lexer

1 files changed, 103 insertions, 0 deletions

diff --git a/src/lexer/lexer.cpp b/src/lexer/lexer.cpp
new file mode 100644
index 0000000..42700dd
--- /dev/null
+++ b/src/lexer/lexer.cpp
@@ -0,0 +1,103 @@
+#include "lexer/lexer.h"
+
+Lexer::Lexer(const std::string& src) : src(src), position(0), line(1), column(1) {}
+
+std::vector<Token> Lexer::tokenise() {
+    while (position < src.size()) {
+        if (std::isdigit(src[position])) {
+            std::string digit;
+            int original_column = column;
+
+            while (std::isdigit(src[position])) {
+                digit.push_back(src[position]);
+                advance();
+            }
+
+            tokens.push_back(Token(TokenType::NUMBER, digit, line, original_column));
+
+        } else if (std::isalpha(src[position])) {
+            if (src.substr(position, 3) == "int") {
+                tokens.push_back(Token(TokenType::INT, "int", line, column));
+                advance();
+                advance();
+                advance();
+
+            } else {
+                std::string identifier;
+                int original_column = column;
+
+                while (std::isalnum(src[position])) {
+                    identifier.push_back(src[position]);
+                    advance();
+                }
+
+                tokens.push_back(Token(TokenType::IDENTIFIER, identifier, line, original_column));
+            }
+
+        } else if (src[position] == '+') {
+            tokens.push_back(Token(TokenType::PLUS, std::string(1, src[position]), line, column));
+            advance();
+
+        } else if (src[position] == '-') {
+            tokens.push_back(Token(TokenType::MINUS, std::string(1, src[position]), line, column));
+            advance();
+
+        } else if (src[position] == '*') {
+            tokens.push_back(Token(TokenType::MULTIPLY, std::string(1, src[position]), line, column));
+            advance();
+
+        } else if (src[position] == '/') {
+            tokens.push_back(Token(TokenType::DIVIDE, std::string(1, src[position]), line, column));
+            advance();
+
+        } else if (src[position] == '=') {
+            tokens.push_back(Token(TokenType::ASSIGN, std::string(1, src[position]), line, column));
+            advance();
+
+        } else if (src[position] == ';') {
+            tokens.push_back(Token(TokenType::SEMICOLON, std::string(1, src[position]), line, column));
+            advance();
+
+        } else {
+            tokens.push_back(Token(TokenType::INVALID, std::string(1, src[position]), line, column));
+            advance();
+
+        }
+        skipComment();
+        skipWhitespace();
+
+    }
+    tokens.push_back(Token(TokenType::END_OF_FILE, std::string(), line, column));
+    return tokens;
+}
+
+char Lexer::advance() {
+    column++;
+    return src[position++];
+}
+
+void Lexer::skipWhitespace() {
+    while (src[position] == ' ' || src[position] == '\n') {
+        if (src[position] == ' ') {
+            position++;
+            column++;
+
+        } else if (src[position] == '\n') {
+            position++;
+            column = 1;
+            line++;
+        }
+    }
+}
+
+void Lexer::skipComment() {
+    if (src[position] == '/' && src[++position] == '/') {
+        while (src[position] != '\n') {
+            position++;
+            column++;
+        }
+        position++;
+        line += 1;
+        column = 1;
+    }
+}