6 files changed, 80 insertions, 0 deletions
diff --git a/cobol/BUILD b/cobol/BUILD
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/cobol/BUILD
diff --git a/cobol/def.bzl b/cobol/def.bzl
new file mode 100644
index 0000000..c78094b
--- /dev/null
+++ b/cobol/def.bzl
@@ -0,0 +1,5 @@
+"""Public definitions for rules_cobol"""
+
+load("//cobol/internal:rules.bzl", _cobol_binary = "cobol_binary")
+
+cobol_binary = _cobol_binary
diff --git a/cobol/deps.bzl b/cobol/deps.bzl
new file mode 100644
index 0000000..baaf611
--- /dev/null
+++ b/cobol/deps.bzl
@@ -0,0 +1,22 @@
+"""Macro for declaring repository dependencies"""
+
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
+def cobol_rules_dependencies():
+    """Declares the external repostories that rules_cobol depends on."""
+
+    _maybe(
+        http_archive,
+        name = "bazel_skylib",
+        urls = [
+            "https://mirror.bazel.build/github.com/bazelbuild/bazel-skylib/releases/download/1.0.2/bazel-skylib-1.0.2.tar.gz",
+            "https://github.com/bazelbuild/bazel-skylib/releases/download/1.0.2/bazel-skylib-1.0.2.tar.gz",
+        ],
+        sha256 = "97e70364e9249702246c0e9444bccdc4b847bed1eb03c5a3ece4f83dfe6abc44",
+    )
+
+def _maybe(rule, name, **kwargs):
+    """Declares an external repository if it has not been declared already."""
+
+    if name not in native.existing_rules():
+        rule(name = name, **kwargs)
diff --git a/cobol/internal/BUILD b/cobol/internal/BUILD
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/cobol/internal/BUILD
diff --git a/cobol/internal/actions.bzl b/cobol/internal/actions.bzl
new file mode 100644
index 0000000..a57bd58
--- /dev/null
+++ b/cobol/internal/actions.bzl
@@ -0,0 +1,23 @@
+"""Common functions for creating actions to build COBOL programs"""
+
+load("@bazel_skylib//lib:shell.bzl", "shell")
+
+def cobol_compile_executable(ctx, srcs, out):
+    """Compiles a single COBOL program from sources
+    
+    Args:
+        ctx: the build context
+        srcs: the source files to compile
+        out: the output file
+    """
+
+    ctx.actions.run_shell(
+        outputs = [out],
+        inputs = srcs,
+        command = "cobc -x -o {out} {srcs}".format(
+            out = shell.quote(out.path),
+            srcs = " ".join([shell.quote(src.path) for src in srcs]),
+        ),
+        mnemonic = "COBOLCompile",
+        use_default_shell_env = True,
+    )
diff --git a/cobol/internal/rules.bzl b/cobol/internal/rules.bzl
new file mode 100644
index 0000000..8dac747
--- /dev/null
+++ b/cobol/internal/rules.bzl
@@ -0,0 +1,30 @@
+"Rules for building COBOL programs"
+
+load(":actions.bzl", "cobol_compile_executable")
+
+def _cobol_binary_impl(ctx):
+    prefix = ctx.label.name + "%/"
+    executable = ctx.actions.declare_file(prefix + ctx.label.name)
+
+    cobol_compile_executable(
+        ctx,
+        srcs = ctx.files.srcs,
+        out = executable,
+    )
+
+    return [DefaultInfo(
+        files = depset([executable]),
+        executable = executable,
+    )]
+
+cobol_binary = rule(
+    _cobol_binary_impl,
+    attrs = {
+        "srcs": attr.label_list(
+            allow_files = True,
+            doc = "The COBOL source files to compile for this binary",
+        ),
+    },
+    doc = "Builds an executable program from COBOL source code",
+    executable = True,
+)