Support assert statement (#70)

README.md

@@ -25,7 +25,7 @@ This library enables the creation of arithmetic circuits from circom programs.
 |                 | `UnderscoreSubstitution` |    ❌     |
 |                 | `ConstraintEquality`     |    ❌     |
 |                 | `LogCall`                |    ❌     |
-|                 | `Assert`                 |    ❌     |
+|                 | `Assert`                 |    ✅     |
 | **Expressions** | `Call`                   |    ✅     |
 |                 | `InfixOp`                |    ✅     |
 |                 | `Number`                 |    ✅     |

src/process.rs

@@ -6,7 +6,7 @@ use crate::compiler::{AGateType, Compiler};
 use crate::program::ProgramError;
 use crate::runtime::{
     generate_u32, increment_indices, u32_to_access, Context, DataAccess, DataType, NestedValue,
-    Runtime, Signal, SubAccess, RETURN_VAR,
+    Runtime, RuntimeError, Signal, SubAccess, RETURN_VAR,
 };
 use circom_circom_algebra::num_traits::ToPrimitive;
 use circom_program_structure::ast::{
@@ -170,6 +170,19 @@ pub fn process_statement(
 
             Ok(())
         }
+        Statement::Assert { arg, .. } => {
+            let access = process_expression(ac, runtime, program_archive, arg)?;
+            let result = runtime
+                .current_context()?
+                .get_variable_value(&access)?
+                .ok_or(ProgramError::EmptyDataItem)?;
+
+            if result == 0 {
+                return Err(ProgramError::RuntimeError(RuntimeError::AssertionFailed));
+            }
+
+            Ok(())
+        }
         _ => Err(ProgramError::StatementNotImplemented),
     }
 }

src/runtime.rs

@@ -824,6 +824,8 @@ pub enum RuntimeError {
     NotAValue,
     #[error("Unsupported data type")]
     UnsupportedDataType,
+    #[error("Assertion failed")]
+    AssertionFailed,
 }
 
 impl From<RuntimeError> for ProgramError {