language.rs

  1mod buffer;
  2mod diagnostic_set;
  3mod highlight_map;
  4mod outline;
  5pub mod proto;
  6#[cfg(test)]
  7mod tests;
  8
  9use anyhow::{anyhow, Context, Result};
 10use client::http::HttpClient;
 11use collections::HashMap;
 12use futures::{
 13    future::{BoxFuture, Shared},
 14    FutureExt, TryFutureExt,
 15};
 16use gpui::{MutableAppContext, Task};
 17use highlight_map::HighlightMap;
 18use lazy_static::lazy_static;
 19use parking_lot::{Mutex, RwLock};
 20use regex::Regex;
 21use serde::{de, Deserialize, Deserializer};
 22use serde_json::Value;
 23use std::{
 24    any::Any,
 25    cell::RefCell,
 26    mem,
 27    ops::Range,
 28    path::{Path, PathBuf},
 29    str,
 30    sync::Arc,
 31};
 32use theme::SyntaxTheme;
 33use tree_sitter::{self, Query};
 34use util::ResultExt;
 35
 36#[cfg(any(test, feature = "test-support"))]
 37use futures::channel::mpsc;
 38
 39pub use buffer::Operation;
 40pub use buffer::*;
 41pub use diagnostic_set::DiagnosticEntry;
 42pub use outline::{Outline, OutlineItem};
 43pub use tree_sitter::{Parser, Tree};
 44
 45thread_local! {
 46    static PARSER: RefCell<Parser>  = RefCell::new(Parser::new());
 47}
 48
 49lazy_static! {
 50    pub static ref PLAIN_TEXT: Arc<Language> = Arc::new(Language::new(
 51        LanguageConfig {
 52            name: "Plain Text".into(),
 53            ..Default::default()
 54        },
 55        None,
 56    ));
 57}
 58
 59pub trait ToLspPosition {
 60    fn to_lsp_position(self) -> lsp::Position;
 61}
 62
 63#[derive(Clone, Debug, PartialEq, Eq, Hash)]
 64pub struct LanguageServerName(pub Arc<str>);
 65
 66use async_trait::async_trait;
 67
 68#[async_trait]
 69pub trait LspAdapter: 'static + Send + Sync {
 70    async fn name(&self) -> LanguageServerName;
 71    async fn fetch_latest_server_version(
 72        &self,
 73        http: Arc<dyn HttpClient>,
 74    ) -> Result<Box<dyn 'static + Send + Any>>;
 75    async fn fetch_server_binary(
 76        &self,
 77        version: Box<dyn 'static + Send + Any>,
 78        http: Arc<dyn HttpClient>,
 79        container_dir: PathBuf,
 80    ) -> Result<PathBuf>;
 81    async fn cached_server_binary(&self, container_dir: PathBuf) -> Option<PathBuf>;
 82
 83    async fn process_diagnostics(&self, _: &mut lsp::PublishDiagnosticsParams) {}
 84
 85    async fn label_for_completion(
 86        &self,
 87        _: &lsp::CompletionItem,
 88        _: &Language,
 89    ) -> Option<CodeLabel> {
 90        None
 91    }
 92
 93    async fn label_for_symbol(
 94        &self,
 95        _: &str,
 96        _: lsp::SymbolKind,
 97        _: &Language,
 98    ) -> Option<CodeLabel> {
 99        None
100    }
101
102    async fn server_args(&self) -> Vec<String> {
103        Vec::new()
104    }
105
106    async fn initialization_options(&self) -> Option<Value> {
107        None
108    }
109
110    async fn disk_based_diagnostic_sources(&self) -> Vec<String> {
111        Default::default()
112    }
113
114    async fn disk_based_diagnostics_progress_token(&self) -> Option<String> {
115        None
116    }
117
118    async fn id_for_language(&self, _name: &str) -> Option<String> {
119        None
120    }
121}
122
123#[derive(Clone, Debug, PartialEq, Eq)]
124pub struct CodeLabel {
125    pub text: String,
126    pub runs: Vec<(Range<usize>, HighlightId)>,
127    pub filter_range: Range<usize>,
128}
129
130#[derive(Deserialize)]
131pub struct LanguageConfig {
132    pub name: Arc<str>,
133    pub path_suffixes: Vec<String>,
134    pub brackets: Vec<BracketPair>,
135    #[serde(default = "auto_indent_using_last_non_empty_line_default")]
136    pub auto_indent_using_last_non_empty_line: bool,
137    #[serde(default, deserialize_with = "deserialize_regex")]
138    pub increase_indent_pattern: Option<Regex>,
139    #[serde(default, deserialize_with = "deserialize_regex")]
140    pub decrease_indent_pattern: Option<Regex>,
141    #[serde(default)]
142    pub autoclose_before: String,
143    pub line_comment: Option<String>,
144}
145
146impl Default for LanguageConfig {
147    fn default() -> Self {
148        Self {
149            name: "".into(),
150            path_suffixes: Default::default(),
151            brackets: Default::default(),
152            auto_indent_using_last_non_empty_line: auto_indent_using_last_non_empty_line_default(),
153            increase_indent_pattern: Default::default(),
154            decrease_indent_pattern: Default::default(),
155            autoclose_before: Default::default(),
156            line_comment: Default::default(),
157        }
158    }
159}
160
161fn auto_indent_using_last_non_empty_line_default() -> bool {
162    true
163}
164
165fn deserialize_regex<'de, D: Deserializer<'de>>(d: D) -> Result<Option<Regex>, D::Error> {
166    let source = Option::<String>::deserialize(d)?;
167    if let Some(source) = source {
168        Ok(Some(regex::Regex::new(&source).map_err(de::Error::custom)?))
169    } else {
170        Ok(None)
171    }
172}
173
174#[cfg(any(test, feature = "test-support"))]
175pub struct FakeLspAdapter {
176    pub name: &'static str,
177    pub capabilities: lsp::ServerCapabilities,
178    pub initializer: Option<Box<dyn 'static + Send + Sync + Fn(&mut lsp::FakeLanguageServer)>>,
179    pub disk_based_diagnostics_progress_token: Option<String>,
180    pub disk_based_diagnostics_sources: Vec<String>,
181}
182
183#[derive(Clone, Debug, Deserialize)]
184pub struct BracketPair {
185    pub start: String,
186    pub end: String,
187    pub close: bool,
188    pub newline: bool,
189}
190
191pub struct Language {
192    pub(crate) config: LanguageConfig,
193    pub(crate) grammar: Option<Arc<Grammar>>,
194    pub(crate) adapter: Option<Arc<dyn LspAdapter>>,
195
196    #[cfg(any(test, feature = "test-support"))]
197    fake_adapter: Option<(
198        mpsc::UnboundedSender<lsp::FakeLanguageServer>,
199        Arc<FakeLspAdapter>,
200    )>,
201}
202
203pub struct Grammar {
204    pub(crate) ts_language: tree_sitter::Language,
205    pub(crate) highlights_query: Option<Query>,
206    pub(crate) brackets_query: Option<Query>,
207    pub(crate) indents_query: Option<Query>,
208    pub(crate) outline_query: Option<Query>,
209    pub(crate) highlight_map: Mutex<HighlightMap>,
210}
211
212#[derive(Clone)]
213pub enum LanguageServerBinaryStatus {
214    CheckingForUpdate,
215    Downloading,
216    Downloaded,
217    Cached,
218    Failed { error: String },
219}
220
221pub struct LanguageRegistry {
222    languages: RwLock<Vec<Arc<Language>>>,
223    language_server_download_dir: Option<Arc<Path>>,
224    lsp_binary_statuses_tx: async_broadcast::Sender<(Arc<Language>, LanguageServerBinaryStatus)>,
225    lsp_binary_statuses_rx: async_broadcast::Receiver<(Arc<Language>, LanguageServerBinaryStatus)>,
226    login_shell_env_loaded: Shared<Task<()>>,
227    lsp_binary_paths: Mutex<
228        HashMap<
229            LanguageServerName,
230            Shared<BoxFuture<'static, Result<PathBuf, Arc<anyhow::Error>>>>,
231        >,
232    >,
233}
234
235impl LanguageRegistry {
236    pub fn new(login_shell_env_loaded: Task<()>) -> Self {
237        let (lsp_binary_statuses_tx, lsp_binary_statuses_rx) = async_broadcast::broadcast(16);
238        Self {
239            language_server_download_dir: None,
240            languages: Default::default(),
241            lsp_binary_statuses_tx,
242            lsp_binary_statuses_rx,
243            login_shell_env_loaded: login_shell_env_loaded.shared(),
244            lsp_binary_paths: Default::default(),
245        }
246    }
247
248    #[cfg(any(test, feature = "test-support"))]
249    pub fn test() -> Self {
250        Self::new(Task::ready(()))
251    }
252
253    pub fn add(&self, language: Arc<Language>) {
254        self.languages.write().push(language.clone());
255    }
256
257    pub fn set_theme(&self, theme: &SyntaxTheme) {
258        for language in self.languages.read().iter() {
259            language.set_theme(theme);
260        }
261    }
262
263    pub fn set_language_server_download_dir(&mut self, path: impl Into<Arc<Path>>) {
264        self.language_server_download_dir = Some(path.into());
265    }
266
267    pub fn get_language(&self, name: &str) -> Option<Arc<Language>> {
268        self.languages
269            .read()
270            .iter()
271            .find(|language| language.name().to_lowercase() == name.to_lowercase())
272            .cloned()
273    }
274
275    pub fn to_vec(&self) -> Vec<Arc<Language>> {
276        self.languages.read().iter().cloned().collect()
277    }
278
279    pub fn language_names(&self) -> Vec<String> {
280        self.languages
281            .read()
282            .iter()
283            .map(|language| language.name().to_string())
284            .collect()
285    }
286
287    pub fn select_language(&self, path: impl AsRef<Path>) -> Option<Arc<Language>> {
288        let path = path.as_ref();
289        let filename = path.file_name().and_then(|name| name.to_str());
290        let extension = path.extension().and_then(|name| name.to_str());
291        let path_suffixes = [extension, filename];
292        self.languages
293            .read()
294            .iter()
295            .find(|language| {
296                language
297                    .config
298                    .path_suffixes
299                    .iter()
300                    .any(|suffix| dbg!(path_suffixes.contains(&Some(dbg!(suffix.as_str())))))
301            })
302            .cloned()
303    }
304
305    pub fn start_language_server(
306        self: &Arc<Self>,
307        server_id: usize,
308        language: Arc<Language>,
309        root_path: Arc<Path>,
310        http_client: Arc<dyn HttpClient>,
311        cx: &mut MutableAppContext,
312    ) -> Option<Task<Result<lsp::LanguageServer>>> {
313        #[cfg(any(test, feature = "test-support"))]
314        if language.fake_adapter.is_some() {
315            let language = language.clone();
316            return Some(cx.spawn(|cx| async move {
317                let (servers_tx, fake_adapter) = language.fake_adapter.as_ref().unwrap();
318                let (server, mut fake_server) = lsp::LanguageServer::fake(
319                    fake_adapter.name.to_string(),
320                    fake_adapter.capabilities.clone(),
321                    cx.clone(),
322                );
323
324                if let Some(initializer) = &fake_adapter.initializer {
325                    initializer(&mut fake_server);
326                }
327
328                let servers_tx = servers_tx.clone();
329                cx.background()
330                    .spawn(async move {
331                        if fake_server
332                            .try_receive_notification::<lsp::notification::Initialized>()
333                            .await
334                            .is_some()
335                        {
336                            servers_tx.unbounded_send(fake_server).ok();
337                        }
338                    })
339                    .detach();
340                Ok(server)
341            }));
342        }
343
344        let download_dir = self
345            .language_server_download_dir
346            .clone()
347            .ok_or_else(|| anyhow!("language server download directory has not been assigned"))
348            .log_err()?;
349
350        let this = self.clone();
351        let adapter = language.adapter.clone()?;
352        let lsp_binary_statuses = self.lsp_binary_statuses_tx.clone();
353        let login_shell_env_loaded = self.login_shell_env_loaded.clone();
354        Some(cx.spawn(|cx| async move {
355            login_shell_env_loaded.await;
356            let server_binary_path = this
357                .lsp_binary_paths
358                .lock()
359                .entry(adapter.name().await)
360                .or_insert_with(|| {
361                    get_server_binary_path(
362                        adapter.clone(),
363                        language.clone(),
364                        http_client,
365                        download_dir,
366                        lsp_binary_statuses,
367                    )
368                    .map_err(Arc::new)
369                    .boxed()
370                    .shared()
371                })
372                .clone()
373                .map_err(|e| anyhow!(e));
374
375            let server_binary_path = server_binary_path.await?;
376            let server_args = adapter.server_args().await;
377            let server = lsp::LanguageServer::new(
378                server_id,
379                &server_binary_path,
380                &server_args,
381                &root_path,
382                cx,
383            )?;
384            Ok(server)
385        }))
386    }
387
388    pub fn language_server_binary_statuses(
389        &self,
390    ) -> async_broadcast::Receiver<(Arc<Language>, LanguageServerBinaryStatus)> {
391        self.lsp_binary_statuses_rx.clone()
392    }
393}
394
395async fn get_server_binary_path(
396    adapter: Arc<dyn LspAdapter>,
397    language: Arc<Language>,
398    http_client: Arc<dyn HttpClient>,
399    download_dir: Arc<Path>,
400    statuses: async_broadcast::Sender<(Arc<Language>, LanguageServerBinaryStatus)>,
401) -> Result<PathBuf> {
402    let container_dir = download_dir.join(adapter.name().await.0.as_ref());
403    if !container_dir.exists() {
404        smol::fs::create_dir_all(&container_dir)
405            .await
406            .context("failed to create container directory")?;
407    }
408
409    let path = fetch_latest_server_binary_path(
410        adapter.clone(),
411        language.clone(),
412        http_client,
413        &container_dir,
414        statuses.clone(),
415    )
416    .await;
417    if let Err(error) = path.as_ref() {
418        if let Some(cached_path) = adapter.cached_server_binary(container_dir).await {
419            statuses
420                .broadcast((language.clone(), LanguageServerBinaryStatus::Cached))
421                .await?;
422            return Ok(cached_path);
423        } else {
424            statuses
425                .broadcast((
426                    language.clone(),
427                    LanguageServerBinaryStatus::Failed {
428                        error: format!("{:?}", error),
429                    },
430                ))
431                .await?;
432        }
433    }
434    path
435}
436
437async fn fetch_latest_server_binary_path(
438    adapter: Arc<dyn LspAdapter>,
439    language: Arc<Language>,
440    http_client: Arc<dyn HttpClient>,
441    container_dir: &Path,
442    lsp_binary_statuses_tx: async_broadcast::Sender<(Arc<Language>, LanguageServerBinaryStatus)>,
443) -> Result<PathBuf> {
444    let container_dir: Arc<Path> = container_dir.into();
445    lsp_binary_statuses_tx
446        .broadcast((
447            language.clone(),
448            LanguageServerBinaryStatus::CheckingForUpdate,
449        ))
450        .await?;
451    let version_info = adapter
452        .fetch_latest_server_version(http_client.clone())
453        .await?;
454    lsp_binary_statuses_tx
455        .broadcast((language.clone(), LanguageServerBinaryStatus::Downloading))
456        .await?;
457    let path = adapter
458        .fetch_server_binary(version_info, http_client, container_dir.clone())
459        .await?;
460    lsp_binary_statuses_tx
461        .broadcast((language.clone(), LanguageServerBinaryStatus::Downloaded))
462        .await?;
463    Ok(path)
464}
465
466impl Language {
467    pub fn new(config: LanguageConfig, ts_language: Option<tree_sitter::Language>) -> Self {
468        Self {
469            config,
470            grammar: ts_language.map(|ts_language| {
471                Arc::new(Grammar {
472                    highlights_query: None,
473                    brackets_query: None,
474                    indents_query: None,
475                    outline_query: None,
476                    ts_language,
477                    highlight_map: Default::default(),
478                })
479            }),
480            adapter: None,
481
482            #[cfg(any(test, feature = "test-support"))]
483            fake_adapter: None,
484        }
485    }
486
487    pub fn lsp_adapter(&self) -> Option<Arc<dyn LspAdapter>> {
488        self.adapter.clone()
489    }
490
491    pub fn with_highlights_query(mut self, source: &str) -> Result<Self> {
492        let grammar = self.grammar_mut();
493        grammar.highlights_query = Some(Query::new(grammar.ts_language, source)?);
494        Ok(self)
495    }
496
497    pub fn with_brackets_query(mut self, source: &str) -> Result<Self> {
498        let grammar = self.grammar_mut();
499        grammar.brackets_query = Some(Query::new(grammar.ts_language, source)?);
500        Ok(self)
501    }
502
503    pub fn with_indents_query(mut self, source: &str) -> Result<Self> {
504        let grammar = self.grammar_mut();
505        grammar.indents_query = Some(Query::new(grammar.ts_language, source)?);
506        Ok(self)
507    }
508
509    pub fn with_outline_query(mut self, source: &str) -> Result<Self> {
510        let grammar = self.grammar_mut();
511        grammar.outline_query = Some(Query::new(grammar.ts_language, source)?);
512        Ok(self)
513    }
514
515    fn grammar_mut(&mut self) -> &mut Grammar {
516        Arc::get_mut(self.grammar.as_mut().unwrap()).unwrap()
517    }
518
519    pub fn with_lsp_adapter(mut self, lsp_adapter: Arc<dyn LspAdapter>) -> Self {
520        self.adapter = Some(lsp_adapter);
521        self
522    }
523
524    #[cfg(any(test, feature = "test-support"))]
525    pub fn set_fake_lsp_adapter(
526        &mut self,
527        fake_lsp_adapter: FakeLspAdapter,
528    ) -> mpsc::UnboundedReceiver<lsp::FakeLanguageServer> {
529        let (servers_tx, servers_rx) = mpsc::unbounded();
530        let adapter = Arc::new(fake_lsp_adapter);
531        self.fake_adapter = Some((servers_tx, adapter.clone()));
532        self.adapter = Some(adapter);
533        servers_rx
534    }
535
536    pub fn name(&self) -> Arc<str> {
537        self.config.name.clone()
538    }
539
540    pub fn line_comment_prefix(&self) -> Option<&str> {
541        self.config.line_comment.as_deref()
542    }
543
544    pub async fn disk_based_diagnostic_sources(&self) -> Vec<String> {
545        match self.adapter.as_ref() {
546            Some(adapter) => adapter.disk_based_diagnostic_sources().await,
547            None => Vec::new(),
548        }
549    }
550
551    pub async fn disk_based_diagnostics_progress_token(&self) -> Option<String> {
552        if let Some(adapter) = self.adapter.as_ref() {
553            adapter.disk_based_diagnostics_progress_token().await
554        } else {
555            None
556        }
557    }
558
559    pub async fn process_diagnostics(&self, diagnostics: &mut lsp::PublishDiagnosticsParams) {
560        if let Some(processor) = self.adapter.as_ref() {
561            processor.process_diagnostics(diagnostics).await;
562        }
563    }
564
565    pub async fn label_for_completion(
566        &self,
567        completion: &lsp::CompletionItem,
568    ) -> Option<CodeLabel> {
569        self.adapter
570            .as_ref()?
571            .label_for_completion(completion, self)
572            .await
573    }
574
575    pub async fn label_for_symbol(&self, name: &str, kind: lsp::SymbolKind) -> Option<CodeLabel> {
576        self.adapter
577            .as_ref()?
578            .label_for_symbol(name, kind, self)
579            .await
580    }
581
582    pub fn highlight_text<'a>(
583        &'a self,
584        text: &'a Rope,
585        range: Range<usize>,
586    ) -> Vec<(Range<usize>, HighlightId)> {
587        let mut result = Vec::new();
588        if let Some(grammar) = &self.grammar {
589            let tree = grammar.parse_text(text, None);
590            let mut offset = 0;
591            for chunk in BufferChunks::new(text, range, Some(&tree), self.grammar.as_ref(), vec![])
592            {
593                let end_offset = offset + chunk.text.len();
594                if let Some(highlight_id) = chunk.syntax_highlight_id {
595                    if !highlight_id.is_default() {
596                        result.push((offset..end_offset, highlight_id));
597                    }
598                }
599                offset = end_offset;
600            }
601        }
602        result
603    }
604
605    pub fn brackets(&self) -> &[BracketPair] {
606        &self.config.brackets
607    }
608
609    pub fn path_suffixes(&self) -> &[String] {
610        &self.config.path_suffixes
611    }
612
613    pub fn should_autoclose_before(&self, c: char) -> bool {
614        c.is_whitespace() || self.config.autoclose_before.contains(c)
615    }
616
617    pub fn set_theme(&self, theme: &SyntaxTheme) {
618        if let Some(grammar) = self.grammar.as_ref() {
619            if let Some(highlights_query) = &grammar.highlights_query {
620                *grammar.highlight_map.lock() =
621                    HighlightMap::new(highlights_query.capture_names(), theme);
622            }
623        }
624    }
625
626    pub fn grammar(&self) -> Option<&Arc<Grammar>> {
627        self.grammar.as_ref()
628    }
629}
630
631impl Grammar {
632    fn parse_text(&self, text: &Rope, old_tree: Option<Tree>) -> Tree {
633        PARSER.with(|parser| {
634            let mut parser = parser.borrow_mut();
635            parser
636                .set_language(self.ts_language)
637                .expect("incompatible grammar");
638            let mut chunks = text.chunks_in_range(0..text.len());
639            parser
640                .parse_with(
641                    &mut move |offset, _| {
642                        chunks.seek(offset);
643                        chunks.next().unwrap_or("").as_bytes()
644                    },
645                    old_tree.as_ref(),
646                )
647                .unwrap()
648        })
649    }
650
651    pub fn highlight_map(&self) -> HighlightMap {
652        self.highlight_map.lock().clone()
653    }
654
655    pub fn highlight_id_for_name(&self, name: &str) -> Option<HighlightId> {
656        let capture_id = self
657            .highlights_query
658            .as_ref()?
659            .capture_index_for_name(name)?;
660        Some(self.highlight_map.lock().get(capture_id))
661    }
662}
663
664impl CodeLabel {
665    pub fn plain(text: String, filter_text: Option<&str>) -> Self {
666        let mut result = Self {
667            runs: Vec::new(),
668            filter_range: 0..text.len(),
669            text,
670        };
671        if let Some(filter_text) = filter_text {
672            if let Some(ix) = result.text.find(filter_text) {
673                result.filter_range = ix..ix + filter_text.len();
674            }
675        }
676        result
677    }
678}
679
680#[cfg(any(test, feature = "test-support"))]
681impl Default for FakeLspAdapter {
682    fn default() -> Self {
683        Self {
684            name: "the-fake-language-server",
685            capabilities: lsp::LanguageServer::full_capabilities(),
686            initializer: None,
687            disk_based_diagnostics_progress_token: None,
688            disk_based_diagnostics_sources: Vec::new(),
689        }
690    }
691}
692
693#[cfg(any(test, feature = "test-support"))]
694#[async_trait]
695impl LspAdapter for FakeLspAdapter {
696    async fn name(&self) -> LanguageServerName {
697        LanguageServerName(self.name.into())
698    }
699
700    async fn fetch_latest_server_version(
701        &self,
702        _: Arc<dyn HttpClient>,
703    ) -> Result<Box<dyn 'static + Send + Any>> {
704        unreachable!();
705    }
706
707    async fn fetch_server_binary(
708        &self,
709        _: Box<dyn 'static + Send + Any>,
710        _: Arc<dyn HttpClient>,
711        _: PathBuf,
712    ) -> Result<PathBuf> {
713        unreachable!();
714    }
715
716    async fn cached_server_binary(&self, _: PathBuf) -> Option<PathBuf> {
717        unreachable!();
718    }
719
720    async fn process_diagnostics(&self, _: &mut lsp::PublishDiagnosticsParams) {}
721
722    async fn disk_based_diagnostic_sources(&self) -> Vec<String> {
723        self.disk_based_diagnostics_sources.clone()
724    }
725
726    async fn disk_based_diagnostics_progress_token(&self) -> Option<String> {
727        self.disk_based_diagnostics_progress_token.clone()
728    }
729}
730
731pub fn point_to_lsp(point: PointUtf16) -> lsp::Position {
732    lsp::Position::new(point.row, point.column)
733}
734
735pub fn point_from_lsp(point: lsp::Position) -> PointUtf16 {
736    PointUtf16::new(point.line, point.character)
737}
738
739pub fn range_to_lsp(range: Range<PointUtf16>) -> lsp::Range {
740    lsp::Range {
741        start: point_to_lsp(range.start),
742        end: point_to_lsp(range.end),
743    }
744}
745
746pub fn range_from_lsp(range: lsp::Range) -> Range<PointUtf16> {
747    let mut start = point_from_lsp(range.start);
748    let mut end = point_from_lsp(range.end);
749    if start > end {
750        mem::swap(&mut start, &mut end);
751    }
752    start..end
753}