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authorNadrieril2019-03-01 17:28:19 +0100
committerNadrieril2019-03-01 17:28:19 +0100
commite5d9aee00b0c775df1d8e2d8819aeb80dffa73c2 (patch)
treee763a24a0d635048232e72e167ca37eafec69369 /src/context.rs
parent8a2b7536902831079eddd7b00291b718f5dd7186 (diff)
Split abnf_to_pest and dhall into their own crates
Diffstat (limited to 'src/context.rs')
-rw-r--r--src/context.rs51
1 files changed, 0 insertions, 51 deletions
diff --git a/src/context.rs b/src/context.rs
deleted file mode 100644
index c2e1913..0000000
--- a/src/context.rs
+++ /dev/null
@@ -1,51 +0,0 @@
-use std::collections::HashMap;
-
-/// A `(Context a)` associates `Text` labels with values of type `a`
-///
-/// The `Context` is used for type-checking when `(a = Expr X)`
-///
-/// * You create a `Context` using `empty` and `insert`
-/// * You transform a `Context` using `fmap`
-/// * You consume a `Context` using `lookup` and `toList`
-///
-/// The difference between a `Context` and a `Map` is that a `Context` lets you
-/// have multiple ordered occurrences of the same key and you can query for the
-/// `n`th occurrence of a given key.
-///
-#[derive(Debug, Clone)]
-pub struct Context<'i, T>(HashMap<&'i str, Vec<T>>);
-
-impl<'i, T> Context<'i, T> {
- /// An empty context with no key-value pairs
- pub fn new() -> Self {
- Context(HashMap::new())
- }
-
- /// Look up a key by name and index
- ///
- /// ```c
- /// lookup _ _ empty = Nothing
- /// lookup k 0 (insert k v c) = Just v
- /// lookup k n (insert k v c) = lookup k (n - 1) c -- 1 <= n
- /// lookup k n (insert j v c) = lookup k n c -- k /= j
- /// ```
- pub fn lookup<'a>(&'a self, k: &str, n: usize) -> Option<&'a T> {
- self.0.get(k).and_then(|v| v.get(v.len() - 1 - n))
- }
-
- pub fn map<U, F: Fn(&T) -> U>(&self, f: F) -> Context<'i, U> {
- Context(self.0.iter().map(|(k, v)| (*k, v.iter().map(&f).collect())).collect())
- }
-}
-
-impl<'i, T: Clone> Context<'i, T> {
- /// Add a key-value pair to the `Context`
- pub fn insert(&self, k: &'i str, v: T) -> Self {
- let mut ctx = (*self).clone();
- {
- let m = ctx.0.entry(k).or_insert_with(Vec::new);
- m.push(v);
- }
- ctx
- }
-}