interpret_ahhh.cpp

// 
// AHHH Programming Language Interpreter
// by: Kyle Morgenstein
// kyle.morgenstein@gmail.com
// www.kylemorgenstein.com
//
// License: GPL v3.0
// Heavily inspired by COW (by BigZaphod)
// The structure for the interpreter was also borrowed from COW
// Feel free to edit/use/distribute, but please don't sell AHHH or any derivative work
// If you use AHHH, attribution would be cool too, I suppose
//
#include<vector>
#include<stdio.h>
#include<cstdlib>
#include<cstring>
#include<iostream>

typedef std::vector<int> mem;
mem program;
mem memory;
mem::iterator memory_position;
mem::iterator program_position;

int register1_value;
int register2_value;

bool register1_has_value = false;
bool register2_has_value = false;

void quit( bool error )
{
	if (error)
	{
		printf("Error!/n");
		exit(1);
	}
	#ifndef NO_GREETINGS
		printf("\nDone.\n");
	#endif 
		exit(0);
}

bool exec( int instruction )
{
	switch( instruction )
	{
		// hhhh
		case 0:
		{
			if ( program_position == program.begin() )
				quit( true );
			program_position--;
			int level = 1;
			while( level > 0 )
			{
				if (program_position == program.begin() )
					break;
			
				program_position--;
					
				if ( (*program_position) == 0 )
					level++;
				
				else
				if ( (*program_position) == 15 )
					level--;
			}
			if( level != 0 )
				quit(true);
			
			return exec( *program_position );
		}
		// hhhH
		case 1:
		{
			memory_position++;
        		if( memory_position == memory.end() )
        		{
            			memory.push_back(0);
            			memory_position = memory.end();
            			memory_position--;
        		}
        		break;
		}
		// hhHh
		case 2:
		{
		        if( memory_position == memory.begin() )
            			quit( true );
        		else
            			memory_position--;
        		break;
		}
		// hhHH
		case 3:
		{
			printf( "%d\n", *memory_position );
        		break;
		}
		// hHhh
		case 4:
		{
			if( register1_has_value )
			{
                		(*memory_position) = register1_value;
				register1_value = 0;
			}
			else
            			register1_value = (*memory_position);
        		register1_has_value = !register1_has_value;
			break;
		}
		// hHhH
		case 5:
		{
			if( register2_has_value )
			{
                                (*memory_position) = register2_value;
				register2_value = 0;
			}
                        else
                                register2_value = (*memory_position);
                        register2_has_value = !register2_has_value;
			break;

		}
		// hHHh
		case 6:
		{
			register1_value += (*memory_position);
			register1_has_value = true;
			break;
		}
		// hHHH
		case 7:
		{
			register2_value += (*memory_position);
			register2_has_value = true;
			break;
		}
		// Hhhh
		case 8:
		{
		        if( (*memory_position) != 0 )
				printf( "%c", *memory_position );
        		else
        		{
		        	(*memory_position) = getchar();
            			while( getchar() != '\n' );
        		}
        		break;
		}
		// HhhH
		case 9:
		{
			(*memory_position)++;
			break;
		}
		// HhHh
		case 10:
		{
			(*memory_position)--;
			break;
		}
		// HhHH
		case 11:
		{
                	char buffer[100];
            		int c = 0;
            		int buffer_size = sizeof(buffer)-1;
			while( c < buffer_size )
            		{
                		buffer[c] = getchar();
                		c++;
                		buffer[c] = 0;
                
                		if( buffer[c-1] == '\n' )
                    		break;
            		}
          
            		if( c == sizeof(buffer) )
                		while( getchar() != '\n' );
            
            		(*memory_position) = atoi( buffer );

            		break;
        	}
		// HHhh
		case 12:
		{
			(*memory_position) = 0;
			break;
		}
		// HHhH
		case 13:
		{
			(*memory_position) *= 2;
		       break;	
		}	
		// HHHh
		case 14:
		{
			(*memory_position) *= *memory_position;
			break;
		}
		// HHHH
		case 15:
		{
			if( (*memory_position) == 0 )
        		{
            			int level = 1;
            			int prev = 0;
            			program_position++;	  // have to skip past next command when looking for next hhhh.
            			if( program_position == program.end() )
                			break;
            			while( level > 0 )
            			{
                			prev = *program_position;
                			program_position++;

                			if( program_position == program.end() )
                    				break;

                			if( (*program_position) == 15 )
                    				level++;
                			else
                			if( (*program_position) == 0 )	// look for hhhh command.
                			{
                    				level--;
                    				if( prev == 15 )
                        				level--;
                			}			
            			}
            			if( level != 0 )
                			quit( true );
        		}
        		break;
		}
		// hhh!
		case 16:
		{
			printf( "\n" );
			break;
		}
		default:
			quit( false );
		};
		
		program_position++;

		return true;
}

int main( int argc, char** argv )
{
	if( argc < 2 )
	{
		printf( "\nUsage: %s main.ahhh\n\n", argv[0] );
		exit( 1 );
	}

	FILE* f = fopen( argv[1], "rb" );

	if( f == NULL )
	{
		printf( "Cannot open source file [%s].\n", argv[1] );
        exit( 1 );
	}

	char buffer[4];
    	memset( buffer, 0, 4 );	
	bool reading = false;
	int counter = 0;

    	while( !feof(f) )
    	{
        	int found = 0;
        	buffer[3] = fgetc( f );

        	if( (found = !strncmp( "AHHH", buffer, 4 )) )
			reading = true;
		
		else if( reading )
		{
			if( (found = !strncmp( "hhhh", buffer, 4 )) )
            			program.push_back( 0 );
        		else if( (found = !strncmp( "hhhH", buffer, 4 )) )
            			program.push_back( 1 );
        		else if( (found = !strncmp( "hhHh", buffer, 4 )) )
            			program.push_back( 2 );
        		else if( (found = !strncmp( "hhHH", buffer, 4 )) )
            			program.push_back( 3 );
        		else if( (found = !strncmp( "hHhh", buffer, 4 )) )
            			program.push_back( 4 );
        		else if( (found = !strncmp( "hHhH", buffer, 4 )) )
            			program.push_back( 5 );
        		else if( (found = !strncmp( "hHHh", buffer, 4 )) )
            			program.push_back( 6 );
        		else if( (found = !strncmp( "hHHH", buffer, 4 )) )
            			program.push_back( 7 );
        		else if( (found = !strncmp( "Hhhh", buffer, 4 )) )
            			program.push_back( 8 );
        		else if( (found = !strncmp( "HhhH", buffer, 4 )) )
            			program.push_back( 9 );
        		else if( (found = !strncmp( "HhHh", buffer, 4 )) )
            			program.push_back( 10 );
        		else if( (found = !strncmp( "HhHH", buffer, 4 )) )
            			program.push_back( 11 );
			else if( (found = !strncmp( "HHhh", buffer, 4 )) )
            			program.push_back( 12 );
			else if( (found = !strncmp( "HHhH", buffer, 4 )) )
            			program.push_back( 13 );
			else if( (found = !strncmp( "HHHh", buffer, 4 )) )
            			program.push_back( 14 );
			else if( (found = !strncmp( "HHHH", buffer, 4 )) )
            			program.push_back( 15 );
			else if( (found = !strncmp( "hhh!", buffer, 4 )) )
				program.push_back( 16 );
		}
		else if( counter > 4 )
		{
			printf( "\nSyntax Error: program must begin with 'AHHH'\n\n" );
			exit( 1 );
		}
		else
			counter++;
		
		if( found )
        	{
            		memset( buffer, 0, 4 );
        	}
        	else
        	{
            		buffer[0] = buffer[1];
            		buffer[1] = buffer[2];
            		buffer[2] = buffer[3];
	    		buffer[3] = 0;
        	}
    	}

	fclose( f );

#ifndef NO_GREETINGS
	printf( "\nAHHHHHHHHHHHH!\n\nExecuting [%s]...\n\n", argv[1] );
#endif

    // init main memory.
    memory.push_back( 0 );
    memory_position = memory.begin();

    program_position = program.begin();
    while( program_position != program.end() )
        if( !exec( *program_position ) )
            break;

    quit( false );

	return 0;
}