implied circuit name works

ast/src/circuits/circuit_variable_definition.rs

@@ -15,7 +15,7 @@
 // along with the Leo library. If not, see <https://www.gnu.org/licenses/>.
 
 use crate::{Expression, Identifier};
-use leo_grammar::circuits::CircuitVariable;
+use leo_grammar::circuits::{CircuitImpliedVariable, CircuitVariable};
 
 use serde::{Deserialize, Serialize};
 
@@ -33,3 +33,24 @@ impl<'ast> From<CircuitVariable<'ast>> for CircuitVariableDefinition {
         }
     }
 }
+
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct CircuitImpliedVariableDefinition {
+    pub identifier: Identifier,
+    pub expression: Option<Expression>,
+}
+
+impl<'ast> From<CircuitImpliedVariable<'ast>> for CircuitImpliedVariableDefinition {
+    fn from(member: CircuitImpliedVariable<'ast>) -> Self {
+        match member {
+            CircuitImpliedVariable::CircuitVariable(circuit_variable) => Self {
+                identifier: Identifier::from(circuit_variable.identifier),
+                expression: Some(Expression::from(circuit_variable.expression)),
+            },
+            CircuitImpliedVariable::Identifier(identifier) => Self {
+                identifier: Identifier::from(identifier),
+                expression: None,
+            },
+        }
+    }
+}

ast/src/expression/circuit_init.rs

@@ -19,7 +19,7 @@ use super::*;
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub struct CircuitInitExpression {
     pub name: Identifier,
-    pub members: Vec<CircuitVariableDefinition>,
+    pub members: Vec<CircuitImpliedVariableDefinition>,
     pub span: Span,
 }
 
@@ -27,7 +27,11 @@ impl fmt::Display for CircuitInitExpression {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "{} {{", self.name)?;
         for (i, member) in self.members.iter().enumerate() {
-            write!(f, "{}: {}", member.identifier, member.expression)?;
+            match &member.expression {
+                Some(expression) => write!(f, "{}: {}", member.identifier, expression)?,
+                None => write!(f, "{}", member.identifier)?,
+            };
+
             if i < self.members.len() - 1 {
                 write!(f, ", ")?;
             }

ast/src/expression/mod.rs

@@ -16,7 +16,7 @@
 
 use crate::{
     ArrayDimensions,
-    CircuitVariableDefinition,
+    CircuitImpliedVariableDefinition,
     GroupValue,
     Identifier,
     IntegerType,
@@ -177,12 +177,13 @@ impl<'ast> fmt::Display for Expression {
 
 impl<'ast> From<CircuitInlineExpression<'ast>> for Expression {
     fn from(expression: CircuitInlineExpression<'ast>) -> Self {
+        // println!("from CircuitInlineExpression");
         let circuit_name = Identifier::from(expression.name);
         let members = expression
             .members
             .into_iter()
-            .map(CircuitVariableDefinition::from)
-            .collect::<Vec<CircuitVariableDefinition>>();
+            .map(CircuitImpliedVariableDefinition::from)
+            .collect::<Vec<CircuitImpliedVariableDefinition>>();
 
         Expression::CircuitInit(CircuitInitExpression {
             name: circuit_name,
@@ -485,3 +486,9 @@ impl<'ast> From<GrammarIdentifier<'ast>> for Expression {
         Expression::Identifier(Identifier::from(identifier))
     }
 }
+
+impl From<Identifier> for Expression {
+    fn from(identifier: Identifier) -> Self {
+        Expression::Identifier(identifier)
+    }
+}

compiler/src/expression/circuit/circuit.rs

@@ -22,7 +22,7 @@ use crate::{
     value::{ConstrainedCircuitMember, ConstrainedValue},
     GroupType,
 };
-use leo_ast::{CircuitMember, CircuitVariableDefinition, Identifier, Span};
+use leo_ast::{CircuitImpliedVariableDefinition, CircuitMember, Expression, Identifier, Span};
 
 use snarkvm_models::{
     curves::{Field, PrimeField},
@@ -36,7 +36,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
         file_scope: &str,
         function_scope: &str,
         identifier: Identifier,
-        members: Vec<CircuitVariableDefinition>,
+        members: Vec<CircuitImpliedVariableDefinition>,
         span: Span,
     ) -> Result<ConstrainedValue<F, G>, ExpressionError> {
         // Circuit definitions are located at the minimum file scope
@@ -64,14 +64,25 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
                         .into_iter()
                         .find(|variable| variable.identifier.eq(&identifier));
                     match matched_variable {
-                        Some(variable) => {
+                        Some(variable) if variable.expression.is_some() => {
                             // Resolve and enforce circuit variable
                             let variable_value = self.enforce_expression(
                                 cs,
                                 file_scope,
                                 function_scope,
                                 Some(type_.clone()),
-                                variable.expression,
+                                variable.expression.unwrap(),
+                            )?;
+
+                            resolved_members.push(ConstrainedCircuitMember(identifier, variable_value))
+                        }
+                        Some(variable) => {
+                            let variable_value = self.enforce_expression(
+                                cs,
+                                file_scope,
+                                function_scope,
+                                Some(type_.clone()),
+                                Expression::from(variable.identifier),
                             )?;
 
                             resolved_members.push(ConstrainedCircuitMember(identifier, variable_value))

grammar/src/circuits/circuit_implied_variable.rs

@@ -0,0 +1,27 @@
+// Copyright (C) 2019-2020 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/>.
+
+use crate::{ast::Rule, circuits::CircuitVariable, common::Identifier};
+
+use pest_ast::FromPest;
+use serde::Serialize;
+
+#[derive(Clone, Debug, FromPest, PartialEq, Serialize)]
+#[pest_ast(rule(Rule::circuit_implied_variable))]
+pub enum CircuitImpliedVariable<'ast> {
+    CircuitVariable(CircuitVariable<'ast>),
+    Identifier(Identifier<'ast>),
+}

grammar/src/circuits/mod.rs

@@ -17,6 +17,9 @@
 pub mod circuit;
 pub use circuit::*;
 
+pub mod circuit_implied_variable;
+pub use circuit_implied_variable::*;
+
 pub mod circuit_variable;
 pub use circuit_variable::*;
 

grammar/src/expressions/circuit_inline_expression.rs

@@ -14,7 +14,7 @@
 // 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/>.
 
-use crate::{ast::Rule, circuits::CircuitVariable, common::Identifier, types::SelfType, SpanDef};
+use crate::{ast::Rule, circuits::CircuitImpliedVariable, common::Identifier, types::SelfType, SpanDef};
 
 use pest::Span;
 use pest_ast::FromPest;
@@ -24,7 +24,7 @@ use serde::Serialize;
 #[pest_ast(rule(Rule::expression_circuit_inline))]
 pub struct CircuitInlineExpression<'ast> {
     pub name: CircuitName<'ast>,
-    pub members: Vec<CircuitVariable<'ast>>,
+    pub members: Vec<CircuitImpliedVariable<'ast>>,
     #[pest_ast(outer())]
     #[serde(with = "SpanDef")]
     pub span: Span<'ast>,

grammar/src/leo.pest

@@ -322,6 +322,12 @@ circuit = { "circuit " ~ identifier ~ "{" ~ circuit_member* ~ "}" }
 // Declared in circuits/circuit_variable.rs
 circuit_variable = { identifier ~ ":" ~ expression }
 
+// Declared in circuits/circuit_implied_variable.rs
+circuit_implied_variable = {
+    circuit_variable
+    | identifier
+}
+
 // Declared in circuits/circuit_variable_definition.rs
 circuit_variable_definition = { identifier ~ ":" ~ type_ ~ ","?}
 
@@ -371,7 +377,7 @@ circuit_name = {
 }
 
 // Declared in expressions/circuit_inline_expression.rs
-circuit_variable_list = _{ (circuit_variable ~ ("," ~ circuit_variable)*)? ~ ","? }
+circuit_variable_list = _{ (circuit_implied_variable ~ ("," ~ circuit_implied_variable)*)? ~ ","? }
 
 // Declared in expressions/unary_expression.rs
 expression_unary = { operation_unary ~ expression_term }

type-inference/src/objects/frame.rs

@@ -22,7 +22,7 @@ use leo_ast::{
     Assignee,
     AssigneeAccess,
     Block,
-    CircuitVariableDefinition,
+    CircuitImpliedVariableDefinition,
     Expression,
     Function,
     Identifier,
@@ -877,7 +877,7 @@ impl Frame {
     fn parse_circuit(
         &mut self,
         identifier: &Identifier,
-        members: &[CircuitVariableDefinition],
+        members: &[CircuitImpliedVariableDefinition],
         span: &Span,
     ) -> Result<Type, FrameError> {
         // Check if identifier is Self circuit type.
@@ -904,11 +904,16 @@ impl Frame {
         // Assert members are circuit type member types.
         for (expected_variable, actual_variable) in circuit_type.variables.iter().zip(members) {
             // Parse actual variable expression.
-            let actual_type = self.parse_expression(&actual_variable.expression)?;
+            match &actual_variable.expression {
+                Some(expression) => {
+                    let actual_type = self.parse_expression(expression)?;
 
                     // Assert expected variable type == actual variable type.
                     self.assert_equal(expected_variable.type_.clone(), actual_type, span)
                 }
+                None => {}
+            }
+        }
 
         Ok(Type::Circuit(circuit_type.identifier))
     }