feat(whiskers): add read_file function (#217)

Co-authored-by: backwardspy <backwardspy@pigeon.life>

whiskers/README.md

@@ -169,6 +169,7 @@ These types are designed to closely match the [palette.json](https://github.com/
 | `css_rgba` | Convert a color to an RGBA CSS string | `css_rgba(color=red)` => `rgba(210, 15, 57, 1.00)` |
 | `css_hsl` | Convert a color to an HSL CSS string | `css_hsl(color=red)` => `hsl(347, 87%, 44%)` |
 | `css_hsla` | Convert a color to an HSLA CSS string | `css_hsla(color=red)` => `hsla(347, 87%, 44%, 1.00)` |
+| `read_file` | Read and include the contents of a file, path is relative to the template file | `read_file(path="abc.txt")` => `abc` |
 
 ### Filters
 

whiskers/src/functions.rs

@@ -1,4 +1,8 @@
-use std::collections::{BTreeMap, HashMap};
+use std::{
+    collections::{BTreeMap, HashMap},
+    fs,
+    path::PathBuf,
+};
 
 use crate::models::Color;
 
@@ -67,3 +71,19 @@ pub fn css_hsla(args: &HashMap<String, tera::Value>) -> Result<tera::Value, tera
     let color: css_colors::HSLA = (&color).into();
     Ok(tera::to_value(color.to_string())?)
 }
+
+pub fn read_file_handler(
+    template_directory: PathBuf,
+) -> impl Fn(&HashMap<String, tera::Value>) -> Result<tera::Value, tera::Error> {
+    move |args| -> Result<tera::Value, tera::Error> {
+        let path: String = tera::from_value(
+            args.get("path")
+                .ok_or_else(|| tera::Error::msg("path is required"))?
+                .clone(),
+        )?;
+        let path = template_directory.join(path);
+        let contents = fs::read_to_string(&path)
+            .map_err(|_| format!("Failed to open file {}", path.display()))?;
+        Ok(tera::to_value(contents)?)
+    }
+}

whiskers/src/main.rs

@@ -83,6 +83,8 @@ fn main() -> anyhow::Result<()> {
         .expect("args.template is guaranteed by clap to be set");
     let template_from_stdin = matches!(template.source, clap_stdin::Source::Stdin);
     let template_name = template_name(template);
+    let template_directory =
+        template_directory(template).context("Template file does not exist")?;
 
     let mut decoder = DecodeReaderBytes::new(
         template
@@ -149,7 +151,7 @@ fn main() -> anyhow::Result<()> {
     }
 
     // build the Tera engine
-    let mut tera = templating::make_engine();
+    let mut tera = templating::make_engine(&template_directory);
     tera.add_raw_template(&template_name, &doc.body)
         .context("Template is invalid")?;
 
@@ -258,6 +260,17 @@ fn template_name(template: &clap_stdin::FileOrStdin) -> String {
     }
 }
 
+fn template_directory(template: &clap_stdin::FileOrStdin) -> anyhow::Result<PathBuf> {
+    match &template.source {
+        clap_stdin::Source::Stdin => Ok(std::env::current_dir()?),
+        clap_stdin::Source::Arg(arg) => Ok(Path::new(&arg)
+            .canonicalize()?
+            .parent()
+            .expect("file path must have a parent")
+            .to_owned()),
+    }
+}
+
 fn template_is_compatible(template_opts: &TemplateOptions) -> bool {
     let whiskers_version = semver::Version::parse(env!("CARGO_PKG_VERSION"))
         .expect("CARGO_PKG_VERSION is always valid");

whiskers/src/templating.rs

@@ -1,3 +1,5 @@
+use std::path::Path;
+
 use indexmap::IndexMap;
 
 use crate::{filters, functions};
@@ -42,7 +44,7 @@ macro_rules! filter_example {
     };
 }
 
-pub fn make_engine() -> tera::Tera {
+pub fn make_engine(template_directory: &Path) -> tera::Tera {
     let mut tera = tera::Tera::default();
     tera.register_filter("add", filters::add);
     tera.register_filter("sub", filters::sub);
@@ -60,6 +62,10 @@ pub fn make_engine() -> tera::Tera {
     tera.register_function("css_rgba", functions::css_rgba);
     tera.register_function("css_hsl", functions::css_hsl);
     tera.register_function("css_hsla", functions::css_hsla);
+    tera.register_function(
+        "read_file",
+        functions::read_file_handler(template_directory.to_owned()),
+    );
     tera
 }
 
@@ -103,6 +109,13 @@ pub fn all_functions() -> Vec<Function> {
             description: "Convert a color to an HSLA CSS string".to_string(),
             examples: vec![function_example!(css_hsla(color=red) => "hsla(347, 87%, 44%, 1.00)")],
         },
+        Function {
+            name: "read_file".to_string(),
+            description:
+                "Read and include the contents of a file, path is relative to the template file"
+                    .to_string(),
+            examples: vec![function_example!(read_file(path="abc.txt") => "abc")],
+        },
     ]
 }
 

whiskers/tests/cli.rs

@@ -37,6 +37,18 @@ mod happy_path {
         ));
     }
 
+    /// Test that the CLI can render a template which uses read_file
+    #[test]
+    fn test_read_file() {
+        let mut cmd = Command::cargo_bin("whiskers").expect("binary exists");
+        let assert = cmd
+            .args(["tests/fixtures/read_file/read_file.tera", "-f", "latte"])
+            .assert();
+        assert
+            .success()
+            .stdout(include_str!("fixtures/read_file/read_file.md"));
+    }
+
     /// Test that the CLI can render a UTF-8 template file
     #[test]
     fn test_utf8() {
@@ -89,7 +101,7 @@ mod sad_path {
         cmd.arg("test/file/doesnt/exist");
         cmd.assert()
             .failure()
-            .stderr(predicate::str::contains("Failed to open template file"));
+            .stderr(predicate::str::contains("Template file does not exist"));
     }
 
     #[test]

whiskers/tests/fixtures/read_file/abc.txt

@@ -0,0 +1 @@
+Aute tempor minim eiusmod.

whiskers/tests/fixtures/read_file/read_file.md

@@ -0,0 +1,23 @@
+Aute tempor minim eiusmod.
+
+MIT License
+
+Copyright (c) 2021 Catppuccin
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

whiskers/tests/fixtures/read_file/read_file.tera

@@ -0,0 +1,7 @@
+---
+whiskers:
+  version: 2.0.0
+---
+
+{{- read_file(path="abc.txt") }}
+{{ read_file(path="../../../LICENSE") -}}