Implement formatter_composite

Author: pauldraper

WORKSPACE.bazel

@@ -73,6 +73,17 @@ load("@com_github_bazelbuild_buildtools//buildifier:deps.bzl", "buildifier_depen
 
 buildifier_dependencies()
 
+# Rivet Bazel Util
+
+RIVET_BAZEL_UTIL_VERSION = "f0c1bbe0935c3994e4c1ea4b3370a47d8df9819e"
+
+http_archive(
+    name = "rivet_bazel_util",
+    sha256 = "fca24b50c6544c0c2146bca6de7b00558c276020e64692b770361d650ed97b6e",
+    strip_prefix = "rivet-bazel-util-%s" % RIVET_BAZEL_UTIL_VERSION,
+    url = "https://github.com/rivethealth/rivet-bazel-util/archive/%s.tar.gz" % RIVET_BAZEL_UTIL_VERSION,
+)
+
 # Format
 
 load("//file:workspace.bzl", "files")

generate/rules.bzl

@@ -145,6 +145,30 @@ format = rule(
     implementation = _format_impl,
 )
 
+def _formatter_composite_impl(ctx):
+    formatters = [target[FormatterInfo] for target in ctx.attr.formatters]
+    fns = [formatter.fn for formatter in formatters]
+
+    def _fn(ctx, path, src, formatted):
+        actions = ctx.actions
+        name = ctx.attr
+        for i, fn in enumerate(fns):
+            tmp = formatted if i == len(fns) - 1 else actions.declare_file("%s.out.%s/%s" % (name, i + 1, src.path))
+            fn(ctx, path, src, tmp)
+            src = tmp
+
+    formatter_info = FormatterInfo(fn = _fn)
+
+    return [formatter_info]
+
+formatter_composite = rule(
+    attrs = {
+        "formatters": attr.label_list(mandatory = True, providers = [FormatterInfo]),
+    },
+    implementation = _formatter_composite_impl,
+    provides = [FormatterInfo],
+)
+
 def _generate_impl(ctx):
     actions = ctx.actions
     bash_runfiles = ctx.files._bash_runfiles