Handle NDJSON differently for greppable

Author: IvanIsCoding

docs/manual.md

@@ -476,6 +476,8 @@ json.bin[0].path = "src/main.rs";
 
 If you need deterministic outputs, we recommend using the `-S` flag for sorting the output.
 
+For NDJSON inputs, `--greppable` outputs only the last line. This happens to prevent redefinitions of the `json` variable. If you are dealing with NDJSON and want this feature, consider using the `--slurp` flag.
+
 ### Reverting filtered grep output
 
 `celq` also has a `--from-gron` flag that parsers the output of `gron` and `celq --greppable`. It is equivalent to `gron -u`. That can be useful for converting output filtered by grep back to JSON.

src/main.rs

@@ -91,8 +91,16 @@ fn main() -> io::Result<()> {
         Ok(results) => {
             // Print all outputs, unless void mode is enabled
             if !cli.void {
-                for (output, _) in &results {
-                    println!("{}", output);
+                if !cli.greppable {
+                    for (output, _) in &results {
+                        println!("{}", output);
+                    }
+                } else {
+                    let last_gron = results
+                        .last()
+                        .map(|(output, _)| output.as_str())
+                        .unwrap_or("");
+                    println!("{}", last_gron);
                 }
             }