Added lexer from previous project

Lexer/src/Lexer.cpp

@@ -0,0 +1,181 @@
+#include <Lexer.h>
+#include <Util.h>
+
+#include <unordered_map>
+#include <string_view>
+#include <fstream>
+#include <vector>
+
+#include <iostream>
+
+namespace LX
+{
+	// Local macros cause im lazy //
+
+	#define ITERATE index++; continue
+	#define TOKEN_CASE(type) case type: return #type;
+
+	static std::string ToString(Token::TokenType type)
+	{
+		switch (type)
+		{
+			TOKEN_CASE(Token::STRING_LITERAL);
+			TOKEN_CASE(Token::IDENTIFIER);
+			TOKEN_CASE(Token::FOR);
+			TOKEN_CASE(Token::WHILE);
+			TOKEN_CASE(Token::IF);
+			TOKEN_CASE(Token::ELSE);
+			TOKEN_CASE(Token::ELIF);
+			TOKEN_CASE(Token::FUNCTION);
+
+			default:
+				return std::string("Unknown: " + (short)type);
+		}
+	}
+
+	static const std::unordered_map<std::string, Token::TokenType> keywords =
+	{
+		{ "for", Token::FOR },
+		{ "while", Token::WHILE },
+		{ "if", Token::IF },
+		{ "else", Token::ELSE },
+		{ "elif", Token::ELIF },
+		{ "func", Token::FUNCTION },
+	};
+
+	const std::vector<Token> LX::LexicalAnalyze(std::ifstream& src, std::ofstream* log)
+	{
+		// Logs the start of the lexical analysis
+		SafeLog(log, LOG_BREAK, "Started lexing file", LOG_BREAK);
+
+		// Allocates a large ammount of memory to hold the output
+		// Will shrink the size later on to stop excess memory
+		std::vector<Token> tokens = {};
+		tokens.reserve(0xFFFF);
+
+		// Turns the contents of the file into a string //
+
+		// Gets length of the file because it is opened at the end
+		const std::streamsize len = src.tellg();
+		src.seekg(0, std::ios::beg); // Goes back to the beginning
+
+		std::string contents(len, '\0'); // Preallocates all space needed
+		src.read(&contents[0], len); // Transfers file to string
+
+		// Trackers for when the program is iterating over the file //
+
+		std::streamsize index = 0;
+
+		std::streamsize startOfWord = 0;
+		std::streamsize startOfStringLiteral = 0;
+
+		bool inComment = false;
+		bool inStringLiteral = false;
+		bool wasLastCharAlpha = false;
+		
+		// Iterates over the file and turns it into tokens //
+		while (index < len)
+		{
+			// Stores the current character for easy access
+			const char current = contents[index];
+
+			// Updates string literal tracker and skips over rest if in a string literal
+			if (current == '"')
+			{
+				// Start of string literal
+				if (inStringLiteral == false)
+				{
+					// Updates the neccesarry trackers
+					startOfStringLiteral = index + 1;
+					inStringLiteral = true;
+					ITERATE;
+				}
+
+				// End of string literal
+				else
+				{
+					// Adds the string literal token to the token vector
+					std::string lit(contents.data() + startOfStringLiteral, index - startOfStringLiteral);
+					tokens.push_back({ Token::STRING_LITERAL, lit });
+
+					// Updates trackers
+					inStringLiteral = false;
+					ITERATE;
+				}
+			}
+
+			// Skips over rest if within a string literal
+			if (inStringLiteral) { ITERATE; }
+
+			// Updates comment state
+			if (current == '#')
+			{
+				inComment = !inComment;
+
+				ITERATE;
+			}
+
+			// Skips over if within a comment
+			if (inComment) { ITERATE; }
+
+			// Works out if the current character is alphabetic
+			bool isAlpha = (current >= 'a' && current <= 'z') || (current >= 'A' && current <= 'Z');
+
+			if (isAlpha == true)
+			{
+				// Start of a word
+				if (wasLastCharAlpha == false)
+				{
+					// Updates trackers
+					wasLastCharAlpha = true;
+					startOfWord = index;
+				}
+
+				ITERATE;
+			}
+
+			// End of a word
+			if (isAlpha == false && wasLastCharAlpha == true)
+			{
+				// Adds the word token to the token vector
+				std::string word(contents.data() + startOfWord, index - startOfWord);
+
+				if (auto keyword = keywords.find(word); keyword != keywords.end())
+				{
+					tokens.push_back({ keyword->second, word });
+				}
+
+				else
+				{
+					tokens.push_back({ Token::IDENTIFIER, word });
+				}
+			}
+
+			// Operators will eventually go here
+
+			// If it is here and not whitespace that means it's an invalid character
+			if (current == ' ' || current == '\t' || current == '\r' || current == '\n')
+			{
+				// Updates trackers
+				wasLastCharAlpha = isAlpha;
+				ITERATE;
+			}
+
+			// Throws an error to alert the user
+			throw InvalidCharInSource(index, current);
+		}
+
+		// Logs the tokens if logging is on //
+		if (log != nullptr)
+		{
+			for (auto& token : tokens)
+			{
+				SafeLog(log, ToString(token.type), ":\t", token.contents);
+			}
+		}
+
+		// Shrinks the vector down to minimum size before returning to avoid excess memory being allocated
+		tokens.shrink_to_fit();
+		return tokens;
+	}
+}