Experiment with outputs DO NOT MERGE

examples/postcss-sprites/BUILD

@@ -0,0 +1,14 @@
+load("//internal:binary.bzl", "postcss_binary")
+
+postcss_binary(
+    name = "style_processed",
+    src = "style.css",
+    plugins = {
+        "postcss-sprites": "[{spritePath: './bazel-out/darwin-fastbuild/bin/examples/postcss-sprites', verbose: true}]",
+    },
+    data = ["green.png", "red.png"],
+    additional_outputs = ["sprite.png"],
+    deps = [
+        "@npm//postcss-sprites",
+    ],
+)

examples/postcss-sprites/style.css

@@ -0,0 +1,2 @@
+.red { background: url(red.png) no-repeat 0 0; }
+.green { background: url(green.png) no-repeat 0 0; }

internal/binary.bzl

@@ -27,6 +27,8 @@ def postcss_binary(
         plugins,
         deps,
         src,
+        data = [],
+        additional_outputs = [],
         output_name = "",
         map_annotation = False,
         visibility = None):
@@ -39,6 +41,8 @@ def postcss_binary(
             for each respective plugin.
         deps: A list of NodeJS modules the config depends on. The PostCSS module
             is always implicitly included.
+        data: Foo
+        additional_outputs: Foo
         src: The input .css, and optionally .css.map files. (This includes
             outputs from preprocessors such as sass_binary.)
         output_name: Output name.
@@ -54,14 +58,19 @@ def postcss_binary(
         name = runner_name,
         plugins = plugins,
         deps = deps,
+        data = data,
         map_annotation = map_annotation,
         visibility = ["//visibility:private"],
     )
 
+    output_name = output_name or "%s.css" % name
     postcss_run(
         name = name,
         src = src,
-        output_name = output_name,
+        data = data,
+        output_css = output_name,
+        output_css_map = "%s.map" % output_name,
+        additional_outputs = additional_outputs,
         runner = runner_name,
         visibility = visibility,
     )

internal/gen_runner.bzl

@@ -54,6 +54,10 @@ postcss_runner_src = rule(
             allow_single_file = [".js"],
             mandatory = True,
         ),
+        "data": attr.label_list(
+            allow_files = True,
+            mandatory = False,
+        ),
     },
     outputs = {
         "postcss_runner_src": "%{name}.js",
@@ -65,6 +69,7 @@ def postcss_gen_runner(
         plugins,
         deps,
         map_annotation,
+        data = [],
         visibility = None):
     """Generates a PostCSS runner binary.
 
@@ -80,6 +85,7 @@ def postcss_gen_runner(
         map_annotation: Whether to add (or modify, if already existing) the
             sourceMappingURL comment in the output .css to point to the output
             .css.map.
+        data: Foo
         visibility: The visibility of the build rule.
     """
 
@@ -89,6 +95,7 @@ def postcss_gen_runner(
         name = runner_src_name,
         plugins = plugins,
         map_annotation = map_annotation,
+        data = data,
         template = "//internal:runner-template.js",
         visibility = ["//visibility:private"],
     )
@@ -100,5 +107,6 @@ def postcss_gen_runner(
             "@npm//minimist",
             "@npm//postcss",
         ] + deps,
+        data = data,
         visibility = visibility,
     )

internal/run.bzl

@@ -47,44 +47,45 @@ def _postcss_run_impl(ctx):
     # Generate the command line.
     args = [
         "--cssFile=%s" % css_file.path,
-        "--outCssFile=%s" % ctx.outputs.css_file.path,
-        "--outCssMapFile=%s" % ctx.outputs.css_map_file.path,
+        "--outCssFile=%s" % ctx.outputs.output_css.path,
+        "--outCssMapFile=%s" % ctx.outputs.output_css_map.path,
     ]
     if css_map_file:
         args.append("--cssMapFile=%s" % css_map_file.path)
 
+    for out in ctx.outputs.additional_outputs:
+        print(out.path)
+
     # The command may only access files declared in inputs.
-    inputs = [css_file] + ([css_map_file] if css_map_file else [])
+    inputs = [css_file] + ([css_map_file] if css_map_file else []) + (ctx.files.data if ctx.files.data else [])
 
     ctx.actions.run(
-        outputs = [ctx.outputs.css_file, ctx.outputs.css_map_file],
+        outputs = [ctx.outputs.output_css, ctx.outputs.output_css_map] + ctx.outputs.additional_outputs,
         inputs = inputs,
         executable = ctx.executable.runner,
         arguments = args,
         progress_message = "Running PostCSS runner on %s" % ctx.attr.src.label,
     )
 
-def _postcss_run_outputs(output_name):
-    output_name = output_name or "%{name}.css"
-    return {
-        "css_file": output_name,
-        "css_map_file": "%s.map" % output_name,
-    }
-
 postcss_run = rule(
     implementation = _postcss_run_impl,
     attrs = {
         "src": attr.label(
             allow_files = [".css", ".css.map"],
             mandatory = True,
         ),
-        "output_name": attr.string(default = ""),
+        "data": attr.label_list(
+            allow_files = True,
+            mandatory = False,
+        ),
+        "output_css": attr.output(mandatory = True),
+        "output_css_map": attr.output(mandatory = True),
+        "additional_outputs": attr.output_list(),
         "runner": attr.label(
             executable = True,
             cfg = "host",
             allow_files = True,
             mandatory = True,
         ),
     },
-    outputs = _postcss_run_outputs,
 )

internal/runner-template.js

@@ -45,10 +45,18 @@ const options = {
   }
 };
 
+const testFolder = './';
+fs.readdirSync(testFolder).forEach(file => {
+  console.log('File: '+file);
+});
+
 postcss(TEMPLATED_plugins)
     .process(cssString, options)
     .then(
         result => {
+          console.log('cwd', process.cwd());
+          console.log('will write to', args.outCssFile);
+          console.log('which is the same as', require('path').resolve(args.outCssFile));
           fs.writeFileSync(args.outCssFile, result.css);
           if (result.map) {
             fs.writeFileSync(args.outCssMapFile, result.map);

internal/runner_bin.bzl

@@ -24,19 +24,21 @@ def postcss_runner_bin(
         name,
         src,
         deps,
+        data = [],
         visibility = None):
     """Convenience helper for using nodejs_binary with the PostCSS runner.
 
     Args:
         name: The name of the build rule.
         src: The source file and entry point of the nodejs_binary.
         deps: What the nodejs_binary depends on.
+        data: Foo
         visibility: The visibility of the build rule.
     """
 
     nodejs_binary(
         name = name,
         entry_point = ":%s" % (src),
-        data = deps,
+        data = deps + data,
         visibility = visibility,
     )

package.json

@@ -7,6 +7,7 @@
         "autoprefixer": "9.4.3",
         "minimist": "1.2.0",
         "postcss": "7.0.7",
+        "postcss-sprites": "^4.2.1",
         "rtlcss": "^2.4.0",
         "typescript": "^3.7.2"
     },