add previous answer access

1 files changed, 18 insertions, 9 deletions

diff --git a/src/main.rs b/src/main.rs
index 91d91e5..0742ee8 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -43,7 +43,7 @@ lazy_static! {
 fn main() {
     if CONFIGURATION.input.len() > 0 {
         // command mode //
-        let evaled = eval_math_expression(&CONFIGURATION.input[..]);
+        let evaled = eval_math_expression(&CONFIGURATION.input[..], &mut 0f64);
         match evaled {
             Ok(ans) => pprint(ans),
             Err(e) => {
@@ -56,6 +56,9 @@ fn main() {
         // create fancy readline 
         let mut rl = create_readline();
 
+        // previous answer
+        let mut prev_ans = 0f64;
+
         // handle history storage
         let eva_dirs = ProjectDirs::from("com", "NerdyPepper", "eva").unwrap();
         let eva_data_dir = eva_dirs.data_dir();
@@ -75,7 +78,7 @@ fn main() {
             match readline {
                 Ok(line) => {
                     rl.add_history_entry(line.as_str());
-                    let evaled = eval_math_expression(&line[..]);
+                    let evaled = eval_math_expression(&line[..], &mut prev_ans);
                     match evaled {
                         Ok(ans) => pprint(ans),
                         Err(e) => println!("{}", handler(e)),
@@ -142,16 +145,17 @@ fn parse_arguments() -> Configuration {
     }
 }
 
-pub fn eval_math_expression(input: &str) -> Result<f64, CalcError> {
+pub fn eval_math_expression(input: &str, prev_ans: &mut f64) -> Result<f64, CalcError> {
     let input = input.trim();
     let input = input.replace(" ", "");
     if input.len() == 0 {
         return Ok(0.)
     }
     let input        = format::autobalance_parens(&input[..])?;
-    let lexed        = lexer(&input[..])?;
+    let lexed        = lexer(&input[..], prev_ans)?;
     let postfixed    = to_postfix(lexed)?;
     let evaled       = eval_postfix(postfixed)?;
+    *prev_ans         = evaled;
     let evaled_fixed = format!("{:.*}", CONFIGURATION.fix, evaled).parse::<f64>().unwrap();
     Ok(evaled_fixed)
 }
@@ -162,27 +166,32 @@ mod tests {
 
     #[test]
     fn basic_ops() {
-        let evaled = eval_math_expression("6*2 + 3 + 12 -3").unwrap();
+        let evaled = eval_math_expression("6*2 + 3 + 12 -3", &0f64).unwrap();
         assert_eq!(24., evaled);
     }
     #[test]
     fn trignometric_fns() {
-        let evaled = eval_math_expression("sin(30) + tan(45").unwrap();
+        let evaled = eval_math_expression("sin(30) + tan(45", &0f64).unwrap();
         assert_eq!(1.5, evaled);
     }
     #[test]
     fn brackets() {
-        let evaled = eval_math_expression("(((1 + 2 + 3) ^ 2 ) - 4)").unwrap();
+        let evaled = eval_math_expression("(((1 + 2 + 3) ^ 2 ) - 4)", &0f64).unwrap();
         assert_eq!(32., evaled);
     }
     #[test]
     fn floating_ops() {
-        let evaled = eval_math_expression("1.2816 + 1 + 1.2816/1.2").unwrap();
+        let evaled = eval_math_expression("1.2816 + 1 + 1.2816/1.2", &0f64).unwrap();
         assert_eq!(3.3496, evaled);
     }
     #[test]
     fn inverse_trignometric_fns() {
-        let evaled = eval_math_expression("deg(asin(1) + acos(1))").unwrap();
+        let evaled = eval_math_expression("deg(asin(1) + acos(1))", &0f64).unwrap();
         assert_eq!(90., evaled);
     }
+    #[test]
+    fn prev_ans() {
+        let evaled = eval_math_expression("_ + 9", &9f64).unwrap();
+        assert_eq!(18.0, evaled);
+    }
 }