Use the Go Jsonnet port instead of the C++ port (#113)

* Use the Go Jsonnet port instead of the C++ port

* Allow use of the C++ port via command-line flag

By default, Bazel will use the Go port of Jsonnet. To use the C++ port
of Jsonnet instead, invoke Bazel with the "--define jsonnet_port=cpp"
command-line flag. To select the Go port explicitly, invoke Bazel with
the "--define jsonnet_port=go" command-line flag.

* Change default Jsonnet port back from Go to C++

Retain use of C++ as the default port for one more release, with the
intention to change the default to the Go port and eventually remove
support for the C++ port.

* Use the latest version of the Jsonnet Go port

The selected commit is the latest along the "master" branch as of 24
August 2019.

README.md

@@ -25,15 +25,37 @@ external repositories for Jsonnet:
 ```python
 http_archive(
     name = "io_bazel_rules_jsonnet",
+    # TODO: Update this to reflect a later release.
     sha256 = "59bf1edb53bc6b5adb804fbfabd796a019200d4ef4dd5cc7bdee03acc7686806",
     strip_prefix = "rules_jsonnet-0.1.0",
     urls = ["https://github.com/bazelbuild/rules_jsonnet/archive/0.1.0.tar.gz"],
 )
 load("@io_bazel_rules_jsonnet//jsonnet:jsonnet.bzl", "jsonnet_repositories")
 
 jsonnet_repositories()
+
+load("@jsonnet_go//bazel:repositories.bzl", "jsonnet_go_repositories")
+
+jsonnet_go_repositories()
+
+load("@jsonnet_go//bazel:deps.bzl", "jsonnet_go_dependencies")
+
+jsonnet_go_dependencies()
 ```
 
+## Jsonnet Port Selection
+
+By default, Bazel will use [the C++ port](https://github.com/google/jsonnet) of Jsonnet. To use [the Go port](https://github.com/google/go-jsonnet) of Jsonnet instead, invoke Bazel with the `--define jsonnet_port=go` command-line flag. To select the C++ port explicitly, invoke Bazel with the `--define jsonnet_port=cpp` command-line flag.
+
+_bazel_ Flag | Jsonnet Port
+------------ | ------------
+(none)                     | C++
+`--define jsonnet_port=cpp`| C++
+`--define jsonnet_port=go` | Go
+
+Note that the primary development focus of the Jsonnet project is now with the Go port. This repository's support for using the C++ port is deprecated, and may be removed in a future release. Before then, its default port will likely change from C++ to Go in the next release.
+
+
 <a name="#jsonnet_library"></a>
 ## jsonnet_library
 

WORKSPACE

@@ -17,6 +17,14 @@ load("//jsonnet:jsonnet.bzl", "jsonnet_repositories")
 
 jsonnet_repositories()
 
+load("@jsonnet_go//bazel:repositories.bzl", "jsonnet_go_repositories")
+
+jsonnet_go_repositories()
+
+load("@jsonnet_go//bazel:deps.bzl", "jsonnet_go_dependencies")
+
+jsonnet_go_dependencies()
+
 # Used for documenting Jsonnet rules.
 # TODO: Move this to docs/WORKSPACE when recursive repositories are enabled.
 git_repository(

examples/BUILD

@@ -7,7 +7,6 @@ package(default_visibility = ["//visibility:public"])
 load(
     "@io_bazel_rules_jsonnet//jsonnet:jsonnet.bzl",
     "jsonnet_library",
-    "jsonnet_to_json",
     "jsonnet_to_json_test",
 )
 
@@ -51,6 +50,7 @@ jsonnet_to_json_test(
     src = "invalid.jsonnet",
     error = 1,
     golden = "invalid.out",
+    regex = 1,
 )
 
 jsonnet_to_json_test(

examples/invalid.out

@@ -1,2 +1,3 @@
-RUNTIME ERROR: Foo.
-	../examples/invalid.jsonnet:15:1-13	
+^RUNTIME ERROR: Foo\.
+	../examples/invalid\.jsonnet:15:1-13	($|\$
+	During evaluation	)

jsonnet/BUILD

@@ -8,3 +8,25 @@ py_binary(
     main = "stamper.py",
     visibility = ["//visibility:public"],
 )
+
+config_setting(
+    name = "port_cpp",
+    define_values = {
+        "jsonnet_port": "cpp",
+    },
+)
+
+config_setting(
+    name = "port_go",
+    define_values = {
+        "jsonnet_port": "go",
+    },
+)
+
+alias(
+    name = "jsonnet_tool",
+    actual = select({
+        "//jsonnet:port_go": "@jsonnet_go//cmd/jsonnet",
+        "//conditions:default": "@jsonnet//cmd:jsonnet",
+    }),
+)

jsonnet/jsonnet.bzl

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
 """Jsonnet Rules
@@ -288,7 +289,7 @@ _REGEX_DIFF_COMMAND = """
 GOLDEN_REGEX=$(%s %s)
 if [[ ! "$OUTPUT" =~ $GOLDEN_REGEX ]]; then
   echo "FAIL (regex mismatch): %s"
-  if [ %s = true]; then
+  if [ %s = true ]; then
     echo "Output: $OUTPUT"
   fi
   exit 1
@@ -412,7 +413,7 @@ _jsonnet_common_attrs = {
     ),
     "imports": attr.string_list(),
     "jsonnet": attr.label(
-        default = Label("@jsonnet//cmd:jsonnet"),
+        default = Label("//jsonnet:jsonnet_tool"),
         cfg = "host",
         executable = True,
         allow_single_file = True,
@@ -806,3 +807,10 @@ def jsonnet_repositories():
             "https://github.com/google/jsonnet/archive/v0.13.0.tar.gz",
         ],
     )
+    git_repository(
+        name = "jsonnet_go",
+        remote = "https://github.com/google/go-jsonnet",
+        commit = "13437c69e1834da8ca99dc8471adc97d0eb776d5",
+        init_submodules = True,
+        shallow_since = "1566677218 +0200",
+    )