wallet: add compiler for exprs

bin/darkwallet/src/error.rs

@@ -113,4 +113,7 @@ pub enum Error {
 
     #[error("Channel closed")]
     ChannelClosed = 36,
+
+    #[error("Unexpected token found")]
+    UnexpectedToken = 38,
 }

bin/darkwallet/src/expr/compile.rs

@@ -0,0 +1,321 @@
+/* This file is part of DarkFi (https://dark.fi)
+ *
+ * Copyright (C) 2020-2024 Dyne.org foundation
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+use crate::{
+    error::{Error, Result},
+    //prop::{Property, PropertySubType, PropertyType, PropertySExprValue},
+};
+
+use super::{Op, SExprCode};
+
+fn remove_whitespace(s: &str) -> String {
+    s.chars().filter(|c| !c.is_whitespace()).collect()
+}
+
+pub fn compile(stmts: &str) -> Result<SExprCode> {
+    let mut code = vec![];
+    for stmt in stmts.split(';') {
+        code.push(compile_line(stmt)?);
+    }
+    Ok(code)
+}
+
+#[derive(Debug, Clone)]
+enum Token {
+    LoadVar(String),
+    Add,
+    Sub,
+    Mul,
+    Div,
+    LeftParen,
+    RightParen,
+    ConstFloat32(f32),
+    NestedExpr(Box<Vec<Token>>),
+}
+
+impl Token {
+    fn flatten(self) -> Vec<Self> {
+        match self {
+            Self::NestedExpr(tokens) => {
+                let tokens = Box::into_inner(tokens);
+                tokens.into_iter().map(|t| t.flatten()).flatten().collect()
+            }
+            _ => vec![self],
+        }
+    }
+}
+
+fn tokenize(stmt: &str) -> Vec<Token> {
+    let mut tokens = Vec::new();
+    let mut current_token = String::new();
+    for chr in stmt.chars() {
+        match chr {
+            '+' => {
+                clear_accum(&mut current_token, &mut tokens);
+                tokens.push(Token::Add);
+            }
+            '-' => {
+                clear_accum(&mut current_token, &mut tokens);
+                tokens.push(Token::Sub);
+            }
+            '*' => {
+                clear_accum(&mut current_token, &mut tokens);
+                tokens.push(Token::Mul);
+            }
+            '/' => {
+                clear_accum(&mut current_token, &mut tokens);
+                tokens.push(Token::Div);
+            }
+            '(' => {
+                clear_accum(&mut current_token, &mut tokens);
+                tokens.push(Token::LeftParen);
+            }
+            ')' => {
+                clear_accum(&mut current_token, &mut tokens);
+                tokens.push(Token::RightParen);
+            }
+            _ => current_token.push(chr),
+        }
+    }
+    clear_accum(&mut current_token, &mut tokens);
+    tokens
+}
+
+fn clear_accum(current_token: &mut String, tokens: &mut Vec<Token>) {
+    let prev_token = std::mem::replace(current_token, String::new());
+    if prev_token.is_empty() {
+        return
+    }
+
+    // Number or var?
+    match prev_token.parse::<f32>() {
+        Ok(v) => tokens.push(Token::ConstFloat32(v)),
+        Err(_) => tokens.push(Token::LoadVar(prev_token)),
+    }
+}
+
+/// Convert from infix to reverse polish notation
+fn to_rpn(tokens: Vec<Token>) -> Result<Vec<Token>> {
+    //println!("to_rpn = {tokens:#?}");
+    let mut out = Vec::new();
+    let mut stack = Vec::new();
+
+    // Parens
+    let mut paren = 0;
+    for token in tokens {
+        match token {
+            Token::LeftParen => {
+                // Is this the first opening paren for this subexpr?
+                if paren > 0 {
+                    stack.push(token);
+                }
+                paren += 1;
+                continue
+            }
+            Token::RightParen => {
+                paren -= 1;
+
+                // Whoops non-matching number of parens!
+                if paren < 0 {
+                    return Err(Error::UnexpectedToken)
+                }
+
+                // Did we finally reach the closing paren for this subexpr?
+                if paren == 0 {
+                    let stack = std::mem::take(&mut stack);
+                    let mut rpn = to_rpn(stack)?;
+                    out.push(Token::NestedExpr(Box::new(rpn)));
+                } else {
+                    stack.push(token);
+                }
+
+                continue
+            }
+            _ => {}
+        }
+        if paren > 0 {
+            stack.push(token);
+        } else {
+            out.push(token);
+        }
+    }
+    out.append(&mut stack);
+
+    // */
+    let tokens = out.clone();
+    assert!(stack.is_empty());
+    out.clear();
+    let mut is_op = false;
+    for token in tokens {
+        match token {
+            Token::Mul | Token::Div => {
+                if is_op {
+                    return Err(Error::UnexpectedToken)
+                }
+                is_op = true;
+
+                let Some(prev_item) = out.pop() else { return Err(Error::UnexpectedToken) };
+                stack.push(token);
+                stack.push(prev_item);
+            }
+            _ => {
+                if is_op {
+                    is_op = false;
+                    let mut expr = std::mem::take(&mut stack);
+                    expr.push(token);
+                    out.push(Token::NestedExpr(Box::new(expr)));
+
+                    continue
+                }
+
+                out.push(token)
+            }
+        }
+    }
+    //println!("out = {out:#?}");
+    //println!("stack = {stack:#?}");
+    //assert!(!is_op);
+    //assert!(stack.is_empty());
+    if is_op || !stack.is_empty() {
+        return Err(Error::UnexpectedToken)
+    }
+
+    // +-
+    let tokens = out.clone();
+    out.clear();
+    let mut is_op = false;
+    for token in tokens {
+        match token {
+            Token::Add | Token::Sub => {
+                if is_op {
+                    return Err(Error::UnexpectedToken)
+                }
+                is_op = true;
+
+                let Some(prev_item) = out.pop() else { return Err(Error::UnexpectedToken) };
+                stack.push(token);
+                stack.push(prev_item);
+            }
+            _ => {
+                if is_op {
+                    is_op = false;
+                    let mut expr = std::mem::take(&mut stack);
+                    expr.push(token);
+                    out.push(Token::NestedExpr(Box::new(expr)));
+
+                    continue
+                }
+
+                out.push(token)
+            }
+        }
+    }
+    //assert!(!is_op);
+    //assert!(stack.is_empty());
+    if is_op || !stack.is_empty() {
+        return Err(Error::UnexpectedToken)
+    }
+
+    // Flatten everything
+    let out = out.into_iter().map(|t| t.flatten()).flatten().collect();
+    Ok(out)
+}
+
+fn convert<I: Iterator<Item = Token>>(iter: &mut I) -> Result<Op> {
+    let Some(token) = iter.next() else { return Err(Error::UnexpectedToken) };
+
+    let op = match token {
+        Token::ConstFloat32(v) => Op::ConstFloat32(v),
+        Token::LoadVar(v) => Op::LoadVar(v),
+        Token::Add => {
+            let lhs = convert(iter)?;
+            let rhs = convert(iter)?;
+            Op::Add((Box::new(lhs), Box::new(rhs)))
+        }
+        Token::Sub => {
+            let lhs = convert(iter)?;
+            let rhs = convert(iter)?;
+            Op::Sub((Box::new(lhs), Box::new(rhs)))
+        }
+        Token::Mul => {
+            let lhs = convert(iter)?;
+            let rhs = convert(iter)?;
+            Op::Mul((Box::new(lhs), Box::new(rhs)))
+        }
+        Token::Div => {
+            let lhs = convert(iter)?;
+            let rhs = convert(iter)?;
+            Op::Div((Box::new(lhs), Box::new(rhs)))
+        }
+        _ => return Err(Error::UnexpectedToken),
+    };
+    Ok(op)
+}
+
+fn compile_line(stmt: &str) -> Result<Op> {
+    let stmt = remove_whitespace(stmt);
+    let tokens = tokenize(&stmt);
+    //println!("{tokens:#?}");
+    let tokens = to_rpn(tokens)?;
+    //println!("{tokens:#?}");
+    Ok(convert(&mut tokens.into_iter())?)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn single_line() {
+        let code = compile("h/2 - 200").unwrap();
+        #[rustfmt::skip]
+        let code2 = vec![Op::Sub((
+            Box::new(Op::Div((
+                Box::new(Op::LoadVar("h".to_string())),
+                Box::new(Op::ConstFloat32(2.)),
+            ))),
+            Box::new(Op::ConstFloat32(200.)),
+        ))];
+        assert_eq!(code, code2);
+
+        let code = compile("(x + h/2 + (y + 7)/5) - 200").unwrap();
+        #[rustfmt::skip]
+        let code2 = vec![Op::Sub((
+            Box::new(Op::Add((
+                Box::new(Op::Add((
+                    Box::new(Op::LoadVar("x".to_string())),
+                    Box::new(Op::Div((
+                        Box::new(Op::LoadVar("h".to_string())),
+                        Box::new(Op::ConstFloat32(2.))
+                    ))),
+                ))),
+
+                Box::new(Op::Div((
+                    Box::new(Op::Add((
+                        Box::new(Op::LoadVar("y".to_string())),
+                        Box::new(Op::ConstFloat32(7.))
+                    ))),
+                    Box::new(Op::ConstFloat32(5.))
+                ))),
+            ))),
+
+            Box::new(Op::ConstFloat32(200.))
+        ))];
+        assert_eq!(code, code2);
+    }
+}

bin/darkwallet/src/expr.rs → bin/darkwallet/src/expr/mod.rs

@@ -25,6 +25,9 @@ use darkfi_serial::{
 };
 use std::io::{Read, Write};
 
+mod compile;
+pub use compile::compile;
+
 #[derive(Clone, Debug, PartialEq, SerialEncodable, SerialDecodable)]
 pub enum SExprVal {
     Null,

bin/darkwallet/src/main.rs

@@ -26,6 +26,8 @@
 #![feature(stmt_expr_attributes)]
 // if let Some(is_foo) = is_foo && is_foo { ... }
 #![feature(let_chains)]
+// consume a box
+#![feature(box_into_inner)]
 
 // Use these to incrementally fix warnings with cargo fix
 //#![allow(warnings, unused)]