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ZoKrates/zokrates_core/src/flatten/mod.rs
2019-03-15 17:33:23 +01:00

2243 lines
90 KiB
Rust

//! Module containing the `Flattener` to process a program that it is R1CS-able.
//!
//! @file flatten.rs
//! @author Dennis Kuhnert <dennis.kuhnert@campus.tu-berlin.de>
//! @author Jacob Eberhardt <jacob.eberhardt@tu-berlin.de>
//! @date 2017
use bimap::BiMap;
use flat_absy::*;
use helpers::{DirectiveStatement, Helper, RustHelper};
use std::collections::HashMap;
use typed_absy::*;
use types::conversions::cast;
use types::Signature;
use types::Type;
use zokrates_field::field::Field;
/// Flattener, computes flattened program.
#[derive(Debug)]
pub struct Flattener {
/// Index of the next introduced variable while processing the program.
next_var_idx: usize,
///
bijection: BiMap<String, FlatVariable>,
}
impl Flattener {
pub fn flatten<T: Field>(p: TypedProg<T>) -> FlatProg<T> {
Flattener::new().flatten_program(p)
}
/// Returns a `Flattener` with fresh a fresh [substitution] and [variables].
///
/// # Arguments
///
/// * `bits` - Number of bits needed to represent the maximum value.
fn new() -> Flattener {
Flattener {
next_var_idx: 0,
bijection: BiMap::new(),
}
}
/// Loads the code library
fn load_corelib<T: Field>(&mut self, functions_flattened: &mut Vec<FlatFunction<T>>) -> () {
// Load type casting functions
functions_flattened.push(cast(&Type::Boolean, &Type::FieldElement));
// Load IfElse helper
let ie = TypedFunction {
id: "_if_else_field".to_string(),
arguments: vec![
Parameter {
id: Variable {
id: "condition".to_string(),
_type: Type::Boolean,
},
private: true,
},
Parameter {
id: Variable {
id: "consequence".to_string(),
_type: Type::FieldElement,
},
private: true,
},
Parameter {
id: Variable {
id: "alternative".to_string(),
_type: Type::FieldElement,
},
private: true,
},
],
statements: vec![
TypedStatement::Definition(
TypedAssignee::Identifier(Variable::field_element("condition_as_field")),
FieldElementExpression::FunctionCall(
"_bool_to_field".to_string(),
vec![BooleanExpression::Identifier("condition".to_string()).into()],
)
.into(),
),
TypedStatement::Return(vec![FieldElementExpression::Add(
box FieldElementExpression::Mult(
box FieldElementExpression::Identifier("condition_as_field".to_string()),
box FieldElementExpression::Identifier("consequence".to_string()),
),
box FieldElementExpression::Mult(
box FieldElementExpression::Sub(
box FieldElementExpression::Number(T::one()),
box FieldElementExpression::Identifier(
"condition_as_field".to_string(),
),
),
box FieldElementExpression::Identifier("alternative".to_string()),
),
)
.into()]),
],
signature: Signature::new()
.inputs(vec![Type::Boolean, Type::FieldElement, Type::FieldElement])
.outputs(vec![Type::FieldElement]),
};
let ief = self.flatten_function(functions_flattened, ie);
functions_flattened.push(ief);
}
/// Flattens a boolean expression
///
/// # Arguments
///
/// * `statements_flattened` - Vector where new flattened statements can be added.
/// * `condition` - `Condition` that will be flattened.
///
/// # Postconditions
///
/// * `flatten_boolean_expressions` always returns a linear expression,
/// * in order to preserve composability.
fn flatten_boolean_expression<T: Field>(
&mut self,
functions_flattened: &Vec<FlatFunction<T>>,
statements_flattened: &mut Vec<FlatStatement<T>>,
expression: BooleanExpression<T>,
) -> FlatExpression<T> {
// those will be booleans in the future
match expression {
BooleanExpression::Identifier(x) => {
FlatExpression::Identifier(self.bijection.get_by_left(&x).unwrap().clone())
}
BooleanExpression::Lt(box lhs, box rhs) => {
// Get the bitwidth to know the size of the binary decompsitions for this Field
let bitwidth = T::get_required_bits();
// We know from semantic checking that lhs and rhs have the same type
// What the expression will flatten to depends on that type
let lhs_flattened =
self.flatten_field_expression(functions_flattened, statements_flattened, lhs);
let rhs_flattened =
self.flatten_field_expression(functions_flattened, statements_flattened, rhs);
// lhs
let lhs_id = self.use_sym();
statements_flattened.push(FlatStatement::Definition(lhs_id, lhs_flattened));
// check that lhs and rhs are within the right range, ie, their last two bits are zero
// lhs
{
// define variables for the bits
let lhs_bits: Vec<FlatVariable> =
(0..bitwidth).map(|_| self.use_sym()).collect();
// add a directive to get the bits
statements_flattened.push(FlatStatement::Directive(DirectiveStatement::new(
lhs_bits.clone(),
Helper::bits(),
vec![lhs_id],
)));
// bitness checks
for i in 0..bitwidth - 2 {
statements_flattened.push(FlatStatement::Condition(
FlatExpression::Identifier(lhs_bits[i + 2]),
FlatExpression::Mult(
box FlatExpression::Identifier(lhs_bits[i + 2]),
box FlatExpression::Identifier(lhs_bits[i + 2]),
),
));
}
// bit decomposition check
let mut lhs_sum = FlatExpression::Number(T::from(0));
for i in 0..bitwidth - 2 {
lhs_sum = FlatExpression::Add(
box lhs_sum,
box FlatExpression::Mult(
box FlatExpression::Identifier(lhs_bits[i + 2]),
box FlatExpression::Number(T::from(2).pow(bitwidth - 2 - i - 1)),
),
);
}
statements_flattened.push(FlatStatement::Condition(
FlatExpression::Identifier(lhs_id),
lhs_sum,
));
}
// rhs
let rhs_id = self.use_sym();
statements_flattened.push(FlatStatement::Definition(rhs_id, rhs_flattened));
// rhs
{
// define variables for the bits
let rhs_bits: Vec<FlatVariable> =
(0..bitwidth).map(|_| self.use_sym()).collect();
// add a directive to get the bits
statements_flattened.push(FlatStatement::Directive(DirectiveStatement::new(
rhs_bits.clone(),
Helper::bits(),
vec![rhs_id],
)));
// bitness checks
for i in 0..bitwidth - 2 {
statements_flattened.push(FlatStatement::Condition(
FlatExpression::Identifier(rhs_bits[i + 2]),
FlatExpression::Mult(
box FlatExpression::Identifier(rhs_bits[i + 2]),
box FlatExpression::Identifier(rhs_bits[i + 2]),
),
));
}
// bit decomposition check
let mut rhs_sum = FlatExpression::Number(T::from(0));
for i in 0..bitwidth - 2 {
rhs_sum = FlatExpression::Add(
box rhs_sum,
box FlatExpression::Mult(
box FlatExpression::Identifier(rhs_bits[i + 2]),
box FlatExpression::Number(T::from(2).pow(bitwidth - 2 - i - 1)),
),
);
}
statements_flattened.push(FlatStatement::Condition(
FlatExpression::Identifier(rhs_id),
rhs_sum,
));
}
// sym := (lhs * 2) - (rhs * 2)
let subtraction_result = FlatExpression::Sub(
box FlatExpression::Mult(
box FlatExpression::Number(T::from(2)),
box FlatExpression::Identifier(lhs_id),
),
box FlatExpression::Mult(
box FlatExpression::Number(T::from(2)),
box FlatExpression::Identifier(rhs_id),
),
);
// define variables for the bits
let sub_bits: Vec<FlatVariable> = (0..bitwidth).map(|_| self.use_sym()).collect();
// add a directive to get the bits
statements_flattened.push(FlatStatement::Directive(DirectiveStatement::new(
sub_bits.clone(),
Helper::bits(),
vec![subtraction_result.clone()],
)));
// bitness checks
for i in 0..bitwidth {
statements_flattened.push(FlatStatement::Condition(
FlatExpression::Identifier(sub_bits[i]),
FlatExpression::Mult(
box FlatExpression::Identifier(sub_bits[i]),
box FlatExpression::Identifier(sub_bits[i]),
),
));
}
// sum(sym_b{i} * 2**i)
let mut expr = FlatExpression::Number(T::from(0));
for i in 0..bitwidth {
expr = FlatExpression::Add(
box expr,
box FlatExpression::Mult(
box FlatExpression::Identifier(sub_bits[i]),
box FlatExpression::Number(T::from(2).pow(bitwidth - i - 1)),
),
);
}
statements_flattened.push(FlatStatement::Condition(subtraction_result, expr));
FlatExpression::Identifier(sub_bits[0])
}
BooleanExpression::Eq(box lhs, box rhs) => {
// We know from semantic checking that lhs and rhs have the same type
// What the expression will flatten to depends on that type
// Wanted: (Y = (X != 0) ? 1 : 0)
// X = a - b
// # Y = if X == 0 then 0 else 1 fi
// # M = if X == 0 then 1 else 1/X fi
// Y == X * M
// 0 == (1-Y) * X
let name_y = self.use_sym();
let name_m = self.use_sym();
let x = self.flatten_field_expression(
functions_flattened,
statements_flattened,
FieldElementExpression::Sub(box lhs, box rhs),
);
statements_flattened.push(FlatStatement::Directive(DirectiveStatement::new(
vec![name_y, name_m],
Helper::Rust(RustHelper::ConditionEq),
vec![x.clone()],
)));
statements_flattened.push(FlatStatement::Condition(
FlatExpression::Identifier(name_y),
FlatExpression::Mult(box x.clone(), box FlatExpression::Identifier(name_m)),
));
let res = FlatExpression::Sub(
box FlatExpression::Number(T::one()),
box FlatExpression::Identifier(name_y),
);
statements_flattened.push(FlatStatement::Condition(
FlatExpression::Number(T::zero()),
FlatExpression::Mult(box res.clone(), box x),
));
res
}
BooleanExpression::Le(box lhs, box rhs) => {
let lt = self.flatten_boolean_expression(
functions_flattened,
statements_flattened,
BooleanExpression::Lt(box lhs.clone(), box rhs.clone()),
);
let eq = self.flatten_boolean_expression(
functions_flattened,
statements_flattened,
BooleanExpression::Eq(box lhs.clone(), box rhs.clone()),
);
FlatExpression::Add(box eq, box lt)
}
BooleanExpression::Gt(lhs, rhs) => self.flatten_boolean_expression(
functions_flattened,
statements_flattened,
BooleanExpression::Lt(rhs, lhs),
),
BooleanExpression::Ge(lhs, rhs) => self.flatten_boolean_expression(
functions_flattened,
statements_flattened,
BooleanExpression::Le(rhs, lhs),
),
BooleanExpression::Or(box lhs, box rhs) => {
let x = box self.flatten_boolean_expression(
functions_flattened,
statements_flattened,
lhs,
);
let y = box self.flatten_boolean_expression(
functions_flattened,
statements_flattened,
rhs,
);
assert!(x.is_linear() && y.is_linear());
let name_x_and_y = self.use_sym();
statements_flattened.push(FlatStatement::Definition(
name_x_and_y,
FlatExpression::Mult(x.clone(), y.clone()),
));
FlatExpression::Sub(
box FlatExpression::Add(x, y),
box FlatExpression::Identifier(name_x_and_y),
)
}
BooleanExpression::And(box lhs, box rhs) => {
let x =
self.flatten_boolean_expression(functions_flattened, statements_flattened, lhs);
let y =
self.flatten_boolean_expression(functions_flattened, statements_flattened, rhs);
let name_x_and_y = self.use_sym();
assert!(x.is_linear() && y.is_linear());
statements_flattened.push(FlatStatement::Definition(
name_x_and_y,
FlatExpression::Mult(box x, box y),
));
FlatExpression::Identifier(name_x_and_y)
}
BooleanExpression::Not(box exp) => {
let x =
self.flatten_boolean_expression(functions_flattened, statements_flattened, exp);
FlatExpression::Sub(box FlatExpression::Number(T::one()), box x)
}
BooleanExpression::Value(b) => FlatExpression::Number(match b {
true => T::from(1),
false => T::from(0),
}),
}
}
fn flatten_function_call<T: Field>(
&mut self,
functions_flattened: &Vec<FlatFunction<T>>,
statements_flattened: &mut Vec<FlatStatement<T>>,
id: &String,
return_types: Vec<Type>,
param_expressions: &Vec<TypedExpression<T>>,
) -> FlatExpressionList<T> {
let passed_signature = Signature::new()
.inputs(param_expressions.iter().map(|e| e.get_type()).collect())
.outputs(return_types);
let funct = self
.get_function(passed_signature, &functions_flattened, id)
.clone();
let mut replacement_map = HashMap::new();
// Handle complex parameters and assign values:
// Rename Parameters, assign them to values in call. Resolve complex expressions with definitions
let params_flattened = param_expressions
.into_iter()
.map(|param_expr| {
self.flatten_expression(
functions_flattened,
statements_flattened,
param_expr.clone(),
)
})
.into_iter()
.flat_map(|x| x)
.collect::<Vec<_>>();
for (concrete_argument, formal_argument) in
params_flattened.into_iter().zip(funct.arguments)
{
let new_var = self.use_sym();
statements_flattened.push(FlatStatement::Definition(new_var, concrete_argument));
replacement_map.insert(formal_argument.id, new_var);
}
// Ensure Renaming and correct returns:
// add all flattened statements, adapt return statement
let (return_statements, statements): (Vec<_>, Vec<_>) =
funct.statements.into_iter().partition(|s| match s {
FlatStatement::Return(..) => true,
_ => false,
});
let statements: Vec<_> = statements
.into_iter()
.map(|stat| match stat {
// set return statements right sidreturne as expression result
FlatStatement::Return(..) => unreachable!(),
FlatStatement::Definition(var, rhs) => {
let new_var = self.issue_new_variable();
replacement_map.insert(var, new_var);
let new_rhs = rhs.apply_substitution(&replacement_map);
FlatStatement::Definition(new_var, new_rhs)
}
FlatStatement::Condition(lhs, rhs) => {
let new_lhs = lhs.apply_substitution(&replacement_map);
let new_rhs = rhs.apply_substitution(&replacement_map);
FlatStatement::Condition(new_lhs, new_rhs)
}
FlatStatement::Directive(d) => {
let new_outputs = d
.outputs
.into_iter()
.map(|o| {
let new_o = self.issue_new_variable();
replacement_map.insert(o, new_o);
new_o
})
.collect();
let new_inputs = d
.inputs
.into_iter()
.map(|i| i.apply_substitution(&replacement_map))
.collect();
FlatStatement::Directive(DirectiveStatement {
outputs: new_outputs,
helper: d.helper,
inputs: new_inputs,
})
}
})
.collect();
statements_flattened.extend(statements);
match return_statements[0].clone() {
FlatStatement::Return(list) => FlatExpressionList {
expressions: list
.expressions
.into_iter()
.map(|x| x.apply_substitution(&replacement_map))
.collect(),
},
_ => unreachable!(),
}
}
fn flatten_expression<T: Field>(
&mut self,
functions_flattened: &Vec<FlatFunction<T>>,
statements_flattened: &mut Vec<FlatStatement<T>>,
expr: TypedExpression<T>,
) -> Vec<FlatExpression<T>> {
match expr {
TypedExpression::FieldElement(e) => {
vec![self.flatten_field_expression(functions_flattened, statements_flattened, e)]
}
TypedExpression::Boolean(e) => {
vec![self.flatten_boolean_expression(functions_flattened, statements_flattened, e)]
}
TypedExpression::FieldElementArray(e) => {
self.flatten_field_array_expression(functions_flattened, statements_flattened, e)
}
}
}
fn flatten_field_expression<T: Field>(
&mut self,
functions_flattened: &Vec<FlatFunction<T>>,
statements_flattened: &mut Vec<FlatStatement<T>>,
expr: FieldElementExpression<T>,
) -> FlatExpression<T> {
match expr {
FieldElementExpression::Number(x) => FlatExpression::Number(x), // force to be a field element
FieldElementExpression::Identifier(x) => {
FlatExpression::Identifier(self.bijection.get_by_left(&x).unwrap().clone())
}
FieldElementExpression::Add(box left, box right) => {
let left_flattened =
self.flatten_field_expression(functions_flattened, statements_flattened, left);
let right_flattened =
self.flatten_field_expression(functions_flattened, statements_flattened, right);
let new_left = if left_flattened.is_linear() {
left_flattened
} else {
let id = self.use_sym();
statements_flattened.push(FlatStatement::Definition(id, left_flattened));
FlatExpression::Identifier(id)
};
let new_right = if right_flattened.is_linear() {
right_flattened
} else {
let id = self.use_sym();
statements_flattened.push(FlatStatement::Definition(id, right_flattened));
FlatExpression::Identifier(id)
};
FlatExpression::Add(box new_left, box new_right)
}
FieldElementExpression::Sub(box left, box right) => {
let left_flattened =
self.flatten_field_expression(functions_flattened, statements_flattened, left);
let right_flattened =
self.flatten_field_expression(functions_flattened, statements_flattened, right);
let new_left = if left_flattened.is_linear() {
left_flattened
} else {
let id = self.use_sym();
statements_flattened.push(FlatStatement::Definition(id, left_flattened));
FlatExpression::Identifier(id)
};
let new_right = if right_flattened.is_linear() {
right_flattened
} else {
let id = self.use_sym();
statements_flattened.push(FlatStatement::Definition(id, right_flattened));
FlatExpression::Identifier(id)
};
FlatExpression::Sub(box new_left, box new_right)
}
FieldElementExpression::Mult(box left, box right) => {
let left_flattened =
self.flatten_field_expression(functions_flattened, statements_flattened, left);
let right_flattened =
self.flatten_field_expression(functions_flattened, statements_flattened, right);
let new_left = if left_flattened.is_linear() {
left_flattened
} else {
let id = self.use_sym();
statements_flattened.push(FlatStatement::Definition(id, left_flattened));
FlatExpression::Identifier(id)
};
let new_right = if right_flattened.is_linear() {
right_flattened
} else {
let id = self.use_sym();
statements_flattened.push(FlatStatement::Definition(id, right_flattened));
FlatExpression::Identifier(id)
};
FlatExpression::Mult(box new_left, box new_right)
}
FieldElementExpression::Div(box left, box right) => {
let left_flattened =
self.flatten_field_expression(functions_flattened, statements_flattened, left);
let right_flattened =
self.flatten_field_expression(functions_flattened, statements_flattened, right);
let new_left: FlatExpression<T> = {
let id = self.use_sym();
statements_flattened.push(FlatStatement::Definition(id, left_flattened));
id.into()
};
let new_right: FlatExpression<T> = {
let id = self.use_sym();
statements_flattened.push(FlatStatement::Definition(id, right_flattened));
id.into()
};
let invb = self.use_sym();
let inverse = self.use_sym();
// # invb = 1/b
statements_flattened.push(FlatStatement::Directive(DirectiveStatement::new(
vec![invb],
Helper::Rust(RustHelper::Div),
vec![FlatExpression::Number(T::one()), new_right.clone()],
)));
// assert(invb * b == 1)
statements_flattened.push(FlatStatement::Condition(
FlatExpression::Number(T::one()),
FlatExpression::Mult(box invb.into(), box new_right.clone().into()),
));
// # c = a/b
statements_flattened.push(FlatStatement::Directive(DirectiveStatement::new(
vec![inverse],
Helper::Rust(RustHelper::Div),
vec![new_left.clone(), new_right.clone()],
)));
// assert(c * b == a)
statements_flattened.push(FlatStatement::Condition(
new_left.into(),
FlatExpression::Mult(box new_right, box inverse.into()),
));
inverse.into()
}
FieldElementExpression::Pow(box base, box exponent) => {
match exponent {
FieldElementExpression::Number(ref e) => {
// flatten the base expression
let base_flattened = self.flatten_field_expression(
functions_flattened,
statements_flattened,
base.clone(),
);
// we require from the base to be linear
// TODO change that
assert!(base_flattened.is_linear());
match e {
e if *e == T::zero() => FlatExpression::Number(T::one()),
// flatten(base ** 1) == flatten(base)
e if *e == T::one() => base_flattened,
// flatten(base ** 2) == flatten(base) * flatten(base)
// in this case, no need to define an intermediate variable
// as if a is linear, a ** 2 quadratic
e if *e == T::from(2) => {
FlatExpression::Mult(box base_flattened.clone(), box base_flattened)
}
// flatten(base ** n) = flatten(base) * flatten(base ** (n-1))
e => {
// flatten(base ** (n-1))
let tmp_expression = self.flatten_field_expression(
functions_flattened,
statements_flattened,
FieldElementExpression::Pow(
box base,
box FieldElementExpression::Number(e.clone() - T::one()),
),
);
let id = self.use_sym();
statements_flattened
.push(FlatStatement::Definition(id, tmp_expression));
FlatExpression::Mult(
box FlatExpression::Identifier(id),
box base_flattened,
)
}
}
}
_ => panic!("Expected number as pow exponent"),
}
}
FieldElementExpression::IfElse(box condition, box consequent, box alternative) => self
.flatten_function_call(
functions_flattened,
statements_flattened,
&"_if_else_field".to_string(),
vec![Type::FieldElement],
&vec![condition.into(), consequent.into(), alternative.into()],
)
.expressions[0]
.clone(),
FieldElementExpression::FunctionCall(ref id, ref param_expressions) => {
let exprs_flattened = self.flatten_function_call(
functions_flattened,
statements_flattened,
id,
vec![Type::FieldElement],
param_expressions,
);
assert!(exprs_flattened.expressions.len() == 1); // outside of MultipleDefinition, FunctionCalls must return a single value
exprs_flattened.expressions[0].clone()
}
FieldElementExpression::Select(box array, box index) => {
match index {
FieldElementExpression::Number(n) => match array {
FieldElementArrayExpression::Identifier(size, id) => {
assert!(n < T::from(size));
FlatExpression::Identifier(
self.get_latest_var_substitution(&format!("{}_c{}", id, n))
.clone(),
)
}
FieldElementArrayExpression::Value(size, expressions) => {
assert!(n < T::from(size));
self.flatten_field_expression(
functions_flattened,
statements_flattened,
expressions[n.to_dec_string().parse::<usize>().unwrap()].clone(),
)
}
FieldElementArrayExpression::FunctionCall(..) => {
unimplemented!("please use intermediate variables for now")
}
FieldElementArrayExpression::IfElse(
condition,
consequence,
alternative,
) => {
// [if cond then [a, b] else [c, d]][1] == if cond then [a, b][1] else [c, d][1]
self.flatten_field_expression(
functions_flattened,
statements_flattened,
FieldElementExpression::IfElse(
condition,
box FieldElementExpression::Select(
consequence,
box FieldElementExpression::Number(n.clone()),
),
box FieldElementExpression::Select(
alternative,
box FieldElementExpression::Number(n),
),
),
)
}
},
e => {
let size = array.size();
// we have array[e] with e an arbitrary expression
// first we check that e is in 0..array.len(), so we check that sum(if e == i then 1 else 0) == 1
// here depending on the size, we could use a proper range check based on bits
let range_check = (0..size)
.map(|i| {
FieldElementExpression::IfElse(
box BooleanExpression::Eq(
box e.clone(),
box FieldElementExpression::Number(T::from(i)),
),
box FieldElementExpression::Number(T::from(1)),
box FieldElementExpression::Number(T::from(0)),
)
})
.fold(FieldElementExpression::Number(T::from(0)), |acc, e| {
FieldElementExpression::Add(box acc, box e)
});
let range_check_statement = TypedStatement::Condition(
FieldElementExpression::Number(T::from(1)).into(),
range_check.into(),
);
self.flatten_statement(
functions_flattened,
statements_flattened,
range_check_statement,
);
// now we flatten to sum(if e == i then array[i] else 0)
let lookup = (0..size)
.map(|i| {
FieldElementExpression::IfElse(
box BooleanExpression::Eq(
box e.clone(),
box FieldElementExpression::Number(T::from(i)),
),
box match array.clone() {
FieldElementArrayExpression::Identifier(_, id) => {
FieldElementExpression::Identifier(format!(
"{}_c{}",
id, i
))
}
FieldElementArrayExpression::Value(size, expressions) => {
assert_eq!(size, expressions.len());
expressions[i].clone()
}
FieldElementArrayExpression::FunctionCall(..) => {
unimplemented!(
"please use intermediate variables for now"
)
}
FieldElementArrayExpression::IfElse(
condition,
consequence,
alternative,
) => FieldElementExpression::IfElse(
condition,
box FieldElementExpression::Select(
consequence,
box FieldElementExpression::Number(T::from(i)),
),
box FieldElementExpression::Select(
alternative,
box FieldElementExpression::Number(T::from(i)),
),
),
},
box FieldElementExpression::Number(T::from(0)),
)
})
.fold(FieldElementExpression::Number(T::from(0)), |acc, e| {
FieldElementExpression::Add(box acc, box e)
});
self.flatten_field_expression(
functions_flattened,
statements_flattened,
lookup,
)
}
}
}
}
}
fn flatten_field_array_expression<T: Field>(
&mut self,
functions_flattened: &Vec<FlatFunction<T>>,
statements_flattened: &mut Vec<FlatStatement<T>>,
expr: FieldElementArrayExpression<T>,
) -> Vec<FlatExpression<T>> {
match expr {
FieldElementArrayExpression::Identifier(size, x) => (0..size)
.map(|index| {
FlatExpression::Identifier(
self.get_latest_var_substitution(&format!("{}_c{}", x, index))
.clone(),
)
})
.collect(),
FieldElementArrayExpression::Value(size, values) => {
assert_eq!(size, values.len());
values
.into_iter()
.map(|v| {
self.flatten_field_expression(functions_flattened, statements_flattened, v)
})
.collect()
}
FieldElementArrayExpression::FunctionCall(size, ref id, ref param_expressions) => {
let exprs_flattened = self.flatten_function_call(
functions_flattened,
statements_flattened,
id,
vec![Type::FieldElementArray(size)],
param_expressions,
);
assert!(exprs_flattened.expressions.len() == size); // outside of MultipleDefinition, FunctionCalls must return a single value
exprs_flattened.expressions
}
FieldElementArrayExpression::IfElse(
ref condition,
ref consequence,
ref alternative,
) => {
let size = match consequence.get_type() {
Type::FieldElementArray(n) => n,
_ => unreachable!(),
};
(0..size)
.map(|i| {
self.flatten_field_expression(
functions_flattened,
statements_flattened,
FieldElementExpression::IfElse(
condition.clone(),
box FieldElementExpression::Select(
consequence.clone(),
box FieldElementExpression::Number(T::from(i)),
),
box FieldElementExpression::Select(
alternative.clone(),
box FieldElementExpression::Number(T::from(i)),
),
),
)
})
.collect()
}
}
}
fn flatten_statement<T: Field>(
&mut self,
functions_flattened: &Vec<FlatFunction<T>>,
statements_flattened: &mut Vec<FlatStatement<T>>,
stat: TypedStatement<T>,
) {
match stat {
TypedStatement::Return(exprs) => {
let flat_expressions = exprs
.into_iter()
.map(|expr| {
self.flatten_expression(functions_flattened, statements_flattened, expr)
})
.flat_map(|x| x)
.collect::<Vec<_>>();
statements_flattened.push(FlatStatement::Return(FlatExpressionList {
expressions: flat_expressions,
}));
}
TypedStatement::Declaration(_) => {
// declarations have already been checked
()
}
TypedStatement::Definition(assignee, expr) => {
// define n variables with n the number of primitive types for v_type
// assign them to the n primitive types for expr
let rhs = self.flatten_expression(
functions_flattened,
statements_flattened,
expr.clone(),
);
match expr.get_type() {
Type::FieldElement | Type::Boolean => {
match assignee {
TypedAssignee::Identifier(ref v) => {
let debug_name = v.clone().id;
let var = self.use_variable(&debug_name);
// handle return of function call
statements_flattened
.push(FlatStatement::Definition(var, rhs[0].clone()));
}
TypedAssignee::ArrayElement(ref array, ref index) => {
let expr = match expr {
TypedExpression::FieldElement(e) => e,
_ => panic!("not a field element as rhs of array element update, should have been caught at semantic")
};
match index {
box FieldElementExpression::Number(n) => match array {
box TypedAssignee::Identifier(id) => {
let debug_name = format!("{}_c{}", id.id, n);
let var = self.use_variable(&debug_name);
statements_flattened.push(FlatStatement::Definition(
var,
rhs[0].clone(),
));
}
_ => panic!("no multidimension array for now"),
},
box e => {
// we have array[e] with e an arbitrary expression
// first we check that e is in 0..array.len(), so we check that sum(if e == i then 1 else 0) == 1
// here depending on the size, we could use a proper range check based on bits
let size = match array.get_type() {
Type::FieldElementArray(n) => n,
_ => panic!("checker should generate array element based on non array")
};
let range_check = (0..size)
.map(|i| {
FieldElementExpression::IfElse(
box BooleanExpression::Eq(
box e.clone(),
box FieldElementExpression::Number(
T::from(i),
),
),
box FieldElementExpression::Number(T::from(1)),
box FieldElementExpression::Number(T::from(0)),
)
})
.fold(
FieldElementExpression::Number(T::from(0)),
|acc, e| {
FieldElementExpression::Add(box acc, box e)
},
);
let range_check_statement = TypedStatement::Condition(
FieldElementExpression::Number(T::from(1)).into(),
range_check.into(),
);
self.flatten_statement(
functions_flattened,
statements_flattened,
range_check_statement,
);
// now we redefine the whole array, updating only the piece that changed
// stat(array[i] = if e == i then `expr` else `array[i]`)
for i in 0..size {
let rhs = FieldElementExpression::IfElse(
box BooleanExpression::Eq(
box e.clone(),
box FieldElementExpression::Number(T::from(i)),
),
box expr.clone(),
box e.clone(),
);
let rhs_flattened = self.flatten_field_expression(
functions_flattened,
statements_flattened,
rhs,
);
let var =
self.use_variable(&format!("{}_c{}", array, i));
statements_flattened.push(FlatStatement::Definition(
var,
rhs_flattened,
));
}
}
}
}
}
}
Type::FieldElementArray(..) => {
for (index, r) in rhs.into_iter().enumerate() {
let debug_name = match assignee {
TypedAssignee::Identifier(ref v) => format!("{}_c{}", v.id, index),
_ => unimplemented!(),
};
let var = self.use_variable(&debug_name);
statements_flattened.push(FlatStatement::Definition(var, r));
}
}
}
}
TypedStatement::Condition(expr1, expr2) => {
// flatten expr1 and expr2 to n flattened expressions with n the number of primitive types for expr1
// add n conditions to check equality of the n expressions
match (expr1, expr2) {
(TypedExpression::FieldElement(e1), TypedExpression::FieldElement(e2)) => {
let (lhs, rhs) = (
self.flatten_field_expression(
functions_flattened,
statements_flattened,
e1,
),
self.flatten_field_expression(
functions_flattened,
statements_flattened,
e2,
),
);
if lhs.is_linear() {
statements_flattened.push(FlatStatement::Condition(lhs, rhs));
} else if rhs.is_linear() {
// swap so that left side is linear
statements_flattened.push(FlatStatement::Condition(rhs, lhs));
} else {
unimplemented!()
}
}
(TypedExpression::Boolean(e1), TypedExpression::Boolean(e2)) => {
let (lhs, rhs) = (
self.flatten_boolean_expression(
functions_flattened,
statements_flattened,
e1,
),
self.flatten_boolean_expression(
functions_flattened,
statements_flattened,
e2,
),
);
if lhs.is_linear() {
statements_flattened.push(FlatStatement::Condition(lhs, rhs));
} else if rhs.is_linear() {
// swap so that left side is linear
statements_flattened.push(FlatStatement::Condition(rhs, lhs));
} else {
unimplemented!()
}
}
(
TypedExpression::FieldElementArray(e1),
TypedExpression::FieldElementArray(e2),
) => {
let (lhs, rhs) = (
self.flatten_field_array_expression(
functions_flattened,
statements_flattened,
e1,
),
self.flatten_field_array_expression(
functions_flattened,
statements_flattened,
e2,
),
);
assert_eq!(lhs.len(), rhs.len());
for (l, r) in lhs.into_iter().zip(rhs.into_iter()) {
if l.is_linear() {
statements_flattened.push(FlatStatement::Condition(l, r));
} else if r.is_linear() {
// swap so that left side is linear
statements_flattened.push(FlatStatement::Condition(r, l));
} else {
unimplemented!()
}
}
}
_ => panic!(
"non matching types in condition should have been caught at semantic stage"
),
}
}
TypedStatement::For(var, start, end, statements) => {
let mut current = start;
while current < end {
statements_flattened.push(FlatStatement::Definition(
self.use_variable(&var.id),
FlatExpression::Number(current.clone()),
));
for s in statements.clone() {
self.flatten_statement(functions_flattened, statements_flattened, s);
}
current = T::one() + &current;
}
}
TypedStatement::MultipleDefinition(vars, rhs) => {
// flatten the right side to p = sum(var_i.type.primitive_count) expressions
// define p new variables to the right side expressions
let var_types = vars.iter().map(|v| v.get_type()).collect();
match rhs {
TypedExpressionList::FunctionCall(fun_id, exprs, _) => {
let rhs_flattened = self.flatten_function_call(
functions_flattened,
statements_flattened,
&fun_id,
var_types,
&exprs,
);
let mut iterator = rhs_flattened.expressions.into_iter();
// take each new variable being assigned
for v in vars {
// determine how many field elements it carries
match v.get_type() {
Type::FieldElementArray(size) => {
for index in 0..size {
let debug_name = format!("{}_c{}", v.id, index);
let var = self.use_variable(&debug_name);
statements_flattened.push(FlatStatement::Definition(
var,
iterator.next().unwrap(),
));
}
}
Type::Boolean | Type::FieldElement => {
let debug_name = v.id;
let var = self.use_variable(&debug_name);
statements_flattened.push(FlatStatement::Definition(
var,
iterator.next().unwrap(),
));
}
}
}
// we should have exhausted the return values
assert_eq!(iterator.next(), None);
}
}
}
}
}
/// Returns a flattened `TypedFunction` based on the given `funct`.
///
/// # Arguments
///
/// * `functions_flattened` - Vector where new flattened functions can be added.
/// * `funct` - `TypedFunction` that will be flattened.
fn flatten_function<T: Field>(
&mut self,
functions_flattened: &mut Vec<FlatFunction<T>>,
funct: TypedFunction<T>,
) -> FlatFunction<T> {
self.bijection = BiMap::new();
self.next_var_idx = 0;
let mut arguments_flattened: Vec<FlatParameter> = Vec::new();
let mut statements_flattened: Vec<FlatStatement<T>> = Vec::new();
// push parameters
for arg in &funct.arguments {
let arg_type = arg.id.get_type();
match arg_type {
Type::FieldElement => {
arguments_flattened.push(FlatParameter {
id: self.use_variable(&arg.id.id),
private: arg.private,
});
}
Type::Boolean => {
arguments_flattened.push(FlatParameter {
id: self.use_variable(&arg.id.id),
private: arg.private,
});
}
Type::FieldElementArray(size) => {
for i in 0..size {
arguments_flattened.push(FlatParameter {
id: self.use_variable(&format!("{}_c{}", arg.id.id, i)),
private: arg.private,
})
}
}
}
}
// flatten statements in functions and apply substitution
for stat in funct.statements {
self.flatten_statement(functions_flattened, &mut statements_flattened, stat);
}
FlatFunction {
id: funct.id.clone(),
arguments: arguments_flattened,
statements: statements_flattened,
signature: funct.signature,
}
}
/// Returns a flattened `Prog`ram based on the given `prog`.
///
/// # Arguments
///
/// * `prog` - `Prog`ram that will be flattened.
fn flatten_program<T: Field>(&mut self, prog: TypedProg<T>) -> FlatProg<T> {
let mut functions_flattened = Vec::new();
self.load_corelib(&mut functions_flattened);
for func in prog.imported_functions {
functions_flattened.push(func);
}
for func in prog.functions {
let flattened_func = self.flatten_function(&mut functions_flattened, func);
functions_flattened.push(flattened_func);
}
FlatProg {
functions: functions_flattened,
}
}
/// Checks if the given name is a not used variable and returns a fresh variable.
/// # Arguments
///
/// * `name` - a String that holds the name of the variable
fn use_variable(&mut self, name: &String) -> FlatVariable {
// issue the variable we'll use
let var = self.issue_new_variable();
self.bijection.insert(name.to_string(), var);
var
}
fn issue_new_variable(&mut self) -> FlatVariable {
let var = FlatVariable::new(self.next_var_idx);
self.next_var_idx += 1;
var
}
fn use_sym(&mut self) -> FlatVariable {
let name = format!("sym_{}", self.next_var_idx);
let var = self.issue_new_variable();
self.bijection.insert(name, var);
var
}
fn get_latest_var_substitution(&mut self, name: &String) -> FlatVariable {
// start with the variable name
self.bijection.get_by_left(name).unwrap().clone()
}
fn get_function<'a, T: Field>(
&self,
s: Signature,
functions_flattened: &'a Vec<FlatFunction<T>>,
id: &str,
) -> &'a FlatFunction<T> {
functions_flattened
.iter()
.find(|f| f.id == id && f.signature == s)
.unwrap()
}
}
#[cfg(test)]
mod tests {
use super::*;
use types::Signature;
use types::Type;
use zokrates_field::field::FieldPrime;
#[test]
fn multiple_definition() {
// def foo()
// return 1, 2
// def main()
// a, b = foo()
let mut flattener = Flattener::new();
let mut functions_flattened = vec![FlatFunction {
id: "foo".to_string(),
arguments: vec![],
statements: vec![FlatStatement::Return(FlatExpressionList {
expressions: vec![
FlatExpression::Number(FieldPrime::from(1)),
FlatExpression::Number(FieldPrime::from(2)),
],
})],
signature: Signature::new()
.inputs(vec![])
.outputs(vec![Type::FieldElement, Type::FieldElement]),
}];
let mut statements_flattened = vec![];
let statement = TypedStatement::MultipleDefinition(
vec![
Variable::field_element("a".to_string()),
Variable::field_element("b".to_string()),
],
TypedExpressionList::FunctionCall(
"foo".to_string(),
vec![],
vec![Type::FieldElement, Type::FieldElement],
),
);
flattener.flatten_statement(
&mut functions_flattened,
&mut statements_flattened,
statement,
);
let a = FlatVariable::new(0);
assert_eq!(
statements_flattened[0],
FlatStatement::Definition(a, FlatExpression::Number(FieldPrime::from(1)))
);
}
#[test]
fn multiple_definition2() {
// def dup(x)
// return x, x
// def main()
// a, b = dup(2)
let a = FlatVariable::new(0);
let mut flattener = Flattener::new();
let mut functions_flattened = vec![FlatFunction {
id: "dup".to_string(),
arguments: vec![FlatParameter {
id: a,
private: true,
}],
statements: vec![FlatStatement::Return(FlatExpressionList {
expressions: vec![FlatExpression::Identifier(a), FlatExpression::Identifier(a)],
})],
signature: Signature::new()
.inputs(vec![Type::FieldElement])
.outputs(vec![Type::FieldElement, Type::FieldElement]),
}];
let statement = TypedStatement::MultipleDefinition(
vec![
Variable::field_element("a".to_string()),
Variable::field_element("b".to_string()),
],
TypedExpressionList::FunctionCall(
"dup".to_string(),
vec![TypedExpression::FieldElement(
FieldElementExpression::Number(FieldPrime::from(2)),
)],
vec![Type::FieldElement, Type::FieldElement],
),
);
let fun = TypedFunction {
id: String::from("main"),
arguments: vec![],
statements: vec![statement],
signature: Signature {
inputs: vec![],
outputs: vec![],
},
};
let f = flattener.flatten_function(&mut functions_flattened, fun);
let a = FlatVariable::new(0);
assert_eq!(
f.statements[0],
FlatStatement::Definition(a, FlatExpression::Number(FieldPrime::from(2)))
);
}
#[test]
fn simple_definition() {
// def foo()
// return 1
// def main()
// a = foo()
let mut flattener = Flattener::new();
let mut functions_flattened = vec![FlatFunction {
id: "foo".to_string(),
arguments: vec![],
statements: vec![FlatStatement::Return(FlatExpressionList {
expressions: vec![FlatExpression::Number(FieldPrime::from(1))],
})],
signature: Signature::new()
.inputs(vec![])
.outputs(vec![Type::FieldElement]),
}];
let mut statements_flattened = vec![];
let statement = TypedStatement::Definition(
TypedAssignee::Identifier(Variable::field_element("a")),
TypedExpression::FieldElement(FieldElementExpression::FunctionCall(
"foo".to_string(),
vec![],
)),
);
flattener.flatten_statement(
&mut functions_flattened,
&mut statements_flattened,
statement,
);
let a = FlatVariable::new(0);
assert_eq!(
statements_flattened[0],
FlatStatement::Definition(a, FlatExpression::Number(FieldPrime::from(1)))
);
}
#[test]
fn redefine_argument() {
// def foo(a)
// a = a + 1
// return 1
// should flatten to no redefinition
// def foo(a)
// a_0 = a + 1
// return 1
let mut flattener = Flattener::new();
let mut functions_flattened = vec![];
let funct = TypedFunction {
id: "foo".to_string(),
signature: Signature::new()
.inputs(vec![Type::FieldElement])
.outputs(vec![Type::FieldElement]),
arguments: vec![Parameter {
id: Variable::field_element("a"),
private: true,
}],
statements: vec![
TypedStatement::Definition(
TypedAssignee::Identifier(Variable::field_element("a")),
FieldElementExpression::Add(
box FieldElementExpression::Identifier("a".to_string()),
box FieldElementExpression::Number(FieldPrime::from(1)),
)
.into(),
),
TypedStatement::Return(vec![
FieldElementExpression::Number(FieldPrime::from(1)).into()
]),
],
};
let flat_funct = flattener.flatten_function(&mut functions_flattened, funct);
let a = FlatVariable::new(0);
let a_0 = FlatVariable::new(1);
assert_eq!(
flat_funct.statements[0],
FlatStatement::Definition(
a_0,
FlatExpression::Add(
box FlatExpression::Identifier(a),
box FlatExpression::Number(FieldPrime::from(1))
)
)
);
}
#[test]
fn call_with_def() {
// def foo():
// a = 3
// return a
// def main():
// return foo()
let foo = TypedFunction {
id: String::from("foo"),
arguments: vec![],
statements: vec![
TypedStatement::Definition(
TypedAssignee::Identifier(Variable::field_element("a")),
FieldElementExpression::Number(FieldPrime::from(3)).into(),
),
TypedStatement::Return(vec![
FieldElementExpression::Identifier(String::from("a")).into()
]),
],
signature: Signature {
inputs: vec![],
outputs: vec![Type::FieldElement],
},
};
let main = TypedFunction {
id: String::from("main"),
arguments: vec![],
statements: vec![TypedStatement::Return(vec![
FieldElementExpression::FunctionCall(String::from("foo"), vec![]).into(),
])],
signature: Signature {
inputs: vec![],
outputs: vec![Type::FieldElement],
},
};
let mut flattener = Flattener::new();
let foo_flattened = flattener.flatten_function(&mut vec![], foo);
let expected = FlatFunction {
id: String::from("main"),
arguments: vec![],
statements: vec![
FlatStatement::Definition(
FlatVariable::new(0),
FlatExpression::Number(FieldPrime::from(3)),
),
FlatStatement::Return(FlatExpressionList {
expressions: vec![FlatExpression::Identifier(FlatVariable::new(0))],
}),
],
signature: Signature::new().outputs(vec![Type::FieldElement]),
};
let main_flattened = flattener.flatten_function(&mut vec![foo_flattened], main);
assert_eq!(main_flattened, expected);
}
#[test]
fn powers() {
// def main():
// field a = 7
// field b = a**4
// return b
// def main():
// _0 = 7
// _1 = (_0 * _0)
// _2 = (_1 * _0)
// _3 = (_2 * _0)
// return _3
let function = TypedFunction {
id: String::from("main"),
arguments: vec![],
statements: vec![
TypedStatement::Definition(
TypedAssignee::Identifier(Variable::field_element("a")),
FieldElementExpression::Number(FieldPrime::from(7)).into(),
),
TypedStatement::Definition(
TypedAssignee::Identifier(Variable::field_element("b")),
FieldElementExpression::Pow(
box FieldElementExpression::Identifier(String::from("a")),
box FieldElementExpression::Number(FieldPrime::from(4)),
)
.into(),
),
TypedStatement::Return(vec![
FieldElementExpression::Identifier(String::from("b")).into()
]),
],
signature: Signature {
inputs: vec![],
outputs: vec![Type::FieldElement],
},
};
let mut flattener = Flattener::new();
let expected = FlatFunction {
id: String::from("main"),
arguments: vec![],
statements: vec![
FlatStatement::Definition(
FlatVariable::new(0),
FlatExpression::Number(FieldPrime::from(7)),
),
FlatStatement::Definition(
FlatVariable::new(1),
FlatExpression::Mult(
box FlatExpression::Identifier(FlatVariable::new(0)),
box FlatExpression::Identifier(FlatVariable::new(0)),
),
),
FlatStatement::Definition(
FlatVariable::new(2),
FlatExpression::Mult(
box FlatExpression::Identifier(FlatVariable::new(1)),
box FlatExpression::Identifier(FlatVariable::new(0)),
),
),
FlatStatement::Definition(
FlatVariable::new(3),
FlatExpression::Mult(
box FlatExpression::Identifier(FlatVariable::new(2)),
box FlatExpression::Identifier(FlatVariable::new(0)),
),
),
FlatStatement::Return(FlatExpressionList {
expressions: vec![FlatExpression::Identifier(FlatVariable::new(3))],
}),
],
signature: Signature::new().outputs(vec![Type::FieldElement]),
};
let flattened = flattener.flatten_function(&mut vec![], function);
assert_eq!(flattened, expected);
}
#[test]
fn overload() {
// def foo()
// return 1
// def foo()
// return 1, 2
// def main()
// a = foo()
// b, c = foo()
// return 1
//
// should not panic
//
let mut flattener = Flattener::new();
let functions = vec![
TypedFunction {
id: "foo".to_string(),
arguments: vec![],
statements: vec![TypedStatement::Return(vec![TypedExpression::FieldElement(
FieldElementExpression::Number(FieldPrime::from(1)),
)])],
signature: Signature::new()
.inputs(vec![])
.outputs(vec![Type::FieldElement]),
},
TypedFunction {
id: "foo".to_string(),
arguments: vec![],
statements: vec![TypedStatement::Return(vec![
TypedExpression::FieldElement(FieldElementExpression::Number(
FieldPrime::from(1),
)),
TypedExpression::FieldElement(FieldElementExpression::Number(
FieldPrime::from(2),
)),
])],
signature: Signature::new()
.inputs(vec![])
.outputs(vec![Type::FieldElement, Type::FieldElement]),
},
TypedFunction {
id: "main".to_string(),
arguments: vec![],
statements: vec![
TypedStatement::Definition(
TypedAssignee::Identifier(Variable::field_element("a")),
TypedExpression::FieldElement(FieldElementExpression::FunctionCall(
"foo".to_string(),
vec![],
)),
),
TypedStatement::MultipleDefinition(
vec![
Variable::field_element("b".to_string()),
Variable::field_element("c".to_string()),
],
TypedExpressionList::FunctionCall(
"foo".to_string(),
vec![],
vec![Type::FieldElement, Type::FieldElement],
),
),
TypedStatement::Return(vec![TypedExpression::FieldElement(
FieldElementExpression::Number(FieldPrime::from(1)),
)]),
],
signature: Signature::new()
.inputs(vec![])
.outputs(vec![Type::FieldElement]),
},
];
flattener.flatten_program(TypedProg {
functions: functions,
imported_functions: vec![],
imports: vec![],
});
// shouldn't panic
}
#[test]
fn if_else() {
let mut flattener = Flattener::new();
let expression = FieldElementExpression::IfElse(
box BooleanExpression::Eq(
box FieldElementExpression::Number(FieldPrime::from(32)),
box FieldElementExpression::Number(FieldPrime::from(4)),
),
box FieldElementExpression::Number(FieldPrime::from(12)),
box FieldElementExpression::Number(FieldPrime::from(51)),
);
let mut functions_flattened = vec![];
flattener.load_corelib(&mut functions_flattened);
flattener.flatten_field_expression(&functions_flattened, &mut vec![], expression);
}
#[test]
fn geq_leq() {
let mut flattener = Flattener::new();
let expression_le = BooleanExpression::Le(
box FieldElementExpression::Number(FieldPrime::from(32)),
box FieldElementExpression::Number(FieldPrime::from(4)),
);
let expression_ge = BooleanExpression::Ge(
box FieldElementExpression::Number(FieldPrime::from(32)),
box FieldElementExpression::Number(FieldPrime::from(4)),
);
flattener.flatten_boolean_expression(&mut vec![], &mut vec![], expression_le);
flattener.flatten_boolean_expression(&mut vec![], &mut vec![], expression_ge);
}
#[test]
fn bool_and() {
let expression = FieldElementExpression::IfElse(
box BooleanExpression::And(
box BooleanExpression::Eq(
box FieldElementExpression::Number(FieldPrime::from(4)),
box FieldElementExpression::Number(FieldPrime::from(4)),
),
box BooleanExpression::Lt(
box FieldElementExpression::Number(FieldPrime::from(4)),
box FieldElementExpression::Number(FieldPrime::from(20)),
),
),
box FieldElementExpression::Number(FieldPrime::from(12)),
box FieldElementExpression::Number(FieldPrime::from(51)),
);
let mut flattener = Flattener::new();
let mut functions_flattened = vec![];
flattener.load_corelib(&mut functions_flattened);
flattener.flatten_field_expression(&functions_flattened, &mut vec![], expression);
}
#[test]
fn div() {
// a = 5 / b / b
let mut flattener = Flattener::new();
let mut functions_flattened = vec![];
let mut statements_flattened = vec![];
let definition = TypedStatement::Definition(
TypedAssignee::Identifier(Variable::field_element("b")),
FieldElementExpression::Number(FieldPrime::from(42)).into(),
);
let statement = TypedStatement::Definition(
TypedAssignee::Identifier(Variable::field_element("a")),
FieldElementExpression::Div(
box FieldElementExpression::Div(
box FieldElementExpression::Number(FieldPrime::from(5)),
box FieldElementExpression::Identifier(String::from("b")),
),
box FieldElementExpression::Identifier(String::from("b")),
)
.into(),
);
flattener.flatten_statement(
&mut functions_flattened,
&mut statements_flattened,
definition,
);
flattener.flatten_statement(
&mut functions_flattened,
&mut statements_flattened,
statement,
);
// define b
let b = FlatVariable::new(0);
// define new wires for members of Div
let five = FlatVariable::new(1);
let b0 = FlatVariable::new(2);
// Define inverse of denominator to prevent div by 0
let invb0 = FlatVariable::new(3);
// Define inverse
let sym_0 = FlatVariable::new(4);
// Define result, which is first member to next Div
let sym_1 = FlatVariable::new(5);
// Define second member
let b1 = FlatVariable::new(6);
// Define inverse of denominator to prevent div by 0
let invb1 = FlatVariable::new(7);
// Define inverse
let sym_2 = FlatVariable::new(8);
// Define left hand side
let a = FlatVariable::new(9);
assert_eq!(
statements_flattened,
vec![
FlatStatement::Definition(b, FlatExpression::Number(FieldPrime::from(42))),
// inputs to first div (5/b)
FlatStatement::Definition(five, FlatExpression::Number(FieldPrime::from(5))),
FlatStatement::Definition(b0, b.into()),
// check div by 0
FlatStatement::Directive(DirectiveStatement::new(
vec![invb0],
Helper::Rust(RustHelper::Div),
vec![FlatExpression::Number(FieldPrime::from(1)), b0.into()]
)),
FlatStatement::Condition(
FlatExpression::Number(FieldPrime::from(1)),
FlatExpression::Mult(box invb0.into(), box b0.into()),
),
// execute div
FlatStatement::Directive(DirectiveStatement::new(
vec![sym_0],
Helper::Rust(RustHelper::Div),
vec![five, b0]
)),
FlatStatement::Condition(
five.into(),
FlatExpression::Mult(box b0.into(), box sym_0.into()),
),
// inputs to second div (res/b)
FlatStatement::Definition(sym_1, sym_0.into()),
FlatStatement::Definition(b1, b.into()),
// check div by 0
FlatStatement::Directive(DirectiveStatement::new(
vec![invb1],
Helper::Rust(RustHelper::Div),
vec![FlatExpression::Number(FieldPrime::from(1)), b1.into()]
)),
FlatStatement::Condition(
FlatExpression::Number(FieldPrime::from(1)),
FlatExpression::Mult(box invb1.into(), box b1.into()),
),
// execute div
FlatStatement::Directive(DirectiveStatement::new(
vec![sym_2],
Helper::Rust(RustHelper::Div),
vec![sym_1, b1]
)),
FlatStatement::Condition(
sym_1.into(),
FlatExpression::Mult(box b1.into(), box sym_2.into()),
),
// result
FlatStatement::Definition(a, sym_2.into()),
]
);
}
#[test]
fn field_array() {
// foo = [ , , ]
let mut flattener = Flattener::new();
let mut functions_flattened = vec![];
let mut statements_flattened = vec![];
let statement = TypedStatement::Definition(
TypedAssignee::Identifier(Variable::field_array("foo", 3)),
FieldElementArrayExpression::Value(
3,
vec![
FieldElementExpression::Number(FieldPrime::from(1)),
FieldElementExpression::Number(FieldPrime::from(2)),
FieldElementExpression::Number(FieldPrime::from(3)),
],
)
.into(),
);
let expression = FieldElementArrayExpression::Identifier(3, String::from("foo"));
flattener.flatten_statement(
&mut functions_flattened,
&mut statements_flattened,
statement,
);
let expressions = flattener.flatten_field_array_expression(
&mut functions_flattened,
&mut statements_flattened,
expression,
);
assert_eq!(
expressions,
vec![
FlatExpression::Identifier(FlatVariable::new(0)),
FlatExpression::Identifier(FlatVariable::new(1)),
FlatExpression::Identifier(FlatVariable::new(2)),
]
);
}
#[test]
fn array_definition() {
// field[3] foo = [1, 2, 3]
let mut flattener = Flattener::new();
let mut functions_flattened = vec![];
let mut statements_flattened = vec![];
let statement = TypedStatement::Definition(
TypedAssignee::Identifier(Variable::field_array("foo", 3)),
FieldElementArrayExpression::Value(
3,
vec![
FieldElementExpression::Number(FieldPrime::from(1)),
FieldElementExpression::Number(FieldPrime::from(2)),
FieldElementExpression::Number(FieldPrime::from(3)),
],
)
.into(),
);
flattener.flatten_statement(
&mut functions_flattened,
&mut statements_flattened,
statement,
);
assert_eq!(
statements_flattened,
vec![
FlatStatement::Definition(
FlatVariable::new(0),
FlatExpression::Number(FieldPrime::from(1))
),
FlatStatement::Definition(
FlatVariable::new(1),
FlatExpression::Number(FieldPrime::from(2))
),
FlatStatement::Definition(
FlatVariable::new(2),
FlatExpression::Number(FieldPrime::from(3))
),
]
);
}
#[test]
fn array_selection() {
// field[3] foo = [1, 2, 3]
// foo[1]
let mut flattener = Flattener::new();
let mut functions_flattened = vec![];
let mut statements_flattened = vec![];
let statement = TypedStatement::Definition(
TypedAssignee::Identifier(Variable::field_array("foo", 3)),
FieldElementArrayExpression::Value(
3,
vec![
FieldElementExpression::Number(FieldPrime::from(1)),
FieldElementExpression::Number(FieldPrime::from(2)),
FieldElementExpression::Number(FieldPrime::from(3)),
],
)
.into(),
);
let expression = FieldElementExpression::Select(
box FieldElementArrayExpression::Identifier(3, String::from("foo")),
box FieldElementExpression::Number(FieldPrime::from(1)),
);
flattener.flatten_statement::<FieldPrime>(
&mut functions_flattened,
&mut statements_flattened,
statement,
);
let flat_expression = flattener.flatten_field_expression::<FieldPrime>(
&mut functions_flattened,
&mut statements_flattened,
expression,
);
assert_eq!(
flat_expression,
FlatExpression::Identifier(FlatVariable::new(1)),
);
}
#[test]
fn array_sum() {
// field[3] foo = [1, 2, 3]
// bar = foo[0] + foo[1] + foo[2]
// we don't optimise detecting constants, this will be done in an optimiser pass
let mut flattener = Flattener::new();
let mut functions_flattened = vec![];
let mut statements_flattened = vec![];
let def = TypedStatement::Definition(
TypedAssignee::Identifier(Variable::field_array("foo", 3)),
FieldElementArrayExpression::Value(
3,
vec![
FieldElementExpression::Number(FieldPrime::from(1)),
FieldElementExpression::Number(FieldPrime::from(2)),
FieldElementExpression::Number(FieldPrime::from(3)),
],
)
.into(),
);
let sum = TypedStatement::Definition(
TypedAssignee::Identifier(Variable::field_element("bar")),
FieldElementExpression::Add(
box FieldElementExpression::Add(
box FieldElementExpression::Select(
box FieldElementArrayExpression::Identifier(3, String::from("foo")),
box FieldElementExpression::Number(FieldPrime::from(0)),
),
box FieldElementExpression::Select(
box FieldElementArrayExpression::Identifier(3, String::from("foo")),
box FieldElementExpression::Number(FieldPrime::from(1)),
),
),
box FieldElementExpression::Select(
box FieldElementArrayExpression::Identifier(3, String::from("foo")),
box FieldElementExpression::Number(FieldPrime::from(2)),
),
)
.into(),
);
flattener.flatten_statement::<FieldPrime>(
&mut functions_flattened,
&mut statements_flattened,
def,
);
flattener.flatten_statement::<FieldPrime>(
&mut functions_flattened,
&mut statements_flattened,
sum,
);
assert_eq!(
statements_flattened[3],
FlatStatement::Definition(
FlatVariable::new(3),
FlatExpression::Add(
box FlatExpression::Add(
box FlatExpression::Identifier(FlatVariable::new(0)),
box FlatExpression::Identifier(FlatVariable::new(1)),
),
box FlatExpression::Identifier(FlatVariable::new(2)),
)
)
);
}
#[test]
fn array_if() {
// if 1 == 1 then [1] else [3] fi
let with_arrays = {
let mut flattener = Flattener::new();
let mut functions_flattened = vec![];
flattener.load_corelib(&mut functions_flattened);
let mut statements_flattened = vec![];
let e = FieldElementArrayExpression::IfElse(
box BooleanExpression::Eq(
box FieldElementExpression::Number(FieldPrime::from(1)),
box FieldElementExpression::Number(FieldPrime::from(1)),
),
box FieldElementArrayExpression::Value(
1,
vec![FieldElementExpression::Number(FieldPrime::from(1))],
),
box FieldElementArrayExpression::Value(
1,
vec![FieldElementExpression::Number(FieldPrime::from(3))],
),
);
(
flattener.flatten_field_array_expression(
&mut functions_flattened,
&mut statements_flattened,
e,
)[0]
.clone(),
statements_flattened,
)
};
let without_arrays = {
let mut flattener = Flattener::new();
let mut functions_flattened = vec![];
flattener.load_corelib(&mut functions_flattened);
let mut statements_flattened = vec![];
// if 1 == 1 then 1 else 3 fi
let e = FieldElementExpression::IfElse(
box BooleanExpression::Eq(
box FieldElementExpression::Number(FieldPrime::from(1)),
box FieldElementExpression::Number(FieldPrime::from(1)),
),
box FieldElementExpression::Number(FieldPrime::from(1)),
box FieldElementExpression::Number(FieldPrime::from(3)),
);
(
flattener.flatten_field_expression(
&mut functions_flattened,
&mut statements_flattened,
e,
),
statements_flattened,
)
};
assert_eq!(with_arrays, without_arrays);
}
#[test]
fn next_variable() {
let mut flattener = Flattener::new();
assert_eq!(
FlatVariable::new(0),
flattener.use_variable(&String::from("a"))
);
assert_eq!(
flattener.get_latest_var_substitution(&String::from("a")),
FlatVariable::new(0)
);
assert_eq!(
FlatVariable::new(1),
flattener.use_variable(&String::from("a"))
);
assert_eq!(
flattener.get_latest_var_substitution(&String::from("a")),
FlatVariable::new(1)
);
assert_eq!(
FlatVariable::new(2),
flattener.use_variable(&String::from("a"))
);
assert_eq!(
flattener.get_latest_var_substitution(&String::from("a")),
FlatVariable::new(2)
);
}
}