Phase Scalafmt (bazelbuild#912)

* Phase Scalafmt

* Reuse formatter

* Remove glob

* Remove rules_jvm_external

* Rename argparse

* Remove executable

* Use shared code

* Remove imports

* Add comment

* Change file name

* Move args to private function

* Change to true

* Change conf location

* Change default conf

* Test custom conf

* Fix lint

* Fix build

* Remove trailing commas

* Add formatted and unformatted folder

* Rename test function

* Remove template file

* Better handle failing case

* Drop argparser

* Remove resolve_command

* Add comments

* Remove unnecessary code

* Change to RUNPATH

* Rename gitignore backup

* Remove comment

* Move conf file

* Add doc to attribute

* Switch to match readme

* Add doc

* Move doc to separate md

* Fix wording

* Fix lint

* Add url

* Add url

.gitignore

@@ -7,3 +7,4 @@ hash2
 .bazel_cache
 .ijwb
 .metals
+unformatted-*.backup.scala

.scalafmt.conf

@@ -0,0 +1,15 @@
+align.openParenCallSite = false
+align.openParenDefnSite = false
+continuationIndent.defnSite = 2
+danglingParentheses = true
+docstrings = JavaDoc
+importSelectors = singleLine
+maxColumn = 120
+verticalMultiline.newlineBeforeImplicitKW = true
+rewrite.redundantBraces.stringInterpolation = true
+rewrite.rules = [
+  RedundantParens,
+  PreferCurlyFors,
+  SortImports
+]
+unindentTopLevelOperators = false

README.md

@@ -201,6 +201,9 @@ Phases provide 3 major benefits:
 
 See [Customizable Phase](docs/customizable_phase.md) for more info.
 
+### Phase extensions
+ - [Scala Format](docs/phase_scalafmt.md)
+
 ## Building from source
 Test & Build:
 ```

WORKSPACE

@@ -40,6 +40,12 @@ load("//specs2:specs2_junit.bzl", "specs2_junit_repositories")
 
 specs2_junit_repositories()
 
+load("//scala/scalafmt:scalafmt_repositories.bzl", "scalafmt_default_config", "scalafmt_repositories")
+
+scalafmt_default_config()
+
+scalafmt_repositories()
+
 load("//scala:scala_cross_version.bzl", "default_scala_major_version", "scala_mvn_artifact")
 
 MAVEN_SERVER_URLS = [

docs/phase_scalafmt.md

@@ -0,0 +1,43 @@
+# Phase Scalafmt
+
+## Contents
+*  [Overview](#overview)
+*  [How to set up](#how-to-set-up)
+
+## Overview
+A phase extension `phase_scalafmt` can format Scala source code via [Scalafmt](https://scalameta.org/scalafmt/).
+
+## How to set up
+Add this snippet to `WORKSPACE`
+```
+load("//scala/scalafmt:scalafmt_repositories.bzl", "scalafmt_default_config", "scalafmt_repositories")
+scalafmt_default_config()
+scalafmt_repositories()
+```
+
+To add this phase to a rule, you have to pass the extension to a rule macro. Take `scala_binary` for example,
+```
+load("//scala:advanced_usage/scala.bzl", "make_scala_binary")
+load("//scala/scalafmt:phase_scalafmt_ext.bzl", "ext_scalafmt")
+
+scalafmt_scala_binary = make_scala_binary(ext_scalafmt)
+```
+Then use `scalafmt_scala_binary` as normal.
+
+The extension adds 2 additional attributes to the rule
+ - `format`: enable formatting
+ - `config`: the Scalafmt configuration file
+
+When `format` is set to `true`, you can do
+```
+bazel run <TARGET>.format
+```
+to format the source code, and do
+```
+bazel run <TARGET>.format-test
+```
+to check the format (without modifying source code).
+
+The extension provides default configuration, but there are 2 ways to use custom configuration
+ - Put `.scalafmt.conf` at root of your workspace
+ - Pass `.scalafmt.conf` in via `config` attribute

scala/private/macros/scala_repositories.bzl

@@ -56,7 +56,10 @@ def scala_repositories(
             _default_scala_version(),
             _default_scala_version_jar_shas(),
         ),
-        maven_servers = ["https://repo.maven.apache.org/maven2"],
+        maven_servers = [
+            "https://repo.maven.apache.org/maven2",
+            "https://maven-central.storage-download.googleapis.com/maven2",
+        ],
         scala_extra_jars = _default_scala_extra_jars()):
     (scala_version, scala_version_jar_shas) = scala_version_shas
     major_version = _extract_major_version(scala_version)

scala/private/phases/phase_scalafmt.bzl

@@ -0,0 +1,68 @@
+#
+# PHASE: phase scalafmt
+#
+# Outputs to format the scala files when it is explicitly specified
+#
+def phase_scalafmt(ctx, p):
+    if ctx.attr.format:
+        manifest, files = _build_format(ctx)
+        _formatter(ctx, manifest, files, ctx.file._runner, ctx.outputs.scalafmt_runner)
+        _formatter(ctx, manifest, files, ctx.file._testrunner, ctx.outputs.scalafmt_testrunner)
+    else:
+        _write_empty_content(ctx, ctx.outputs.scalafmt_runner)
+        _write_empty_content(ctx, ctx.outputs.scalafmt_testrunner)
+
+def _build_format(ctx):
+    files = []
+    manifest_content = []
+    for src in ctx.files.srcs:
+        # only format scala source files, not generated files
+        if src.path.endswith(".scala") and src.is_source:
+            file = ctx.actions.declare_file("{}.fmt.output".format(src.short_path))
+            files.append(file)
+            ctx.actions.run(
+                arguments = ["--jvm_flag=-Dfile.encoding=UTF-8", _format_args(ctx, src, file)],
+                executable = ctx.executable._fmt,
+                outputs = [file],
+                inputs = [ctx.file.config, src],
+                execution_requirements = {"supports-workers": "1"},
+                mnemonic = "ScalaFmt",
+            )
+            manifest_content.append("{} {}".format(src.short_path, file.short_path))
+
+    # record the source path and the formatted file path
+    # so that we know where to copy the formatted file to replace the source file
+    manifest = ctx.actions.declare_file("format/{}/manifest.txt".format(ctx.label.name))
+    ctx.actions.write(manifest, "\n".join(manifest_content) + "\n")
+
+    return manifest, files
+
+def _formatter(ctx, manifest, files, template, output_runner):
+    ctx.actions.run_shell(
+        inputs = [template, manifest] + files,
+        outputs = [output_runner],
+        # replace %workspace% and %manifest% in template and rewrite it to output_runner
+        command = "cat $1 | sed -e s#%workspace%#$2# -e s#%manifest%#$3# > $4",
+        arguments = [
+            template.path,
+            ctx.workspace_name,
+            manifest.short_path,
+            output_runner.path,
+        ],
+        execution_requirements = {},
+    )
+
+def _write_empty_content(ctx, output_runner):
+    ctx.actions.write(
+        output = output_runner,
+        content = "",
+    )
+
+def _format_args(ctx, src, file):
+    args = ctx.actions.args()
+    args.add(ctx.file.config.path)
+    args.add(src.path)
+    args.add(file.path)
+    args.set_param_file_format("multiline")
+    args.use_param_file("@%s", use_always = True)
+    return args

scala/private/phases/phases.bzl

@@ -60,6 +60,7 @@ load("@io_bazel_rules_scala//scala/private:phases/phase_declare_executable.bzl",
 load("@io_bazel_rules_scala//scala/private:phases/phase_merge_jars.bzl", _phase_merge_jars = "phase_merge_jars")
 load("@io_bazel_rules_scala//scala/private:phases/phase_jvm_flags.bzl", _phase_jvm_flags = "phase_jvm_flags")
 load("@io_bazel_rules_scala//scala/private:phases/phase_coverage_runfiles.bzl", _phase_coverage_runfiles = "phase_coverage_runfiles")
+load("@io_bazel_rules_scala//scala/private:phases/phase_scalafmt.bzl", _phase_scalafmt = "phase_scalafmt")
 
 # API
 run_phases = _run_phases
@@ -129,3 +130,6 @@ phase_runfiles_common = _phase_runfiles_common
 phase_default_info_binary = _phase_default_info_binary
 phase_default_info_library = _phase_default_info_library
 phase_default_info_scalatest = _phase_default_info_scalatest
+
+# scalafmt
+phase_scalafmt = _phase_scalafmt

scala/scalafmt/BUILD

@@ -0,0 +1,36 @@
+load("//scala:scala.bzl", "scala_binary")
+
+filegroup(
+    name = "runner",
+    srcs = ["private/format.template.sh"],
+    visibility = ["//visibility:public"],
+)
+
+filegroup(
+    name = "testrunner",
+    srcs = ["private/format-test.template.sh"],
+    visibility = ["//visibility:public"],
+)
+
+scala_binary(
+    name = "scalafmt",
+    srcs = ["scalafmt/ScalafmtRunner.scala"],
+    main_class = "io.bazel.rules_scala.scalafmt.ScalafmtRunner",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//src/java/io/bazel/rulesscala/worker",
+        "@com_geirsson_metaconfig_core_2_11",
+        "@org_scalameta_parsers_2_11",
+        "@org_scalameta_scalafmt_core_2_11",
+    ],
+)
+
+load(
+    "//scala/scalafmt:phase_scalafmt_ext.bzl",
+    "scalafmt_singleton",
+)
+
+scalafmt_singleton(
+    name = "phase_scalafmt",
+    visibility = ["//visibility:public"],
+)

scala/scalafmt/phase_scalafmt_ext.bzl

@@ -0,0 +1,55 @@
+load(
+    "//scala:advanced_usage/providers.bzl",
+    _ScalaRulePhase = "ScalaRulePhase",
+)
+load(
+    "//scala/private:phases/phases.bzl",
+    _phase_scalafmt = "phase_scalafmt",
+)
+
+ext_scalafmt = {
+    "attrs": {
+        "config": attr.label(
+            allow_single_file = [".conf"],
+            default = "@scalafmt_default//:config",
+            doc = "The Scalafmt configuration file.",
+        ),
+        "format": attr.bool(
+            default = False,
+            doc = "Switch of enabling formatting.",
+        ),
+        "_fmt": attr.label(
+            cfg = "host",
+            default = "//scala/scalafmt",
+            executable = True,
+        ),
+        "_runner": attr.label(
+            allow_single_file = True,
+            default = "//scala/scalafmt:runner",
+        ),
+        "_testrunner": attr.label(
+            allow_single_file = True,
+            default = "//scala/scalafmt:testrunner",
+        ),
+    },
+    "outputs": {
+        "scalafmt_runner": "%{name}.format",
+        "scalafmt_testrunner": "%{name}.format-test",
+    },
+    "phase_providers": [
+        "//scala/scalafmt:phase_scalafmt",
+    ],
+}
+
+def _scalafmt_singleton_implementation(ctx):
+    return [
+        _ScalaRulePhase(
+            custom_phases = [
+                ("$", "", "scalafmt", _phase_scalafmt),
+            ],
+        ),
+    ]
+
+scalafmt_singleton = rule(
+    implementation = _scalafmt_singleton_implementation,
+)

scala/scalafmt/private/format-test.template.sh

@@ -0,0 +1,18 @@
+#!/bin/bash -e
+WORKSPACE_ROOT="${1:-$BUILD_WORKSPACE_DIRECTORY}"
+RUNPATH="${TEST_SRCDIR-$0.runfiles}"/%workspace%
+RUNPATH=(${RUNPATH//bin/ })
+RUNPATH="${RUNPATH[0]}"bin
+
+EXIT=0
+while read original formatted; do
+    if [[ ! -z "$original" ]] && [[ ! -z "$formatted" ]]; then
+        if ! cmp -s "$WORKSPACE_ROOT/$original" "$RUNPATH/$formatted"; then
+            echo $original
+            diff "$WORKSPACE_ROOT/$original" "$RUNPATH/$formatted" || true
+            EXIT=1
+        fi
+    fi
+done < "$RUNPATH"/%manifest%
+
+exit $EXIT

scala/scalafmt/private/format.template.sh

@@ -0,0 +1,14 @@
+#!/bin/bash -e
+WORKSPACE_ROOT="${1:-$BUILD_WORKSPACE_DIRECTORY}"
+RUNPATH="${TEST_SRCDIR-$0.runfiles}"/%workspace%
+RUNPATH=(${RUNPATH//bin/ })
+RUNPATH="${RUNPATH[0]}"bin
+
+while read original formatted; do
+    if [[ ! -z "$original" ]] && [[ ! -z "$formatted" ]]; then
+        if ! cmp -s "$WORKSPACE_ROOT/$original" "$RUNPATH/$formatted"; then
+            echo "Formatting $original"
+            cp "$RUNPATH/$formatted" "$WORKSPACE_ROOT/$original"
+        fi
+    fi
+done < "$RUNPATH"/%manifest%

scala/scalafmt/scalafmt/ScalafmtRunner.scala

@@ -0,0 +1,51 @@
+package io.bazel.rules_scala.scalafmt
+
+import io.bazel.rulesscala.worker.{GenericWorker, Processor};
+import java.io.File
+import java.nio.file.Files
+import org.scalafmt.Scalafmt
+import org.scalafmt.config.Config
+import org.scalafmt.util.FileOps
+import scala.annotation.tailrec
+import scala.collection.JavaConverters._
+import scala.io.Codec
+
+object ScalafmtRunner extends GenericWorker(new ScalafmtProcessor) {
+  def main(args: Array[String]) {
+    try run(args)
+    catch {
+      case x: Exception =>
+        x.printStackTrace()
+        System.exit(1)
+    }
+  }
+}
+
+class ScalafmtProcessor extends Processor {
+  def processRequest(args: java.util.List[String]) {
+    val argName = List("config", "input", "output")
+    val argFile = args.asScala.map{x => new File(x)}
+    val namespace = argName.zip(argFile).toMap
+
+    val source = FileOps.readFile(namespace.getOrElse("input", new File("")))(Codec.UTF8)
+
+    val config = Config.fromHoconFile(namespace.getOrElse("config", new File(""))).get
+    @tailrec
+    def format(code: String): String = {
+      val formatted = Scalafmt.format(code, config).get
+      if (code == formatted) code else format(formatted)
+    }
+
+    val output = try {
+      format(source)
+    } catch {
+      case e @ (_: org.scalafmt.Error | _: scala.meta.parsers.ParseException) => {
+        System.out.println("Unable to format file due to bug in scalafmt")
+        System.out.println(e.toString)
+        source
+      }
+    }
+
+    Files.write(namespace.getOrElse("output", new File("")).toPath, output.getBytes)
+  }
+}