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add conditional statement module

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This commit is contained in:
collin 2020-07-08 02:36:12 -07:00
parent a7888f5b29
commit 6d52a28161
6 changed files with 175 additions and 137 deletions
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38
compiler/src/statement/branch/branch.rs Normal file
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@ -0,0 +1,38 @@
//! Enforces a branch of a conditional or iteration statement in a compiled Leo program.
use crate::{errors::StatementError, program::ConstrainedProgram, value::ConstrainedValue, GroupType};
use leo_types::{Statement, Type};
use snarkos_models::{
curves::{Field, PrimeField},
gadgets::{r1cs::ConstraintSystem, utilities::boolean::Boolean},
};
impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
pub fn evaluate_branch<CS: ConstraintSystem<F>>(
&mut self,
cs: &mut CS,
file_scope: String,
function_scope: String,
indicator: Option<Boolean>,
statements: Vec<Statement>,
return_types: Vec<Type>,
) -> Result<Vec<(Option<Boolean>, ConstrainedValue<F, G>)>, StatementError> {
let mut results = vec![];
// Evaluate statements. Only allow a single return argument to be returned.
for statement in statements.iter() {
let mut value = self.enforce_statement(
cs,
file_scope.clone(),
function_scope.clone(),
indicator.clone(),
statement.clone(),
return_types.clone(),
)?;
results.append(&mut value);
}
Ok(results)
}
}

5
compiler/src/statement/branch/mod.rs Normal file
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@ -0,0 +1,5 @@
//! Methods to enforce constraints on a branch of a conditional or iteration statement
//! in a compiled Leo program.
pub mod branch;
pub use self::branch::*;

121
compiler/src/statement/conditional/conditional.rs Normal file
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@ -0,0 +1,121 @@
//! Methods to enforce constraints on statements in a compiled Leo program.
use crate::{errors::StatementError, program::ConstrainedProgram, value::ConstrainedValue, GroupType};
use leo_types::{ConditionalNestedOrEndStatement, ConditionalStatement, Span, Type};
use snarkos_models::{
curves::{Field, PrimeField},
gadgets::{r1cs::ConstraintSystem, utilities::boolean::Boolean},
};
fn indicator_to_string(indicator: &Boolean) -> String {
indicator
.get_value()
.map(|b| b.to_string())
.unwrap_or(format!("[input]"))
}
impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
/// Enforces a conditional statement with one or more branches.
/// Due to R1CS constraints, we must evaluate every branch to properly construct the circuit.
/// At program execution, we will pass an `indicator` bit down to all child statements within each branch.
/// The `indicator` bit will select that branch while keeping the constraint system satisfied.
pub fn enforce_conditional_statement<CS: ConstraintSystem<F>>(
&mut self,
cs: &mut CS,
file_scope: String,
function_scope: String,
indicator: Option<Boolean>,
statement: ConditionalStatement,
return_types: Vec<Type>,
span: Span,
) -> Result<Vec<(Option<Boolean>, ConstrainedValue<F, G>)>, StatementError> {
let statement_string = statement.to_string();
// Inherit the indicator from a previous conditional statement or assume that we are the outer parent
let outer_indicator = indicator.unwrap_or(Boolean::Constant(true));
// Evaluate the conditional boolean as the inner indicator
let inner_indicator = match self.enforce_expression(
cs,
file_scope.clone(),
function_scope.clone(),
&vec![Type::Boolean],
statement.condition.clone(),
)? {
ConstrainedValue::Boolean(resolved) => resolved,
value => return Err(StatementError::conditional_boolean(value.to_string(), span)),
};
// If outer_indicator && inner_indicator, then select branch 1
let outer_indicator_string = indicator_to_string(&outer_indicator);
let inner_indicator_string = indicator_to_string(&inner_indicator);
let branch_1_name = format!(
"branch indicator 1 {} && {}",
outer_indicator_string, inner_indicator_string
);
let branch_1_indicator = Boolean::and(
&mut cs.ns(|| format!("branch 1 {} {}:{}", statement_string, span.line, span.start)),
&outer_indicator,
&inner_indicator,
)
.map_err(|_| StatementError::indicator_calculation(branch_1_name, span.clone()))?;
let mut results = vec![];
// Evaluate branch 1
let mut branch_1_result = self.evaluate_branch(
cs,
file_scope.clone(),
function_scope.clone(),
Some(branch_1_indicator),
statement.statements,
return_types.clone(),
)?;
results.append(&mut branch_1_result);
// If outer_indicator && !inner_indicator, then select branch 2
let inner_indicator = inner_indicator.not();
let inner_indicator_string = indicator_to_string(&inner_indicator);
let branch_2_name = format!(
"branch indicator 2 {} && {}",
outer_indicator_string, inner_indicator_string
);
let branch_2_indicator = Boolean::and(
&mut cs.ns(|| format!("branch 2 {} {}:{}", statement_string, span.line, span.start)),
&outer_indicator,
&inner_indicator,
)
.map_err(|_| StatementError::indicator_calculation(branch_2_name, span.clone()))?;
// Evaluate branch 2
let mut branch_2_result = match statement.next {
Some(next) => match next {
ConditionalNestedOrEndStatement::Nested(nested) => self.enforce_conditional_statement(
cs,
file_scope,
function_scope,
Some(branch_2_indicator),
*nested,
return_types,
span,
)?,
ConditionalNestedOrEndStatement::End(statements) => self.evaluate_branch(
cs,
file_scope,
function_scope,
Some(branch_2_indicator),
statements,
return_types,
)?,
},
None => vec![],
};
results.append(&mut branch_2_result);
// We return the results of both branches and leave it up to the caller to select the appropriate return
Ok(results)
}
}

4
compiler/src/statement/conditional/mod.rs Normal file
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@ -0,0 +1,4 @@
//! Methods to enforce constraints on conditional statements in a compiled Leo program.
pub mod conditional;
pub use self::conditional::*;

6
compiler/src/statement/mod.rs
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@ -1,6 +1,12 @@
pub mod assign;
pub use self::assign::*;
pub mod branch;
pub use self::branch::*;
pub mod conditional;
pub use self::conditional::*;
pub mod definition;
pub use self::definition::*;

138
compiler/src/statement/statement.rs
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@ -8,7 +8,7 @@ use crate::{
GroupType,
Integer,
};
use leo_types::{ConditionalNestedOrEndStatement, ConditionalStatement, Expression, Identifier, Span, Statement, Type};
use leo_types::{Expression, Identifier, Span, Statement, Type};
use snarkos_models::{
curves::{Field, PrimeField},
@ -19,142 +19,6 @@ use snarkos_models::{
};
impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
fn evaluate_branch<CS: ConstraintSystem<F>>(
&mut self,
cs: &mut CS,
file_scope: String,
function_scope: String,
indicator: Option<Boolean>,
statements: Vec<Statement>,
return_types: Vec<Type>,
) -> Result<Vec<(Option<Boolean>, ConstrainedValue<F, G>)>, StatementError> {
let mut results = vec![];
// Evaluate statements. Only allow a single return argument to be returned.
for statement in statements.iter() {
let mut value = self.enforce_statement(
cs,
file_scope.clone(),
function_scope.clone(),
indicator.clone(),
statement.clone(),
return_types.clone(),
)?;
results.append(&mut value);
}
Ok(results)
}
/// Enforces a statements.conditional statement with one or more branches.
/// Due to R1CS constraints, we must evaluate every branch to properly construct the circuit.
/// At program execution, we will pass an `indicator bit` down to all child statements within each branch.
/// The `indicator bit` will select that branch while keeping the constraint system satisfied.
fn enforce_conditional_statement<CS: ConstraintSystem<F>>(
&mut self,
cs: &mut CS,
file_scope: String,
function_scope: String,
indicator: Option<Boolean>,
statement: ConditionalStatement,
return_types: Vec<Type>,
span: Span,
) -> Result<Vec<(Option<Boolean>, ConstrainedValue<F, G>)>, StatementError> {
let statement_string = statement.to_string();
let outer_indicator = indicator.unwrap_or(Boolean::Constant(true));
let expected_types = vec![Type::Boolean];
let inner_indicator = match self.enforce_expression(
cs,
file_scope.clone(),
function_scope.clone(),
&expected_types,
statement.condition.clone(),
)? {
ConstrainedValue::Boolean(resolved) => resolved,
value => return Err(StatementError::conditional_boolean(value.to_string(), span)),
};
// Determine nested branch 1 selection
let outer_indicator_string = outer_indicator
.get_value()
.map(|b| b.to_string())
.unwrap_or(format!("[allocated]"));
let inner_indicator_string = inner_indicator
.get_value()
.map(|b| b.to_string())
.unwrap_or(format!("[allocated]"));
let branch_1_name = format!(
"branch indicator 1 {} && {}",
outer_indicator_string, inner_indicator_string
);
let branch_1_indicator = Boolean::and(
&mut cs.ns(|| format!("branch 1 {} {}:{}", statement_string, span.line, span.start)),
&outer_indicator,
&inner_indicator,
)
.map_err(|_| StatementError::indicator_calculation(branch_1_name, span.clone()))?;
let mut results = vec![];
// Execute branch 1
let mut branch_1_result = self.evaluate_branch(
cs,
file_scope.clone(),
function_scope.clone(),
Some(branch_1_indicator),
statement.statements,
return_types.clone(),
)?;
results.append(&mut branch_1_result);
// Determine nested branch 2 selection
let inner_indicator = inner_indicator.not();
let inner_indicator_string = inner_indicator
.get_value()
.map(|b| b.to_string())
.unwrap_or(format!("[allocated]"));
let branch_2_name = format!(
"branch indicator 2 {} && {}",
outer_indicator_string, inner_indicator_string
);
let branch_2_indicator = Boolean::and(
&mut cs.ns(|| format!("branch 2 {} {}:{}", statement_string, span.line, span.start)),
&outer_indicator,
&inner_indicator,
)
.map_err(|_| StatementError::indicator_calculation(branch_2_name, span.clone()))?;
// Execute branch 2
let mut branch_2_result = match statement.next {
Some(next) => match next {
ConditionalNestedOrEndStatement::Nested(nested) => self.enforce_conditional_statement(
cs,
file_scope,
function_scope,
Some(branch_2_indicator),
*nested,
return_types,
span,
)?,
ConditionalNestedOrEndStatement::End(statements) => self.evaluate_branch(
cs,
file_scope,
function_scope,
Some(branch_2_indicator),
statements,
return_types,
)?,
},
None => vec![],
};
results.append(&mut branch_2_result);
Ok(results)
}
fn enforce_for_statement<CS: ConstraintSystem<F>>(
&mut self,
cs: &mut CS,