feat: add initial injection rendering support

src/syntax.zig

@@ -20,12 +20,26 @@ const Query = treez.Query;
 pub const Node = treez.Node;
 
 allocator: std.mem.Allocator,
+query_cache: *QueryCache,
 lang: *const Language,
 parser: *Parser,
 query: *Query,
 errors_query: *Query,
 injections: ?*Query,
 tree: ?*treez.Tree = null,
+injection_list: std.ArrayListUnmanaged(Injection) = .{},
+
+pub const Injection = struct {
+    lang_name: []const u8,
+    start_point: Point,
+    end_row: u32,
+    syntax: *Self,
+
+    fn deinit(self: *Injection, allocator: std.mem.Allocator) void {
+        self.syntax.destroy();
+        allocator.free(self.lang_name);
+    }
+};
 
 pub fn create(file_type: FileType, allocator: std.mem.Allocator, query_cache: *QueryCache) !*Self {
     const query = try query_cache.get(file_type, .highlights);
@@ -36,10 +50,13 @@ pub fn create(file_type: FileType, allocator: std.mem.Allocator, query_cache: *Q
     errdefer if (injections) |injections_| query_cache.release(injections_, .injections);
     const self = try allocator.create(Self);
     errdefer allocator.destroy(self);
+    const parser = try Parser.create();
+    errdefer parser.destroy();
     self.* = .{
         .allocator = allocator,
+        .query_cache = query_cache,
         .lang = file_type.lang_fn() orelse std.debug.panic("tree-sitter parser function failed for language: {s}", .{file_type.name}),
-        .parser = try Parser.create(),
+        .parser = parser,
         .query = query,
         .errors_query = errors_query,
         .injections = injections,
@@ -58,25 +75,35 @@ pub fn create_guess_file_type_static(allocator: std.mem.Allocator, content: []co
     return create(file_type, allocator, query_cache);
 }
 
-pub fn destroy(self: *Self, query_cache: *QueryCache) void {
+pub fn destroy(self: *Self) void {
+    self.clear_injections();
+    self.injection_list.deinit(self.allocator);
     if (self.tree) |tree| tree.destroy();
-    query_cache.release(self.query, .highlights);
+    self.query_cache.release(self.query, .highlights);
-    query_cache.release(self.errors_query, .highlights);
+    self.query_cache.release(self.errors_query, .highlights);
-    if (self.injections) |injections| query_cache.release(injections, .injections);
+    if (self.injections) |injections| self.query_cache.release(injections, .injections);
     self.parser.destroy();
     self.allocator.destroy(self);
 }
 
 pub fn reset(self: *Self) void {
+    self.clear_injections();
     if (self.tree) |tree| {
         tree.destroy();
         self.tree = null;
     }
 }
 
+fn clear_injections(self: *Self) void {
+    for (self.injection_list.items) |*inj| inj.deinit(self.allocator);
+    self.injection_list.clearRetainingCapacity();
+}
+
 pub fn refresh_full(self: *Self, content: []const u8) !void {
-    self.reset();
+    self.clear_injections();
+    if (self.tree) |tree| tree.destroy();
     self.tree = try self.parser.parseString(null, content);
+    try self.refresh_injections(content);
 }
 
 pub fn edit(self: *Self, ed: Edit) void {
@@ -140,6 +167,170 @@ pub fn refresh_from_string(self: *Self, content: [:0]const u8) !void {
         .encoding = .utf_8,
     };
     self.tree = try self.parser.parse(old_tree, input);
+    try self.refresh_injections(content);
+}
+
+pub fn refresh_injections(self: *Self, content: []const u8) !void {
+    self.clear_injections();
+
+    const injections_query = self.injections orelse return;
+    const tree = self.tree orelse return;
+
+    const cursor = try Query.Cursor.create();
+    defer cursor.destroy();
+    cursor.execute(injections_query, tree.getRootNode());
+
+    while (cursor.nextMatch()) |match| {
+        var lang_range: ?Range = null;
+        var content_range: ?Range = null;
+
+        for (match.captures()) |capture| {
+            const name = injections_query.getCaptureNameForId(capture.id);
+            if (std.mem.eql(u8, name, "injection.language")) {
+                lang_range = capture.node.getRange();
+            } else if (std.mem.eql(u8, name, "injection.content")) {
+                content_range = capture.node.getRange();
+            }
+        }
+
+        const crange = content_range orelse continue;
+
+        // Determine language name: dynamic @injection.language capture takes priority,
+        // then fall back to a static #set! injection.language predicate.
+        const lang_name: []const u8 = if (lang_range) |lr|
+            extract_node_text(content, lr) orelse continue
+        else
+            get_static_injection_language(injections_query, match.pattern_index) orelse continue;
+
+        if (lang_name.len == 0) continue;
+
+        const file_type = FileType.get_by_name_static(lang_name) orelse
+            FileType.get_by_name_static(normalize_lang_name(lang_name)) orelse
+            continue;
+
+        const start_byte = crange.start_byte;
+        const end_byte = crange.end_byte;
+        if (start_byte >= end_byte or end_byte > content.len) continue;
+        const child_content = content[start_byte..end_byte];
+
+        const child = try Self.create(file_type, self.allocator, self.query_cache);
+        errdefer child.destroy();
+        if (child.tree) |t| t.destroy();
+        child.tree = try child.parser.parseString(null, child_content);
+
+        const lang_name_owned = try self.allocator.dupe(u8, lang_name);
+        errdefer self.allocator.free(lang_name_owned);
+
+        try self.injection_list.append(self.allocator, .{
+            .lang_name = lang_name_owned,
+            .start_point = crange.start_point,
+            .end_row = crange.end_point.row,
+            .syntax = child,
+        });
+    }
+}
+
+fn extract_node_text(content: []const u8, range: Range) ?[]const u8 {
+    const s = range.start_byte;
+    const e = range.end_byte;
+    if (s >= e or e > content.len) return null;
+    return std.mem.trim(u8, content[s..e], &std.ascii.whitespace);
+}
+
+/// Normalize common language name aliases found in markdown
+/// This should probably be in file_types
+fn normalize_lang_name(name: []const u8) []const u8 {
+    const aliases = .{
+        .{ "js", "javascript" },
+        .{ "ts", "typescript" },
+        .{ "py", "python" },
+        .{ "rb", "ruby" },
+        .{ "sh", "bash" },
+        .{ "shell", "bash" },
+        .{ "zsh", "bash" },
+        .{ "c++", "cpp" },
+        .{ "cs", "c-sharp" },
+        .{ "csharp", "c-sharp" },
+        .{ "yml", "yaml" },
+        .{ "md", "markdown" },
+        .{ "rs", "rust" },
+    };
+    inline for (aliases) |alias| {
+        if (std.ascii.eqlIgnoreCase(name, alias[0])) return alias[1];
+    }
+    return name;
+}
+
+/// Read a static `#set! injection.language "name"` predicate from the query's
+/// internal predicate table for the given pattern index, returning the language
+/// name string if found or null otherwise.
+///
+/// This accesses TSQuery internals via the same cast used in ts_bin_query_gen.zig
+fn get_static_injection_language(query: *Query, pattern_idx: u16) ?[]const u8 {
+    const tss = @import("ts_serializer.zig");
+    const ts_query: *tss.TSQuery = @ptrCast(@alignCast(query));
+
+    const patterns = ts_query.patterns;
+    if (patterns.contents == null or @as(u32, pattern_idx) >= patterns.size) return null;
+    const pattern_arr: [*]tss.QueryPattern = @ptrCast(patterns.contents.?);
+    const pattern = pattern_arr[pattern_idx];
+
+    const pred_steps = ts_query.predicate_steps;
+    if (pred_steps.contents == null or pred_steps.size == 0) return null;
+    const steps_arr: [*]tss.PredicateStep = @ptrCast(pred_steps.contents.?);
+
+    const pred_values = ts_query.predicate_values;
+    if (pred_values.slices.contents == null or pred_values.characters.contents == null) return null;
+    const slices_arr: [*]tss.Slice = @ptrCast(pred_values.slices.contents.?);
+    const chars: [*]u8 = @ptrCast(pred_values.characters.contents.?);
+
+    // Walk the predicate steps for this pattern looking for the sequence:
+    //   string("set!")  string("injection.language")  string("<name>")  done
+    const step_start = pattern.predicate_steps.offset;
+    const step_end = step_start + pattern.predicate_steps.length;
+
+    var i = step_start;
+    while (i < step_end) {
+        const s = steps_arr[i];
+        if (s.type == .done) {
+            i += 1;
+            continue;
+        }
+
+        // We need at least 4 steps: 3 strings + done.
+        if (i + 3 >= step_end) break;
+
+        const s0 = steps_arr[i];
+        const s1 = steps_arr[i + 1];
+        const s2 = steps_arr[i + 2];
+        const s3 = steps_arr[i + 3];
+
+        if (s0.type == .string and s1.type == .string and
+            s2.type == .string and s3.type == .done)
+        {
+            if (s0.value_id < pred_values.slices.size and
+                s1.value_id < pred_values.slices.size and
+                s2.value_id < pred_values.slices.size)
+            {
+                const sl0 = slices_arr[s0.value_id];
+                const sl1 = slices_arr[s1.value_id];
+                const sl2 = slices_arr[s2.value_id];
+                const n0 = chars[sl0.offset .. sl0.offset + sl0.length];
+                const n1 = chars[sl1.offset .. sl1.offset + sl1.length];
+                const n2 = chars[sl2.offset .. sl2.offset + sl2.length];
+                if (std.mem.eql(u8, n0, "set!") and
+                    std.mem.eql(u8, n1, "injection.language"))
+                {
+                    return n2;
+                }
+            }
+        }
+
+        // Advance past this predicate group to the next .done boundary.
+        while (i < step_end and steps_arr[i].type != .done) i += 1;
+        if (i < step_end) i += 1;
+    }
+    return null;
 }
 
 fn find_line_begin(s: []const u8, line: usize) ?usize {
@@ -160,6 +351,66 @@ fn CallBack(comptime T: type) type {
 }
 
 pub fn render(self: *const Self, ctx: anytype, comptime cb: CallBack(@TypeOf(ctx)), range: ?Range) !void {
+    try self.render_highlights_only(ctx, cb, range);
+
+    for (self.injection_list.items) |*inj| {
+        if (range) |r| {
+            if (inj.end_row < r.start_point.row) continue;
+            if (inj.start_point.row > r.end_point.row) continue;
+        }
+
+        const child_range: ?Range = if (range) |r| blk: {
+            const child_start_row: u32 = if (r.start_point.row > inj.start_point.row)
+                r.start_point.row - inj.start_point.row
+            else
+                0;
+            const child_end_row: u32 = r.end_point.row - inj.start_point.row;
+            break :blk .{
+                .start_point = .{ .row = child_start_row, .column = 0 },
+                .end_point = .{ .row = child_end_row, .column = 0 },
+                .start_byte = 0,
+                .end_byte = 0,
+            };
+        } else null;
+
+        // Wrap the context so we can translate local ranges to absolute
+        // document coordinates before forwarding to the callback
+        const InjCtx = struct {
+            parent_ctx: @TypeOf(ctx),
+            inj: *const Injection,
+
+            fn translated_cb(
+                self_: *const @This(),
+                child_sel: Range,
+                scope: []const u8,
+                id: u32,
+                capture_idx: usize,
+                node: *const Node,
+            ) error{Stop}!void {
+                const start_row = child_sel.start_point.row + self_.inj.start_point.row;
+                const end_row = child_sel.end_point.row + self_.inj.start_point.row;
+                // Column offset only applies on the very first line of the injection
+                const start_col = child_sel.start_point.column +
+                    if (child_sel.start_point.row == 0) self_.inj.start_point.column else 0;
+                const end_col = child_sel.end_point.column +
+                    if (child_sel.end_point.row == 0) self_.inj.start_point.column else 0;
+
+                const doc_range: Range = .{
+                    .start_point = .{ .row = start_row, .column = start_col },
+                    .end_point = .{ .row = end_row, .column = end_col },
+                    .start_byte = child_sel.start_byte,
+                    .end_byte = child_sel.end_byte,
+                };
+                try cb(self_.parent_ctx, doc_range, scope, id, capture_idx, node);
+            }
+        };
+
+        var inj_ctx: InjCtx = .{ .parent_ctx = ctx, .inj = inj };
+        try inj.syntax.render_highlights_only(&inj_ctx, InjCtx.translated_cb, child_range);
+    }
+}
+
+fn render_highlights_only(self: *const Self, ctx: anytype, comptime cb: CallBack(@TypeOf(ctx)), range: ?Range) !void {
     const cursor = try Query.Cursor.create();
     defer cursor.destroy();
     const tree = self.tree orelse return;

src/treez_dummy.zig

@@ -64,6 +64,7 @@ pub const Query = struct {
         pub fn destroy(_: *@This()) void {}
 
         pub const Match = struct {
+            pattern_index: u16 = 0,
             pub fn captures(_: *@This()) []Capture {
                 return &[_]Capture{};
             }