Closure Tools for Bazel

Overview

These rules define targets for JavaScript, stylesheets, and templates that will be compiled with the Closure Tools toolchain. The following rules are defined:

• closure_js_binary
• closure_js_library
• closure_stylesheet_library
• closure_template_library

Setup

The rules defined in //tools/build_rules/closure/closure.WORKSPACE must be copied into your WORKSPACE file before using these rules. These rules define the locations of the various Closure Tools binaries.

You must also have a local copy of the Closure Library source code and reference the path in your WORKSPACE file. The following commands provide an example of how this can be accomplished:

mkdir -p src/github/google
pushd src/github/google
git clone https://github.com/google/closure-library.git
popd

Finally, modify your WORKSPACE file:

new_local_repository(
    name = "closure_library",
    build_file = "tools/build_rules/closure/closure_library.BUILD",
    path = "/home/user/src/github/google/closure-library",
)

Usage

Suppose we are building a web application with template, stylesheet, and JavaScript files: hello.soy, hello.gss, and hello.js.

hello.soy

{namespace hello.templates autoescape="strict"}

/**
 * Renders an element containing the text "hello".
 */
{template .hello}
  <div class="{css hello-container}">Hello.</div>
{/template}

hello.gss

.hello-container {
  color: red;
  font-weight: bold;
}

hello.js

goog.provide('hello');

goog.require('goog.soy');
goog.require('hello.templates');

goog.soy.renderElement(document.body, hello.templates.hello);

We can create a BUILD file to compile these and produce two files:

• hello_combined.css
• hello_combined.js

BUILD

load("/tools/build_rules/closure/closure_js_binary", "closure_js_binary")
load("/tools/build_rules/closure/closure_js_library", "closure_js_library")
load("/tools/build_rules/closure/closure_stylesheet_library", "closure_stylesheet_library")
load("/tools/build_rules/closure/closure_template_library", "closure_template_library")

closure_js_binary(
    name = "hello",
    main = "hello",
    deps = [":hello_lib"],
)

closure_js_library(
    name = "hello_lib",
    srcs = ["hello.js"],
    deps = [
        "@closure_library//:closure_library",
        "@closure_templates//:closure_templates_js",
        ":hello_css",
        ":hello_soy",
    ]
)

closure_stylesheet_library(
    name = "hello_css",
    srcs = ["hello.gss"],
    deps = ["@closure_library//:closure_library_css"],
)

closure_template_library(
    name = "hello_soy",
    srcs = ["hello.soy"],
)

Known Issues

The version of the Closure Templates compiler that is used will emit warnings about an invalid JSDOc tag (@notypecheck) and about a missing enum value. These issues have been fixed in the source, but are not yet available as a downloadable archive. These warnings are safe to ignore.

You may define a new_local_repository target if you wish to check out the source from Github yourself. Otherwise you may wish to wait until the Closure tools are available as Bazel workspaces.