Add LaTeX support

README.md

@@ -26,6 +26,7 @@ Options:
                         Use only this section from the configuration
   --strict              Disallow undefined variables to be used within the
                         template
+  --latex               Use markers that are compatible with LaTeX
 ```
 
 ## Optional YAML support
@@ -43,6 +44,30 @@ If `xmltodict` is present, you can use XML as an input data source.
 
 `$ pip install jinja2-cli[xml]`
 
+## LaTeX support
+The default markers used by Jinja2 are incompatible with LaTeX, as explained
+in blog posts by [Brad Erickson] and [Arthur Miller]. The option `--latex`
+changes the default markers to the following ones by passing , which are compatible with
+LaTeX and do not require any special escaping.
+
+| Default markers       | LaTeX mode        | Jinja2 env settings     |
+| :-------------------- | :---------------- | :---------------------- |
+| `{%` ... `%}`         | `\BLOCK{` ... `}` | `block_*_string`        |
+| `{{` ... `}}`         |  `\VAR{`... `}`   | `variable_*_string`     |
+| `{#` ... `#}`         |  `\#{` ... `}`    | `comment_*_string`      |
+|	*disabled by default* | `%%`              | `line_statement_prefix` |
+|	*disabled by default* | `%#`              | `line_comment_prefix`   |
+
+In addition, the option `trim_blocks` is set to true, and `autoescape` set to
+false.
+
+Example usage:
+```
+jinja2 --latex samples/sample.tex samples/sample.json
+```
+
+[Brad Erickson]: http://eosrei.net/articles/2015/11/latex-templates-python-and-jinja2-generate-pdfs
+[Arthur Miller]: https://miller-blog.com/latex-with-jinja2/
 ## TODO
  * Variable inheritance and overrides
   * Tests!

jinja2cli/cli.py

@@ -212,12 +212,13 @@ def _parse_env(data):
 }
 
 
-def render(template_path, data, extensions, strict=False):
+def render(template_path, data, extensions, env_options, strict=False):
     from jinja2 import Environment, FileSystemLoader, StrictUndefined
 
     env = Environment(
         loader=FileSystemLoader(os.path.dirname(template_path)),
         extensions=extensions,
+        **env_options,
         keep_trailing_newline=True,
     )
     if strict:
@@ -300,6 +301,23 @@ def cli(opts, args):
             sys.stderr.write("ERROR: unknown section. Exiting.")
             return 1
 
+    # Set up environment options suitable to use LaTeX templates
+    if opts.latex:
+        env_options = dict(
+            block_start_string = '\BLOCK{',
+            block_end_string = '}',
+            variable_start_string = '\VAR{',
+            variable_end_string = '}',
+            comment_start_string = '\#{',
+            comment_end_string = '}',
+            line_statement_prefix = '%%',
+            line_comment_prefix = '%#',
+            trim_blocks = True,
+            autoescape = False)
+
+    else:
+        env_options = dict()
+
     data.update(parse_kv_string(opts.D or []))
 
     if opts.outfile is None:
@@ -312,7 +330,7 @@ def cli(opts, args):
 
         out = codecs.getwriter("utf8")(out)
 
-    out.write(render(template_path, data, extensions, opts.strict))
+    out.write(render(template_path, data, extensions, env_options, opts.strict))
     out.flush()
     return 0
 
@@ -398,6 +416,15 @@ def main():
         dest="strict",
         action="store_true",
     )
+    parser.add_option(
+        # These marker types might be compatible with TeX, too, so --tex
+        # might be more accurate (but also harder to find)
+        "--latex",
+        "--tex",
+        help="Use variable/block/... markers that are compatible with LaTeX",
+        dest="latex",
+        action="store_true",
+    )
     parser.add_option(
         "-o",
         "--outfile",

samples/sample.tex

@@ -0,0 +1,11 @@
+\documentclass{article}
+
+\begin{document}
+
+\begin{itemize}
+\BLOCK{ for i in items }
+  \item \VAR{i}
+\BLOCK{ endfor }
+\end{itemize}
+
+\end{document}