From 3d2b68b0b19f3ab284147d5d85003ee2463e902a Mon Sep 17 00:00:00 2001
From: Adrien Burgun <adrien.burgun@orange.fr>
Date: Wed, 27 Jul 2022 12:55:22 +0200
Subject: [PATCH] :sparkles: Use a generic method for handling partials

This fixes a few issues:
- https://github.com/nickel-org/rust-mustache/issues/67
- https://github.com/nickel-org/rust-mustache/issues/62 (by implementing
  a custom PartialLoader without the set_extension)

But it also adds a lot of complexity and breaks previous code.
---
 Cargo.toml        |   5 +-
 README.md         |   2 +-
 src/compiler.rs   |  67 ++++++++++--------------
 src/context.rs    | 128 +++++++++++++++++++++++++++++++++++-----------
 src/lib.rs        |  13 ++---
 src/template.rs   |  18 +++----
 tests/template.rs |   8 +--
 7 files changed, 147 insertions(+), 94 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 4586cea..8d6d94d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,9 +3,10 @@ name = "mustache"
 description = "Rust implementation of Mustache"
 repository = "https://github.com/nickel-org/rust-mustache"
 documentation = "http://nickel-org.github.io/rust-mustache"
-version = "0.9.0"
-authors = ["erick.tryzelaar@gmail.com"]
+version = "0.10.0"
+authors = ["erick.tryzelaar@gmail.com", "Shad Amethyst <adrien.burgun@orange.fr>"]
 license = "MIT/Apache-2.0"
+autotests = false
 
 [features]
 unstable = []
diff --git a/README.md b/README.md
index 89755a3..50ccca0 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-Mustache [![Ohloh statistics](http://www.ohloh.net/p/rust-mustache/widgets/project_thin_badge.gif)](https://www.ohloh.net/p/rust-mustache) [![Build Status](http://travis-ci.org/nickel-org/rust-mustache.png?branch=master)](https://travis-ci.org/nickel-org/rust-mustache) [![](http://meritbadge.herokuapp.com/mustache)](https://crates.io/crates/mustache)
+Mustache (customization fork)
 ========
 
 Inspired by [ctemplate][1] and [et][2], [Mustache][3] is a framework-agnostic way
diff --git a/src/compiler.rs b/src/compiler.rs
index b40e558..9acdc5a 100644
--- a/src/compiler.rs
+++ b/src/compiler.rs
@@ -4,24 +4,24 @@ use std::io::Read;
 use std::fs::File;
 
 use parser::{Parser, Token};
-use super::Context;
+use super::{Context, PartialLoader};
 
 use Result;
 
 pub type PartialsMap = HashMap<String, Vec<Token>>;
 
 /// `Compiler` is a object that compiles a string into a `Vec<Token>`.
-pub struct Compiler<T> {
-    ctx: Context,
+pub struct Compiler<T, P: PartialLoader> {
+    ctx: Context<P>,
     reader: T,
     partials: PartialsMap,
     otag: String,
     ctag: String,
 }
 
-impl<T: Iterator<Item = char>> Compiler<T> {
+impl<T: Iterator<Item = char>, P: PartialLoader> Compiler<T, P> {
     /// Construct a default compiler.
-    pub fn new(ctx: Context, reader: T) -> Compiler<T> {
+    pub fn new(ctx: Context<P>, reader: T) -> Compiler<T, P> {
         Compiler {
             ctx: ctx,
             reader: reader,
@@ -32,12 +32,13 @@ impl<T: Iterator<Item = char>> Compiler<T> {
     }
 
     /// Construct a default compiler.
-    pub fn new_with(ctx: Context,
-                    reader: T,
-                    partials: PartialsMap,
-                    otag: String,
-                    ctag: String)
-                    -> Compiler<T> {
+    pub fn new_with(
+        ctx: Context<P>,
+        reader: T,
+        partials: PartialsMap,
+        otag: String,
+        ctag: String
+    ) -> Compiler<T, P> {
         Compiler {
             ctx: ctx,
             reader: reader,
@@ -56,38 +57,26 @@ impl<T: Iterator<Item = char>> Compiler<T> {
 
         // Compile the partials if we haven't done so already.
         for name in partials.into_iter() {
-            let path =
-                self.ctx.template_path.join(&(name.clone() + "." + &self.ctx.template_extension));
-
             if !self.partials.contains_key(&name) {
                 // Insert a placeholder so we don't recurse off to infinity.
                 self.partials.insert(name.to_string(), Vec::new());
 
-                match File::open(&path) {
-                    Ok(mut file) => {
-                        let mut string = String::new();
-                        file.read_to_string(&mut string)?;
-
-                        let compiler = Compiler {
-                            ctx: self.ctx.clone(),
-                            reader: string.chars(),
-                            partials: self.partials.clone(),
-                            otag: "{{".to_string(),
-                            ctag: "}}".to_string(),
-                        };
-
-                        let (tokens, subpartials) = compiler.compile()?;
-
-                        // Include subpartials
-                        self.partials.extend(subpartials.into_iter());
-
-                        // Set final compiled tokens for *this* partial
-                        self.partials.insert(name, tokens);
-                    }
-                    // Ignore missing files.
-                    Err(ref e) if e.kind() == NotFound => {},
-                    Err(e) => return Err(e.into()),
-                }
+                let string = self.ctx.partial_loader.load(&name)?;
+                let compiler = Compiler {
+                    ctx: self.ctx.clone(),
+                    reader: string.chars(),
+                    partials: self.partials.clone(),
+                    otag: "{{".to_string(),
+                    ctag: "}}".to_string(),
+                };
+
+                let (tokens, subpartials) = compiler.compile()?;
+
+                // Include subpartials
+                self.partials.extend(subpartials.into_iter());
+
+                // Set final compiled tokens for *this* partial
+                self.partials.insert(name, tokens);
             }
         }
 
diff --git a/src/context.rs b/src/context.rs
index 16ef0db..307d021 100644
--- a/src/context.rs
+++ b/src/context.rs
@@ -10,32 +10,39 @@ use std::path::{Path, PathBuf};
 
 /// Represents the shared metadata needed to compile and render a mustache
 /// template.
-#[derive(Clone)]
-pub struct Context {
-    pub template_path: PathBuf,
-    pub template_extension: String,
+#[derive(Debug, Clone)]
+pub struct Context<P: PartialLoader> {
+    pub partial_loader: P,
 }
 
-impl fmt::Debug for Context {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f,
-               "Context {{ template_path: {:?}, template_extension: {} }}",
-               &*self.template_path,
-               self.template_extension)
+impl Context<DefaultLoader> {
+    /// Configures a mustache context the specified path to the templates.
+    pub fn new(path: PathBuf) -> Self {
+        Context {
+            // template_path: path.clone(),
+            // template_extension: "mustache".to_string(),
+            partial_loader: DefaultLoader::new(path, "mustache".to_string()),
+        }
     }
-}
 
-impl Context {
-    /// Configures a mustache context the specified path to the templates.
-    pub fn new(path: PathBuf) -> Context {
+    /// Configures a mustache context the specified path and extension to the templates.
+    pub fn with_extension(path: PathBuf, extension: String) -> Self {
         Context {
-            template_path: path,
-            template_extension: "mustache".to_string(),
+            partial_loader: DefaultLoader::new(path, extension),
+        }
+    }
+}
+
+impl<P: PartialLoader> Context<P> {
+    /// Configures a mustache context to use a custom loader
+    pub fn with_loader(loader: P) -> Self {
+        Self {
+            partial_loader: loader
         }
     }
 
     /// Compiles a template from a string
-    pub fn compile<IT: Iterator<Item = char>>(&self, reader: IT) -> Result<Template> {
+    pub fn compile<IT: Iterator<Item = char>>(&self, reader: IT) -> Result<Template<P>> {
         let compiler = compiler::Compiler::new(self.clone(), reader);
         let (tokens, partials) = compiler.compile()?;
 
@@ -43,23 +50,82 @@ impl Context {
     }
 
     /// Compiles a template from a path.
-    pub fn compile_path<U: AsRef<Path>>(&self, path: U) -> Result<Template> {
+    pub fn compile_path(&self, path: impl AsRef<Path>) -> Result<Template<P>> {
+        let template = self.partial_loader.load(path)?;
+
+        self.compile(template.chars())
+    }
+}
+
+/// A trait that defines how partials should be loaded.
+/// Types implementing this trait must also implement [`Clone`],
+/// and must provide the [`PartialLoader::load`] method.
+///
+/// Its default implementation, [`DefaultLoader`], simply loads the corresponding file from the disk.
+///
+/// # Example
+///
+/// ```
+/// use mustache::{PartialLoader, Error};
+/// use std::path::Path;
+///
+/// // A simple loader, that returns the name of the partial as the partial's body
+/// #[derive(Clone, Debug)]
+/// pub struct MyLoader {}
+///
+/// impl PartialLoader for MyLoader {
+///     fn load(&self, name: impl AsRef<Path>) -> Result<String, Error> {
+///         let name = name.as_ref().to_str().ok_or(Error::InvalidStr)?;
+///         Ok(name.to_string())
+///     }
+/// }
+/// ```
+pub trait PartialLoader: Clone {
+    fn load(&self, name: impl AsRef<Path>) -> Result<String>;
+}
+
+/// Default [`PartialLoader`].
+///
+/// For a given partial with `name`, loads `{template_path}/{name}.{template_extension}`.
+/// Uses `set_extension` to set the extension.
+#[derive(Clone, Debug, PartialEq)]
+pub struct DefaultLoader {
+    pub template_path: PathBuf,
+    pub template_extension: String,
+}
+
+impl DefaultLoader {
+    pub fn new(
+        template_path: PathBuf,
+        template_extension: String
+    ) -> Self {
+        Self {
+            template_path,
+            template_extension,
+        }
+    }
+}
+
+impl PartialLoader for DefaultLoader {
+    fn load(&self, name: impl AsRef<Path>) -> Result<String> {
+        let mut path = self.template_path.join(name.as_ref());
+        path.set_extension(&self.template_extension);
+
         // FIXME(#6164): This should use the file decoding tools when they are
         // written. For now we'll just read the file and treat it as UTF-8file.
-        let mut path = self.template_path.join(path.as_ref());
-        path.set_extension(&self.template_extension);
-        let mut s = vec![];
-        let mut file = File::open(&path)?;
-        file.read_to_end(&mut s)?;
-
-        // TODO: maybe allow UTF-16 as well?
-        let template = match str::from_utf8(&*s) {
-            Ok(string) => string,
-            _ => {
-                return Err(Error::InvalidStr);
+
+        match File::open(path) {
+            Ok(mut file) => {
+                let mut string = String::new();
+                file.read_to_string(&mut string)?;
+
+                Ok(string)
             }
-        };
 
-        self.compile(template.chars())
+            Err(ref e) if e.kind() == std::io::ErrorKind::NotFound => {
+                Ok(String::new())
+            },
+            Err(e) => return Err(e.into()),
+        }
     }
 }
diff --git a/src/lib.rs b/src/lib.rs
index 5a5e705..a990c41 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -21,7 +21,7 @@ mod parser;
 mod template;
 
 pub use builder::{MapBuilder, VecBuilder};
-pub use context::Context;
+pub use context::{Context, PartialLoader, DefaultLoader};
 pub use data::Data;
 pub use encoder::Encoder;
 pub use encoder::Error as EncoderError;
@@ -38,13 +38,13 @@ where
 }
 
 /// Compiles a template from an `Iterator<char>`.
-pub fn compile_iter<T: Iterator<Item = char>>(iter: T) -> Result<Template> {
+pub fn compile_iter<T: Iterator<Item = char>>(iter: T) -> Result<Template<DefaultLoader>> {
     Context::new(PathBuf::from(".")).compile(iter)
 }
 
 /// Compiles a template from a path.
 /// returns None if the file cannot be read OR the file is not UTF-8 encoded
-pub fn compile_path<U: AsRef<Path>>(path: U) -> Result<Template> {
+pub fn compile_path<U: AsRef<Path>>(path: U) -> Result<Template<DefaultLoader>> {
     let path = path.as_ref();
 
     match path.file_name() {
@@ -54,10 +54,7 @@ pub fn compile_path<U: AsRef<Path>>(path: U) -> Result<Template> {
             // the extension is not utf8 :(
             let extension = path.extension().and_then(|ext| ext.to_str()).unwrap_or("mustache");
 
-            let context = Context {
-                template_path: template_dir.to_path_buf(),
-                template_extension: extension.to_string(),
-            };
+            let context = Context::with_extension(template_dir.to_path_buf(), extension.to_string());
             context.compile_path(filename)
         }
         None => Err(Error::NoFilename),
@@ -65,6 +62,6 @@ pub fn compile_path<U: AsRef<Path>>(path: U) -> Result<Template> {
 }
 
 /// Compiles a template from a string.
-pub fn compile_str(template: &str) -> Result<Template> {
+pub fn compile_str(template: &str) -> Result<Template<DefaultLoader>> {
     compile_iter(template.chars())
 }
diff --git a/src/template.rs b/src/template.rs
index 49be26a..5d9f2ad 100644
--- a/src/template.rs
+++ b/src/template.rs
@@ -9,19 +9,19 @@ use log::{log, error};
 use parser::Token;
 use serde::Serialize;
 
-use super::{Context, Data, Error, Result, to_data};
+use super::{Context, PartialLoader, Data, Error, Result, to_data};
 
 /// `Template` represents a compiled mustache file.
 #[derive(Debug, Clone)]
-pub struct Template {
-    ctx: Context,
+pub struct Template<P: PartialLoader> {
+    ctx: Context<P>,
     tokens: Vec<Token>,
     partials: HashMap<String, Vec<Token>>,
 }
 
 /// Construct a `Template`. This is not part of the impl of Template so it is
 /// not exported outside of mustache.
-pub fn new(ctx: Context, tokens: Vec<Token>, partials: HashMap<String, Vec<Token>>) -> Template {
+pub fn new<P: PartialLoader>(ctx: Context<P>, tokens: Vec<Token>, partials: HashMap<String, Vec<Token>>) -> Template<P> {
     Template {
         ctx: ctx,
         tokens: tokens,
@@ -29,7 +29,7 @@ pub fn new(ctx: Context, tokens: Vec<Token>, partials: HashMap<String, Vec<Token
     }
 }
 
-impl Template {
+impl<P: PartialLoader> Template<P> {
     /// Renders the template with the `Encodable` data.
     pub fn render<W, T>(&self, wr: &mut W, data: &T) -> Result<()>
     where W: Write,
@@ -62,14 +62,14 @@ impl Template {
     }
 }
 
-struct RenderContext<'a> {
-    template: &'a Template,
+struct RenderContext<'a, P: PartialLoader> {
+    template: &'a Template<P>,
     indent: String,
     line_start: bool,
 }
 
-impl<'a> RenderContext<'a> {
-    fn new(template: &'a Template) -> RenderContext<'a> {
+impl<'a, P: PartialLoader> RenderContext<'a, P> {
+    fn new(template: &'a Template<P>) -> RenderContext<'a, P> {
         RenderContext {
             template: template,
             indent: "".to_string(),
diff --git a/tests/template.rs b/tests/template.rs
index f6053a9..29a8012 100644
--- a/tests/template.rs
+++ b/tests/template.rs
@@ -6,7 +6,7 @@ use std::io::Write;
 use std::path::{PathBuf, Path};
 use std::collections::HashMap;
 
-use mustache::{self, Data, Error, to_data};
+use mustache::{self, DefaultLoader, PartialLoader, Data, Error, to_data};
 use mustache::{Context, Template};
 
 use serde::Serialize;
@@ -32,7 +32,7 @@ struct Person {
     age: Option<u32>,
 }
 
-fn compile_str(s: &str) -> Template {
+fn compile_str(s: &str) -> Template<DefaultLoader> {
     mustache::compile_str(s).expect(&format!("Failed to compile: {}", s))
 }
 
@@ -292,7 +292,7 @@ fn test_render_option_complex() {
                                                population of 7300000000");
 }
 
-fn render_data(template: &Template, data: &Data) -> String {
+fn render_data<P: PartialLoader>(template: &Template<P>, data: &Data) -> String {
     let mut bytes = vec![];
     template.render_data(&mut bytes, data).expect("Failed to render data");
     String::from_utf8(bytes).expect("Failed ot encode as String")
@@ -408,7 +408,7 @@ fn test_render_inverted_sections() {
     assert_eq!(render_data(&template, &Data::Map(ctx0)), "05".to_string());
 }
 
-fn assert_partials_data(template: Template) {
+fn assert_partials_data<P: PartialLoader>(template: Template<P>) {
     let ctx = HashMap::new();
     assert_eq!(render_data(&template, &Data::Map(ctx)),
                "<h2>Names</h2>\n".to_string());