1 //! This module contains functions for editing syntax trees. As the trees are
2 //! immutable, all function here return a fresh copy of the tree, instead of
3 //! doing an in-place modification.
4 use std::{fmt, iter, ops};
7 ast::{self, make, AstNode},
8 ted, AstToken, NodeOrToken, SyntaxElement, SyntaxNode, SyntaxToken,
11 #[derive(Debug, Clone, Copy)]
12 pub struct IndentLevel(pub u8);
14 impl From<u8> for IndentLevel {
15 fn from(level: u8) -> IndentLevel {
20 impl fmt::Display for IndentLevel {
21 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
24 let len = self.0 as usize * 4;
25 let indent = if len <= spaces.len() {
28 buf = " ".repeat(len);
31 fmt::Display::fmt(indent, f)
35 impl ops::Add<u8> for IndentLevel {
36 type Output = IndentLevel;
37 fn add(self, rhs: u8) -> IndentLevel {
38 IndentLevel(self.0 + rhs)
43 pub fn single() -> IndentLevel {
46 pub fn is_zero(&self) -> bool {
49 pub fn from_element(element: &SyntaxElement) -> IndentLevel {
51 rowan::NodeOrToken::Node(it) => IndentLevel::from_node(it),
52 rowan::NodeOrToken::Token(it) => IndentLevel::from_token(it),
56 pub fn from_node(node: &SyntaxNode) -> IndentLevel {
57 match node.first_token() {
58 Some(it) => Self::from_token(&it),
59 None => IndentLevel(0),
63 pub fn from_token(token: &SyntaxToken) -> IndentLevel {
64 for ws in prev_tokens(token.clone()).filter_map(ast::Whitespace::cast) {
65 let text = ws.syntax().text();
66 if let Some(pos) = text.rfind('\n') {
67 let level = text[pos + 1..].chars().count() / 4;
68 return IndentLevel(level as u8);
74 /// XXX: this intentionally doesn't change the indent of the very first token.
75 /// Ie, in something like
81 /// if you indent the block, the `{` token would stay put.
82 pub(super) fn increase_indent(self, node: &SyntaxNode) {
83 let tokens = node.preorder_with_tokens().filter_map(|event| match event {
84 rowan::WalkEvent::Leave(NodeOrToken::Token(it)) => Some(it),
88 if let Some(ws) = ast::Whitespace::cast(token) {
89 if ws.text().contains('\n') {
90 let new_ws = make::tokens::whitespace(&format!("{}{}", ws.syntax(), self));
91 ted::replace(ws.syntax(), &new_ws);
97 pub(super) fn decrease_indent(self, node: &SyntaxNode) {
98 let tokens = node.preorder_with_tokens().filter_map(|event| match event {
99 rowan::WalkEvent::Leave(NodeOrToken::Token(it)) => Some(it),
102 for token in tokens {
103 if let Some(ws) = ast::Whitespace::cast(token) {
104 if ws.text().contains('\n') {
105 let new_ws = make::tokens::whitespace(
106 &ws.syntax().text().replace(&format!("\n{}", self), "\n"),
108 ted::replace(ws.syntax(), &new_ws);
115 fn prev_tokens(token: SyntaxToken) -> impl Iterator<Item = SyntaxToken> {
116 iter::successors(Some(token), |token| token.prev_token())
119 /// Soft-deprecated in favor of mutable tree editing API `edit_in_place::Ident`.
120 pub trait AstNodeEdit: AstNode + Clone + Sized {
121 fn indent_level(&self) -> IndentLevel {
122 IndentLevel::from_node(self.syntax())
125 fn indent(&self, level: IndentLevel) -> Self {
126 fn indent_inner(node: &SyntaxNode, level: IndentLevel) -> SyntaxNode {
127 let res = node.clone_subtree().clone_for_update();
128 level.increase_indent(&res);
132 Self::cast(indent_inner(self.syntax(), level)).unwrap()
135 fn dedent(&self, level: IndentLevel) -> Self {
136 fn dedent_inner(node: &SyntaxNode, level: IndentLevel) -> SyntaxNode {
137 let res = node.clone_subtree().clone_for_update();
138 level.decrease_indent(&res);
142 Self::cast(dedent_inner(self.syntax(), level)).unwrap()
145 fn reset_indent(&self) -> Self {
146 let level = IndentLevel::from_node(self.syntax());
151 impl<N: AstNode + Clone> AstNodeEdit for N {}
154 fn test_increase_indent() {
156 let arm = make::match_arm(iter::once(make::wildcard_pat().into()), None, make::expr_unit());
157 make::match_arm_list(vec![arm.clone(), arm])
160 arm_list.syntax().to_string(),
166 let indented = arm_list.indent(IndentLevel(2));
168 indented.syntax().to_string(),