Make Debug output match Postgres

sfackler · sfackler · commit 8fde724ad380 · 2015-05-31T22:52:41.000-07:00
diff --git a/src/array.rs b/src/array.rs
@@ -1,16 +1,50 @@
 use std::ops::{Index, IndexMut};
 use std::slice;
 use std::vec;
+use std::fmt;
 
 use Dimension;
 
 /// A multi-dimensional array.
-#[derive(Debug, PartialEq, Eq, Clone)]
+#[derive(PartialEq, Eq, Clone)]
 pub struct Array<T> {
     dims: Vec<Dimension>,
     data: Vec<T>,
 }
 
+impl<T: fmt::Debug> fmt::Debug for Array<T> {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        if self.dims.iter().any(|dim| dim.lower_bound != 1) {
+            for dim in &self.dims {
+                try!(write!(fmt, "[{}:{}]", dim.lower_bound,
+                            dim.lower_bound + dim.len as isize - 1));
+            }
+            try!(write!(fmt, "="));
+        }
+        fmt_helper(0, &self.dims, &mut self.data.iter(), fmt)
+    }
+}
+
+fn fmt_helper<'a, T, I>(depth: usize,
+                        dims: &[Dimension],
+                        mut data: &mut I,
+                        fmt: &mut fmt::Formatter)
+                        -> fmt::Result
+        where I: Iterator<Item=&'a T>, T: 'a+fmt::Debug {
+    if depth == dims.len() {
+        return write!(fmt, "{:?}", data.next().unwrap());
+    }
+
+    try!(write!(fmt, "{{"));
+    for i in 0..dims[depth].len {
+        if i != 0 {
+            try!(write!(fmt, ","));
+        }
+        try!(fmt_helper(depth + 1, dims, data, fmt));
+    }
+    write!(fmt, "}}")
+}
+
 impl<T> Array<T> {
     /// Creates a new `Array` from its underlying components.
     ///
diff --git a/src/lib.rs b/src/lib.rs
@@ -118,4 +118,19 @@ mod tests {
         a[(0, 0)] = 3;
         assert_eq!(3, a[(0, 0)]);
     }
+
+    #[test]
+    fn test_debug() {
+        let a = Array::from_vec(vec![0i32, 1, 2, 3, 4], 1);
+        assert_eq!("{0,1,2,3,4}", &format!("{:?}", a));
+
+        let a = Array::from_vec(vec![0i32, 1, 2, 3, 4], -3);
+        assert_eq!("[-3:1]={0,1,2,3,4}", &format!("{:?}", a));
+
+        let mut a = Array::from_vec(vec![1i32, 2, 3], 3);
+        a.wrap(-2);
+        a.push(Array::from_vec(vec![4, 5, 6], 3));
+        a.wrap(1);
+        assert_eq!("[1:1][-2:-1][3:5]={{{1,2,3},{4,5,6}}}", &format!("{:?}", a));
+    }
 }
