcpos);
                
    EMIT_SINGLE(STPopStackBytecode);
    STACK_POP;
}
- (void)emitReturn
{
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x return",bcpos);
                
    EMIT_SINGLE(STReturnBytecode);
}
- (void)emitReturnFromBlock
{
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x return from block",bcpos);
                
    EMIT_SINGLE(STReturnBlockBytecode);
}
- (void)emitBlockCopy
{
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x create block",bcpos);
                
    EMIT_SINGLE(STBlockCopyBytecode);
}
- (void)emitLongJump:(short)offset
{
    NSDebugLLog(@"STCompiler-emit",
                @"#%04x long jump %i (0x%04x)",bcpos,offset,bcpos+offset);
                
    EMIT_TRIPPLE(STLongJumpBytecode,STLongJumpFirstByte(offset),
                                    STLongJumpSecondByte(offset));
}
- (void)fixupLongJumpAt:(unsigned)index with:(short)offset
{
    char bytes[2] = {STLongJumpFirstByte(offset),STLongJumpSecondByte(offset)};

    NSDebugLLog(@"STCompiler-emit",
                @"# fixup long jump at 0x%04x to 0x%04x",index, index + offset);

    [byteCodes replaceBytesInRange:NSMakeRange(index+1,2) withBytes:bytes];

}
- (unsigned)currentBytecode
{
    return [byteCodes length];
}

@end