File output for benchmark results.

Cargo.toml

@@ -18,7 +18,12 @@ divan-macros = { version = "=0.1.14", path = "macros" }
 cfg-if = "1"
 clap = { version = "4", default-features = false, features = ["std", "env"] }
 condtype = "1.3"
-regex = { package = "regex-lite", version = "0.1", default-features = false, features = ["std", "string"] }
+regex = { package = "regex-lite", version = "0.1", default-features = false, features = [
+    "std",
+    "string",
+] }
+
+serde_json = "1.0"
 
 [target.'cfg(unix)'.dependencies]
 libc = { workspace = true }

src/cli.rs

@@ -1,7 +1,9 @@
+use std::path::PathBuf;
+
 use clap::{builder::PossibleValue, value_parser, Arg, ArgAction, ColorChoice, Command, ValueEnum};
 
 use crate::{
-    config::{ParsedSeconds, SortingAttr},
+    config::{FileFormat, ParsedSeconds, SortingAttr},
     counter::MaxCountUInt,
     time::TimerKind,
 };
@@ -156,6 +158,21 @@ pub(crate) fn command() -> Command {
                 .help("Set every benchmark to have a throughput of N string scalars")
                 .value_parser(value_parser!(MaxCountUInt)),
         )
+        .arg(
+            option("file")
+                .env("DIVAN_WRITE_FILE")
+                .value_name("PATH")
+                .help("Set the file path to append the results to")
+                .value_parser(value_parser!(PathBuf))
+        )
+        .arg(
+            option("format")
+                .env("DIVAN_FILE_FORMAT")
+                .requires("file")
+                .value_name("FORMAT")
+                .help("Set output file type")
+                .value_parser(value_parser!(FileFormat))
+        )
         // ignored:
         .args([ignored_flag("bench"), ignored_flag("nocapture"), ignored_flag("show-output")])
 }
@@ -188,3 +205,17 @@ impl ValueEnum for SortingAttr {
         Some(PossibleValue::new(name))
     }
 }
+
+impl ValueEnum for FileFormat {
+    fn value_variants<'a>() -> &'a [Self] {
+        &[Self::Json, Self::JsonFlat]
+    }
+
+    fn to_possible_value(&self) -> Option<PossibleValue> {
+        let name = match self {
+            FileFormat::Json => "json",
+            FileFormat::JsonFlat => "jsonflat",
+        };
+        Some(PossibleValue::new(name))
+    }
+}

src/config.rs

@@ -182,3 +182,10 @@ impl SortingAttr {
         Ordering::Equal
     }
 }
+
+#[derive(Clone, Copy, Default)]
+pub(crate) enum FileFormat {
+    #[default]
+    Json,
+    JsonFlat,
+}