Allow tabs and spaces

src/alejandra/src/builder.rs

@@ -22,6 +22,7 @@ pub(crate) struct BuildCtx {
     pub pos_old:            crate::position::Position,
     pub path:               String,
     pub vertical:           bool,
+    pub indent:             String,
 }
 
 pub(crate) fn build(
@@ -99,7 +100,7 @@ fn build_step(
                 add_token(
                     builder,
                     rnix::SyntaxKind::TOKEN_WHITESPACE,
-                    &format!("{0:<1$}", "", 2 * build_ctx.indentation),
+                    &build_ctx.indent.repeat(build_ctx.indentation),
                 );
             }
         }

src/alejandra/src/format.rs

@@ -39,6 +39,7 @@ pub fn in_memory(
         path,
         pos_old: crate::position::Position::default(),
         vertical: true,
+        indent,
     };
 
     let after = crate::builder::build(&mut build_ctx, ast.node().into())

src/alejandra/tests/indent/apply/in.nix

@@ -0,0 +1,6 @@
+{
+  foo =
+      bar:
+          baz:
+            fnbody;
+}

src/alejandra/tests/indent/apply/out.nix

@@ -0,0 +1,4 @@
+{
+	foo = bar: baz:
+		fnbody;
+}

src/alejandra/tests/indent/attr_set/in.nix

@@ -0,0 +1,11 @@
+{
+    a = rec {
+      a = {
+        a = rec {
+          a = {
+            a = rec {a = {a = rec {a = {a = rec {a = {};};};};};};
+          };
+        };
+      };
+    };
+  }

src/alejandra/tests/indent/attr_set/out.nix

@@ -0,0 +1,11 @@
+{
+	a = rec {
+		a = {
+			a = rec {
+				a = {
+					a = rec {a = {a = rec {a = {a = rec {a = {};};};};};};
+				};
+			};
+		};
+	};
+}

src/alejandra/tests/indent/list/in.nix

@@ -0,0 +1,11 @@
+[
+      # over indented
+  1
+ # under indented
+  2
+# no indentation
+    [1 2]
+    [
+    1 2 3
+    ]
+]

src/alejandra/tests/indent/list/out.nix

@@ -0,0 +1,13 @@
+[
+	# over indented
+	1
+	# under indented
+	2
+	# no indentation
+	[1 2]
+	[
+		1
+		2
+		3
+	]
+]