From dd0b15e1f1540d6ca8c58594be302c66005d755c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bla=C5=BE=20Hrastnik?= <blaz@mxxn.io>
Date: Thu, 16 Sep 2021 15:47:51 +0900
Subject: [PATCH] syntax: Properly handle injection-regex for language
 injections

---
 helix-core/src/syntax.rs      | 36 ++++++++++++++++++++++++++++++++++-
 helix-term/src/ui/editor.rs   |  3 +--
 helix-term/src/ui/markdown.rs |  2 +-
 3 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/helix-core/src/syntax.rs b/helix-core/src/syntax.rs
index 93da869b8..8bbf363fa 100644
--- a/helix-core/src/syntax.rs
+++ b/helix-core/src/syntax.rs
@@ -21,6 +21,15 @@ use std::{
 use once_cell::sync::{Lazy, OnceCell};
 use serde::{Deserialize, Serialize};
 
+fn deserialize_regex<'de, D>(deserializer: D) -> Result<Option<Regex>, D::Error>
+where
+    D: serde::Deserializer<'de>,
+{
+    Option::<String>::deserialize(deserializer)?
+        .map(|buf| Regex::new(&buf).map_err(serde::de::Error::custom))
+        .transpose()
+}
+
 #[derive(Debug, Serialize, Deserialize)]
 pub struct Configuration {
     pub language: Vec<LanguageConfiguration>,
@@ -42,7 +51,8 @@ pub struct LanguageConfiguration {
     pub auto_format: bool,
 
     // content_regex
-    // injection_regex
+    #[serde(default, skip_serializing, deserialize_with = "deserialize_regex")]
+    injection_regex: Option<Regex>,
     // first_line_regex
     //
     #[serde(skip)]
@@ -243,6 +253,30 @@ impl Loader {
             .cloned()
     }
 
+    pub fn language_configuration_for_injection_string(
+        &self,
+        string: &str,
+    ) -> Option<Arc<LanguageConfiguration>> {
+        let mut best_match_length = 0;
+        let mut best_match_position = None;
+        for (i, configuration) in self.language_configs.iter().enumerate() {
+            if let Some(injection_regex) = &configuration.injection_regex {
+                if let Some(mat) = injection_regex.find(string) {
+                    let length = mat.end() - mat.start();
+                    if length > best_match_length {
+                        best_match_position = Some(i);
+                        best_match_length = length;
+                    }
+                }
+            }
+        }
+
+        if let Some(i) = best_match_position {
+            let configuration = &self.language_configs[i];
+            return Some(configuration.clone());
+        }
+        None
+    }
     pub fn language_configs_iter(&self) -> impl Iterator<Item = &Arc<LanguageConfiguration>> {
         self.language_configs.iter()
     }
diff --git a/helix-term/src/ui/editor.rs b/helix-term/src/ui/editor.rs
index 52cf3d2bf..0605e2c7c 100644
--- a/helix-term/src/ui/editor.rs
+++ b/helix-term/src/ui/editor.rs
@@ -147,8 +147,7 @@ impl EditorView {
                 let scopes = theme.scopes();
                 syntax
                     .highlight_iter(text.slice(..), Some(range), None, |language| {
-                        loader
-                            .language_config_for_scope(&format!("source.{}", language))
+                        loader.language_configuration_for_injection_string(language)
                             .and_then(|language_config| {
                                 let config = language_config.highlight_config(scopes)?;
                                 let config_ref = config.as_ref();
diff --git a/helix-term/src/ui/markdown.rs b/helix-term/src/ui/markdown.rs
index 87b35a2db..4144ed3c4 100644
--- a/helix-term/src/ui/markdown.rs
+++ b/helix-term/src/ui/markdown.rs
@@ -88,7 +88,7 @@ fn parse<'a>(
                     if let Some(theme) = theme {
                         let rope = Rope::from(text.as_ref());
                         let syntax = loader
-                            .language_config_for_scope(&format!("source.{}", language))
+                            .language_configuration_for_injection_string(language)
                             .and_then(|config| config.highlight_config(theme.scopes()))
                             .map(|config| Syntax::new(&rope, config));