diff --git a/README.md b/README.md index 9fd23c2..1f0ed5c 100644 --- a/README.md +++ b/README.md @@ -12,7 +12,7 @@ This is not an officially supported Google product. ## Preparation ### Update your workspace -Load the bazel_rules in your [`WORKSPACE` file][be_workspace]: +Load the **bazel_rules** in your [`WORKSPACE` file][be_workspace]: load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository") @@ -39,18 +39,31 @@ Load the bazel_rules in your [`WORKSPACE` file][be_workspace]: Then, this rule can be used as one of the `srcs` of another rules, such as a `java_library`. -## Example - The example "jflex.examples.helloworld" generates a lexer from `helloworld.flex` with: +### Attributes + +* **name** (Name; required) + Unique name for this target. +* **srcs** (List of labels; required) + List of flex specifications. +* **outputs** (list of labels; required) + List of the generated java files. +* **skeleton** (Label; optional) + Skeleton use by the JFlex Emitter. **Only use this option if you know what you are doing.** + + +### Example + +The example **//java/jflex/examples/helloworld** generates a lexer from `helloworld.flex` with: jflex( name = "gen_hello_lexer", srcs = ["helloworld.flex"], outputs = ["HelloWorld.java"], ) + +See [//java/jflex/examples/helloworld](/java/jflex/examples/helloworld) for more information. - See `java/jflex/examples/helloworld`. - - ## Directory layout +## Directory layout ``` ├── assets → assets for the web site ├── java → main Java source code diff --git a/java/jflex/examples/helloworld/README.md b/java/jflex/examples/helloworld/README.md new file mode 100644 index 0000000..d0bc383 --- /dev/null +++ b/java/jflex/examples/helloworld/README.md @@ -0,0 +1,118 @@ +# Hello World + +## Generate the lexer + +Example usage of the `jflex()` rule itself: + + jflex( + name = "gen_hello_lexer", + srcs = ["helloworld.flex"], + outputs = ["HelloWorld.java"], + visibility = ["//visibility:private"], + ) + +Invoke this target: + + blaze build //java/jflex/examples/helloworld:gen_hello_lexer + + +**Tip** The Bazel commands work from any directory within the workspace. + +**Expected output:** + +* (`examples/`)`bazel-genfiles/java/jflex/examples/helloworld/Yylex.java` + Java code generated from the flex file. + + +## Build + +The output (generated Java sources) of the `jflex()` rule can be reused in other targets, for +instance as the source of a `java_library()`: + + java_library( + name = "helloworld", + srcs = [":gen_hello_lexer"], + ) + +Generate the Java library + + blaze build //java/jflex/examples/helloworld:helloworld + +**Tip:** Since ":helloworld" depends on ":gen_hello_lexer", you don't need to invoke the previous +target manually. This is true for any target. + +**Tip** Since the target name is the same as the last part of the path, you can use the short form +`//java/jflex/examples/helloworld`. + +**Expected output:** + +* (`examples/`)`bazel-bin/java/jflex/examples/helloworld/libhelloworld.jar` + The Java archive containing the HelloWorld class + + +## Run + +From a `java_library()`, it's easy to build an executable with the `java_binary()` rule: + + java_binary( + name = "helloworld_bin", + main_class = "jflex.examples.helloworld.HelloWorld", + runtime_deps = [":helloworld"], + ) + +To build the executable: + + bazel build //java/jflex/examples/helloworld:helloworld_bin + +To run this sample program: + + bazel run //java/jflex/examples/helloworld:helloworld_bin + +Everything works, but the program complains that no input file was provided: + +> Usage : java HelloWorld [ --encoding ] + +We provide a sample input file in `javatest/flex/examples/helloworld/data/test.txt` with the +following content: + +``` +hello +name John Doe +hello +``` + +You can pass arguments to the program after `--`. +Hence you can invoke: + + bazel run //java/jflex/examples/helloworld:helloworld_bin -- /full/path/to/javatests/jflex/examples/helloworld/testdata.txt + +You should see + +> Hello World! +> Hello John Doe! + +**N.B.** Relative paths don't work in `bazel run`. + +Alternatively, you can use the generated artifact. From the `examples` directory: + + bazel-bin/java/jflex/examples/helloworld/helloworld_bin javatests/jflex/examples/helloworld/testdata.txt + + + +## Test + +To execute the tests + + blaze test //javatests/jflex/examples/helloworld/... + +In this sample, there is only one test: + +- `//javatests/jflex/examples/helloworld:HelloWorldTest` + +The example: + +1. Creates an in-memory OutputStream +2. Redirects `System.out` to this in-memory stream +3. Calls the `main` method of the `HelloWorld` lexer +4. Compares line by line the content of the in-memory output + with a hard-coded string that contains the expected output. diff --git a/javatests/jflex/examples/helloworld/README.md b/javatests/jflex/examples/helloworld/README.md new file mode 100644 index 0000000..484a1ae --- /dev/null +++ b/javatests/jflex/examples/helloworld/README.md @@ -0,0 +1,3 @@ +# Hello World test + +Please read [//java/jflex/examples/helloworld:README.md](/java/jflex/examples/helloworld/README.md).