Implemented very basic fuzzy search on the history buffer

src/env.rs

@@ -3,7 +3,11 @@
 
 use super::{ Error, Result, exec, };
 
-use std::{collections::HashMap, io::Write, iter::FromIterator};
+use std::{
+    io::Write,
+    collections::HashMap,
+    iter::FromIterator
+};
 
 /// An environment used to [evaluate expressions](mod@super::eval) or 
 /// [execute programs](mod@super::exec).
@@ -19,7 +23,9 @@ pub trait Env {
         V: AsRef<str>;
 
     /// Get a bound value from the env.
-    fn get (&self, name: &str) -> Option<String>;
+    fn get <N> (&self, name: N) -> Option<String>
+    where
+        N: AsRef<str>;
 
     /// Get the current working directory.
     fn working_dir (&self) -> Result<std::path::PathBuf>;
@@ -132,7 +138,10 @@ impl<E: Env> Env for SetArgs<E> {
         self.parent.bind(name, value);
     }
 
-    fn get (&self, name: &str) -> Option<String> {
+    fn get <N> (&self, name: N) -> Option<String>
+    where
+        N: AsRef<str>
+    {
         self.parent.get(name)
     }
 
@@ -188,9 +197,12 @@ impl<E: Env> Env for Scope<'_, E> {
         );
     }
 
-    fn get (&self, name: &str) -> Option<String> {
+    fn get <N> (&self, name: N) -> Option<String>
+    where
+        N: AsRef<str>
+    {
         self.bindings
-            .get(name)
+            .get(name.as_ref())
             .cloned()
             .or_else(|| {
                 self.parent.get(name)
@@ -200,15 +212,20 @@ impl<E: Env> Env for Scope<'_, E> {
 
 /// An iterator of arguments.
 #[derive(Default, Clone)]
-pub struct Args (Vec<String>);
+pub struct Args {
+    args: Vec<String>,
+    cur: usize
+}
 
 impl<S: ToString> FromIterator<S> for Args {
     fn from_iter <T: IntoIterator<Item = S>> (iter: T) -> Args {
-        Args (
-            iter.into_iter()
+        Args {
+            args: iter
+                .into_iter()
                 .map(|s| s.to_string())
-                .collect()
-        )
+                .collect(),
+            cur: 0
+        }
     }
 }
 
@@ -216,11 +233,12 @@ impl Iterator for Args {
     type Item = String;
 
     fn next (&mut self) -> Option<Self::Item> {
-        if self.0.len() > 0 {
-            Some (self.0.remove(0))
-        } else {
-            None
-        }
+        let Args { args, cur } = self;
+
+        let val = args.get(*cur)?;
+        *cur += 1;
+        
+        Some (val.clone())
     }
 }
 
@@ -257,8 +275,11 @@ impl Env for Pure {
         );
     }
 
-    fn get (&self, name: &str) -> Option<String> {
-        self.bindings.get(name).cloned()
+    fn get <N> (&self, name: N) -> Option<String>
+    where
+        N: AsRef<str>
+    {
+        self.bindings.get(name.as_ref()).cloned()
     }
 
     fn stdout <R> (&mut self, data: R) -> Result<()>
@@ -310,8 +331,11 @@ impl Env for Inherit {
         std::env::set_var(name.as_ref(), value.as_ref());
     }
 
-    fn get (&self, name: &str) -> Option<String> {
-        std::env::var(name).ok()
+    fn get <N> (&self, name: N) -> Option<String>
+    where
+        N: AsRef<str>
+    {
+        std::env::var(name.as_ref()).ok()
     }
 
     fn working_dir (&self) -> Result<std::path::PathBuf> {
@@ -334,7 +358,8 @@ impl Env for Inherit {
         R: ToString
     {
         std::io::stdout().write(
-            data.to_string().as_bytes()
+            data.to_string()
+                .as_bytes()
         )?;
         
         Ok (())

src/env/history.rs

@@ -1 +1,191 @@
 //! History control.
+
+/// An entry in the [`History`] buffer.
+#[derive(Debug)]
+pub struct Entry {
+    raw: String,
+}
+
+impl Entry {
+    /// Returns `None` if the string does not match the given
+    /// fuzzy pattern. Returns `Some(score)` which can be used
+    /// to rank the results depending on how well they match.
+    pub fn fuzzy_match (&self, s: &str) -> Option<usize> {
+        
+        let mut i = 0;
+
+        for c in s.chars() {
+            i = self.raw[i..].find(c)?;
+        }
+        
+        Some (0)
+
+    }
+
+    /// Returns `true` if the entry contains the substring `s`.
+    pub fn exact_match (&self, s: &str) -> bool {
+        self.raw.contains(s)
+    }
+}
+
+/// A buffer that keeps track of the shell history.
+#[derive(Default)]
+pub struct History {
+    buf: Vec<Entry>,
+    cfg: Config,
+    cur: usize,
+}
+
+impl History {
+
+    /// Create a new empty history buffer with the given configuration.
+    ///
+    /// To create one with the default configuration, you can use [`History::default`].
+    pub fn new (cfg: Config) -> History {
+        History {
+            buf: Vec::new(),
+            cur: 0,
+            cfg,
+        } 
+    }
+
+    /// Move the cursor backwards in time.
+    pub fn prev (&mut self) -> &mut Self {
+        self.back(1)
+    }
+
+    /// Move the cursor forwards in time.
+    pub fn next (&mut self) -> &mut Self {
+        self.skip(1)
+    }
+
+    /// Time travel backwards.
+    fn back (&mut self, n: usize) -> &mut Self {
+        let History { buf, cur, .. } = self;
+        *cur = if *cur + n >= buf.len() { buf.len() - 1 } else { *cur + n };
+        self
+    }
+
+    /// Time travel into the "future".
+    fn skip (&mut self, n: usize) -> &mut Self {
+        let History { cur, .. } = self;
+        *cur = if *cur > n { *cur - n } else { 0 }; 
+        self
+    }
+
+    /// Append the given entry to the history buffer.
+    pub fn append (&mut self, entry: impl Into<Entry>) -> &mut Self {
+        let entry = entry.into();
+        self.buf.push(entry);
+        self
+    }
+
+    /// Remove the last entry of the buffer, if one exists.
+    pub fn pop (&mut self) -> Option<Entry> {
+        self.buf.pop()
+    }
+
+    /// Search the command history.
+    pub fn search <'s: 'x, 'x> (&'x self, s: &'s str) -> impl Iterator<Item = &'x Entry> {
+        self.buf.iter()
+            .rev()
+            .skip(self.cur)
+            .filter(move |Entry { raw }| {
+                raw.contains(s)
+            })
+    }
+
+    /// Search the command history using the fuzzy algorithm of
+    /// [`fuzzy_match`](Entry::fuzzy_match). The matching entries are
+    /// returned in the order in which they are entered in the buffer,
+    /// reversed. The fuzzy matching score is ignored.
+    pub fn fuzzy_search <'s: 'x, 'x> (&'x self, s: &'s str) -> impl Iterator<Item = &'x Entry> {
+        self.buf.iter()
+            .rev()
+            .skip(self.cur)
+            .filter(move |e| {
+                e.fuzzy_match(&s).is_some()
+            })
+    }
+}
+
+impl<S: ToString> From<S> for Entry {
+    fn from (text: S) -> Entry {
+        Entry { raw: text.to_string() }
+    }
+}
+
+/// Configuration for the [`History`] buffer.
+#[derive(Clone)]
+pub struct Config {
+    ignore: Vec<String>,
+    ignore_dups: bool,
+    limit: usize,
+}
+
+impl Config {
+
+    /// Create a new config.
+    ///
+    /// This is an alias for [`Config::default`].
+    pub fn new () -> Config {
+        Config::default()
+    }
+
+    /// Configure the history to ignore consecutive exactly equal
+    /// history entries.
+    pub fn ignore_dups (mut self) -> Self {
+        self.ignore_dups = true;
+        self
+    }
+
+    /// Set the history size limit.
+    pub fn limit (mut self, limit: usize) -> Self {
+        self.limit = limit;
+        self
+    }
+
+    /// Create a [`History`] buffer which uses this configuration.
+    pub fn into_history (self) -> History {
+        History::new(self)
+    }
+
+}
+
+impl Default for Config {
+    fn default () -> Self {
+        Config {
+            ignore: Vec::new(),
+            ignore_dups: false,
+            limit: 10000,
+        }
+    }
+}
+
+#[test]
+fn fuzzy_search () {
+    let mut hist = History::default();
+    
+    hist.append("z /etc/nixos")
+        .append("exa /home/riley")
+        .append("bat /home/riley/default.nix")
+        .append("exa /etc")
+        .append("nv ~/.config/sway/config")
+        .append("exa /etc/nixos")
+        .append("nv /etc/nixos/configuration.nix");
+
+    assert!(hist.fuzzy_search("cosw").count() == 1);
+    assert!(hist.fuzzy_search("conf").count() == 2);
+    assert!(hist.fuzzy_search("nix").count() == 4);
+
+    // Matches `nv /etc/nixos/configuration.nix` and
+    // `nv ~/.config/sway/config`, in that order.
+    let mut iter = hist.fuzzy_search("cfg");
+    assert!(iter.next().unwrap().raw == "nv /etc/nixos/configuration.nix");
+    assert!(iter.next().unwrap().raw == "nv ~/.config/sway/config");
+}
+
+#[test]
+fn fuzzy_match () {
+    Entry::from("exa /home/riley").fuzzy_match("exa").unwrap();
+}