WIP nix

topiary-cli/Cargo.toml

@@ -3,12 +3,12 @@ name = "topiary-cli"
 description = "CLI app for Topiary, the universal code formatter."
 categories = ["command-line-utilities", "development-tools", "text-processing"]
 keywords = [
-  "cli",
-  "code-formatter",
-  "formatter",
-  "text",
-  "tree-sitter",
-  "utility",
+    "cli",
+    "code-formatter",
+    "formatter",
+    "text",
+    "tree-sitter",
+    "utility",
 ]
 version.workspace = true
 edition.workspace = true
@@ -35,7 +35,12 @@ itertools = { workspace = true }
 log = { workspace = true }
 serde = { workspace = true, features = ["derive"] }
 tempfile = { workspace = true }
-tokio = { workspace = true, features = ["fs", "rt-multi-thread", "sync", "macros"] }
+tokio = { workspace = true, features = [
+    "fs",
+    "rt-multi-thread",
+    "sync",
+    "macros",
+] }
 toml = { workspace = true }
 topiary-core = { path = "../topiary-core" }
 topiary-config = { path = "../topiary-config" }
@@ -58,34 +63,37 @@ predicates = { workspace = true }
 
 [features]
 default = [
-  "contributed",
-  "json",
-  "nickel",
-  "ocaml",
-  "ocaml_interface",
-  "ocamllex",
-  "toml",
-  "tree_sitter_query"
+    "contributed",
+    "json",
+    "nickel",
+    "nix",
+    "ocaml",
+    "ocaml_interface",
+    "ocamllex",
+    "toml",
+    "tree_sitter_query",
 ]
 
 # Included by default
-contributed = [
-  "css"
-]
+contributed = ["css"]
 
 # Excluded by default
-experimental = [
-  "bash",
-  "rust",
-]
+experimental = ["bash", "rust"]
 
+nix = ["topiary-config/nix", "topiary-queries/nix"]
 bash = ["topiary-config/bash", "topiary-queries/bash"]
 css = ["topiary-config/css", "topiary-queries/css"]
 json = ["topiary-config/json", "topiary-queries/json"]
 nickel = ["topiary-config/nickel", "topiary-queries/nickel"]
 ocaml = ["topiary-config/ocaml", "topiary-queries/ocaml"]
-ocaml_interface = ["topiary-config/ocaml_interface", "topiary-queries/ocaml_interface"]
+ocaml_interface = [
+    "topiary-config/ocaml_interface",
+    "topiary-queries/ocaml_interface",
+]
 ocamllex = ["topiary-config/ocamllex", "topiary-queries/ocamllex"]
 rust = ["topiary-config/rust", "topiary-queries/rust"]
 toml = ["topiary-config/toml", "topiary-queries/toml"]
-tree_sitter_query = ["topiary-config/tree_sitter_query", "topiary-queries/tree_sitter_query"]
+tree_sitter_query = [
+    "topiary-config/tree_sitter_query",
+    "topiary-queries/tree_sitter_query",
+]

topiary-cli/src/io.rs

@@ -350,6 +350,9 @@ where
         #[cfg(feature = "toml")]
         "toml" => Ok(topiary_queries::toml().into()),
 
+        #[cfg(feature = "nix")]
+        "nix" => Ok(topiary_queries::nix().into()),
+
         #[cfg(feature = "tree_sitter_query")]
         "tree_sitter_query" => Ok(topiary_queries::tree_sitter_query().into()),
 

topiary-config/Cargo.toml

@@ -33,11 +33,11 @@ git2.workspace = true
 libloading.workspace = true
 
 [features]
-default = [ "parallel" ]
+default = ["parallel"]
 
 # Enabling the `parallel` feature enables parallel computation where possible.
 # At the moment, this is only in grammar prefetching
-parallel = [ "dep:rayon" ]
+parallel = ["dep:rayon"]
 
 bash = []
 css = []
@@ -46,21 +46,23 @@ nickel = []
 ocaml = []
 ocaml_interface = []
 ocamllex = []
+nix = []
 rust = []
 toml = []
 tree_sitter_query = []
 
 # This a convenience for the sake of downstream applications which don't
 # wish to cherry-pick grammars (e.g., the playground)
 all = [
-  "bash",
-  "css",
-  "json",
-  "nickel",
-  "ocaml",
-  "ocaml_interface",
-  "ocamllex",
-  "rust",
-  "toml",
-  "tree_sitter_query"
+    "bash",
+    "css",
+    "json",
+    "nickel",
+    "ocaml",
+    "ocaml_interface",
+    "ocamllex",
+    "rust",
+    "nix",
+    "toml",
+    "tree_sitter_query",
 ]

topiary-config/languages.ncl

@@ -16,6 +16,14 @@
       },
     },
 
+    nix = {
+      extensions = ["nix"],
+      grammar = {
+        git = "https://github.com/nix-community/tree-sitter-nix",
+        rev = "456b14a2fa6315abc7e02fcffaf4a1f35d4955d3",
+      },
+    },
+
     json = {
       extensions = [
         "json",

topiary-queries/Cargo.toml

@@ -24,4 +24,5 @@ ocaml_interface = []
 ocamllex = []
 rust = []
 toml = []
+nix = []
 tree_sitter_query = []

topiary-queries/queries/nix.scm

@@ -0,0 +1,207 @@
+;; Nix Formatter based on RFC 166
+
+; Leaf nodes (strings, paths, etc.) should be preserved as-is
+[ (string)
+  (indented_string)
+  (path)
+] @leaf
+
+; Comments
+(comment) @comment
+
+; Convert single-line /* */ comments to #
+(comment) @convert_to_hash_comment
+
+; Preserve multiline comments
+(comment) @preserve_multiline_comment
+
+; Append space after specific tokens
+":" @append_space
+"=" @append_space
+"," @append_spaced_softline
+
+; Handle indentation and line breaks
+; Define softline breaks and indentation starts/ends
+"{" @append_spaced_softline @append_indent_start
+"}" @prepend_spaced_softline @prepend_indent_end
+"[" @append_spaced_softline @append_indent_start
+"]" @prepend_spaced_softline @prepend_indent_end
+
+; Functions
+
+(function
+  parameters: (formals
+    "(" @append_spaced_softline @append_indent_start
+    (formal_parameter) @formal_param
+    ")" @prepend_spaced_softline @prepend_indent_end
+  )
+  body: (_) @function_body
+) @function_declaration
+
+; Ensure each parameter is on a new line with proper indentation
+(formal_parameter) @prepend_spaced_softline
+
+; Attribute Sets
+
+(attrset
+  "{" @append_spaced_softline @append_indent_start
+  (binding) @attr_binding
+  "}" @prepend_spaced_softline @prepend_indent_end
+) @attribute_set
+
+; Ensure each key-value pair is on its own line
+(binding
+  attrpath: (_) @attr_key
+  "=" @append_space
+  value: (_) @attr_value
+  ";" @append_spaced_softline
+)
+
+; Lists
+
+(list
+  "[" @append_spaced_softline @append_indent_start
+  (_) @list_item
+  "]" @prepend_spaced_softline @prepend_indent_end
+) @list
+
+; Ensure each list element is on its own line
+(list
+  "," @append_spaced_softline
+)
+
+; If-Then-Else Expressions
+
+(if_expression
+  "if" @keyword_if @append_space @prepend_spaced_softline
+  condition: (_) @if_condition
+  "then" @keyword_then @append_space @prepend_spaced_softline @append_indent_start
+  body: (_) @if_body @append_indent_end
+  "else" @keyword_else @append_space @prepend_spaced_softline @append_indent_start
+  alternative: (_) @else_body @append_indent_end
+)
+
+; Let-In Expressions
+
+(let_expression
+  "let" @keyword_let @append_spaced_softline @append_indent_start
+  (binding
+    attrpath: (_) @let_binding_name
+    "=" @append_space
+    value: (_) @let_binding_value
+    ";" @append_spaced_softline
+  )+
+  "in" @keyword_in @prepend_spaced_softline @prepend_indent_end @append_spaced_softline
+  body: (_) @let_body
+)
+
+; With Expressions
+
+(with_expression
+  "with" @keyword_with @append_space
+  (_) @with_expression
+  ";" @append_spaced_softline
+  body: (_) @with_body
+)
+
+; Assert Expressions
+
+(assert_expression
+  "assert" @keyword_assert @append_space
+  (_) @assert_condition
+  ";" @append_spaced_softline
+  body: (_) @assert_body
+)
+
+; Operator Formatting
+
+(binary_expression
+  left: (_) @op_left
+  operator: (_) @op_symbol
+  right: (_) @op_right
+)
+
+; Ensure operators start on new lines if they don't fit on a single line
+(binary_expression
+  operator: (_) @prepend_spaced_softline
+)
+
+; Inherit Statements
+
+(inherit
+  "inherit" @keyword_inherit @append_space
+  (inherited_attrs
+    (attrpath) @inherit_item
+  )+
+  ";" @inherit_semicolon
+)
+
+; Handle inherit with source
+(inherit
+  "inherit" @keyword_inherit @append_space
+  "(" @inherit_parentheses_start
+  (_) @inherit_source
+  ")" @inherit_parentheses_end
+  (inherited_attrs
+    (attrpath) @inherit_item
+  )+
+  ";" @inherit_semicolon
+)
+
+; Empty Objects and Arrays
+
+(attrset
+  "{" @object_open
+  "}" @object_close
+) @empty_attribute_set
+
+(list
+  "[" @array_open
+  "]" @array_close
+) @empty_array
+
+; String Interpolation
+
+(interpolation
+  "${" @interp_start
+  (_) @interp_content
+  "}" @interp_end
+)
+
+; Additional Rules
+
+; Handle let bindings indentation
+(let_expression
+  (binding) @let_binding_indent
+)
+
+; Handle assertions
+(assert_expression
+  "assert" @keyword_assert @append_space
+  (_) @assert_condition
+  ";" @assert_semicolon
+)
+
+; Handle comments within expressions
+(comment) @comment_within_expr
+
+; Leaf Nodes Preservation
+(_) @leaf
+
+; Handle semicolon placement in bindings
+(binding
+  ";" @semicolon_end
+)
+
+; Handle indentation for nested attribute sets
+(attrset
+  (binding
+    value: (attrset) @nested_attribute_set
+  )
+)
+
+; Handle newline preservation rules
+(ERROR) @collapse_empty_lines
+
+; Ensure consistent indentation levels
+(_) @indent_block

topiary-queries/src/lib.rs

@@ -52,6 +52,12 @@ pub fn toml() -> &'static str {
     include_str!("../queries/toml.scm")
 }
 
+/// Returns the Topiary-compatible query file for Nix.
+#[cfg(feature = "nix")]
+pub fn nix() -> &'static str {
+    include_str!("../queries/nix.scm")
+}
+
 /// Returns the Topiary-compatible query file for the
 /// Tree-sitter query language.
 #[cfg(feature = "tree_sitter_query")]