Add parser for don't

src/solutions/day_3.rs

@@ -10,6 +10,12 @@ enum ParserState {
     ExpectLParen,
     ReadNum1,
     ReadNum2,
+    ExpectO,
+    ExpectNorLParen,
+    ExpectApostrophe,
+    ExpectT,
+    ExpectDontLParen,
+    ExpectRParen(bool),
 }
 
 pub fn run(mut args: env::Args) -> std::io::Result<()> {
@@ -20,10 +26,13 @@ pub fn run(mut args: env::Args) -> std::io::Result<()> {
     let f = File::open(filename)?;
     let reader = BufReader::new(f);
 
-    let mut sum = 0;
+    let mut sum_a = 0;
+    let mut sum_b = 0;
     let mut num_buf = String::with_capacity(3);
     let mut a = 0;
 
+    let mut mul_enabled = true;
+
     for line in reader.lines() {
         let l = line.unwrap();
         if l.is_empty() {
@@ -37,6 +46,8 @@ pub fn run(mut args: env::Args) -> std::io::Result<()> {
                 ParserState::Search => {
                     if c == 'm' {
                         ParserState::ExpectU
+                    } else if c == 'd' {
+                        ParserState::ExpectO
                     } else {
                         ParserState::Search
                     }
@@ -86,7 +97,10 @@ pub fn run(mut args: env::Args) -> std::io::Result<()> {
                         if c == ')' && !num_buf.is_empty() {
                             // parse the number, assign to b, set to ParserState::ReadNum2
                             let b = u32::from_str(&num_buf).unwrap();
-                            sum += a * b;
+                            sum_a += a * b;
+                            if mul_enabled {
+                                sum_b += a * b;
+                            }
                         }
 
                         // teardown in any case
@@ -95,15 +109,58 @@ pub fn run(mut args: env::Args) -> std::io::Result<()> {
                         ParserState::Search
                     }
                 }
+                ParserState::ExpectO => {
+                    if c == 'o' {
+                        ParserState::ExpectNorLParen
+                    } else {
+                        ParserState::Search
+                    }
+                }
+                ParserState::ExpectNorLParen => {
+                    if c == '(' {
+                        ParserState::ExpectRParen(true)
+                    } else if c == 'n' {
+                        ParserState::ExpectApostrophe
+                    } else {
+                        ParserState::Search
+                    }
+                }
+                ParserState::ExpectApostrophe => {
+                    if c == '\'' {
+                        ParserState::ExpectT
+                    } else {
+                        ParserState::Search
+                    }
+                }
+                ParserState::ExpectT => {
+                    if c == 't' {
+                        ParserState::ExpectDontLParen
+                    } else {
+                        ParserState::Search
+                    }
+                }
+                ParserState::ExpectDontLParen => {
+                    if c == '(' {
+                        ParserState::ExpectRParen(false)
+                    } else {
+                        ParserState::Search
+                    }
+                }
+                ParserState::ExpectRParen(enable) => {
+                    if c == ')' {
+                        mul_enabled = enable;
+                    }
+                    ParserState::Search
+                }
             };
         }
     }
 
     // Task 1
-    println!("Sum of all multiplications: {sum}");
+    println!("Sum of all multiplications:            {sum_a}");
 
     // Task 2
-    // TBD
+    println!("Sum of all multiplications (do/don't): {sum_b}");
 
     Ok(())
 }