Support determining mode based on shebang interpreter directive

zee-grammar/Cargo.toml

@@ -18,6 +18,7 @@ libloading = "0.7.3"
 log = "0.4.16"
 once_cell = { version = "1.10.0", features = ["parking_lot"] }
 rayon = "1.5.2"
+regex = "1.5.5"
 serde = "1.0.136"
 serde_derive = "1.0.136"
 tree-sitter = "0.20.6"

zee-grammar/src/config.rs

@@ -17,6 +17,8 @@ pub struct ModeConfig {
     pub comment: Option<CommentConfig>,
     pub indentation: IndentationConfig,
     pub grammar: Option<GrammarConfig>,
+    #[serde(default)]
+    pub shebangs: Vec<String>,
 }
 
 #[derive(Clone, Debug, Deserialize, Serialize)]

zee-grammar/src/lib.rs

@@ -5,11 +5,15 @@ mod git;
 
 use anyhow::Result;
 use once_cell::sync::Lazy;
+use regex::Regex;
 use std::path::Path;
 use tree_sitter::{Language, Query};
 
 use self::config::{CommentConfig, FilenamePattern, IndentationConfig, ModeConfig};
 
+static SHEBANG_REGEX: Lazy<Regex> =
+    Lazy::new(|| Regex::new(r"^#!\s*(?:\S*[/\\](?:env\s+(?:\-\S+\s+)*)?)?([^\s\.\d]+)").unwrap());
+
 #[derive(Debug)]
 pub struct Mode {
     pub name: String,
@@ -19,6 +23,7 @@ pub struct Mode {
     pub comment: Option<CommentConfig>,
     pub indentation: IndentationConfig,
     grammar: LazyGrammar,
+    pub shebangs: Vec<String>,
 }
 
 impl Mode {
@@ -31,6 +36,7 @@ impl Mode {
             comment,
             indentation,
             grammar: grammar_config,
+            shebangs,
         } = config;
         Self {
             name,
@@ -44,6 +50,7 @@ impl Mode {
                     .map(|grammar_config| grammar_config.grammar_id)
                     .map(builder::load_grammar)
             })),
+            shebangs,
         }
     }
 
@@ -53,6 +60,13 @@ impl Mode {
             .any(|pattern| pattern.matches(filename.as_ref()))
     }
 
+    pub fn matches_by_shebang(&self, shebang: &str) -> bool {
+        SHEBANG_REGEX
+            .captures(shebang)
+            .and_then(|captures| self.shebangs.contains(&captures[1].into()).then(|| 0))
+            .is_some()
+    }
+
     pub fn language(&self) -> Option<Result<Language, &anyhow::Error>> {
         Some(self.grammar()?.map(|parser| parser.language))
     }
@@ -74,6 +88,7 @@ impl Default for Mode {
             comment: None,
             indentation: Default::default(),
             grammar: Lazy::new(Box::new(|| None)),
+            shebangs: vec![],
         }
     }
 }

zee/config/config.ron

@@ -146,6 +146,7 @@
                 width: 4,
                 unit: Space,
             ),
+            shebangs: ["node"],
             grammar: Some(
                 Grammar(
                     id: "javascript",
@@ -248,6 +249,7 @@
                 width: 4,
                 unit: Space,
             ),
+            shebangs: ["python"],
             grammar: Some(
                 Grammar(
                     id: "python",
@@ -464,6 +466,7 @@
                 width: 2,
                 unit: Space,
             ),
+            shebangs: ["sh", "bash", "dash", "zsh"],
             grammar: Some(
                 Grammar(
                     id: "bash",

zee/src/editor/buffer.rs

@@ -17,12 +17,13 @@ use zee_grammar::Mode;
 
 use super::{ContextHandle, Editor};
 use crate::{
-    config::PLAIN_TEXT_MODE,
     error::Result,
     syntax::parse::{ParseTree, ParserPool, ParserStatus},
     versioned::{Versioned, WeakHandle},
 };
 
+const MAX_SHEBANG_LENGTH: usize = 256;
+
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 pub struct BufferId(usize);
 
@@ -173,10 +174,11 @@ impl Buffer {
         file_path: Option<PathBuf>,
         repo: Option<RepositoryRc>,
     ) -> Self {
-        let mode = file_path
-            .as_ref()
-            .map(|path| context.0.mode_by_filename(path))
-            .unwrap_or(&PLAIN_TEXT_MODE);
+        let shebang_range = 0..std::cmp::min(text.len_chars(), MAX_SHEBANG_LENGTH);
+
+        let mode = context
+            .0
+            .mode_by_file(file_path.as_ref(), &text.slice(shebang_range));
 
         let mut parser = mode
             .language()

zee/src/editor/mod.rs

@@ -5,13 +5,13 @@ mod windows;
 pub use self::buffer::{BufferId, ModifiedStatus};
 
 use git2::Repository;
-use ropey::Rope;
+use ropey::{Rope, RopeSlice};
 use std::{
     borrow::Cow,
     fmt::Display,
     fs::File,
     io::{self, BufReader},
-    path::{Path, PathBuf},
+    path::PathBuf,
     sync::Arc,
 };
 use zi::{
@@ -94,11 +94,20 @@ pub struct Context {
 }
 
 impl Context {
-    pub fn mode_by_filename(&self, filename: impl AsRef<Path>) -> &Mode {
-        self.modes
-            .iter()
-            .find(|&mode| mode.matches_by_filename(filename.as_ref()))
-            .unwrap_or(&PLAIN_TEXT_MODE)
+    pub fn mode_by_file(&self, path: Option<&PathBuf>, content: &RopeSlice) -> &Mode {
+        path.and_then(|path| {
+            self.modes
+                .iter()
+                .find(|&mode| mode.matches_by_filename(path))
+        })
+        .or_else(|| {
+            content.as_str().and_then(|shebang| {
+                self.modes
+                    .iter()
+                    .find(|&mode| mode.matches_by_shebang(shebang))
+            })
+        })
+        .unwrap_or(&PLAIN_TEXT_MODE)
     }
 }