BrainfuckPP/Parser.cpp at master · sebbert/BrainfuckPP · GitHub

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#include "Parser.h"

const char* PREFIX =
"#include <iostream>\n"
"int main()\n"
"{\n"
"char buffers[131072];\n"
"for(int i = 0; i < 131072; i++) buffers[i] = 0;\n"
"unsigned long p = 0;\n"
"\n\n";

const char* SUFFIX =
"std::cout << std::endl;\n"
"return 0;\n"
"}";

Parser::Parser()
{

}

Parser::Parser(std::string& input)
{
	m_input = input;
}

void Parser::Parse()
{
	size_t len = m_input.length();

	for(size_t i = 0; i < len; i++)	///< Loop through all the instructions.
	{
		char inst = m_input.at(i);	///< Fetch the next instruction.

		switch(inst)
		{
			case '+':
				m_instructions.push_back(ADD);
				break;
			case '-':
				m_instructions.push_back(SUB);
				break;
			case '>':
				m_instructions.push_back(NEXT);
				break;
			case '<':
				m_instructions.push_back(PREV);
				break;
			case '[':
				m_instructions.push_back(L_BEG);
				break;
			case ']':
				m_instructions.push_back(L_END);
				break;
			case '.':
				m_instructions.push_back(OUTPUT);
				break;
			case ',':
				m_instructions.push_back(INPUT);
				break;
			case '{':
				m_instructions.push_back(I_BEG);
				break;
			case '}':
				m_instructions.push_back(I_END);
				break;
			case '(':
				m_instructions.push_back(I_ELSE);
				break;
			case ')':
				m_instructions.push_back(I_ENDELSE);
				break;
			case '!':
				m_instructions.push_back(I_NOT);
				break;
			case '/':
				m_instructions.push_back(I_GT);
				break;
			case '\\':
				m_instructions.push_back(I_LT);
				break;
			case '=':
				m_instructions.push_back(I_EQ);
				break;
			case '#':
				m_instructions.push_back(I_NEQ);
				break;
			case ';':
				m_instructions.push_back(BREAK);
				break;
			case ':':
				m_instructions.push_back(CONTINUE);
			default:
				break;
		}
	}
}

void Parser::Build(Stdin in)
{
	m_output.append(PREFIX);

	size_t len = m_instructions.size();
	for(size_t i = 0; i < len; i++)
	{
		Instruction inst = m_instructions[i];
		switch(inst)
		{
			case ADD:
				if(m_instructions[i + 1] != ADD) ///< If there's no point in optimizing.
				{
					m_output.append("buffers[p]++;\n");
					break;
				}

				int c = 0;
				bool br = false;
				for(int ci = 1; !br; ci++) ///< Loop through the ADD instructions
				{
					if(m_instructions[i + ci] == ADD)
						c++;
					else
						br = true;
				}

				std::stringstream ss;
				std::string s;

				ss << "buffers[p] += " << (c + 1) << ";\n";
				ss >> s;

				m_output.append(s);
				i += c;
				break;
			case SUB:
				if(m_instructions[i + 1] != ADD) ///< If there's no point in optimizing.
				{
					m_output.append("buffers[p]++;\n");
					break;
				}

				int c = 0;
				bool br = false;
				for(int ci = 1; !br; ci++) ///< Loop through the ADD instructions
				{
					if(m_instructions[i + ci] == ADD)
						c++;
					else
						br = true;
				}

				std::stringstream ss;
				std::string s;

				ss << "buffers[p] += " << (c + 1) << ";\n";
				ss >> s;

				m_output.append(s);
				i += c;
				break;
			case NEXT:
				m_output.append("if(p<131072)p++;else p=0;\n");
				break;
			case PREV:
				m_output.append("if(p>0)p--;else p=131072;\n");
				break;
			case L_BEG:
				m_output.append("while(buffers[p] != 0) {\n");
				break;
			case L_END:
				m_output.append("}\n");
				break;
			case I_BEG:
				m_output.append("if(buffers[p] ");
				switch(m_instructions[i-1]) ///< If modifiers.
				{
					case I_NOT:
						m_output.append("!= 0");
						break;
					case I_GT:
						m_output.append(" > buffers[p+1]");
						break;
					case I_LT:
						m_output.append(" < buffers[p+1]");
						break;
					case I_EQ:
						m_output.append(" == buffers[p+1]");
						break;
					case I_NEQ:
						m_output.append(" != buffers[p+1]");
						break;

					default:
						break;
				}
				m_output.append(")\n\t{\n");

				break;
			case I_END:
				m_output.append("}\n");
				break;
			case I_ELSE:
				m_output.append("else\n{\n");
				break;
			case I_ENDELSE:
				m_output.append("}");
				break;
			case OUTPUT:
				m_output.append("std::cout << (char)buffers[p];\n");
				break;
			case INPUT:
				m_output.append("std::cin >> buffers[p];\n");
				break;
			case BREAK:
				m_output.append("break;\n");
				break;
			case CONTINUE:
				m_output.append("continue;\n");
			default:
				break;

		}
	}

	m_output.append(SUFFIX);
}

void Parser::SetInput(std::string& input)
{
	m_input = input;
}

std::string& Parser::GetOutput()
{
	return m_output;
}