Suggest alternatives to uknown recipes (#91)

Kind of silly, but why not. Will only suggest an alternative if edit
distance is less than 3. This could probably increase if the names are
longer.

Cargo.lock

@@ -6,6 +6,7 @@ dependencies = [
  "atty 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "brev 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "clap 2.17.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "edit-distance 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 0.1.80 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -65,6 +66,11 @@ dependencies = [
  "vec_map 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "edit-distance"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "either"
 version = "1.0.1"
@@ -212,6 +218,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum bitflags 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "aad18937a628ec6abcd26d1489012cc0e18c21798210f491af69ded9b881106d"
 "checksum brev 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "79571b60a8aa293f43b46370d8ba96fed28a5bee1303ea0e015d175ed0c63b40"
 "checksum clap 2.17.1 (registry+https://github.com/rust-lang/crates.io-index)" = "27dac76762fb56019b04aed3ccb43a770a18f80f9c2eb62ee1a18d9fb4ea2430"
+"checksum edit-distance 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "cd50a61206c09132fdf9cbaccc64a82cfccb6be528453903e03d4eb4ec80a61d"
 "checksum either 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "8aa2c82b7e1abd89a8a59fd89c4a51576ea76a894edf5d5b28944dd46edfed8d"
 "checksum glob 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "8be18de09a56b60ed0edf84bc9df007e30040691af7acd1c41874faac5895bfb"
 "checksum itertools 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)" = "ef81b0a15a9e1808cfd3ebe6a87277d29ee88b34ac1197cc7547f1dd6d9f5424"

Cargo.toml

@@ -11,6 +11,7 @@ ansi_term     = "^0.9.0"
 atty          = "^0.2.1"
 brev          = "^0.1.6"
 clap          = "^2.0.0"
+edit-distance = "^1.0.0"
 itertools     = "^0.5.5"
 lazy_static   = "^0.2.1"
 regex         = "^0.1.77"

src/app.rs

@@ -211,7 +211,13 @@ pub fn app() {
         println!("{}", recipe);
         process::exit(0);
       }
-      None => die!("justfile contains no recipe \"{}\"", name)
+      None => {
+        warn!("Justfile does not contain recipe `{}`.", name);
+        if let Some(suggestion) = justfile.suggest(name) {
+          warn!("Did you mean `{}`?", suggestion);
+        }
+        process::exit(-1)
+      }
     }
   }
 

src/integration.rs

@@ -914,7 +914,7 @@ fn unknown_recipe() {
     "hello:",
     255,
     "",
-    "error: Justfile does not contain recipe `foo`\n",
+    "error: Justfile does not contain recipe `foo`.\n",
   );
 }
 
@@ -925,7 +925,7 @@ fn unknown_recipes() {
     "hello:",
     255,
     "",
-    "error: Justfile does not contain recipes `foo` or `bar`\n",
+    "error: Justfile does not contain recipes `foo` or `bar`.\n",
   );
 }
 
@@ -1093,3 +1093,51 @@ a Z="\t z":
     "",
   );
 }
+
+#[test]
+fn show_suggestion() {
+  integration_test(
+    &["--show", "hell"],
+    r#"
+hello a b='B	' c='C':
+  echo {{a}} {{b}} {{c}}
+
+a Z="\t z":
+"#,
+    255,
+    "",
+    "Justfile does not contain recipe `hell`.\nDid you mean `hello`?\n",
+  );
+}
+
+#[test]
+fn show_no_suggestion() {
+  integration_test(
+    &["--show", "hell"],
+    r#"
+helloooooo a b='B	' c='C':
+  echo {{a}} {{b}} {{c}}
+
+a Z="\t z":
+"#,
+    255,
+    "",
+    "Justfile does not contain recipe `hell`.\n",
+  );
+}
+
+#[test]
+fn run_suggestion() {
+  integration_test(
+    &["hell"],
+    r#"
+hello a b='B	' c='C':
+  echo {{a}} {{b}} {{c}}
+
+a Z="\t z":
+"#,
+    255,
+    "",
+    "error: Justfile does not contain recipe `hell`.\nDid you mean `hello`?\n",
+  );
+}

src/lib.rs

@@ -15,6 +15,7 @@ extern crate tempdir;
 extern crate itertools;
 extern crate ansi_term;
 extern crate unicode_width;
+extern crate edit_distance;
 
 use std::io::prelude::*;
 
@@ -1064,6 +1065,19 @@ impl<'a, 'b> Justfile<'a> where 'a: 'b {
     self.recipes.keys().cloned().collect()
   }
 
+  fn suggest(&self, name: &str) -> Option<&'a str> {
+    let mut suggestions = self.recipes.keys()
+      .map(|suggestion| (edit_distance::edit_distance(suggestion, name), suggestion))
+      .collect::<Vec<_>>();
+    suggestions.sort();
+    if let Some(&(distance, suggestion)) = suggestions.first() {
+      if distance < 3 {
+        return Some(suggestion)
+      }
+    }
+    None
+  }
+
   fn run(
     &'a self,
     arguments: &[&'a str],
@@ -1117,7 +1131,12 @@ impl<'a, 'b> Justfile<'a> where 'a: 'b {
       }
     }
     if !missing.is_empty() {
-      return Err(RunError::UnknownRecipes{recipes: missing});
+      let suggestion = if missing.len() == 1 {
+        self.suggest(missing.first().unwrap())
+      } else {
+        None
+      };
+      return Err(RunError::UnknownRecipes{recipes: missing, suggestion: suggestion});
     }
     for recipe in arguments.iter().map(|name| &self.recipes[name]) {
       self.run_recipe(recipe, &[], &scope, &mut ran, options)?;
@@ -1178,7 +1197,7 @@ enum RunError<'a> {
   Signal{recipe: &'a str, signal: i32},
   TmpdirIoError{recipe: &'a str, io_error: io::Error},
   UnknownFailure{recipe: &'a str},
-  UnknownRecipes{recipes: Vec<&'a str>},
+  UnknownRecipes{recipes: Vec<&'a str>, suggestion: Option<&'a str>},
   UnknownOverrides{overrides: Vec<&'a str>},
   BacktickCode{token: Token<'a>, code: i32},
   BacktickIoError{token: Token<'a>, io_error: io::Error},
@@ -1196,9 +1215,12 @@ impl<'a> Display for RunError<'a> {
     let mut error_token = None;
 
     match *self {
-      RunError::UnknownRecipes{ref recipes} => {
+      RunError::UnknownRecipes{ref recipes, ref suggestion} => {
-        write!(f, "Justfile does not contain recipe{} {}",
+        write!(f, "Justfile does not contain recipe{} {}.",
                   maybe_s(recipes.len()), Or(&ticks(&recipes)))?;
+        if let Some(suggestion) = *suggestion {
+          write!(f, "\nDid you mean `{}`?", suggestion)?;
+        }
       },
       RunError::UnknownOverrides{ref overrides} => {
         write!(f, "Variable{} {} overridden on the command line but not present in justfile",

src/unit.rs

@@ -711,7 +711,10 @@ fn range() {
 #[test]
 fn unknown_recipes() {
   match parse_success("a:\nb:\nc:").run(&["a", "x", "y", "z"], &Default::default()).unwrap_err() {
-    RunError::UnknownRecipes{recipes} => assert_eq!(recipes, &["x", "y", "z"]),
+    RunError::UnknownRecipes{recipes, suggestion} => {
+      assert_eq!(recipes, &["x", "y", "z"]);
+      assert_eq!(suggestion, None);
+    }
     other => panic!("expected an unknown recipe error, but got: {}", other),
   }
 }