feat: support --output-dir flag (#7)

docs/swc.md

@@ -7,7 +7,7 @@ swc rule
 ## swc
 
 <pre>
-swc(<a href="#swc-name">name</a>, <a href="#swc-srcs">srcs</a>, <a href="#swc-args">args</a>, <a href="#swc-data">data</a>, <a href="#swc-swcrc">swcrc</a>, <a href="#swc-source_maps">source_maps</a>, <a href="#swc-source_map_outputs">source_map_outputs</a>, <a href="#swc-kwargs">kwargs</a>)
+swc(<a href="#swc-name">name</a>, <a href="#swc-srcs">srcs</a>, <a href="#swc-args">args</a>, <a href="#swc-data">data</a>, <a href="#swc-output_dir">output_dir</a>, <a href="#swc-swcrc">swcrc</a>, <a href="#swc-source_maps">source_maps</a>, <a href="#swc-source_map_outputs">source_map_outputs</a>, <a href="#swc-kwargs">kwargs</a>)
 </pre>
 
 Execute the swc compiler
@@ -21,6 +21,7 @@ Execute the swc compiler
 | <a id="swc-srcs"></a>srcs |  source files, typically .ts files in the source tree   |  <code>None</code> |
 | <a id="swc-args"></a>args |  additional arguments to pass to swc cli, see https://swc.rs/docs/usage/cli   |  <code>[]</code> |
 | <a id="swc-data"></a>data |  runtime dependencies to be propagated in the runfiles   |  <code>[]</code> |
+| <a id="swc-output_dir"></a>output_dir |  whether to produce a directory output rather than individual files   |  <code>False</code> |
 | <a id="swc-swcrc"></a>swcrc |  label of a configuration file for swc, see https://swc.rs/docs/configuration/swcrc   |  <code>None</code> |
 | <a id="swc-source_maps"></a>source_maps |  If set, the --source-maps argument is passed to the swc cli with the value. True/False are automaticaly converted to "true"/"false" string values the cli expects. If source_maps is "true" or "both" then source_map_outputs is automatically set to True.   |  <code>None</code> |
 | <a id="swc-source_map_outputs"></a>source_map_outputs |  if the rule is expected to produce a .js.map file output for each .js file output   |  <code>False</code> |

examples/directory/BUILD.bazel

@@ -0,0 +1,33 @@
+"""Directory use case for swc: minifying a folder of code-split files
+
+This has to be a directory-in, directory-out pattern since the codesplitter produces unpredictable filenames.
+
+Note that this example also depends on the setup in /WORKSPACE at the root of this repository.
+"""
+
+load("@aspect_rules_swc//swc:swc.bzl", "swc")
+load(":mocks.bzl", "mock_codesplit")
+
+mock_codesplit(
+    name = "split_app",
+)
+
+# Runs `swc path/to/split_app --out-dir ../../bazel-bin/examples/directory/minify`
+# You can run `bazel build --subcommands //examples/directory:minify`
+# to see the exact command line Bazel runs.
+# Note that by default, sources are found by glob(["**/*.ts"])
+swc(
+    name = "minify",
+    srcs = ["split_app"],
+    output_dir = True,
+)
+
+sh_test(
+    name = "test",
+    srcs = ["test.sh"],
+    # Workaround https://github.com/swc-project/swc/issues/3028
+    # The test will need to know this folder to make the assertion
+    args = ["$(TARGET_CPU)-$(COMPILATION_MODE)"],
+    data = ["minify"],
+    deps = ["@bazel_tools//tools/bash/runfiles"],
+)

examples/directory/mocks.bzl

@@ -0,0 +1,22 @@
+"Placeholder for a rule like webpack which may produce an unpredictable number of JS chunks"
+
+load("@aspect_bazel_lib//lib:copy_to_directory.bzl", "copy_to_directory")
+load("@bazel_skylib//rules:write_file.bzl", "write_file")
+
+def mock_codesplit(name):
+    write_file(
+        name = "write1",
+        out = "file1.js",
+        content = ["const a = 1"],
+    )
+
+    write_file(
+        name = "write2",
+        out = "file2.js",
+        content = ["const a = 2"],
+    )
+
+    copy_to_directory(
+        name = name,
+        srcs = ["file1.js", "file2.js"],
+    )

examples/directory/test.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+# --- begin runfiles.bash initialization v2 ---
+# Copy-pasted from the Bazel Bash runfiles library v2.
+set -uo pipefail; f=bazel_tools/tools/bash/runfiles/runfiles.bash
+source "${RUNFILES_DIR:-/dev/null}/$f" 2>/dev/null || \
+  source "$(grep -sm1 "^$f " "${RUNFILES_MANIFEST_FILE:-/dev/null}" | cut -f2- -d' ')" 2>/dev/null || \
+  source "$0.runfiles/$f" 2>/dev/null || \
+  source "$(grep -sm1 "^$f " "$0.runfiles_manifest" | cut -f2- -d' ')" 2>/dev/null || \
+  source "$(grep -sm1 "^$f " "$0.exe.runfiles_manifest" | cut -f2- -d' ')" 2>/dev/null || \
+  { echo>&2 "ERROR: cannot find $f"; exit 1; }; f=; set -e
+# --- end runfiles.bash initialization v2 ---
+
+set -o errexit
+
+ARCH=$1
+readonly in_folder=$(rlocation $TEST_WORKSPACE/$(dirname $TEST_BINARY)/minify)
+
+# Due to https://github.com/swc-project/swc/issues/3028 the path is longer than we'd like
+# It should really just contain $in_folder/file1.js
+if ! [[ -e $in_folder/$ARCH/bin/examples/directory/split_app/file1.js ]]; then
+    echo >&2 "Missing expected output file in directory"
+    exit 1
+fi

swc/private/swc.bzl

@@ -6,6 +6,7 @@ _attrs = {
     "srcs": attr.label_list(allow_files = True, mandatory = True),
     "args": attr.string_list(),
     "source_maps": attr.string(),
+    "output_dir": attr.bool(),
     "data": attr.label_list(default = [], allow_files = True),
     "swcrc": attr.label(allow_single_file = True),
     "swc_cli": attr.label(
@@ -21,60 +22,89 @@ _outputs = {
 }
 
 def _impl(ctx):
-    outputs = ctx.outputs.js_outs + ctx.outputs.map_outs
+    outputs = []
     source_maps = len(ctx.outputs.map_outs) > 0
+    binding = ctx.toolchains["@aspect_rules_swc//swc:toolchain_type"].swcinfo.binding
+    args = ctx.actions.args()
 
-    for src in ctx.files.srcs:
-        js_out = ctx.actions.declare_file(paths.replace_extension(src.basename, ".js"), sibling = src)
-        outs = [js_out]
-        if source_maps:
-            outs.append(ctx.actions.declare_file(paths.replace_extension(src.basename, ".js.map"), sibling = src))
-        args = ctx.actions.args()
-
-        # Add user specified arguments *before* rule supplied arguments
-        args.add_all(ctx.attr.args)
-
-        # Pass in the swcrc config if it is set; if it is
-        # then source paths are expected to be relative to the swcrc directory
-        src_path = src.path
-        if ctx.file.swcrc:
-            swcrc_path = ctx.file.swcrc.path
-            swcrc_directory = paths.dirname(swcrc_path)
-            args.add_all([
-                "--config-file",
-                swcrc_path,
-            ])
-
-            # TODO(greg): determine if this is needed, given that relativize below should provide a correct path
-            # if not src_path.startswith(swcrc_directory):
-            #     fail("sources must be in swcrc directory or subdirectory if swcrc is specified")
-            src_path = paths.relativize(src_path, swcrc_directory)
+    # Add user specified arguments *before* rule supplied arguments
+    args.add_all(ctx.attr.args)
 
+    if ctx.attr.output_dir:
+        if len(ctx.attr.srcs) != 1:
+            fail("Under output_dir, there must be a single entry in srcs")
+        if not ctx.files.srcs[0].is_directory:
+            fail("Under output_dir, the srcs must be directories, not files")
+        out = ctx.actions.declare_file(ctx.label.name)
+        outputs.append(out)
         args.add_all([
-            src_path,
-            "--out-file",
-            js_out.path,
+            ctx.files.srcs[0].path,
+            "--out-dir",
+            out.path,
             "--no-swcrc",
             "-q",
         ])
 
-        binding = ctx.toolchains["@aspect_rules_swc//swc:toolchain_type"].swcinfo.binding
-
         ctx.actions.run(
-            inputs = [src] + ctx.toolchains["@aspect_rules_swc//swc:toolchain_type"].swcinfo.tool_files,
+            inputs = ctx.files.srcs + ctx.toolchains["@aspect_rules_swc//swc:toolchain_type"].swcinfo.tool_files,
             arguments = [args],
-            outputs = outs,
+            outputs = [out],
             env = {
                 # Our patch for @swc/core uses this environment variable to locate the rust binding
                 "SWC_BINARY_PATH": binding,
             },
             executable = ctx.executable.swc_cli,
-            progress_message = "Transpiling with swc %s [swc %s]" % (
-                ctx.label,
-                src.short_path,
-            ),
+            progress_message = "Transpiling with swc %s" % ctx.label,
         )
 
+    else:
+        outputs.extend(ctx.outputs.js_outs)
+        outputs.extend(ctx.outputs.map_outs)
+        for src in ctx.files.srcs:
+            js_out = ctx.actions.declare_file(paths.replace_extension(src.basename, ".js"), sibling = src)
+            outs = [js_out]
+            if source_maps:
+                outs.append(ctx.actions.declare_file(paths.replace_extension(src.basename, ".js.map"), sibling = src))
+
+            # Pass in the swcrc config if it is set; if it is
+            # then source paths are expected to be relative to the swcrc directory
+            src_path = src.path
+            if ctx.file.swcrc:
+                swcrc_path = ctx.file.swcrc.path
+                swcrc_directory = paths.dirname(swcrc_path)
+                args.add_all([
+                    "--config-file",
+                    swcrc_path,
+                ])
+
+                # TODO(greg): determine if this is needed, given that relativize below should provide a correct path
+                # if not src_path.startswith(swcrc_directory):
+                #     fail("sources must be in swcrc directory or subdirectory if swcrc is specified")
+                src_path = paths.relativize(src_path, swcrc_directory)
+
+            args.add_all([
+                src_path,
+                "--out-file",
+                js_out.path,
+                "--no-swcrc",
+                "-q",
+            ])
+
+            ctx.actions.run(
+                inputs = [src] + ctx.toolchains["@aspect_rules_swc//swc:toolchain_type"].swcinfo.tool_files,
+                arguments = [args],
+                outputs = outs,
+                env = {
+                    # Our patch for @swc/core uses this environment variable to locate the rust binding
+                    "SWC_BINARY_PATH": binding,
+                },
+                executable = ctx.executable.swc_cli,
+                progress_message = "Transpiling with swc %s [swc %s]" % (
+                    ctx.label,
+                    src.short_path,
+                ),
+            )
+
     providers = [
         DefaultInfo(
             files = depset(outputs),

swc/swc.bzl

@@ -20,13 +20,14 @@ def _is_supported_src(src):
             return True
     return False
 
-def swc(name, srcs = None, args = [], data = [], swcrc = None, source_maps = None, source_map_outputs = False, **kwargs):
+def swc(name, srcs = None, args = [], data = [], output_dir = False, swcrc = None, source_maps = None, source_map_outputs = False, **kwargs):
     """Execute the swc compiler
 
     Args:
         name: A name for the target
         srcs: source files, typically .ts files in the source tree
         data: runtime dependencies to be propagated in the runfiles
+        output_dir: whether to produce a directory output rather than individual files
         args: additional arguments to pass to swc cli, see https://swc.rs/docs/usage/cli
         source_maps: If set, the --source-maps argument is passed to the swc cli with the value.
           True/False are automaticaly converted to "true"/"false" string values the cli expects.
@@ -55,17 +56,20 @@ def swc(name, srcs = None, args = [], data = [], swcrc = None, source_maps = Non
     # Determine js & map outputs
     js_outs = []
     map_outs = []
-    for f in srcs:
-        if _is_supported_src(f):
-            js_outs.append(paths.replace_extension(f, ".js"))
-            if source_map_outputs:
-                map_outs.append(paths.replace_extension(f, ".js.map"))
+
+    if not output_dir:
+        for f in srcs:
+            if _is_supported_src(f):
+                js_outs.append(paths.replace_extension(f, ".js"))
+                if source_map_outputs:
+                    map_outs.append(paths.replace_extension(f, ".js.map"))
 
     _swc(
         name = name,
         srcs = srcs,
         js_outs = js_outs,
         map_outs = map_outs,
+        output_dir = output_dir,
         args = args,
         data = data,
         swcrc = swcrc,