latest pushes

src/lexer/lexer.rs

@@ -0,0 +1,128 @@
+// Copyright (C) 2024 Bellande Architecture Mechanism Research Innovation Center, Ronaldson Bellande
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+use crate::utilities::Token;
+
+pub struct Lexer {
+    input: Vec<char>,
+    position: usize,
+}
+
+impl Lexer {
+    pub fn new(input: String) -> Self {
+        Lexer {
+            input: input.chars().collect(),
+            position: 0,
+        }
+    }
+    fn next_token(&mut self) -> Option<Token> {
+        self.skip_whitespace();
+
+        if self.position >= self.input.len() {
+            return None;
+        }
+
+        match self.input[self.position] {
+            '=' => {
+                self.position += 1;
+                Some(Token::Assignment)
+            }
+            '|' => {
+                self.position += 1;
+                Some(Token::Pipe)
+            }
+            '>' => {
+                self.position += 1;
+                Some(Token::Redirect(">".to_string()))
+            }
+            '<' => {
+                self.position += 1;
+                Some(Token::Redirect("<".to_string()))
+            }
+            '(' => {
+                self.position += 1;
+                Some(Token::LeftParen)
+            }
+            ')' => {
+                self.position += 1;
+                Some(Token::RightParen)
+            }
+            ';' => {
+                self.position += 1;
+                Some(Token::Semicolon)
+            }
+            '\n' => {
+                self.position += 1;
+                Some(Token::NewLine)
+            }
+            '&' => {
+                self.position += 1;
+                Some(Token::Ampersand)
+            }
+            '"' => Some(self.read_string()),
+            _ => Some(self.read_word()),
+        }
+    }
+
+    fn skip_whitespace(&mut self) {
+        while self.position < self.input.len() && self.input[self.position].is_whitespace() {
+            self.position += 1;
+        }
+    }
+
+    fn read_word(&mut self) -> Token {
+        let start = self.position;
+        while self.position < self.input.len()
+            && !self.input[self.position].is_whitespace()
+            && !matches!(
+                self.input[self.position],
+                '=' | '|' | '>' | '<' | '(' | ')' | ';' | '&' | '\n'
+            )
+        {
+            self.position += 1;
+        }
+        let word: String = self.input[start..self.position].iter().collect();
+        match word.as_str() {
+            "if" => Token::If,
+            "then" => Token::Then,
+            "else" => Token::Else,
+            "fi" => Token::Fi,
+            "while" => Token::While,
+            "for" => Token::For,
+            "do" => Token::Do,
+            "done" => Token::Done,
+            "in" => Token::In,
+            _ => Token::Word(word),
+        }
+    }
+
+    fn read_string(&mut self) -> Token {
+        self.position += 1; // Skip opening quote
+        let start = self.position;
+        while self.position < self.input.len() && self.input[self.position] != '"' {
+            self.position += 1;
+        }
+        let result = Token::Word(self.input[start..self.position].iter().collect());
+        self.position += 1; // Skip closing quote
+        result
+    }
+}
+
+impl Iterator for Lexer {
+    type Item = Token;
+    fn next(&mut self) -> Option<Self::Item> {
+        self.next_token()
+    }
+}

src/lexer/mod.rs

@@ -0,0 +1 @@
+pub mod lexer;