Improved history storage

src/context.rs

@@ -0,0 +1,31 @@
+use crate::parser::Token;
+use std::collections::HashMap;
+
+#[derive(Debug)]
+pub struct Context {
+	history: Vec<Token>,
+	variables: HashMap<String, Token>
+}
+
+impl Context {
+	pub fn new() -> Context {
+		Context{ history: Vec::new(), variables: HashMap::new() }
+	}
+
+	pub fn push_hist(&mut self, t: Token) { self.history.push(t); }
+	pub fn push_var(&mut self, s: String, t: Token) { self.variables.insert(s, t); }
+	pub fn del_var(&mut self, s: &String) { self.variables.remove(s); }
+
+	pub fn get_variable(&self, s: String) -> Option<Token> {
+
+		let v: Option<&Token>;
+
+		if s == "ans" {
+			v = self.history.last();
+		} else {
+			v = self.variables.get(&s);
+		}
+
+		if v.is_some() { Some(v.unwrap().clone()) } else { None }
+	}
+}

src/entry/unix/unix.rs

@@ -13,20 +13,18 @@ use termion::{
 };
 
 use super::promptbuffer::PromptBuffer;
-//use crate::tokens::EvalError;
 use crate::parser;
 use crate::command;
 use crate::evaluate::evaluate;
 use crate::evaluate::EvalError;
-
-
+use crate::context::Context;
 
 
 #[inline(always)]
 fn do_expression(
 	stdout: &mut RawTerminal<std::io::Stdout>,
 	s: &String,
-	history: &Vec<parser::Token>
+	context: &Context
 ) -> Result<parser::Token, ()> {
 	#[cfg(debug_assertions)]
 	RawTerminal::suspend_raw_mode(&stdout).unwrap();
@@ -62,7 +60,7 @@ fn do_expression(
 	// Evaluate expression
 	#[cfg(debug_assertions)]
 	RawTerminal::suspend_raw_mode(&stdout).unwrap();
-	let g = evaluate(&g, history);
+	let g = evaluate(&g, context);
 	#[cfg(debug_assertions)]
 	RawTerminal::activate_raw_mode(&stdout).unwrap();
 
@@ -158,7 +156,7 @@ pub fn main() -> Result<(), std::io::Error> {
 	//write!(stdout, "{:?}", size).unwrap();
 
 	let mut pb: PromptBuffer = PromptBuffer::new(64);
-	let mut history: Vec<parser::Token> = Vec::new();
+	let mut context: Context = Context::new();
 
 
 	'outer: loop {
@@ -179,8 +177,8 @@ pub fn main() -> Result<(), std::io::Error> {
 						} else if command::is_command(&in_str) {
 							command::do_command(&mut stdout, &in_str)?;
 						} else {
-							let r = do_expression(&mut stdout, &in_str, &history);
-							if let Ok(t) = r { history.push(t); }
+							let r = do_expression(&mut stdout, &in_str, &context);
+							if let Ok(t) = r { context.push_hist(t); }
 						}
 
 						break;

src/evaluate/evaluate.rs

@@ -1,12 +1,13 @@
 use crate::parser::Token;
 use crate::parser::Operator;
+use crate::context::Context;
+
 
 use super::operator::eval_operator;
 use super::function::eval_function;
 use super::EvalError;
 
-
-pub fn evaluate(t: &Token, history: &Vec<Token>) -> Result<Token, EvalError> {
+pub fn evaluate(t: &Token, context: &Context) -> Result<Token, EvalError> {
 	let mut g = t.clone();
 	let mut coords: Vec<usize> = Vec::with_capacity(16);
 	coords.push(0);
@@ -31,17 +32,13 @@ pub fn evaluate(t: &Token, history: &Vec<Token>) -> Result<Token, EvalError> {
 				loop {
 					e = match e {
 						Token::Quantity(_) => { break; },
-						Token::Constant(c) => { evaluate(&c.value(), history).unwrap() },
+						Token::Constant(c) => { evaluate(&c.value(), context).unwrap() },
 						Token::Operator(Operator::Function(f), v) => { eval_function(&f, &v)? },
 						Token::Operator(o, v) => { eval_operator(&o, &v)? },
 						Token::Variable(s) => {
-							if s == "ans" {
-								if history.len() == 0 {
-									return Err(EvalError::NoHistory);
-								} else {
-									history.last().unwrap().clone()
-								}
-							} else { panic!(); }
+							if let Some(t) = context.get_variable(s) { t } else {
+								return Err(EvalError::NoHistory);
+							}
 						}
 					};
 				}

src/main.rs

@@ -2,7 +2,7 @@ pub mod parser;
 pub mod command;
 pub mod quantity;
 pub mod evaluate;
-
+pub mod context;
 
 mod entry;
 use crate::entry::main_e;

src/tests.rs

@@ -1,6 +1,7 @@
 // Many of these have been borrowed from insect.
 use crate::parser;
 use crate::evaluate::evaluate;
+use crate::context::Context;
 
 fn eval_to_str(s: &str) -> Result<String, ()> {
 	let g = match parser::parse(&String::from(s)) {
@@ -9,7 +10,7 @@ fn eval_to_str(s: &str) -> Result<String, ()> {
 	};
 	//let out_str = g.print();
 
-	return match evaluate(&g, &Vec::new()) {
+	return match evaluate(&g, &Context::new()) {
 		Ok(x) => Ok(x.to_string_outer()),
 		Err(_) => Err(())
 	};