Merge pull request #601 from AleoHQ/remove-mutable-value

Remove mutable ConstrainedValue

compiler/src/definition/definition.rs

@@ -22,12 +22,8 @@ use leo_asg::Variable;
 use snarkvm_models::curves::{Field, PrimeField};
 
 impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
-    pub fn store_definition(&mut self, variable: &Variable, mut value: ConstrainedValue<F, G>) {
+    pub fn store_definition(&mut self, variable: &Variable, value: ConstrainedValue<F, G>) {
         let variable = variable.borrow();
-        // Store with given mutability
-        if variable.mutable {
-            value = ConstrainedValue::Mutable(Box::new(value));
-        }
 
         self.store(variable.id, value);
     }

compiler/src/expression/array/access.rs

@@ -34,7 +34,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
         index: &Arc<Expression>,
         span: &Span,
     ) -> Result<ConstrainedValue<F, G>, ExpressionError> {
-        let array = match self.enforce_operand(cs, array)? {
+        let array = match self.enforce_expression(cs, array)? {
             ConstrainedValue::Array(array) => array,
             value => return Err(ExpressionError::undefined_array(value.to_string(), span.to_owned())),
         };
@@ -52,7 +52,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
         right: Option<&Arc<Expression>>,
         span: &Span,
     ) -> Result<ConstrainedValue<F, G>, ExpressionError> {
-        let array = match self.enforce_operand(cs, array)? {
+        let array = match self.enforce_expression(cs, array)? {
             ConstrainedValue::Array(array) => array,
             value => return Err(ExpressionError::undefined_array(value.to_string(), span.to_owned())),
         };

compiler/src/expression/array/index.rs

@@ -32,7 +32,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
         index: &Arc<Expression>,
         span: &Span,
     ) -> Result<usize, ExpressionError> {
-        match self.enforce_operand(cs, index)? {
+        match self.enforce_expression(cs, index)? {
             ConstrainedValue::Integer(number) => Ok(number.to_usize(span)?),
             value => Err(ExpressionError::invalid_index(value.to_string(), span)),
         }

compiler/src/expression/binary/binary.rs

@@ -35,8 +35,8 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
         left: &Arc<Expression>,
         right: &Arc<Expression>,
     ) -> Result<ConstrainedValuePair<F, G>, ExpressionError> {
-        let resolved_left = self.enforce_operand(cs, left)?;
-        let resolved_right = self.enforce_operand(cs, right)?;
+        let resolved_left = self.enforce_expression(cs, left)?;
+        let resolved_right = self.enforce_expression(cs, right)?;
 
         Ok((resolved_left, resolved_right))
     }

compiler/src/expression/binary/mod.rs

@@ -18,6 +18,3 @@
 
 pub mod binary;
 pub use self::binary::*;
-
-pub mod operand;
-pub use self::operand::*;

compiler/src/expression/binary/operand.rs

@@ -1,43 +0,0 @@
-// Copyright (C) 2019-2021 Aleo Systems Inc.
-// This file is part of the Leo library.
-
-// The Leo library is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-
-// The Leo library 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 General Public License for more details.
-
-// You should have received a copy of the GNU General Public License
-// along with the Leo library. If not, see <https://www.gnu.org/licenses/>.
-
-//! Enforces one operand in a binary expression in a compiled Leo program.
-
-use crate::{errors::ExpressionError, program::ConstrainedProgram, value::ConstrainedValue, GroupType};
-use leo_asg::Expression;
-use std::sync::Arc;
-
-use snarkvm_models::{
-    curves::{Field, PrimeField},
-    gadgets::r1cs::ConstraintSystem,
-};
-
-impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
-    /// Enforce an operand of a binary expression.
-    /// We don't care about mutability because we are not changing any variables.
-    /// We try to resolve unresolved types here if the type is given explicitly.
-    pub fn enforce_operand<CS: ConstraintSystem<F>>(
-        &mut self,
-        cs: &mut CS,
-        expression: &Arc<Expression>,
-    ) -> Result<ConstrainedValue<F, G>, ExpressionError> {
-        let mut branch = self.enforce_expression(cs, expression)?;
-
-        branch.get_inner_mut();
-
-        Ok(branch)
-    }
-}

compiler/src/expression/circuit/access.rs

@@ -33,7 +33,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
     ) -> Result<ConstrainedValue<F, G>, ExpressionError> {
         if let Some(target) = &expr.target {
             //todo: we can prob pass values by ref here to avoid copying the entire circuit on access
-            let target_value = self.enforce_operand(cs, target)?;
+            let target_value = self.enforce_expression(cs, target)?;
             match target_value {
                 ConstrainedValue::CircuitExpression(def, members) => {
                     assert!(def.circuit == expr.circuit);

compiler/src/expression/conditional/conditional.rs

@@ -41,9 +41,9 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
             value => return Err(ExpressionError::conditional_boolean(value.to_string(), span.to_owned())),
         };
 
-        let first_value = self.enforce_operand(cs, first)?;
+        let first_value = self.enforce_expression(cs, first)?;
 
-        let second_value = self.enforce_operand(cs, second)?;
+        let second_value = self.enforce_expression(cs, second)?;
 
         let unique_namespace = cs.ns(|| {
             format!(

compiler/src/expression/expression.rs

@@ -92,7 +92,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
                     let resolved_inner = self.enforce_expression(cs, inner)?;
                     enforce_negate(cs, resolved_inner, &span)
                 }
-                UnaryOperation::Not => Ok(evaluate_not(self.enforce_operand(cs, inner)?, &span)?),
+                UnaryOperation::Not => Ok(evaluate_not(self.enforce_expression(cs, inner)?, &span)?),
             },
 
             Expression::Ternary(TernaryExpression {

compiler/src/expression/tuple/access.rs

@@ -35,7 +35,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
         span: &Span,
     ) -> Result<ConstrainedValue<F, G>, ExpressionError> {
         // Get the tuple values.
-        let tuple = match self.enforce_operand(cs, tuple)? {
+        let tuple = match self.enforce_expression(cs, tuple)? {
             ConstrainedValue::Tuple(tuple) => tuple,
             value => return Err(ExpressionError::undefined_array(value.to_string(), span.to_owned())),
         };

compiler/src/function/function.rs

@@ -61,13 +61,9 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
 
         // Store input values as new variables in resolved program
         for (variable, input_expression) in function.arguments.iter().zip(arguments.iter()) {
-            let mut input_value = self.enforce_expression(cs, input_expression)?;
+            let input_value = self.enforce_expression(cs, input_expression)?;
             let variable = variable.borrow();
 
-            if variable.mutable {
-                input_value = ConstrainedValue::Mutable(Box::new(input_value))
-            }
-
             self.store(variable.id, input_value);
         }
 

compiler/src/function/mut_target.rs

@@ -109,10 +109,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
         let variable = variable.borrow();
 
         let mut result = vec![match self.get_mut(&variable.id) {
-            Some(value) => match value {
-                ConstrainedValue::Mutable(mutable) => &mut **mutable,
-                _ => return Err(StatementError::immutable_assign(variable.name.to_string(), span)),
-            },
+            Some(value) => value,
             None => return Err(StatementError::undefined_variable(variable.name.to_string(), span)),
         }];
 

compiler/src/prelude/blake2s.rs

@@ -31,8 +31,7 @@ use snarkvm_models::{
 
 pub struct Blake2s;
 
-fn unwrap_argument<F: Field + PrimeField, G: GroupType<F>>(mut arg: ConstrainedValue<F, G>) -> Vec<UInt8> {
-    arg.get_inner_mut();
+fn unwrap_argument<F: Field + PrimeField, G: GroupType<F>>(arg: ConstrainedValue<F, G>) -> Vec<UInt8> {
     if let ConstrainedValue::Array(args) = arg {
         assert_eq!(args.len(), 32); // asg enforced
         args.into_iter()

compiler/src/statement/assign/assignee.rs

@@ -67,10 +67,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
         let variable = assignee.target_variable.borrow();
 
         let mut result = vec![match self.get_mut(&variable.id) {
-            Some(value) => match value {
-                ConstrainedValue::Mutable(mutable) => &mut **mutable,
-                _ => return Err(StatementError::immutable_assign(variable.name.to_string(), span)),
-            },
+            Some(value) => value,
             None => return Err(StatementError::undefined_variable(variable.name.to_string(), span)),
         }];
 
@@ -101,14 +98,6 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
         }
     }
 
-    // discards unnecessary mutable wrappers
-    fn unwrap_mutable(input: &mut ConstrainedValue<F, G>) -> &mut ConstrainedValue<F, G> {
-        match input {
-            ConstrainedValue::Mutable(x) => Self::unwrap_mutable(&mut **x),
-            x => x,
-        }
-    }
-
     // todo: this can prob have most of its error checking removed
     pub(crate) fn resolve_assignee_access<'a>(
         access: ResolvedAssigneeAccess,
@@ -120,7 +109,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
                 if value.len() != 1 {
                     return Err(StatementError::array_assign_interior_index(span.clone()));
                 }
-                match Self::unwrap_mutable(value.remove(0)) {
+                match value.remove(0) {
                     ConstrainedValue::Array(old) => {
                         if index > old.len() {
                             Err(StatementError::array_assign_index_bounds(
@@ -140,7 +129,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
 
                 if value.len() == 1 {
                     // not a range of a range
-                    match Self::unwrap_mutable(value.remove(0)) {
+                    match value.remove(0) {
                         ConstrainedValue::Array(old) => {
                             let stop_index = stop_index.unwrap_or(old.len());
                             Self::check_range_index(start_index, stop_index, old.len(), &span)?;
@@ -154,14 +143,14 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
                     let stop_index = stop_index.unwrap_or(value.len());
                     Self::check_range_index(start_index, stop_index, value.len(), &span)?;
 
-                    Ok(value.drain(start_index..stop_index).map(Self::unwrap_mutable).collect())
+                    Ok(value.drain(start_index..stop_index).collect())
                 }
             }
             ResolvedAssigneeAccess::Tuple(index, span) => {
                 if value.len() != 1 {
                     return Err(StatementError::array_assign_interior_index(span));
                 }
-                match Self::unwrap_mutable(value.remove(0)) {
+                match value.remove(0) {
                     ConstrainedValue::Tuple(old) => {
                         if index > old.len() {
                             Err(StatementError::tuple_assign_index_bounds(index, old.len(), span))
@@ -176,7 +165,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
                 if value.len() != 1 {
                     return Err(StatementError::array_assign_interior_index(span.clone()));
                 }
-                match Self::unwrap_mutable(value.remove(0)) {
+                match value.remove(0) {
                     ConstrainedValue::CircuitExpression(_variable, members) => {
                         // Modify the circuit variable in place
                         let matched_variable = members.iter_mut().find(|member| member.0 == name);

compiler/src/statement/return_/return_.rs

@@ -30,7 +30,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
         cs: &mut CS,
         statement: &ReturnStatement,
     ) -> Result<ConstrainedValue<F, G>, StatementError> {
-        let result = self.enforce_operand(cs, &statement.expression)?;
+        let result = self.enforce_expression(cs, &statement.expression)?;
         Ok(result)
     }
 }

compiler/src/value/value.rs

@@ -49,9 +49,6 @@ pub enum ConstrainedValue<F: Field + PrimeField, G: GroupType<F>> {
 
     // Circuits
     CircuitExpression(Arc<CircuitBody>, Vec<ConstrainedCircuitMember<F, G>>),
-
-    // Modifiers
-    Mutable(Box<ConstrainedValue<F, G>>),
 }
 
 impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedValue<F, G> {
@@ -81,22 +78,8 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedValue<F, G> {
                 Type::Tuple(types)
             }
             ConstrainedValue::CircuitExpression(id, _members) => Type::Circuit(id.circuit.clone()),
-            ConstrainedValue::Mutable(value) => return value.to_type(span),
         })
     }
-
-    ///
-    /// Modifies the `self` [ConstrainedValue] so there are no `mut` keywords wrapping the `self` value.
-    ///
-    pub(crate) fn get_inner_mut(&mut self) {
-        if let ConstrainedValue::Mutable(inner) = self {
-            // Recursively remove `mut` keywords.
-            inner.get_inner_mut();
-
-            // Modify the value.
-            *self = *inner.clone()
-        }
-    }
 }
 
 impl<F: Field + PrimeField, G: GroupType<F>> fmt::Display for ConstrainedValue<F, G> {
@@ -142,7 +125,6 @@ impl<F: Field + PrimeField, G: GroupType<F>> fmt::Display for ConstrainedValue<F
                 }
                 write!(f, "}}")
             }
-            ConstrainedValue::Mutable(ref value) => write!(f, "{}", value),
         }
     }
 }
@@ -265,8 +247,6 @@ impl<F: Field + PrimeField, G: GroupType<F>> CondSelectGadget<F> for Constrained
 
                 ConstrainedValue::CircuitExpression(identifier.clone(), members)
             }
-            (ConstrainedValue::Mutable(first), _) => Self::conditionally_select(cs, cond, first, second)?,
-            (_, ConstrainedValue::Mutable(second)) => Self::conditionally_select(cs, cond, first, second)?,
             (_, _) => return Err(SynthesisError::Unsatisfiable),
         })
     }

compiler/tests/boolean/conditional_mut.leo

@@ -0,0 +1,6 @@
+function main () {
+    let mut x = true;
+    if x {
+        let y = 0u8;
+    }
+}

compiler/tests/boolean/mod.rs

@@ -101,6 +101,14 @@ fn test_not_mutable() {
     assert_satisfied(program);
 }
 
+#[test]
+fn test_conditional_mut() {
+    let program_string = include_str!("conditional_mut.leo");
+    let program = parse_program(program_string).unwrap();
+
+    assert_satisfied(program);
+}
+
 #[test]
 fn test_not_u32() {
     let program_string = include_str!("not_u32.leo");