Normalize primitive and numeric constraints
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e23b31da46
commit
84680e2652
284
crates/decodal-core/src/constraints.rs
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284
crates/decodal-core/src/constraints.rs
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@ -0,0 +1,284 @@
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use alloc::{string::String, vec::Vec};
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use crate::{
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Diagnostic, DiagnosticKind, Span,
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ast::CompareOp,
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runtime::{Constraint, LiteralValue, PrimitiveType},
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};
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pub fn normalize_constraints(
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constraints: Vec<Constraint>,
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span: Span,
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) -> crate::Result<Vec<Constraint>> {
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let mut primitive = None;
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let mut lower: Option<Bound> = None;
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let mut upper: Option<Bound> = None;
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let mut rest = Vec::new();
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for constraint in constraints {
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match constraint {
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Constraint::Type(next) => match primitive {
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Some(current) if current != next => {
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return Err(Diagnostic::new(
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DiagnosticKind::Conflict,
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span,
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"primitive type constraints conflict",
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));
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}
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Some(_) => {}
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None => primitive = Some(next),
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},
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Constraint::Compare(op, value) => {
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let number = Number::from_literal(&value).ok_or_else(|| {
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Diagnostic::new(
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DiagnosticKind::TypeMismatch,
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span,
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"comparison constraints require numeric literals",
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)
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})?;
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match op {
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CompareOp::Gt => merge_lower(&mut lower, Bound::new(number, false)),
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CompareOp::Gte => merge_lower(&mut lower, Bound::new(number, true)),
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CompareOp::Lt => merge_upper(&mut upper, Bound::new(number, false)),
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CompareOp::Lte => merge_upper(&mut upper, Bound::new(number, true)),
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CompareOp::Eq => {
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merge_lower(&mut lower, Bound::new(number, true));
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merge_upper(&mut upper, Bound::new(number, true));
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}
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}
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}
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Constraint::Regex(pattern) => rest.push(Constraint::Regex(pattern)),
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Constraint::BuiltinPredicate(name) => rest.push(Constraint::BuiltinPredicate(name)),
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}
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}
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if matches!(primitive, Some(PrimitiveType::String | PrimitiveType::Bool))
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&& (lower.is_some() || upper.is_some())
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{
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return Err(Diagnostic::new(
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DiagnosticKind::Conflict,
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span,
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"numeric comparison constraints conflict with non-numeric primitive type",
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));
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}
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if primitive == Some(PrimitiveType::Int)
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&& lower
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.iter()
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.chain(upper.iter())
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.any(|bound| !matches!(bound.number, Number::Int(_)))
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{
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return Err(Diagnostic::new(
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DiagnosticKind::Conflict,
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span,
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"Int comparison constraints must use integer literals",
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));
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}
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ensure_bounds_non_empty(primitive, lower, upper, span)?;
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let mut normalized = Vec::new();
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if let Some(primitive) = primitive {
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normalized.push(Constraint::Type(primitive));
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}
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if let Some(lower) = lower {
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normalized.push(Constraint::Compare(
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if lower.inclusive {
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CompareOp::Gte
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} else {
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CompareOp::Gt
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},
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lower.number.into_literal(),
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));
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}
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if let Some(upper) = upper {
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normalized.push(Constraint::Compare(
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if upper.inclusive {
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CompareOp::Lte
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} else {
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CompareOp::Lt
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},
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upper.number.into_literal(),
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));
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}
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normalized.extend(rest);
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Ok(normalized)
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}
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#[derive(Debug, Clone, Copy, PartialEq)]
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struct Bound {
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number: Number,
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inclusive: bool,
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}
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impl Bound {
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fn new(number: Number, inclusive: bool) -> Self {
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Self { number, inclusive }
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}
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}
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#[derive(Debug, Clone, Copy, PartialEq)]
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enum Number {
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Int(i64),
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Float(f64),
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}
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impl Number {
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fn from_literal(value: &LiteralValue) -> Option<Self> {
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match value {
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LiteralValue::Int(value) => Some(Self::Int(*value)),
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LiteralValue::Float(value) => Some(Self::Float(*value)),
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LiteralValue::String(_) | LiteralValue::Bool(_) => None,
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}
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}
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fn into_literal(self) -> LiteralValue {
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match self {
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Self::Int(value) => LiteralValue::Int(value),
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Self::Float(value) => LiteralValue::Float(value),
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}
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}
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fn as_f64(self) -> f64 {
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match self {
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Self::Int(value) => value as f64,
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Self::Float(value) => value,
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}
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}
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}
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fn merge_lower(current: &mut Option<Bound>, next: Bound) {
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match current {
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None => *current = Some(next),
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Some(current_bound) if is_stricter_lower(next, *current_bound) => *current_bound = next,
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Some(_) => {}
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}
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}
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fn merge_upper(current: &mut Option<Bound>, next: Bound) {
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match current {
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None => *current = Some(next),
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Some(current_bound) if is_stricter_upper(next, *current_bound) => *current_bound = next,
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Some(_) => {}
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}
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}
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fn is_stricter_lower(next: Bound, current: Bound) -> bool {
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let next_value = next.number.as_f64();
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let current_value = current.number.as_f64();
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next_value > current_value
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|| (next_value == current_value && !next.inclusive && current.inclusive)
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}
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fn is_stricter_upper(next: Bound, current: Bound) -> bool {
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let next_value = next.number.as_f64();
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let current_value = current.number.as_f64();
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next_value < current_value
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|| (next_value == current_value && !next.inclusive && current.inclusive)
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}
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fn ensure_bounds_non_empty(
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primitive: Option<PrimitiveType>,
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lower: Option<Bound>,
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upper: Option<Bound>,
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span: Span,
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) -> crate::Result<()> {
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if primitive == Some(PrimitiveType::Int) {
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let min = lower.map(int_lower_bound).unwrap_or(i128::from(i64::MIN));
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let max = upper.map(int_upper_bound).unwrap_or(i128::from(i64::MAX));
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if min > max {
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return Err(empty_numeric_bounds(span));
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}
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return Ok(());
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}
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if let (Some(lower), Some(upper)) = (lower, upper) {
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let lower_value = lower.number.as_f64();
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let upper_value = upper.number.as_f64();
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if lower_value > upper_value {
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return Err(empty_numeric_bounds(span));
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}
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if lower_value == upper_value && !(lower.inclusive && upper.inclusive) {
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return Err(empty_numeric_bounds(span));
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}
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}
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Ok(())
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}
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fn int_lower_bound(bound: Bound) -> i128 {
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let Number::Int(value) = bound.number else {
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unreachable!()
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};
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if bound.inclusive {
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i128::from(value)
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} else {
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i128::from(value) + 1
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}
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}
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fn int_upper_bound(bound: Bound) -> i128 {
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let Number::Int(value) = bound.number else {
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unreachable!()
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};
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if bound.inclusive {
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i128::from(value)
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} else {
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i128::from(value) - 1
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}
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}
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fn empty_numeric_bounds(span: Span) -> Diagnostic {
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Diagnostic::new(
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DiagnosticKind::Conflict,
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span,
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String::from("numeric comparison constraints have an empty intersection"),
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)
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use crate::runtime::LiteralValue;
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#[test]
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fn detects_primitive_conflict() {
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assert!(
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normalize_constraints(
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alloc::vec![
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Constraint::Type(PrimitiveType::Int),
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Constraint::Type(PrimitiveType::String),
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],
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Span::default(),
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)
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.is_err()
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);
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}
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#[test]
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fn detects_empty_int_range() {
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assert!(
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normalize_constraints(
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alloc::vec![
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Constraint::Type(PrimitiveType::Int),
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Constraint::Compare(CompareOp::Gt, LiteralValue::Int(10)),
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Constraint::Compare(CompareOp::Lt, LiteralValue::Int(11)),
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],
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Span::default(),
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)
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.is_err()
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);
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}
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#[test]
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fn keeps_regex_constraints_without_intersection_check() {
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let constraints = normalize_constraints(
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alloc::vec![
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Constraint::Regex(String::from("^a$")),
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Constraint::Regex(String::from("^b$")),
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],
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Span::default(),
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)
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.unwrap();
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assert_eq!(constraints.len(), 2);
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}
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}
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@ -3,6 +3,7 @@ use alloc::{format, string::String, vec, vec::Vec};
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use crate::{
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ExprId, SourceForm, SourceId, Span,
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ast::{Ast, BinaryOp, CompareOp, Expr, Field, Literal},
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constraints::normalize_constraints,
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diagnostic::{Diagnostic, DiagnosticKind, Result},
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embedding::HostValue,
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module::{EmptyLoader, LoadedSource, Module, SourceLoader},
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@ -589,6 +590,7 @@ impl<L: SourceLoader> Engine<L> {
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match (lhs, rhs) {
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(RuntimeValue::Abstract(mut lhs), RuntimeValue::Abstract(rhs)) => {
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lhs.constraints.extend(rhs.constraints);
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lhs.constraints = normalize_constraints(lhs.constraints, span)?;
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lhs.default = merge_default(lhs.default, rhs.default, span)?;
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Ok(RuntimeValue::Abstract(lhs))
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}
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@ -765,6 +767,7 @@ impl<L: SourceLoader> Engine<L> {
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} else {
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None
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};
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let constraints = normalize_constraints(constraints, Span::default())?;
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Ok(RuntimeValue::Abstract(AbstractValue {
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constraints,
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default,
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@ -3,6 +3,7 @@
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extern crate alloc;
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pub mod ast;
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pub mod constraints;
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pub mod diagnostic;
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pub mod embedding;
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pub mod eval;
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@ -13,6 +14,7 @@ pub mod runtime;
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pub mod span;
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pub use ast::{Ast, BinaryOp, CompareOp, Expr, ExprId, Field, Literal, Param};
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pub use constraints::normalize_constraints;
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pub use diagnostic::{Diagnostic, DiagnosticKind, Result};
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pub use embedding::{HostField, HostValue};
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pub use eval::Engine;
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@ -31,9 +31,52 @@ A & B = A と B の両方を満たす値または制約
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```dcdl
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Int & String # エラー
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>= 10 & <= 5 # エラーになりうる
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> 10 & < 5 # エラー
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Int & > 10 & < 11 # エラー。整数値の候補が存在しない
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```
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## 制約の正規化
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`&` によって abstract value 同士を合成した場合、処理系は軽量に判定できる制約を正規化する。
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正規化対象:
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- primitive type 制約。
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- 数値比較制約。
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primitive type 制約は、異なる型が同時に要求された場合 conflict になる。
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```dcdl
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Int & Float
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Int & String
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```
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数値比較制約は上下限として正規化される。
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```dcdl
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Int & >= 1 & <= 65535 & > 443
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```
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これは概念的に以下へ正規化される。
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```text
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Type(Int)
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> 443
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<= 65535
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```
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上下限の交差が空であれば conflict になる。
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`Int` 制約がある場合は、整数候補が存在するかも判定する。
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```dcdl
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> 10 & < 5 # conflict
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Int & > 10 & < 11 # conflict
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Int & >= 10 & <= 10 # OK
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```
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`Int` の比較制約は整数リテラルを使う。
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`Float` の比較制約は整数リテラルまたは浮動小数リテラルを使える。
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## 組み込み制約
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最小の組み込み制約は以下である。
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@ -53,13 +96,28 @@ IPv4Address
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## 正規表現制約
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正規表現リテラルは文字列制約として使える候補である。
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正規表現リテラルは文字列制約として使える。
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```dcdl
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Host = /^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/;
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```
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ただし、組み込み向け実装では正規表現エンジンを optional feature にできる。
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正規表現制約は積み重ね可能である。
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複数の正規表現制約が同じ abstract value に付与された場合、具体文字列はすべての正規表現制約に一致しなければならない。
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```dcdl
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String & /^a/ & /z$/
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```
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処理系は、正規表現制約同士の交差が空であるかを合成時に判定する必要はない。
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つまり、以下は合成時には conflict にならず、具体値検証時に失敗する。
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```dcdl
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String & /^a$/ & /^b$/
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```
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正規表現エンジンは optional feature にできる。
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正規表現 feature が無効な処理系では、正規表現制約の検証は unsupported feature diagnostic になる。
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軽量実装では代表的な制約を組み込み述語として提供してもよい。
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```dcdl
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