When bundling JSON, only use JSON.parse when the input is ASCII.

We don't want to add an extra pass over the input to convert it to UTF16. And JS engines storing strings as UTF-16 is more expensive anyway, so the runtime win here probably isn't as big (though open to evidence to the contrary!)

1 files changed, 38 insertions, 0 deletions

diff --git a/src/json_parser.zig b/src/json_parser.zig
index 696b62325..5d65291a7 100644
--- a/src/json_parser.zig
+++ b/src/json_parser.zig
@@ -255,6 +255,44 @@ pub fn ParseJSON(source: *const logger.Source, log: *logger.Log, allocator: *std
     return try parser.parseExpr(false);
 }
 
+pub const JSONParseResult = struct {
+    expr: Expr,
+    tag: Tag,
+
+    pub const Tag = enum {
+        expr,
+        ascii,
+        empty,
+    };
+};
+
+pub fn ParseJSONForBundling(source: *const logger.Source, log: *logger.Log, allocator: *std.mem.Allocator) !JSONParseResult {
+    var parser = try JSONParser.init(allocator, source, log);
+    switch (source.contents.len) {
+        // This is to be consisntent with how disabled JS files are handled
+        0 => {
+            return JSONParseResult{ .expr = Expr{ .loc = logger.Loc{ .start = 0 }, .data = empty_object_data }, .tag = .empty };
+        },
+        // This is a fast pass I guess
+        2 => {
+            if (strings.eqlComptime(source.contents[0..1], "\"\"") or strings.eqlComptime(source.contents[0..1], "''")) {
+                return JSONParseResult{ .expr = Expr{ .loc = logger.Loc{ .start = 0 }, .data = empty_string_data }, .tag = .expr };
+            } else if (strings.eqlComptime(source.contents[0..1], "{}")) {
+                return JSONParseResult{ .expr = Expr{ .loc = logger.Loc{ .start = 0 }, .data = empty_object_data }, .tag = .expr };
+            } else if (strings.eqlComptime(source.contents[0..1], "[]")) {
+                return JSONParseResult{ .expr = Expr{ .loc = logger.Loc{ .start = 0 }, .data = empty_array_data }, .tag = .expr };
+            }
+        },
+        else => {},
+    }
+
+    const result = try parser.parseExpr(false);
+    return JSONParseResult{
+        .tag = if (parser.lexer.is_ascii_only) JSONParseResult.Tag.ascii else JSONParseResult.Tag.expr,
+        .expr = result,
+    };
+}
+
 // threadlocal var env_json_auto_quote_buffer: MutableString = undefined;
 // threadlocal var env_json_auto_quote_buffer_loaded: bool = false;
 pub fn ParseEnvJSON(source: *const logger.Source, log: *logger.Log, allocator: *std.mem.Allocator) !Expr {