Hotreload: Ability to update templates without recompiling

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+- Switch to `proc_macro_error2`
+  [#441](https://github.com/lambda-fairy/maud/issues/441)
+  [#442](https://github.com/lambda-fairy/maud/pull/442)
+
 ## [0.26.0] - 2024-01-15
 
 - Remove `AsRef<str>` restriction from `PreEscaped`

maud/Cargo.toml

@@ -14,13 +14,15 @@ edition.workspace = true
 
 [features]
 default = []
+hotreload = ["maud_macros_impl/hotreload", "maud_macros/hotreload"]
 
 # Web framework integrations
 actix-web = ["actix-web-dep", "futures-util"]
 axum = ["axum-core", "http"]
 
 [dependencies]
 maud_macros = { version = "0.26.0", path = "../maud_macros" }
+maud_macros_impl = { version = "0.26.0", path = "../maud_macros_impl" }
 itoa = "1"
 rocket = { version = "0.5", optional = true }
 futures-util = { version = "0.3.0", optional = true, default-features = false }

maud/src/lib.rs

@@ -1,4 +1,4 @@
-#![no_std]
+#![cfg_attr(not(feature = "hotreload"), no_std)]
 
 //! A macro for writing HTML templates.
 //!
@@ -14,9 +14,13 @@ extern crate alloc;
 use alloc::{borrow::Cow, boxed::Box, string::String, sync::Arc};
 use core::fmt::{self, Arguments, Display, Write};
 
+pub use maud_macros::html as html_static;
+
+#[cfg(not(feature = "hotreload"))]
 pub use maud_macros::html;
 
-mod escape;
+#[cfg(feature = "hotreload")]
+pub use {maud_macros::html_hotreload, maud_macros::html_hotreload as html};
 
 /// An adapter that escapes HTML special characters.
 ///
@@ -52,7 +56,7 @@ impl<'a> Escaper<'a> {
 
 impl fmt::Write for Escaper<'_> {
     fn write_str(&mut self, s: &str) -> fmt::Result {
-        escape::escape_to_string(s, self.0);
+        maud_macros_impl::escape_to_string(s, self.0);
         Ok(())
     }
 }
@@ -110,7 +114,7 @@ pub trait Render {
 
 impl Render for str {
     fn render_to(&self, w: &mut String) {
-        escape::escape_to_string(self, w);
+        maud_macros_impl::escape_to_string(self, w);
     }
 }
 
@@ -415,8 +419,12 @@ mod submillisecond_support {
 #[doc(hidden)]
 pub mod macro_private {
     use crate::{display, Render};
-    use alloc::string::String;
+    pub use alloc::{boxed::Box, string::String, vec::Vec};
     use core::fmt::Display;
+    #[cfg(feature = "hotreload")]
+    pub use std::collections::HashMap;
+    #[cfg(feature = "hotreload")]
+    pub use std::env::var as env_var;
 
     #[doc(hidden)]
     #[macro_export]
@@ -461,4 +469,23 @@ pub mod macro_private {
             display(value).render_to(buffer);
         }
     }
+
+    #[cfg(feature = "hotreload")]
+    pub use maud_macros_impl::*;
+
+    #[cfg(feature = "hotreload")]
+    pub fn render_runtime_error(e: &str) -> crate::Markup {
+        eprintln!("{}", e);
+
+        match env_var("MAUD_ON_ERROR").as_deref() {
+            Ok("panic") => panic!("{}", e),
+            Ok("exit") => {
+                eprintln!("{}", e);
+                ::std::process::exit(2);
+            }
+            _ => {}
+        }
+
+        crate::PreEscaped(alloc::format!("\"> --> <div style='background: black; color: white; position: absolute; top: 0; left: 0; z-index: 1000'><h1 style='red'>Template Errors:</h1><pre>{}</pre></div>", e))
+    }
 }

maud/tests/hotreload.rs

@@ -0,0 +1,63 @@
+//! track regressions specific to the hotreload feature in maud
+use maud::{html, Markup};
+use maud_macros_impl::gather_html_macro_invocations;
+
+#[test]
+fn regression_match_inline_tag() {
+    fn render(x: Option<usize>) -> Markup {
+        html! {
+            div id="main" {
+                @match x {
+                    Some(42) => div.green {
+                        "yes! fourty! two!"
+                    },
+                    Some(_) => div.yellow {
+                        "it's a number?"
+                    },
+                    None => div.red {
+                        "okay."
+                    },
+                }
+            }
+        }
+    }
+
+    assert_eq!(
+        render(Some(42)).into_string(),
+        r#"<div id="main"><div class="green">yes! fourty! two!</div></div>"#
+    );
+    assert_eq!(
+        render(Some(420)).into_string(),
+        r#"<div id="main"><div class="yellow">it's a number?</div></div>"#
+    );
+    assert_eq!(
+        render(None).into_string(),
+        r#"<div id="main"><div class="red">okay.</div></div>"#
+    );
+}
+
+#[test]
+fn regression_basic() {
+    let result = html! {
+        "hello world"
+    };
+
+    assert_eq!(result.into_string(), "hello world");
+}
+
+#[test]
+fn test_gather_html_macro_invocations() {
+    let file = file!();
+    let line = line!();
+
+    let _foo = maud::html! {
+        "Hello world"
+    };
+
+    assert_eq!(
+        gather_html_macro_invocations(file, line)
+            .unwrap()
+            .to_string(),
+        "\"Hello world\""
+    );
+}

maud/tests/warnings/keyword-without-at.stderr

@@ -1,7 +1,8 @@
 error: found keyword `if`
+
+         = help: should this be a `@if`?
+
  --> $DIR/keyword-without-at.rs:5:9
   |
 5 |         if {}
   |         ^^
-  |
-  = help: should this be a `@if`?