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helix/helix-core/src/indent.rs

775 lines
29 KiB
Rust

use std::collections::HashMap;
use tree_sitter::{Query, QueryCursor, QueryPredicateArg};
use crate::{
chars::{char_is_line_ending, char_is_whitespace},
syntax::{LanguageConfiguration, RopeProvider, Syntax},
tree_sitter::Node,
Rope, RopeSlice,
};
/// Enum representing indentation style.
///
/// Only values 1-8 are valid for the `Spaces` variant.
#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
pub enum IndentStyle {
Tabs,
Spaces(u8),
}
impl IndentStyle {
/// Creates an `IndentStyle` from an indentation string.
///
/// For example, passing `" "` (four spaces) will create `IndentStyle::Spaces(4)`.
#[allow(clippy::should_implement_trait)]
#[inline]
pub fn from_str(indent: &str) -> Self {
// XXX: do we care about validating the input more than this? Probably not...?
debug_assert!(!indent.is_empty() && indent.len() <= 8);
if indent.starts_with(' ') {
IndentStyle::Spaces(indent.len() as u8)
} else {
IndentStyle::Tabs
}
}
#[inline]
pub fn as_str(&self) -> &'static str {
match *self {
IndentStyle::Tabs => "\t",
IndentStyle::Spaces(1) => " ",
IndentStyle::Spaces(2) => " ",
IndentStyle::Spaces(3) => " ",
IndentStyle::Spaces(4) => " ",
IndentStyle::Spaces(5) => " ",
IndentStyle::Spaces(6) => " ",
IndentStyle::Spaces(7) => " ",
IndentStyle::Spaces(8) => " ",
// Unsupported indentation style. This should never happen,
// but just in case fall back to two spaces.
IndentStyle::Spaces(n) => {
debug_assert!(n > 0 && n <= 8); // Always triggers. `debug_panic!()` wanted.
" "
}
}
}
}
/// Attempts to detect the indentation style used in a document.
///
/// Returns the indentation style if the auto-detect confidence is
/// reasonably high, otherwise returns `None`.
pub fn auto_detect_indent_style(document_text: &Rope) -> Option<IndentStyle> {
// Build a histogram of the indentation *increases* between
// subsequent lines, ignoring lines that are all whitespace.
//
// Index 0 is for tabs, the rest are 1-8 spaces.
let histogram: [usize; 9] = {
let mut histogram = [0; 9];
let mut prev_line_is_tabs = false;
let mut prev_line_leading_count = 0usize;
// Loop through the lines, checking for and recording indentation
// increases as we go.
'outer: for line in document_text.lines().take(1000) {
let mut c_iter = line.chars();
// Is first character a tab or space?
let is_tabs = match c_iter.next() {
Some('\t') => true,
Some(' ') => false,
// Ignore blank lines.
Some(c) if char_is_line_ending(c) => continue,
_ => {
prev_line_is_tabs = false;
prev_line_leading_count = 0;
continue;
}
};
// Count the line's total leading tab/space characters.
let mut leading_count = 1;
let mut count_is_done = false;
for c in c_iter {
match c {
'\t' if is_tabs && !count_is_done => leading_count += 1,
' ' if !is_tabs && !count_is_done => leading_count += 1,
// We stop counting if we hit whitespace that doesn't
// qualify as indent or doesn't match the leading
// whitespace, but we don't exit the loop yet because
// we still want to determine if the line is blank.
c if char_is_whitespace(c) => count_is_done = true,
// Ignore blank lines.
c if char_is_line_ending(c) => continue 'outer,
_ => break,
}
// Bound the worst-case execution time for weird text files.
if leading_count > 256 {
continue 'outer;
}
}
// If there was an increase in indentation over the previous
// line, update the histogram with that increase.
if (prev_line_is_tabs == is_tabs || prev_line_leading_count == 0)
&& prev_line_leading_count < leading_count
{
if is_tabs {
histogram[0] += 1;
} else {
let amount = leading_count - prev_line_leading_count;
if amount <= 8 {
histogram[amount] += 1;
}
}
}
// Store this line's leading whitespace info for use with
// the next line.
prev_line_is_tabs = is_tabs;
prev_line_leading_count = leading_count;
}
// Give more weight to tabs, because their presence is a very
// strong indicator.
histogram[0] *= 2;
histogram
};
// Find the most frequent indent, its frequency, and the frequency of
// the next-most frequent indent.
let indent = histogram
.iter()
.enumerate()
.max_by_key(|kv| kv.1)
.unwrap()
.0;
let indent_freq = histogram[indent];
let indent_freq_2 = *histogram
.iter()
.enumerate()
.filter(|kv| kv.0 != indent)
.map(|kv| kv.1)
.max()
.unwrap();
// Return the the auto-detected result if we're confident enough in its
// accuracy, based on some heuristics.
if indent_freq >= 1 && (indent_freq_2 as f64 / indent_freq as f64) < 0.66 {
Some(match indent {
0 => IndentStyle::Tabs,
_ => IndentStyle::Spaces(indent as u8),
})
} else {
None
}
}
/// To determine indentation of a newly inserted line, figure out the indentation at the last col
/// of the previous line.
pub fn indent_level_for_line(line: RopeSlice, tab_width: usize) -> usize {
let mut len = 0;
for ch in line.chars() {
match ch {
'\t' => len += tab_width,
' ' => len += 1,
_ => break,
}
}
len / tab_width
}
/// Computes for node and all ancestors whether they are the first node on their line.
/// The first entry in the return value represents the root node, the last one the node itself
fn get_first_in_line(mut node: Node, new_line_byte_pos: Option<usize>) -> Vec<bool> {
let mut first_in_line = Vec::new();
loop {
if let Some(prev) = node.prev_sibling() {
// If we insert a new line, the first node at/after the cursor is considered to be the first in its line
let first = prev.end_position().row != node.start_position().row
|| new_line_byte_pos.map_or(false, |byte_pos| {
node.start_byte() >= byte_pos && prev.start_byte() < byte_pos
});
first_in_line.push(Some(first));
} else {
// Nodes that have no previous siblings are first in their line if and only if their parent is
// (which we don't know yet)
first_in_line.push(None);
}
if let Some(parent) = node.parent() {
node = parent;
} else {
break;
}
}
let mut result = Vec::with_capacity(first_in_line.len());
let mut parent_is_first = true; // The root node is by definition the first node in its line
for first in first_in_line.into_iter().rev() {
if let Some(first) = first {
result.push(first);
parent_is_first = first;
} else {
result.push(parent_is_first);
}
}
result
}
/// The total indent for some line of code.
/// This is usually constructed in one of 2 ways:
/// - Successively add indent captures to get the (added) indent from a single line
/// - Successively add the indent results for each line
#[derive(Default)]
pub struct Indentation {
/// The total indent (the number of indent levels) is defined as max(0, indent-outdent).
/// The string that this results in depends on the indent style (spaces or tabs, etc.)
indent: usize,
outdent: usize,
}
impl Indentation {
/// Add some other [Indentation] to this.
/// The added indent should be the total added indent from one line
fn add_line(&mut self, added: &Indentation) {
if added.indent > 0 && added.outdent == 0 {
self.indent += 1;
} else if added.outdent > 0 && added.indent == 0 {
self.outdent += 1;
}
}
/// Add an indent capture to this indent.
/// All the captures that are added in this way should be on the same line.
fn add_capture(&mut self, added: IndentCaptureType) {
match added {
IndentCaptureType::Indent => {
self.indent = 1;
}
IndentCaptureType::Outdent => {
self.outdent = 1;
}
}
}
fn as_string(&self, indent_style: &IndentStyle) -> String {
let indent_level = if self.indent >= self.outdent {
self.indent - self.outdent
} else {
log::warn!("Encountered more outdent than indent nodes while calculating indentation: {} outdent, {} indent", self.outdent, self.indent);
0
};
indent_style.as_str().repeat(indent_level)
}
}
/// An indent definition which corresponds to a capture from the indent query
struct IndentCapture {
capture_type: IndentCaptureType,
scope: IndentScope,
}
#[derive(Clone, Copy)]
enum IndentCaptureType {
Indent,
Outdent,
}
impl IndentCaptureType {
fn default_scope(&self) -> IndentScope {
match self {
IndentCaptureType::Indent => IndentScope::Tail,
IndentCaptureType::Outdent => IndentScope::All,
}
}
}
/// This defines which part of a node an [IndentCapture] applies to.
/// Each [IndentCaptureType] has a default scope, but the scope can be changed
/// with `#set!` property declarations.
#[derive(Clone, Copy)]
enum IndentScope {
/// The indent applies to the whole node
All,
/// The indent applies to everything except for the first line of the node
Tail,
}
/// A capture from the indent query which does not define an indent but extends
/// the range of a node. This is used before the indent is calculated.
enum ExtendCapture {
Extend,
PreventOnce,
}
/// The result of running a tree-sitter indent query. This stores for
/// each node (identified by its ID) the relevant captures (already filtered
/// by predicates).
struct IndentQueryResult {
indent_captures: HashMap<usize, Vec<IndentCapture>>,
extend_captures: HashMap<usize, Vec<ExtendCapture>>,
}
fn query_indents(
query: &Query,
syntax: &Syntax,
cursor: &mut QueryCursor,
text: RopeSlice,
range: std::ops::Range<usize>,
// Position of the (optional) newly inserted line break.
// Given as (line, byte_pos)
new_line_break: Option<(usize, usize)>,
) -> IndentQueryResult {
let mut indent_captures: HashMap<usize, Vec<IndentCapture>> = HashMap::new();
let mut extend_captures: HashMap<usize, Vec<ExtendCapture>> = HashMap::new();
cursor.set_byte_range(range);
// Iterate over all captures from the query
for m in cursor.matches(query, syntax.tree().root_node(), RopeProvider(text)) {
// Skip matches where not all custom predicates are fulfilled
if !query.general_predicates(m.pattern_index).iter().all(|pred| {
match pred.operator.as_ref() {
"not-kind-eq?" => match (pred.args.get(0), pred.args.get(1)) {
(
Some(QueryPredicateArg::Capture(capture_idx)),
Some(QueryPredicateArg::String(kind)),
) => {
let node = m.nodes_for_capture_index(*capture_idx).next();
match node {
Some(node) => node.kind()!=kind.as_ref(),
_ => true,
}
}
_ => {
panic!("Invalid indent query: Arguments to \"not-kind-eq?\" must be a capture and a string");
}
},
"same-line?" | "not-same-line?" => {
match (pred.args.get(0), pred.args.get(1)) {
(
Some(QueryPredicateArg::Capture(capt1)),
Some(QueryPredicateArg::Capture(capt2))
) => {
let get_line_num = |node: Node| {
let mut node_line = node.start_position().row;
// Adjust for the new line that will be inserted
if let Some((line, byte)) = new_line_break {
if node_line==line && node.start_byte()>=byte {
node_line += 1;
}
}
node_line
};
let n1 = m.nodes_for_capture_index(*capt1).next();
let n2 = m.nodes_for_capture_index(*capt2).next();
match (n1, n2) {
(Some(n1), Some(n2)) => {
let same_line = get_line_num(n1)==get_line_num(n2);
same_line==(pred.operator.as_ref()=="same-line?")
}
_ => true,
}
}
_ => {
panic!("Invalid indent query: Arguments to \"{}\" must be 2 captures", pred.operator);
}
}
}
_ => {
panic!(
"Invalid indent query: Unknown predicate (\"{}\")",
pred.operator
);
}
}
}) {
continue;
}
for capture in m.captures {
let capture_name = query.capture_names()[capture.index as usize].as_str();
let capture_type = match capture_name {
"indent" => IndentCaptureType::Indent,
"outdent" => IndentCaptureType::Outdent,
"extend" => {
extend_captures
.entry(capture.node.id())
.or_insert_with(|| Vec::with_capacity(1))
.push(ExtendCapture::Extend);
continue;
}
"extend.prevent-once" => {
extend_captures
.entry(capture.node.id())
.or_insert_with(|| Vec::with_capacity(1))
.push(ExtendCapture::PreventOnce);
continue;
}
_ => {
// Ignore any unknown captures (these may be needed for predicates such as #match?)
continue;
}
};
let scope = capture_type.default_scope();
let mut indent_capture = IndentCapture {
capture_type,
scope,
};
// Apply additional settings for this capture
for property in query.property_settings(m.pattern_index) {
match property.key.as_ref() {
"scope" => {
indent_capture.scope = match property.value.as_deref() {
Some("all") => IndentScope::All,
Some("tail") => IndentScope::Tail,
Some(s) => {
panic!("Invalid indent query: Unknown value for \"scope\" property (\"{}\")", s);
}
None => {
panic!(
"Invalid indent query: Missing value for \"scope\" property"
);
}
}
}
_ => {
panic!(
"Invalid indent query: Unknown property \"{}\"",
property.key
);
}
}
}
indent_captures
.entry(capture.node.id())
// Most entries only need to contain a single IndentCapture
.or_insert_with(|| Vec::with_capacity(1))
.push(indent_capture);
}
}
IndentQueryResult {
indent_captures,
extend_captures,
}
}
/// Handle extend queries. deepest_preceding is the deepest descendant of node that directly precedes the cursor position.
/// Any ancestor of deepest_preceding which is also a descendant of node may be "extended". In that case, node will be updated,
/// so that the indent computation starts with the correct syntax node.
fn extend_nodes<'a>(
node: &mut Node<'a>,
mut deepest_preceding: Node<'a>,
extend_captures: &HashMap<usize, Vec<ExtendCapture>>,
text: RopeSlice,
line: usize,
tab_width: usize,
) {
let mut stop_extend = false;
while deepest_preceding != *node {
let mut extend_node = false;
// This will be set to true if this node is captured, regardless of whether
// it actually will be extended (e.g. because the cursor isn't indented
// more than the node).
let mut node_captured = false;
if let Some(captures) = extend_captures.get(&deepest_preceding.id()) {
for capture in captures {
match capture {
ExtendCapture::PreventOnce => {
stop_extend = true;
}
ExtendCapture::Extend => {
node_captured = true;
// We extend the node if
// - the cursor is on the same line as the end of the node OR
// - the line that the cursor is on is more indented than the
// first line of the node
if deepest_preceding.end_position().row == line {
extend_node = true;
} else {
let cursor_indent = indent_level_for_line(text.line(line), tab_width);
let node_indent = indent_level_for_line(
text.line(deepest_preceding.start_position().row),
tab_width,
);
if cursor_indent > node_indent {
extend_node = true;
}
}
}
}
}
}
// If we encountered some `StopExtend` capture before, we don't
// extend the node even if we otherwise would
if node_captured && stop_extend {
stop_extend = false;
} else if extend_node && !stop_extend {
*node = deepest_preceding;
break;
}
// If the tree contains a syntax error, `deepest_preceding` may not
// have a parent despite being a descendant of `node`.
deepest_preceding = match deepest_preceding.parent() {
Some(parent) => parent,
None => return,
}
}
}
/// Use the syntax tree to determine the indentation for a given position.
/// This can be used in 2 ways:
///
/// - To get the correct indentation for an existing line (new_line=false), not necessarily equal to the current indentation.
/// - In this case, pos should be inside the first tree-sitter node on that line.
/// In most cases, this can just be the first non-whitespace on that line.
/// - To get the indentation for a new line (new_line=true). This behaves like the first usecase if the part of the current line
/// after pos were moved to a new line.
///
/// The indentation is determined by traversing all the tree-sitter nodes containing the position.
/// Each of these nodes produces some [Indentation] for:
///
/// - The line of the (beginning of the) node. This is defined by the scope `all` if this is the first node on its line.
/// - The line after the node. This is defined by:
/// - The scope `tail`.
/// - The scope `all` if this node is not the first node on its line.
/// Intuitively, `all` applies to everything contained in this node while `tail` applies to everything except for the first line of the node.
/// The indents from different nodes for the same line are then combined.
/// The result [Indentation] is simply the sum of the [Indentation] for all lines.
///
/// Specifying which line exactly an [Indentation] applies to is important because indents on the same line combine differently than indents on different lines:
/// ```ignore
/// some_function(|| {
/// // Both the function parameters as well as the contained block should be indented.
/// // Because they are on the same line, this only yields one indent level
/// });
/// ```
///
/// ```ignore
/// some_function(
/// param1,
/// || {
/// // Here we get 2 indent levels because the 'parameters' and the 'block' node begin on different lines
/// },
/// );
/// ```
#[allow(clippy::too_many_arguments)]
pub fn treesitter_indent_for_pos(
query: &Query,
syntax: &Syntax,
indent_style: &IndentStyle,
tab_width: usize,
text: RopeSlice,
line: usize,
pos: usize,
new_line: bool,
) -> Option<String> {
let byte_pos = text.char_to_byte(pos);
// The innermost tree-sitter node which is considered for the indent
// computation. It may change if some predeceding node is extended
let mut node = syntax
.tree()
.root_node()
.descendant_for_byte_range(byte_pos, byte_pos)?;
let (query_result, deepest_preceding) = {
// The query range should intersect with all nodes directly preceding
// the position of the indent query in case one of them is extended.
let mut deepest_preceding = None; // The deepest node preceding the indent query position
let mut tree_cursor = node.walk();
for child in node.children(&mut tree_cursor) {
if child.byte_range().end <= byte_pos {
deepest_preceding = Some(child);
}
}
deepest_preceding = deepest_preceding.map(|mut prec| {
// Get the deepest directly preceding node
while prec.child_count() > 0 {
prec = prec.child(prec.child_count() - 1).unwrap();
}
prec
});
let query_range = deepest_preceding
.map(|prec| prec.byte_range().end - 1..byte_pos + 1)
.unwrap_or(byte_pos..byte_pos + 1);
crate::syntax::PARSER.with(|ts_parser| {
let mut ts_parser = ts_parser.borrow_mut();
let mut cursor = ts_parser.cursors.pop().unwrap_or_else(QueryCursor::new);
let query_result = query_indents(
query,
syntax,
&mut cursor,
text,
query_range,
new_line.then_some((line, byte_pos)),
);
ts_parser.cursors.push(cursor);
(query_result, deepest_preceding)
})
};
let indent_captures = query_result.indent_captures;
let extend_captures = query_result.extend_captures;
// Check for extend captures, potentially changing the node that the indent calculation starts with
if let Some(deepest_preceding) = deepest_preceding {
extend_nodes(
&mut node,
deepest_preceding,
&extend_captures,
text,
line,
tab_width,
);
}
let mut first_in_line = get_first_in_line(node, new_line.then_some(byte_pos));
let mut result = Indentation::default();
// We always keep track of all the indent changes on one line, in order to only indent once
// even if there are multiple "indent" nodes on the same line
let mut indent_for_line = Indentation::default();
let mut indent_for_line_below = Indentation::default();
loop {
// This can safely be unwrapped because `first_in_line` contains
// one entry for each ancestor of the node (which is what we iterate over)
let is_first = *first_in_line.last().unwrap();
// Apply all indent definitions for this node
if let Some(definitions) = indent_captures.get(&node.id()) {
for definition in definitions {
match definition.scope {
IndentScope::All => {
if is_first {
indent_for_line.add_capture(definition.capture_type);
} else {
indent_for_line_below.add_capture(definition.capture_type);
}
}
IndentScope::Tail => {
indent_for_line_below.add_capture(definition.capture_type);
}
}
}
}
if let Some(parent) = node.parent() {
let mut node_line = node.start_position().row;
let mut parent_line = parent.start_position().row;
if node_line == line && new_line {
// Also consider the line that will be inserted
if node.start_byte() >= byte_pos {
node_line += 1;
}
if parent.start_byte() >= byte_pos {
parent_line += 1;
}
};
if node_line != parent_line {
if node_line < line + (new_line as usize) {
// Don't add indent for the line below the line of the query
result.add_line(&indent_for_line_below);
}
if node_line == parent_line + 1 {
indent_for_line_below = indent_for_line;
} else {
result.add_line(&indent_for_line);
indent_for_line_below = Indentation::default();
}
indent_for_line = Indentation::default();
}
node = parent;
first_in_line.pop();
} else {
// Only add the indentation for the line below if that line
// is not after the line that the indentation is calculated for.
if (node.start_position().row < line)
|| (new_line && node.start_position().row == line && node.start_byte() < byte_pos)
{
result.add_line(&indent_for_line_below);
}
result.add_line(&indent_for_line);
break;
}
}
Some(result.as_string(indent_style))
}
/// Returns the indentation for a new line.
/// This is done either using treesitter, or if that's not available by copying the indentation from the current line
#[allow(clippy::too_many_arguments)]
pub fn indent_for_newline(
language_config: Option<&LanguageConfiguration>,
syntax: Option<&Syntax>,
indent_style: &IndentStyle,
tab_width: usize,
text: RopeSlice,
line_before: usize,
line_before_end_pos: usize,
current_line: usize,
) -> String {
if let (Some(query), Some(syntax)) = (
language_config.and_then(|config| config.indent_query()),
syntax,
) {
if let Some(indent) = treesitter_indent_for_pos(
query,
syntax,
indent_style,
tab_width,
text,
line_before,
line_before_end_pos,
true,
) {
return indent;
};
}
let indent_level = indent_level_for_line(text.line(current_line), tab_width);
indent_style.as_str().repeat(indent_level)
}
pub fn get_scopes(syntax: Option<&Syntax>, text: RopeSlice, pos: usize) -> Vec<&'static str> {
let mut scopes = Vec::new();
if let Some(syntax) = syntax {
let pos = text.char_to_byte(pos);
let mut node = match syntax
.tree()
.root_node()
.descendant_for_byte_range(pos, pos)
{
Some(node) => node,
None => return scopes,
};
scopes.push(node.kind());
while let Some(parent) = node.parent() {
scopes.push(parent.kind());
node = parent;
}
}
scopes.reverse();
3 years ago
scopes
}
#[cfg(test)]
mod test {
use super::*;
use crate::Rope;
#[test]
fn test_indent_level() {
let tab_width = 4;
let line = Rope::from(" fn new"); // 8 spaces
assert_eq!(indent_level_for_line(line.slice(..), tab_width), 2);
let line = Rope::from("\t\t\tfn new"); // 3 tabs
assert_eq!(indent_level_for_line(line.slice(..), tab_width), 3);
// mixed indentation
let line = Rope::from("\t \tfn new"); // 1 tab, 4 spaces, tab
assert_eq!(indent_level_for_line(line.slice(..), tab_width), 3);
}
}