marcohu / rules_stringtemplate

StringTemplate rules for Bazel

StringTemplate Rules for Bazel

These build rules are used for processing StringTemplate templates with Bazel.

• Workspace Setup
  • Details
• Build Rules
  • Example

Workspace Setup

Add the following to your WORKSPACE file to include the external repository:

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

http_archive(
    name = "rules_stringtemplate",
    urls = ["https://github.com/marcohu/rules_stringtemplate/archive/0.1.0.tar.gz"],
    strip_prefix = "rules_stringtemplate-0.1.0",
    sha256 = "e8d7f9e7ff20e73a8c7e9af0b884a4afac15af26c7cb13d1cf916f634252c489",
)

To load the necessary dependencies, you can use the provided convenience function:

load("@rules_stringtemplate//stringtemplate:repositories.bzl", "rules_stringtemplate_dependencies")

rules_stringtemplate_dependencies("4.1")

More detailed instructions can be found in the Setup document.

Build Rules

To add StringTemplate code generation to your BUILD files, you first have to load the StringTemplate extension:

load("@rules_stringtemplate//stringtemplate:st4.bzl", "stringtemplate")

You can then invoke the rule:

stringtemplate(
    name = "hello",
    src = "hello.st",
    out = "messages/hello.txt",
    data = '{ "name": "World" }',
)

The necessary template attributes can be provided in different ways. You can use JSON files or inline data as shown above. Or you can employ a more code centric approach and specify a Java class that returns the attributes as a java.util.Map<String, Object>. This way it's possible to hook in existing POJOs, maybe with the help of model adaptors if objects don't follow the Java Bean naming convention and StringTemplate can't access their properties directly.

Refer to the rule reference documentation for the available attributes:

• StringTemplate 4 reference

Example

Suppose you have the following project structure:

st4/Controller
├── BUILD
├── hello.st
└── src
    └── main
        └── java
            └── hello
                ├── BUILD
                └── World.java
WORKSPACE

To provide the StringTemplate attributes through a controller, you have to add the target that builds the controller class as a dependency:

st4/Controller/BUILD

load("@rules_stringtemplate//stringtemplate:st4.bzl", "stringtemplate")

stringtemplate(
    name = "hello",
    src = "hello.st",
    out = "hello.txt",
    controller = "hello.World",
    deps = ["//st4/Controller/src/main/java/hello:world"],
)

To build the example you use:

$ bazel build //st4/Controller/...

The output would be something like this:

INFO: Analyzed 2 targets (22 packages loaded, 385 targets configured).
INFO: Found 2 targets...
INFO: Elapsed time: 12.869s, Critical Path: 7.60s
INFO: 7 processes: 5 processwrapper-sandbox, 2 worker.
INFO: Build completed successfully, 11 total actions

You can find this and other examples in the examples folder.