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5bfec20244
## description this pr adds [match guards](https://doc.rust-lang.org/reference/expressions/match-expr.html#match-guards) to match patterns ```nushell match $x { _ if $x starts-with 'nu' => {}, $x => {} } ``` these work pretty much like rust's match guards, with few limitations: 1. multiple matches using the `|` are not (yet?) supported ```nushell match $num { 0 | _ if (is-odd $num) => {}, _ => {} } ``` 2. blocks cannot be used as guards, (yet?) ```nushell match $num { $x if { $x ** $x == inf } => {}, _ => {} } ``` ## checklist - [x] syntax - [x] syntax highlighting[^1] - [x] semantics - [x] tests - [x] clean up [^1]: defered for another pr
58 lines
1.5 KiB
Rust
58 lines
1.5 KiB
Rust
use super::Expression;
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use crate::{Span, VarId};
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use serde::{Deserialize, Serialize};
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#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
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pub struct MatchPattern {
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pub pattern: Pattern,
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pub guard: Option<Expression>,
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pub span: Span,
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}
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impl MatchPattern {
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pub fn variables(&self) -> Vec<VarId> {
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self.pattern.variables()
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}
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}
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#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
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pub enum Pattern {
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Record(Vec<(String, MatchPattern)>),
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List(Vec<MatchPattern>),
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Value(Expression),
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Variable(VarId),
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Or(Vec<MatchPattern>),
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Rest(VarId), // the ..$foo pattern
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IgnoreRest, // the .. pattern
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IgnoreValue, // the _ pattern
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Garbage,
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}
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impl Pattern {
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pub fn variables(&self) -> Vec<VarId> {
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let mut output = vec![];
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match self {
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Pattern::Record(items) => {
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for item in items {
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output.append(&mut item.1.variables());
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}
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}
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Pattern::List(items) => {
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for item in items {
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output.append(&mut item.variables());
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}
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}
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Pattern::Variable(var_id) => output.push(*var_id),
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Pattern::Or(patterns) => {
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for pattern in patterns {
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output.append(&mut pattern.variables());
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}
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}
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Pattern::Rest(var_id) => output.push(*var_id),
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Pattern::Value(_) | Pattern::IgnoreValue | Pattern::Garbage | Pattern::IgnoreRest => {}
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}
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output
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}
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}
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