Jinja2 template for textproto config format used by Bazel Buildfarm

textproto.jinja2

{#- 
This template attempts to produce an output that conforms to the 
notoriously poorly documented "textproto" (human-readable protobuf)
format, as used by Bazel Buildfarm for config files.
#}
{%- macro write_boolean(key, value) %}
  {%- if value is sameas true %}
{{ key }}: true
  {%- else %}
{{ key }}: false
  {%- endif %}
{%- endmacro %}

{%- macro write_number(key, value) %}
{{ key }}: {{ value }}
{%- endmacro %}

{%- macro write_string(key, value) %}
{{ key }}: "{{ value }}"
{%- endmacro %}

{%- macro write_default(key, value) %}
{{- write_string(key, value) }}
{%- endmacro %}

{%- macro write_value(key, value) %}
  {%- if value is boolean %}
{{- write_boolean(key, value) }}
  {%- elif value is number %}
{{- write_number(key, value) }}
  {%- elif value is string %}
{{- write_string(key, value) }}
  {%- else %}
{{- write_default(key, value) }}
  {%- endif %}
{%- endmacro %}

{%- macro write_config(config) %}
  {%- for key, value in config.items() %}
    {%- if value is mapping %}
{{ key }}: {
{{- write_config(value) | indent(2) }}
}
    {%- elif value is iterable and value is not string %}
      {%- for item in value %}
{{- write_config({key: item}) }}
      {%- endfor %}
    {%- else %}
{{- write_value(key, value) }}
    {%- endif %}
  {%- endfor %}
{%- endmacro %}
{{- write_config(config) }}