#include <scanner.hpp>

#include <sstream>

#include <map>

#include <error.hpp>

using namespace std;

// this map contains all the single character operator and their token type

static map<char, Type> lookup{{'>', Type::Move}, {'+', Type::Copy}, {'[', Type::ZeroStart}, {']', Type::ZeroEnd}, {'{', Type::EmptyStart}, {'}', Type::EmptyEnd}};

// generates the list of token from the code

vector<Token> scan(const string &code)

{

int line{1}, column{1}, pointer{0}, end{(int)code.length()};

// string stream to contain data for error reporting

stringstream ss,msg;

msg << "unexpected character";

bool err = false;

vector<Token> tokens;

// lambda expressions to common functions

auto clear = [&]() {

stringstream().swap(ss);

};

auto addToken = [&](Type type) {

string value = ss.str();

tokens.push_back(Token{type, value, line, column - (int)value.length() + 1});

clear();

};

auto isAlphabet = [&](int i) -> bool {

return (i >= 0 && i < end) && ((code[i] >= 'a' && code[i] <= 'z') || (code[i] >= 'A' && code[i] <= 'Z'));

};

auto isNumber = [&](int i) -> bool {

return (i >= 0 && i < end) && (code[i] >= '0' && code[i] <= '9');

};

// loops till we ran out of character

while (pointer < end)

{

ss << code[pointer];

// check for different conditions and tokens accordingly

if (isAlphabet(pointer) && !isAlphabet(pointer + 1))

addToken(Type::Stack);

else if (isNumber(pointer) && !isNumber(pointer + 1))

addToken(Type::Number);

else if (!isNumber(pointer) && !isAlphabet(pointer))

{

// search in lookup table

auto iter = lookup.find(code[pointer]);

if (iter != lookup.end())

addToken(iter->second);

// newline condition

else if (code[pointer] == '\n')

{

line++;

column = 0;

}

// the character is unexpected

else if (code[pointer] != ' ' && code[pointer] != '\t')

{

msg << '\n' << code[pointer] << " at line:" << line << " column:" << column;

err = true;

}

clear();

}

column++;

pointer++;

}

// finally, if there was any error

if (err)

error(msg.str());

return tokens;

}