feat: rebase Vladimir's pr

Author: kamadorueda

src/alejandra/src/builder.rs

@@ -1,4 +1,5 @@
 use crate::config::Config;
+use crate::config::Indentation;
 
 #[derive(PartialEq)]
 pub(crate) enum Step {
@@ -15,14 +16,13 @@ pub(crate) enum Step {
 
 #[derive(Clone)]
 pub(crate) struct BuildCtx {
-    pub _config:            Config,
+    pub config:             Config,
     pub force_wide:         bool,
     pub force_wide_success: bool,
     pub indentation:        usize,
     pub pos_old:            crate::position::Position,
     pub path:               String,
     pub vertical:           bool,
-    pub indent:             String,
 }
 
 pub(crate) fn build(
@@ -100,7 +100,12 @@ fn build_step(
                 add_token(
                     builder,
                     rnix::SyntaxKind::TOKEN_WHITESPACE,
-                    &build_ctx.indent.repeat(build_ctx.indentation),
+                    &match build_ctx.config.indentation {
+                        Indentation::FourSpaces => "    ",
+                        Indentation::Tabs => "\t",
+                        Indentation::TwoSpaces => "  ",
+                    }
+                    .repeat(build_ctx.indentation),
                 );
             }
         }

src/alejandra/src/config.rs

@@ -2,4 +2,19 @@ use serde::Deserialize;
 
 /// Configuration used by the formatter
 #[derive(Clone, Copy, Default, Deserialize)]
-pub struct Config {}
+pub struct Config {
+    /// Indentation to use
+    pub indentation: Indentation,
+}
+
+#[derive(Clone, Copy, Default, Deserialize)]
+/// Indentation options
+pub enum Indentation {
+    /// Four spaces
+    FourSpaces,
+    /// Tabs
+    Tabs,
+    #[default]
+    /// Two spaces
+    TwoSpaces,
+}

src/alejandra/src/format.rs

@@ -32,14 +32,13 @@ pub fn in_memory(
     }
 
     let mut build_ctx = crate::builder::BuildCtx {
-        _config: config,
+        config,
         force_wide: false,
         force_wide_success: true,
         indentation: 0,
         path,
         pos_old: crate::position::Position::default(),
         vertical: true,
-        indent,
     };
 
     let after = crate::builder::build(&mut build_ctx, ast.node().into())