diff options
Diffstat (limited to 'src/parse')
| -rw-r--r-- | src/parse/mod.rs | 105 |
1 files changed, 0 insertions, 105 deletions
diff --git a/src/parse/mod.rs b/src/parse/mod.rs deleted file mode 100644 index aa8bd4b..0000000 --- a/src/parse/mod.rs +++ /dev/null | |||
| @@ -1,105 +0,0 @@ | |||
| 1 | /* Copyright (C) 2019 Akshay Oppiliappan <[email protected]> | ||
| 2 | * Refer to LICENCE for more information. | ||
| 3 | * */ | ||
| 4 | |||
| 5 | use crate::error::CalcError; | ||
| 6 | use crate::lex::Token; | ||
| 7 | |||
| 8 | pub fn to_postfix(tokens: Vec<Token>) -> Result<Vec<Token>, CalcError> { | ||
| 9 | let mut postfixed: Vec<Token> = vec![]; | ||
| 10 | let mut op_stack: Vec<Token> = vec![]; | ||
| 11 | for token in tokens { | ||
| 12 | match token { | ||
| 13 | Token::Num(_) => { | ||
| 14 | postfixed.push(token); | ||
| 15 | } | ||
| 16 | Token::Function(_) => { | ||
| 17 | op_stack.push(token); | ||
| 18 | } | ||
| 19 | Token::Operator(current_op) => { | ||
| 20 | while let Some(top_op) = op_stack.last() { | ||
| 21 | match top_op { | ||
| 22 | Token::LParen => { | ||
| 23 | break; | ||
| 24 | } | ||
| 25 | Token::Operator(x) => { | ||
| 26 | let tp = x.precedence; | ||
| 27 | let cp = current_op.precedence; | ||
| 28 | if tp > cp || (tp == cp && x.is_left_associative) { | ||
| 29 | postfixed.push(op_stack.pop().unwrap()); | ||
| 30 | } else { | ||
| 31 | break; | ||
| 32 | } | ||
| 33 | } | ||
| 34 | Token::Function(_) => { | ||
| 35 | postfixed.push(op_stack.pop().unwrap()); | ||
| 36 | } | ||
| 37 | _ => { | ||
| 38 | unreachable!(); | ||
| 39 | } | ||
| 40 | } | ||
| 41 | } | ||
| 42 | op_stack.push(token); | ||
| 43 | } | ||
| 44 | Token::LParen => { | ||
| 45 | op_stack.push(token); | ||
| 46 | } | ||
| 47 | Token::RParen => { | ||
| 48 | let mut push_until_paren: bool = false; | ||
| 49 | while let Some(token) = op_stack.pop() { | ||
| 50 | if token == Token::LParen { | ||
| 51 | push_until_paren = true; | ||
| 52 | break; | ||
| 53 | } | ||
| 54 | postfixed.push(token) | ||
| 55 | } | ||
| 56 | if !push_until_paren { | ||
| 57 | return Err(CalcError::Syntax("Mismatched parentheses!".into())); | ||
| 58 | } | ||
| 59 | } | ||
| 60 | } | ||
| 61 | } | ||
| 62 | while let Some(op) = op_stack.pop() { | ||
| 63 | postfixed.push(op); | ||
| 64 | } | ||
| 65 | Ok(postfixed) | ||
| 66 | } | ||
| 67 | |||
| 68 | pub fn eval_postfix(postfixed: Vec<Token>) -> Result<f64, CalcError> { | ||
| 69 | let mut num_stack: Vec<f64> = vec![]; | ||
| 70 | for token in postfixed { | ||
| 71 | match token { | ||
| 72 | Token::Num(n) => { | ||
| 73 | num_stack.push(n); | ||
| 74 | } | ||
| 75 | Token::Operator(op) => { | ||
| 76 | if let Some(n2) = num_stack.pop() { | ||
| 77 | if let Some(n1) = num_stack.pop() { | ||
| 78 | num_stack.push(op.operate(n1, n2)?); | ||
| 79 | } else { | ||
| 80 | return Err(CalcError::Parser( | ||
| 81 | "Too many operators, Too little operands".to_string(), | ||
| 82 | )); | ||
| 83 | } | ||
| 84 | } else { | ||
| 85 | return Err(CalcError::Parser( | ||
| 86 | "Too many operators, Too little operands".to_string(), | ||
| 87 | )); | ||
| 88 | } | ||
| 89 | } | ||
| 90 | Token::Function(funct) => { | ||
| 91 | if let Some(arg) = num_stack.pop() { | ||
| 92 | num_stack.push(funct.apply(arg)?) | ||
| 93 | } | ||
| 94 | } | ||
| 95 | _ => unreachable!("wut"), | ||
| 96 | } | ||
| 97 | } | ||
| 98 | if num_stack.len() == 1 { | ||
| 99 | Ok(num_stack.pop().unwrap()) | ||
| 100 | } else { | ||
| 101 | Err(CalcError::Parser( | ||
| 102 | "Too many operators, Too little operands".to_string(), | ||
| 103 | )) | ||
| 104 | } | ||
| 105 | } | ||