"""Rule for simple expansion of template files. This performs a simple
search over the template file for the keys in substitutions,
and replaces them with the corresponding values.
Typical usage:
load("//tools/build_rules:expand_template.bzl", "expand_template")
expand_template(
name = "ExpandMyTemplate",
template = "my.template",
out = "my.txt",
substitutions = {
"$VAR1": "foo",
"$VAR2": "bar",
}
)
Args:
name: The name of the rule.
template: The template file to expand
out: The destination of the expanded file
substitutions: A dictionary mapping strings to their substitutions
is_executable: A boolean indicating whether the output file should be executable
"""
def expand_template_impl(ctx):
ctx.actions.expand_template(
template = ctx.file.template,
output = ctx.outputs.out,
substitutions = {
k: ctx.expand_location(v, ctx.attr.data)
for k, v in ctx.attr.substitutions.items()
},
is_executable = ctx.attr.is_executable,
)
expand_template = rule(
implementation = expand_template_impl,
attrs = {
"template": attr.label(mandatory = True, allow_single_file = True),
"substitutions": attr.string_dict(mandatory = True),
"out": attr.output(mandatory = True),
"is_executable": attr.bool(default = False, mandatory = False),
"data": attr.label_list(allow_files = True),
},
)