preview: show the current method/function when it's invisible (#798)

* preview: show the current method/function when it's invisible

Close #663

* Fix test

* Update CHANGELOG.md

* Filter the potential symbols

* Reduce false positives

* Truncate the context line

* .

* .

* .

* .

* .

* .

* .

* Ignore the comment line

* .

* .

* Ensure the results from ctags are sorted in dumb_jump

* par gtags

* Truncate simply

CHANGELOG.md

@@ -5,6 +5,7 @@
 ## Added
 
 - Support generating the source of `tags` provider using the Rust binary, remove the vista.vim dep from `tags` provider. #795
+- Initial support of preview with context. #798
 
 ## Fixed
 

crates/maple_cli/src/command/ctags/buffer_tags.rs

@@ -1,7 +1,8 @@
 use std::ops::Deref;
+use std::path::Path;
 use std::sync::atomic::{AtomicUsize, Ordering};
 
-use anyhow::Result;
+use anyhow::{Context, Result};
 use clap::Parser;
 use filter::subprocess::{Exec, Redirection};
 use itertools::Itertools;
@@ -15,6 +16,10 @@ use crate::tools::ctags::CTAGS_HAS_JSON_FEATURE;
 /// Prints the tags for a specific file.
 #[derive(Parser, Debug, Clone)]
 pub struct BufferTags {
+    /// Show the nearest function/method to a specific line.
+    #[clap(long)]
+    current_context: Option<usize>,
+
     /// Use the raw output format even json output is supported, for testing purpose.
     #[clap(long)]
     force_raw: bool,
@@ -25,6 +30,13 @@ pub struct BufferTags {
 
 impl BufferTags {
     pub fn run(&self, _params: Params) -> Result<()> {
+        if let Some(at) = self.current_context {
+            let context_tag = current_context_tag(self.file.as_path(), at)
+                .context("Error at finding the context tag info")?;
+            println!("Context: {:?}", context_tag);
+            return Ok(());
+        }
+
         let lines = if *CTAGS_HAS_JSON_FEATURE.deref() && !self.force_raw {
             let cmd = build_cmd_in_json_format(self.file.as_ref());
             buffer_tags_lines_inner(cmd, BufferTagInfo::from_ctags_json)?
@@ -41,19 +53,68 @@ impl BufferTags {
     }
 }
 
-#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Default)]
-struct BufferTagInfo {
-    name: String,
-    pattern: String,
-    line: usize,
-    kind: String,
+const CONTEXT_KINDS: &[&str] = &[
+    "function",
+    "method",
+    "module",
+    "macro",
+    "implementation",
+    "interface",
+];
+
+const CONTEXT_SUPERSET: &[&str] = &[
+    "function",
+    "method",
+    "module",
+    "macro",
+    "implementation",
+    "interface",
+    "struct",
+    "field",
+    "typedef",
+    "enumerator",
+];
+
+/// Returns the method/function context associated with line `at`.
+pub fn current_context_tag(file: &Path, at: usize) -> Option<BufferTagInfo> {
+    let superset_tags = if *CTAGS_HAS_JSON_FEATURE.deref() {
+        let cmd = build_cmd_in_json_format(file);
+        collect_superset_context_tags(cmd, BufferTagInfo::from_ctags_json, at).ok()?
+    } else {
+        let cmd = build_cmd_in_raw_format(file);
+        collect_superset_context_tags(cmd, BufferTagInfo::from_ctags_raw, at).ok()?
+    };
+
+    match superset_tags.binary_search_by_key(&at, |tag| tag.line) {
+        Ok(_l) => None, // Skip if the line is exactly a tag line.
+        Err(_l) => {
+            let context_tags = superset_tags
+                .into_par_iter()
+                .filter(|tag| CONTEXT_KINDS.contains(&tag.kind.as_ref()))
+                .collect::<Vec<_>>();
+
+            match context_tags.binary_search_by_key(&at, |tag| tag.line) {
+                Ok(_) => None,
+                Err(l) => {
+                    let maybe_idx = l.checked_sub(1); // use the previous item.
+                    maybe_idx.and_then(|idx| context_tags.into_iter().nth(idx))
+                }
+            }
+        }
+    }
+}
+
+#[derive(Serialize, Deserialize, Clone, Debug, PartialEq, Eq, Default)]
+pub struct BufferTagInfo {
+    pub name: String,
+    pub pattern: String,
+    pub line: usize,
+    pub kind: String,
 }
 
 impl BufferTagInfo {
     /// Returns the display line for BuiltinHandle, no icon attached.
     fn format_buffer_tags(&self, max_name_len: usize) -> String {
-        let pattern_len = self.pattern.len();
-
         let name_line = format!("{}:{}", self.name, self.line);
 
         let kind = format!("[{}]", self.kind);
@@ -63,7 +124,7 @@ impl BufferTagInfo {
             name_group_width = max_name_len + 6,
             kind = kind,
             kind_width = 10,
-            pattern = self.pattern[2..pattern_len - 2].trim()
+            pattern = self.extract_pattern().trim()
         )
     }
 
@@ -105,6 +166,11 @@ impl BufferTagInfo {
             None
         }
     }
+
+    pub fn extract_pattern(&self) -> &str {
+        let pattern_len = self.pattern.len();
+        &self.pattern[2..pattern_len - 2]
+    }
 }
 
 fn build_cmd_in_json_format(file: impl AsRef<std::ffi::OsStr>) -> Exec {
@@ -140,14 +206,9 @@ fn buffer_tags_lines_inner(
     cmd: Exec,
     parse_fn: impl Fn(&str) -> Option<BufferTagInfo> + Send + Sync,
 ) -> Result<Vec<String>> {
-    use std::io::BufRead;
-
-    let stdout = cmd.stream_stdout()?;
-
     let max_name_len = AtomicUsize::new(0);
 
-    let tags = std::io::BufReader::with_capacity(8 * 1024 * 1024, stdout)
-        .lines()
+    let tags = crate::utils::lines(cmd)?
         .flatten()
         .par_bridge()
         .filter_map(|s| {
@@ -166,3 +227,21 @@ fn buffer_tags_lines_inner(
         .map(|s| s.format_buffer_tags(max_name_len))
         .collect::<Vec<_>>())
 }
+
+fn collect_superset_context_tags(
+    cmd: Exec,
+    parse_fn: impl Fn(&str) -> Option<BufferTagInfo> + Send + Sync,
+    target_lnum: usize,
+) -> Result<Vec<BufferTagInfo>> {
+    let mut tags = crate::utils::lines(cmd)?
+        .flatten()
+        .par_bridge()
+        .filter_map(|s| parse_fn(&s))
+        // the line of method/function name is lower.
+        .filter(|tag| tag.line <= target_lnum && CONTEXT_SUPERSET.contains(&tag.kind.as_ref()))
+        .collect::<Vec<_>>();
+
+    tags.par_sort_unstable_by_key(|x| x.line);
+
+    Ok(tags)
+}

crates/maple_cli/src/command/grep/mod.rs

@@ -7,9 +7,9 @@ use std::path::{Path, PathBuf};
 use std::process::Command;
 
 use anyhow::{Context, Result};
+use clap::Parser;
 use itertools::Itertools;
 use rayon::prelude::*;
-use clap::Parser;
 
 use filter::{
     matcher::{Bonus, MatchType},

crates/maple_cli/src/dumb_analyzer/find_usages/mod.rs

@@ -1,11 +1,33 @@
 mod search_engine;
 
+use std::collections::HashMap;
 use std::ops::{Index, IndexMut};
 
+use once_cell::sync::OnceCell;
 use rayon::prelude::*;
 
 pub use self::search_engine::{CtagsSearcher, GtagsSearcher, RegexSearcher, SearchType};
 
+/// Returns a list of comment prefix for a source file.
+///
+/// # Argument
+///
+/// - `ext`: the extension of a file, e.g., `rs`.
+pub fn get_comments_by_ext(ext: &str) -> &[&str] {
+    static LANGUAGE_COMMENT_TABLE: OnceCell<HashMap<&str, Vec<&str>>> = OnceCell::new();
+
+    let table = LANGUAGE_COMMENT_TABLE.get_or_init(|| {
+        serde_json::from_str(include_str!(
+            "../../../../../scripts/dumb_jump/comments_map.json"
+        ))
+        .expect("Wrong path for comments_map.json")
+    });
+
+    table
+        .get(ext)
+        .unwrap_or_else(|| table.get("*").expect("`*` entry exists; qed"))
+}
+
 #[derive(Clone, Debug, Default)]
 pub struct Usage {
     pub line: String,

crates/maple_cli/src/dumb_analyzer/find_usages/search_engine/ctags/mod.rs

@@ -66,17 +66,13 @@ impl<'a, P: AsRef<Path> + Hash> CtagsSearcher<'a, P> {
         search_type: SearchType,
         force_generate: bool,
     ) -> Result<impl Iterator<Item = TagInfo>> {
-        use std::io::BufRead;
-
         if force_generate || !self.tags_exists() {
             self.generate_tags()?;
         }
 
-        let stdout = self.build_exec(query, search_type).stream_stdout()?;
+        let cmd = self.build_exec(query, search_type);
 
-        // We usually have a decent amount of RAM nowdays.
-        Ok(std::io::BufReader::with_capacity(8 * 1024 * 1024, stdout)
-            .lines()
+        Ok(crate::utils::lines(cmd)?
             .flatten()
             .filter_map(|s| TagInfo::from_readtags(&s)))
     }

crates/maple_cli/src/dumb_analyzer/find_usages/search_engine/gtags/mod.rs

@@ -1,4 +1,3 @@
-use std::io::BufRead;
 use std::path::{PathBuf, MAIN_SEPARATOR};
 
 use anyhow::{anyhow, Result};
@@ -121,11 +120,7 @@ impl GtagsSearcher {
 
 // Returns a stream of tag parsed from the gtags output.
 fn execute(cmd: Exec) -> Result<impl Iterator<Item = TagInfo>> {
-    let stdout = cmd.stream_stdout()?;
-
-    // We usually have a decent amount of RAM nowdays.
-    Ok(std::io::BufReader::with_capacity(8 * 1024 * 1024, stdout)
-        .lines()
+    Ok(crate::utils::lines(cmd)?
         .flatten()
         .filter_map(|s| TagInfo::from_gtags(&s)))
 }

crates/maple_cli/src/dumb_analyzer/find_usages/search_engine/regex/definition.rs

@@ -3,7 +3,7 @@ use std::{collections::HashMap, fmt::Display};
 
 use anyhow::{anyhow, Result};
 use itertools::Itertools;
-use once_cell::sync::{Lazy, OnceCell};
+use once_cell::sync::Lazy;
 use rayon::prelude::*;
 use serde::Deserialize;
 
@@ -106,25 +106,6 @@ pub fn get_language_by_ext(ext: &str) -> Result<&&str> {
         .ok_or_else(|| anyhow!("dumb_analyzer is unsupported for {}", ext))
 }
 
-/// Map of file extension to the comment prefix.
-///
-/// Keyed by the extension name.
-pub fn get_comments_by_ext(ext: &str) -> &[&str] {
-    static LANGUAGE_COMMENT_TABLE: OnceCell<HashMap<&str, Vec<&str>>> = OnceCell::new();
-
-    let table = LANGUAGE_COMMENT_TABLE.get_or_init(|| {
-        let comments: HashMap<&str, Vec<&str>> = serde_json::from_str(include_str!(
-            "../../../../../../../scripts/dumb_jump/comments_map.json"
-        ))
-        .expect("Wrong path for comments_map.json");
-        comments
-    });
-
-    table
-        .get(ext)
-        .unwrap_or_else(|| table.get("*").expect("`*` entry exists; qed"))
-}
-
 /// Type of match result of ripgrep.
 #[derive(Clone, Debug, Deserialize, PartialEq, Eq, Hash)]
 pub enum MatchKind {

crates/maple_cli/src/dumb_analyzer/find_usages/search_engine/regex/mod.rs

@@ -19,11 +19,13 @@ use anyhow::Result;
 use rayon::prelude::*;
 
 use self::definition::{
-    definitions_and_references, do_search_usages, get_comments_by_ext, get_language_by_ext,
-    MatchKind,
+    definitions_and_references, do_search_usages, get_language_by_ext, MatchKind,
 };
 use self::worker::find_occurrences_by_ext;
-use crate::dumb_analyzer::find_usages::{Usage, Usages};
+use crate::dumb_analyzer::{
+    find_usages::{Usage, Usages},
+    get_comments_by_ext,
+};
 use crate::tools::ripgrep::{Match, Word};
 use crate::utils::ExactOrInverseTerms;
 

crates/maple_cli/src/dumb_analyzer/find_usages/search_engine/regex/worker.rs

@@ -4,7 +4,8 @@ use std::path::PathBuf;
 use anyhow::Result;
 use rayon::prelude::*;
 
-use super::definition::{build_full_regexp, get_comments_by_ext, is_comment, DefinitionKind};
+use super::definition::{build_full_regexp, is_comment, DefinitionKind};
+use crate::dumb_analyzer::get_comments_by_ext;
 use crate::process::AsyncCommand;
 use crate::tools::ripgrep::{Match, Word};
 

crates/maple_cli/src/dumb_analyzer/mod.rs

@@ -1,5 +1,5 @@
 mod find_usages;
 
 pub use self::find_usages::{
-    CtagsSearcher, GtagsSearcher, RegexSearcher, SearchType, Usage, Usages,
+    get_comments_by_ext, CtagsSearcher, GtagsSearcher, RegexSearcher, SearchType, Usage, Usages,
 };

crates/maple_cli/src/previewer/mod.rs

@@ -4,6 +4,7 @@ use std::path::Path;
 
 use anyhow::{anyhow, Result};
 
+use types::PreviewInfo;
 use utility::{read_first_lines, read_preview_lines};
 
 #[inline]
@@ -61,10 +62,15 @@ pub fn preview_file_at<P: AsRef<Path>>(
 ) -> Result<(Vec<String>, usize)> {
     tracing::debug!(path = %path.as_ref().display(), lnum, "Previewing file");
 
-    let (lines_iter, hi_lnum) = read_preview_lines(path.as_ref(), lnum, half_size)?;
+    let PreviewInfo {
+        lines,
+        highlight_lnum,
+        ..
+    } = read_preview_lines(path.as_ref(), lnum, half_size)?;
+
     let lines = std::iter::once(format!("{}:{}", path.as_ref().display(), lnum))
-        .chain(truncate_preview_lines(max_width, lines_iter.into_iter()))
+        .chain(truncate_preview_lines(max_width, lines.into_iter()))
         .collect::<Vec<_>>();
 
-    Ok((lines, hi_lnum))
+    Ok((lines, highlight_lnum))
 }

crates/maple_cli/src/stdio_server/providers/builtin/mod.rs

@@ -36,7 +36,7 @@ impl EventHandle for BuiltinHandle {
     async fn on_move(&mut self, msg: MethodCall, context: Arc<SessionContext>) -> Result<()> {
         let msg_id = msg.id;
 
-        let source_scale = context.source_scale.lock();
+        let source_scale = context.state.source_scale.lock();
 
         let curline = match (source_scale.deref(), msg.get_u64("lnum").ok()) {
             (SourceScale::Small { ref lines, .. }, Some(lnum)) => {
@@ -67,7 +67,7 @@ impl EventHandle for BuiltinHandle {
     async fn on_typed(&mut self, msg: MethodCall, context: Arc<SessionContext>) -> Result<()> {
         let query = msg.get_query();
 
-        let source_scale = context.source_scale.lock();
+        let source_scale = context.state.source_scale.lock();
 
         match source_scale.deref() {
             SourceScale::Small { ref lines, .. } => {