Added better tests for myers and patience, added capture hook

src/algorithms/hook.rs

@@ -1,3 +1,6 @@
+use std::convert::Infallible;
+use std::mem;
+
 /// A trait for reacting to an edit script from the "old" version to
 /// the "new" version.
 pub trait DiffHook: Sized {
@@ -103,3 +106,115 @@ impl<'a, D: DiffHook + 'a> DiffHook for &'a mut D {
         (*self).finish()
     }
 }
+
+/// Utility enum to capture a diff operation.
+#[derive(Debug, PartialEq, Eq, Hash, Clone, Copy)]
+pub enum DiffOp {
+    Equal {
+        old_index: usize,
+        new_index: usize,
+        len: usize,
+    },
+    Delete {
+        old_index: usize,
+        old_len: usize,
+        new_index: usize,
+    },
+    Insert {
+        old_index: usize,
+        new_index: usize,
+        new_len: usize,
+    },
+    Replace {
+        old_index: usize,
+        old_len: usize,
+        new_index: usize,
+        new_len: usize,
+    },
+}
+
+/// Captures diff operations.
+#[derive(Default, Clone)]
+pub struct CaptureHook(Vec<DiffOp>);
+
+impl CaptureHook {
+    /// Creates a new capture hook.
+    pub fn new() -> CaptureHook {
+        CaptureHook::default()
+    }
+
+    /// Removes all replace operations.
+    pub fn resolve_replace(&mut self) {
+        self.0 = mem::replace(&mut self.0, Vec::new())
+            .into_iter()
+            .filter_map(|op| Some(op))
+            .collect();
+    }
+
+    /// Converts the capture hook into a vector.
+    pub fn into_vec(self) -> Vec<DiffOp> {
+        self.0
+    }
+
+    /// Accesses the captured operations.
+    pub fn ops(&self) -> &[DiffOp] {
+        &self.0
+    }
+}
+
+impl DiffHook for CaptureHook {
+    type Error = Infallible;
+
+    fn equal(&mut self, old_index: usize, new_index: usize, len: usize) -> Result<(), Self::Error> {
+        self.0.push(DiffOp::Equal {
+            old_index,
+            new_index,
+            len,
+        });
+        Ok(())
+    }
+
+    fn delete(
+        &mut self,
+        old_index: usize,
+        old_len: usize,
+        new_index: usize,
+    ) -> Result<(), Self::Error> {
+        self.0.push(DiffOp::Delete {
+            old_index,
+            old_len,
+            new_index,
+        });
+        Ok(())
+    }
+
+    fn insert(
+        &mut self,
+        old_index: usize,
+        new_index: usize,
+        new_len: usize,
+    ) -> Result<(), Self::Error> {
+        self.0.push(DiffOp::Insert {
+            old_index,
+            new_index,
+            new_len,
+        });
+        Ok(())
+    }
+
+    fn replace(
+        &mut self,
+        old_index: usize,
+        old_len: usize,
+        new_index: usize,
+        new_len: usize,
+    ) -> Result<(), Self::Error> {
+        self.0.push(DiffOp::Replace {
+            old_index,
+            old_len,
+            new_index,
+            new_len,
+        });
+        Ok(())
+    }
+}

src/algorithms/myers.rs

@@ -237,21 +237,23 @@ fn test_replace() {
     let a: &[usize] = &[0, 1, 2, 3, 4];
     let b: &[usize] = &[0, 1, 2, 7, 8, 9];
 
-    struct D;
-    impl DiffHook for D {
-        type Error = ();
-        fn delete(&mut self, _o: usize, _len: usize, _new: usize) -> Result<(), ()> {
-            panic!("should not delete")
-        }
-        fn insert(&mut self, _o: usize, _n: usize, _len: usize) -> Result<(), ()> {
-            panic!("should not insert")
-        }
-        fn replace(&mut self, _o: usize, _l: usize, _n: usize, _nl: usize) -> Result<(), ()> {
-            Ok(())
-        }
-    }
-    let mut d = crate::algorithms::Replace::new(D);
-    diff(&mut d, a, 0..a.len(), b, 0..b.len()).unwrap();
+    let mut d = crate::algorithms::Replace::new(crate::algorithms::CaptureHook::new());
+    diff_slices(&mut d, a, b).unwrap();
+    insta::assert_debug_snapshot!(d.into_inner().ops(), @r###"
+    [
+        Equal {
+            old_index: 0,
+            new_index: 0,
+            len: 3,
+        },
+        Replace {
+            old_index: 3,
+            old_len: 2,
+            new_index: 3,
+            new_len: 3,
+        },
+    ]
+    "###);
 }
 
 #[test]
@@ -259,23 +261,35 @@ fn test_pat() {
     let a: &[usize] = &[0, 1, 3, 4, 5];
     let b: &[usize] = &[0, 1, 4, 5, 8, 9];
 
-    struct D;
-    impl DiffHook for D {
-        type Error = ();
-        fn delete(&mut self, _o: usize, _len: usize, _new: usize) -> Result<(), ()> {
-            println!("delete {:?} {:?} {:?}", _o, _len, _new);
-            Ok(())
-        }
-        fn insert(&mut self, _o: usize, _n: usize, _len: usize) -> Result<(), ()> {
-            println!("insert {:?} {:?} {:?}", _o, _n, _len);
-            Ok(())
-        }
-        fn replace(&mut self, _o: usize, _l: usize, _n: usize, _nl: usize) -> Result<(), ()> {
-            println!("replace {:?} {:?} {:?} {:?}", _o, _l, _n, _nl);
-            Ok(())
-        }
-    }
-
-    let mut d = crate::algorithms::Replace::new(D);
-    diff(&mut d, a, 0..a.len(), b, 0..b.len()).unwrap();
+    let mut d = crate::algorithms::CaptureHook::new();
+    diff_slices(&mut d, a, b).unwrap();
+    insta::assert_debug_snapshot!(d.ops(), @r###"
+    [
+        Equal {
+            old_index: 0,
+            new_index: 0,
+            len: 2,
+        },
+        Delete {
+            old_index: 2,
+            old_len: 1,
+            new_index: 2,
+        },
+        Equal {
+            old_index: 3,
+            new_index: 2,
+            len: 2,
+        },
+        Insert {
+            old_index: 5,
+            new_index: 4,
+            new_len: 1,
+        },
+        Insert {
+            old_index: 5,
+            new_index: 5,
+            new_len: 1,
+        },
+    ]
+    "###);
 }

src/algorithms/replace.rs

@@ -128,7 +128,7 @@ impl<D: DiffHook> DiffHook for Replace<D> {
 }
 
 #[test]
-fn myers() {
+fn test_mayers_replace() {
     use crate::algorithms::myers;
     let a: &[&str] = &[
         ">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n",
@@ -153,36 +153,62 @@ fn myers() {
         "<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n",
     ];
 
-    struct D(Vec<String>);
-    impl DiffHook for D {
-        type Error = ();
-        fn equal(&mut self, o: usize, n: usize, len: usize) -> Result<(), ()> {
-            self.0.push(format!("equal {:?} {:?} {:?}", o, n, len));
-            Ok(())
-        }
-        fn delete(&mut self, o: usize, len: usize, new: usize) -> Result<(), ()> {
-            self.0.push(format!("delete {:?} {:?} {:?}", o, len, new));
-            Ok(())
-        }
-        fn insert(&mut self, o: usize, n: usize, len: usize) -> Result<(), ()> {
-            self.0.push(format!("insert {:?} {:?} {:?}", o, n, len));
-            Ok(())
-        }
-        fn replace(&mut self, o: usize, l: usize, n: usize, nl: usize) -> Result<(), ()> {
-            self.0
-                .push(format!("replace {:?} {:?} {:?} {:?}", o, l, n, nl));
-            Ok(())
-        }
-    }
-    let mut d = Replace::new(D(Vec::new()));
-    myers::diff(&mut d, a, 0..a.len(), b, 0..b.len()).unwrap();
+    let mut d = Replace::new(crate::algorithms::CaptureHook::new());
+    myers::diff_slices(&mut d, a, b).unwrap();
 
-    insta::assert_yaml_snapshot!(&d.into_inner().0, @r###"
-    ---
-    - equal 0 0 1
-    - replace 1 1 1 1
-    - equal 2 2 3
-    - replace 5 1 5 1
-    - equal 6 6 3
+    insta::assert_debug_snapshot!(&d.into_inner().ops(), @r###"
+    [
+        Equal {
+            old_index: 0,
+            new_index: 0,
+            len: 1,
+        },
+        Replace {
+            old_index: 1,
+            old_len: 1,
+            new_index: 1,
+            new_len: 1,
+        },
+        Equal {
+            old_index: 2,
+            new_index: 2,
+            len: 3,
+        },
+        Replace {
+            old_index: 5,
+            old_len: 1,
+            new_index: 5,
+            new_len: 1,
+        },
+        Equal {
+            old_index: 6,
+            new_index: 6,
+            len: 3,
+        },
+    ]
+    "###);
+}
+
+#[test]
+fn test_replace() {
+    let a: &[usize] = &[0, 1, 2, 3, 4];
+    let b: &[usize] = &[0, 1, 2, 7, 8, 9];
+
+    let mut d = Replace::new(crate::algorithms::CaptureHook::new());
+    crate::algorithms::myers::diff_slices(&mut d, a, b).unwrap();
+    insta::assert_debug_snapshot!(d.into_inner().ops(), @r###"
+    [
+        Equal {
+            old_index: 0,
+            new_index: 0,
+            len: 3,
+        },
+        Replace {
+            old_index: 3,
+            old_len: 2,
+            new_index: 3,
+            new_len: 3,
+        },
+    ]
     "###);
 }