introduce re_types_builder

Cargo.toml

@@ -56,6 +56,7 @@ re_tensor_ops = { path = "crates/re_tensor_ops", version = "0.7.0-alpha.0", defa
 re_time_panel = { path = "crates/re_time_panel", version = "=0.7.0-alpha.0", default-features = false }
 re_tracing = { path = "crates/re_tracing", version = "0.7.0-alpha.0", default-features = false }
 re_tuid = { path = "crates/re_tuid", version = "0.7.0-alpha.0", default-features = false }
+re_types_builder = { path = "crates/re_types_builder", version = "=0.7.0-alpha.0", default-features = false }
 re_ui = { path = "crates/re_ui", version = "0.7.0-alpha.0", default-features = false }
 re_viewer = { path = "crates/re_viewer", version = "0.7.0-alpha.0", default-features = false }
 re_viewer_context = { path = "crates/re_viewer_context", version = "0.7.0-alpha.0", default-features = false }

crates/re_types_builder/Cargo.toml

@@ -0,0 +1,38 @@
+[package]
+name = "re_types_builder"
+authors.workspace = true
+description = "Generates code for Rerun's SDKs from flatbuffers definitions."
+edition.workspace = true
+homepage.workspace = true
+include.workspace = true
+license.workspace = true
+publish = true
+readme = "README.md"
+repository.workspace = true
+rust-version.workspace = true
+version.workspace = true
+
+
+[package.metadata.docs.rs]
+all-features = true
+
+
+[dependencies]
+
+# External
+anyhow.workspace = true
+arrow2.workspace = true
+convert_case = "0.6"
+flatbuffers = "23.0"
+indent = "0.1"
+unindent = "0.2"
+xshell = "0.2"
+
+
+[build-dependencies]
+
+# Rerun
+re_build_tools.workspace = true
+
+# External
+xshell = "0.2"

crates/re_types_builder/README.md

@@ -0,0 +1,13 @@
+# re_types_builder
+
+Part of the [`rerun`](https://github.com/rerun-io/rerun) family of crates.
+
+[![Latest version](https://img.shields.io/crates/v/re_types_builder.svg)](https://crates.io/crates/re_types_builder)
+[![Documentation](https://docs.rs/re_types_builder/badge.svg)](https://docs.rs/re_types_builder)
+![MIT](https://img.shields.io/badge/license-MIT-blue.svg)
+![Apache](https://img.shields.io/badge/license-Apache-blue.svg)
+
+This crate implements Rerun's code generation tools.
+
+These tools translate language-agnostic IDL definitions (flatbuffers) into code.
+They are invoked from `re_types`' build script (`build.rs`).

crates/re_types_builder/build.rs

@@ -0,0 +1,70 @@
+//! Generates flatbuffers reflection code from `reflection.fbs`.
+
+use xshell::{cmd, Shell};
+
+use re_build_tools::{
+    compute_file_hash, is_tracked_env_var_set, read_versioning_hash, rerun_if_changed,
+    rerun_if_changed_or_doesnt_exist, write_versioning_hash,
+};
+
+// ---
+
+// NOTE: Don't need to add extra context to xshell invocations, it does so on its own.
+
+const SOURCE_HASH_PATH: &str = "./source_hash.txt";
+const FBS_REFLECTION_DEFINITION_PATH: &str = "./definitions/reflection.fbs";
+
+fn main() {
+    if std::env::var("CI").is_ok() {
+        // Don't run on CI!
+        //
+        // The code we're generating here is actual source code that gets committed into the
+        // repository.
+        return;
+    }
+
+    if !is_tracked_env_var_set("IS_IN_RERUN_WORKSPACE") {
+        // Only run if we are in the rerun workspace, not on users machines.
+        return;
+    }
+    if is_tracked_env_var_set("RERUN_IS_PUBLISHING") {
+        // We don't need to rebuild - we should have done so beforehand!
+        // See `RELEASES.md`
+        return;
+    }
+
+    rerun_if_changed_or_doesnt_exist(SOURCE_HASH_PATH);
+    rerun_if_changed(FBS_REFLECTION_DEFINITION_PATH);
+
+    let cur_hash = read_versioning_hash(SOURCE_HASH_PATH);
+    let new_hash = compute_file_hash(FBS_REFLECTION_DEFINITION_PATH);
+
+    // Leave these be please, very useful when debugging.
+    eprintln!("cur_hash: {cur_hash:?}");
+    eprintln!("new_hash: {new_hash:?}");
+
+    if let Some(cur_hash) = cur_hash {
+        if cur_hash == new_hash {
+            // Source definition hasn't changed, no need to do anything.
+            return;
+        }
+    }
+
+    let sh = Shell::new().unwrap();
+    cmd!(
+        sh,
+        "flatc -o src/ --rust --gen-onefile --filename-suffix '' {FBS_REFLECTION_DEFINITION_PATH}"
+    )
+    .run()
+    .unwrap();
+
+    // NOTE: We're purposefully ignoring the error here.
+    //
+    // In the very unlikely chance that the user doesn't have `rustfmt` in their $PATH, there's
+    // still no good reason to fail the build.
+    //
+    // The CI will catch the unformatted file at PR time and complain appropriately anyhow.
+    cmd!(sh, "cargo fmt").run().ok();
+
+    write_versioning_hash(SOURCE_HASH_PATH, new_hash);
+}