nu_protocol/engine/pattern_match.rs
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use crate::{
ast::{Expr, MatchPattern, Pattern, RangeInclusion},
Span, Value, VarId,
};
pub trait Matcher {
fn match_value(&self, value: &Value, matches: &mut Vec<(VarId, Value)>) -> bool;
}
impl Matcher for MatchPattern {
fn match_value(&self, value: &Value, matches: &mut Vec<(VarId, Value)>) -> bool {
self.pattern.match_value(value, matches)
}
}
impl Matcher for Pattern {
fn match_value(&self, value: &Value, matches: &mut Vec<(VarId, Value)>) -> bool {
match self {
Pattern::Garbage => false,
Pattern::IgnoreValue => true,
Pattern::IgnoreRest => false, // `..` and `..$foo` only match in specific contexts
Pattern::Rest(_) => false, // so we return false here and handle them elsewhere
Pattern::Record(field_patterns) => match value {
Value::Record { val, .. } => {
'top: for field_pattern in field_patterns {
for (col, val) in &**val {
if col == &field_pattern.0 {
// We have found the field
let result = field_pattern.1.match_value(val, matches);
if !result {
return false;
} else {
continue 'top;
}
}
}
return false;
}
true
}
_ => false,
},
Pattern::Variable(var_id) => {
// TODO: FIXME: This needs the span of this variable
matches.push((*var_id, value.clone()));
true
}
Pattern::List(items) => match &value {
Value::List { vals, .. } => {
if items.len() > vals.len() {
// We only allow this is to have a rest pattern in the n+1 position
if items.len() == (vals.len() + 1) {
match &items[vals.len()].pattern {
Pattern::IgnoreRest => {}
Pattern::Rest(var_id) => matches.push((
*var_id,
Value::list(Vec::new(), items[vals.len()].span),
)),
_ => {
// There is a pattern which can't skip missing values, so we fail
return false;
}
}
} else {
// There are patterns that can't be matches, so we fail
return false;
}
}
for (val_idx, val) in vals.iter().enumerate() {
// We require that the pattern and the value have the same number of items, or the pattern does not match
// The only exception is if the pattern includes a `..` pattern
if let Some(pattern) = items.get(val_idx) {
match &pattern.pattern {
Pattern::IgnoreRest => {
break;
}
Pattern::Rest(var_id) => {
let rest_vals = vals[val_idx..].to_vec();
matches.push((*var_id, Value::list(rest_vals, pattern.span)));
break;
}
_ => {
if !pattern.match_value(val, matches) {
return false;
}
}
}
} else {
return false;
}
}
true
}
_ => false,
},
Pattern::Value(pattern_value) => {
// TODO: Fill this out with the rest of them
match &pattern_value.expr {
Expr::Nothing => {
matches!(value, Value::Nothing { .. })
}
Expr::Int(x) => {
if let Value::Int { val, .. } = &value {
x == val
} else {
false
}
}
Expr::Float(x) => {
if let Value::Float { val, .. } = &value {
x == val
} else {
false
}
}
Expr::Binary(x) => {
if let Value::Binary { val, .. } = &value {
x == val
} else {
false
}
}
Expr::Bool(x) => {
if let Value::Bool { val, .. } = &value {
x == val
} else {
false
}
}
Expr::String(x) => {
if let Value::String { val, .. } = &value {
x == val
} else {
false
}
}
Expr::DateTime(x) => {
if let Value::Date { val, .. } = &value {
x == val
} else {
false
}
}
Expr::ValueWithUnit(val) => {
let span = val.unit.span;
if let Expr::Int(size) = val.expr.expr {
match &val.unit.item.build_value(size, span) {
Ok(v) => v == value,
_ => false,
}
} else {
false
}
}
Expr::Range(range) => {
// TODO: Add support for floats
let start = if let Some(start) = &range.from {
match &start.expr {
Expr::Int(start) => *start,
_ => return false,
}
} else {
0
};
let end = if let Some(end) = &range.to {
match &end.expr {
Expr::Int(end) => *end,
_ => return false,
}
} else {
i64::MAX
};
let step = if let Some(step) = &range.next {
match &step.expr {
Expr::Int(step) => *step - start,
_ => return false,
}
} else if end < start {
-1
} else {
1
};
let (start, end) = if end < start {
(end, start)
} else {
(start, end)
};
if let Value::Int { val, .. } = &value {
if matches!(range.operator.inclusion, RangeInclusion::RightExclusive) {
*val >= start && *val < end && ((*val - start) % step) == 0
} else {
*val >= start && *val <= end && ((*val - start) % step) == 0
}
} else {
false
}
}
_ => false,
}
}
Pattern::Or(patterns) => {
let mut result = false;
for pattern in patterns {
let mut local_matches = vec![];
if !result {
if pattern.match_value(value, &mut local_matches) {
// TODO: do we need to replace previous variables that defaulted to nothing?
matches.append(&mut local_matches);
result = true;
} else {
// Create variables that don't match and assign them to null
let vars = pattern.variables();
for var in &vars {
let mut found = false;
for match_ in matches.iter() {
if match_.0 == *var {
found = true;
}
}
if !found {
// FIXME: don't use Span::unknown()
matches.push((*var, Value::nothing(Span::unknown())))
}
}
}
} else {
// We already have a match, so ignore the remaining match variables
// And assign them to null
let vars = pattern.variables();
for var in &vars {
let mut found = false;
for match_ in matches.iter() {
if match_.0 == *var {
found = true;
}
}
if !found {
// FIXME: don't use Span::unknown()
matches.push((*var, Value::nothing(Span::unknown())))
}
}
}
}
result
}
}
}
}