From 588c1a5610d07aff34412541f1096947eae2bf38 Mon Sep 17 00:00:00 2001
From: Amaan Qureshi <amaanq12@gmail.com>
Date: Sun, 24 Nov 2024 17:45:47 -0500
Subject: [PATCH] feat: allow external scanners to reuse the internal character
 ranges

---
 cli/generate/src/lib.rs    | 10 ++++++++--
 cli/generate/src/render.rs | 25 ++++++++++++++++++++-----
 lib/src/parser.h           |  6 +++---
 3 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/cli/generate/src/lib.rs b/cli/generate/src/lib.rs
index 14f20672..5be41ace 100644
--- a/cli/generate/src/lib.rs
+++ b/cli/generate/src/lib.rs
@@ -37,6 +37,7 @@ lazy_static! {
 struct GeneratedParser {
     c_code: String,
     node_types_json: String,
+    header_tail: String,
 }
 
 pub const ALLOC_HEADER: &str = include_str!("templates/alloc.h");
@@ -90,13 +91,17 @@ pub fn generate_parser_in_directory(
     let GeneratedParser {
         c_code,
         node_types_json,
+        header_tail,
     } = generate_parser_for_grammar_with_opts(&input_grammar, abi_version, report_symbol_name)?;
 
     write_file(&src_path.join("parser.c"), c_code)?;
     write_file(&src_path.join("node-types.json"), node_types_json)?;
     write_file(&header_path.join("alloc.h"), ALLOC_HEADER)?;
     write_file(&header_path.join("array.h"), ARRAY_HEADER)?;
-    write_file(&header_path.join("parser.h"), tree_sitter::PARSER_HEADER)?;
+    write_file(
+        &header_path.join("parser.h"),
+        format!("{}\n{header_tail}", tree_sitter::PARSER_HEADER),
+    )?;
 
     Ok(())
 }
@@ -132,7 +137,7 @@ fn generate_parser_for_grammar_with_opts(
         &inlines,
         report_symbol_name,
     )?;
-    let c_code = render_c_code(
+    let (c_code, header_tail) = render_c_code(
         &input_grammar.name,
         tables,
         syntax_grammar,
@@ -143,6 +148,7 @@ fn generate_parser_for_grammar_with_opts(
     Ok(GeneratedParser {
         c_code,
         node_types_json: serde_json::to_string_pretty(&node_types_json).unwrap(),
+        header_tail,
     })
 }
 
diff --git a/cli/generate/src/render.rs b/cli/generate/src/render.rs
index 62993d55..c689be5b 100644
--- a/cli/generate/src/render.rs
+++ b/cli/generate/src/render.rs
@@ -60,6 +60,7 @@ macro_rules! dedent {
 
 struct Generator {
     buffer: String,
+    header_buffer: String,
     indent_level: usize,
     language_name: String,
     parse_table: ParseTable,
@@ -89,7 +90,7 @@ struct LargeCharacterSetInfo {
 }
 
 impl Generator {
-    fn generate(mut self) -> String {
+    fn generate(mut self) -> (String, String) {
         self.init();
         self.add_header();
         self.add_includes();
@@ -146,7 +147,7 @@ impl Generator {
 
         self.add_parser_export();
 
-        self.buffer
+        (self.buffer, self.header_buffer)
     }
 
     fn init(&mut self) {
@@ -985,8 +986,21 @@ impl Generator {
 
         add_line!(
             self,
-            "static TSCharacterRange {}[] = {{",
-            info.constant_name
+            "const TSCharacterRange {}[{}] = {{",
+            info.constant_name,
+            characters.range_count()
+        );
+
+        self.header_buffer += &format!(
+            "extern const TSCharacterRange {}[{}];\n",
+            info.constant_name,
+            characters.range_count()
+        );
+
+        self.header_buffer += &format!(
+            "static const uint32_t {}_length = {};\n\n",
+            info.constant_name,
+            characters.range_count()
         );
 
         indent!(self);
@@ -1713,7 +1727,7 @@ pub fn render_c_code(
     lexical_grammar: LexicalGrammar,
     default_aliases: AliasMap,
     abi_version: usize,
-) -> String {
+) -> (String, String) {
     assert!(
         (ABI_VERSION_MIN..=ABI_VERSION_MAX).contains(&abi_version),
         "This version of Tree-sitter can only generate parsers with ABI version {ABI_VERSION_MIN} - {ABI_VERSION_MAX}, not {abi_version}",
@@ -1721,6 +1735,7 @@ pub fn render_c_code(
 
     Generator {
         buffer: String::new(),
+        header_buffer: String::new(),
         indent_level: 0,
         language_name: name.to_string(),
         large_state_count: 0,
diff --git a/lib/src/parser.h b/lib/src/parser.h
index 2338b4a2..13aa49b5 100644
--- a/lib/src/parser.h
+++ b/lib/src/parser.h
@@ -132,13 +132,13 @@ struct TSLanguage {
   const char *name;
 };
 
-static inline bool set_contains(TSCharacterRange *ranges, uint32_t len, int32_t lookahead) {
+static inline bool set_contains(const TSCharacterRange *ranges, uint32_t len, int32_t lookahead) {
   uint32_t index = 0;
   uint32_t size = len - index;
   while (size > 1) {
     uint32_t half_size = size / 2;
     uint32_t mid_index = index + half_size;
-    TSCharacterRange *range = &ranges[mid_index];
+    const TSCharacterRange *range = &ranges[mid_index];
     if (lookahead >= range->start && lookahead <= range->end) {
       return true;
     } else if (lookahead > range->end) {
@@ -146,7 +146,7 @@ static inline bool set_contains(TSCharacterRange *ranges, uint32_t len, int32_t
     }
     size -= half_size;
   }
-  TSCharacterRange *range = &ranges[index];
+  const TSCharacterRange *range = &ranges[index];
   return (lookahead >= range->start && lookahead <= range->end);
 }