feat: Add no_std support

.github/workflows/ci.yml

@@ -23,7 +23,7 @@ jobs:
     permissions:
       contents: none
     name: CI
-    needs: [test, msrv, lockfile, docs, rustfmt, clippy, minimal-versions]
+    needs: [test, msrv, no-std, lockfile, docs, rustfmt, clippy, minimal-versions]
     runs-on: ubuntu-latest
     if: "always()"
     steps:
@@ -68,6 +68,21 @@ jobs:
     - uses: taiki-e/install-action@cargo-hack
     - name: Default features
       run: cargo hack check --each-feature --locked --rust-version --ignore-private --workspace --lib --bins --keep-going
+  no-std:
+    name: "Check no_std"
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v6
+    - name: Install Rust
+      uses: dtolnay/rust-toolchain@stable
+      with:
+        toolchain: stable
+        targets: thumbv6m-none-eabi
+    - uses: Swatinem/rust-cache@v2
+    - uses: taiki-e/install-action@cargo-hack
+    - name: Build
+      run: cargo hack check --each-feature --skip default,std --locked --lib --target thumbv6m-none-eabi --keep-going
   minimal-versions:
     name: Minimal versions
     runs-on: ubuntu-latest

Cargo.toml

@@ -124,8 +124,8 @@ pre-release-replacements = [
 maintenance = { status = "actively-developed" }
 
 [dependencies]
-anstyle = "1.0.4"
-memchr = { version = "2.7.4", optional = true }
+anstyle = { version = "1.0.4", default-features = false }
+memchr = { version = "2.7.4", default-features = false, optional = true }
 unicode-width = "0.2.2"
 
 [dev-dependencies]
@@ -139,7 +139,8 @@ name = "bench"
 harness = false
 
 [features]
-default = []
+default = ["std"]
+std = ["anstyle/std", "memchr?/std"]
 simd = ["dep:memchr"]
 testing-colors = []
 

src/level.rs

@@ -1,10 +1,12 @@
 //! [`Level`] constants for easy importing
 
+use alloc::borrow::Cow;
+
+use anstyle::Style;
+
 use crate::renderer::stylesheet::Stylesheet;
 use crate::snippet::{ERROR_TXT, HELP_TXT, INFO_TXT, NOTE_TXT, WARNING_TXT};
 use crate::{Message, OptionCow, Title};
-use anstyle::Style;
-use std::borrow::Cow;
 
 /// Default `error:` [`Level`]
 pub const ERROR: Level<'_> = Level {

src/lib.rs

@@ -95,11 +95,16 @@
 //! cargo add annotate-snippets --dev --feature testing-colors
 //! ```
 
+#![cfg_attr(not(feature = "std"), no_std)]
 #![cfg_attr(docsrs, feature(doc_cfg))]
 #![warn(clippy::print_stderr)]
 #![warn(clippy::print_stdout)]
 #![warn(missing_debug_implementations)]
 
+extern crate alloc;
+
+use alloc::string::String;
+
 pub mod level;
 pub mod renderer;
 mod snippet;

src/renderer/margin.rs

@@ -1,4 +1,4 @@
-use std::cmp::{max, min};
+use core::cmp::{max, min};
 
 const ELLIPSIS_PASSING: usize = 6;
 const LONG_WHITESPACE: usize = 20;

src/renderer/mod.rs

@@ -25,6 +25,8 @@ pub(crate) mod stylesheet;
 mod margin;
 mod styled_buffer;
 
+use alloc::string::String;
+
 use crate::Report;
 
 pub(crate) use render::normalize_whitespace;

src/renderer/render.rs

@@ -1,9 +1,11 @@
 // Most of this file is adapted from https://github.com/rust-lang/rust/blob/160905b6253f42967ed4aef4b98002944c7df24c/compiler/rustc_errors/src/emitter.rs
 
-use std::borrow::Cow;
-use std::cmp::{max, min, Ordering, Reverse};
-use std::collections::HashMap;
-use std::fmt;
+use alloc::borrow::{Cow, ToOwned};
+use alloc::collections::BTreeMap;
+use alloc::string::{String, ToString};
+use alloc::{format, vec, vec::Vec};
+use core::cmp::{max, min, Ordering, Reverse};
+use core::fmt;
 
 use anstyle::Style;
 
@@ -223,7 +225,7 @@ pub(crate) fn render(renderer: &Renderer, groups: Report<'_>) -> String {
                 .render(&level, &renderer.stylesheet, &mut out_string)
                 .unwrap();
             if g != group_len - 1 {
-                use std::fmt::Write;
+                use core::fmt::Write;
 
                 writeln!(out_string).unwrap();
             }
@@ -701,7 +703,7 @@ fn render_snippet_annotations(
             !is_cont && annotated_line_idx + 1 == annotated_lines.len(),
         );
 
-        let mut to_add = HashMap::new();
+        let mut to_add = BTreeMap::new();
 
         for (depth, style) in depths {
             if let Some(index) = multilines.iter().position(|(d, _)| d == &depth) {

src/renderer/source_map.rs

@@ -1,8 +1,11 @@
+use alloc::borrow::Cow;
+use alloc::string::String;
+use alloc::{vec, vec::Vec};
+use core::cmp::{max, min};
+use core::ops::Range;
+
 use crate::renderer::{char_width, num_overlap, LineAnnotation, LineAnnotationType};
 use crate::{Annotation, AnnotationKind, Patch};
-use std::borrow::Cow;
-use std::cmp::{max, min};
-use std::ops::Range;
 
 #[derive(Debug)]
 pub(crate) struct SourceMap<'a> {
@@ -473,24 +476,24 @@ impl<'a> SourceMap<'a> {
             if prev_hi.line == cur_lo.line {
                 let mut count = push_trailing(&mut buf, prev_line, &prev_hi, Some(&cur_lo));
                 while count > 0 {
-                    highlights.push(std::mem::take(&mut line_highlight));
+                    highlights.push(core::mem::take(&mut line_highlight));
                     acc = 0;
                     count -= 1;
                 }
             } else {
                 acc = 0;
-                highlights.push(std::mem::take(&mut line_highlight));
+                highlights.push(core::mem::take(&mut line_highlight));
                 let mut count = push_trailing(&mut buf, prev_line, &prev_hi, None);
                 while count > 0 {
-                    highlights.push(std::mem::take(&mut line_highlight));
+                    highlights.push(core::mem::take(&mut line_highlight));
                     count -= 1;
                 }
                 // push lines between the previous and current span (if any)
                 for idx in prev_hi.line + 1..(cur_lo.line) {
                     if let Some(line) = self.get_line(idx) {
                         buf.push_str(line.as_ref());
                         buf.push('\n');
-                        highlights.push(std::mem::take(&mut line_highlight));
+                        highlights.push(core::mem::take(&mut line_highlight));
                     }
                 }
                 if let Some(cur_line) = self.get_line(cur_lo.line) {
@@ -527,7 +530,7 @@ impl<'a> SourceMap<'a> {
             prev_line = self.get_line(prev_hi.line);
             for line in part.replacement.split('\n').skip(1) {
                 acc = 0;
-                highlights.push(std::mem::take(&mut line_highlight));
+                highlights.push(core::mem::take(&mut line_highlight));
                 let end: usize = line
                     .chars()
                     .map(|c| match c {
@@ -538,7 +541,7 @@ impl<'a> SourceMap<'a> {
                 line_highlight.push(SubstitutionHighlight { start: 0, end });
             }
         }
-        highlights.push(std::mem::take(&mut line_highlight));
+        highlights.push(core::mem::take(&mut line_highlight));
         if fold {
             // if the replacement already ends with a newline, don't print the next line
             if !buf.ends_with('\n') {
@@ -549,7 +552,7 @@ impl<'a> SourceMap<'a> {
             if let Some(snippet) = self.span_to_snippet(prev_hi.byte..source_len) {
                 buf.push_str(snippet);
                 for _ in snippet.matches('\n') {
-                    highlights.push(std::mem::take(&mut line_highlight));
+                    highlights.push(core::mem::take(&mut line_highlight));
                 }
             }
         }

src/renderer/styled_buffer.rs

@@ -2,13 +2,14 @@
 //!
 //! [styled_buffer]: https://github.com/rust-lang/rust/blob/894f7a4ba6554d3797404bbf550d9919df060b97/compiler/rustc_errors/src/styled_buffer.rs
 
+use alloc::string::String;
+use alloc::{vec, vec::Vec};
+use core::fmt::{self, Write};
+
 use crate::renderer::stylesheet::Stylesheet;
 use crate::renderer::ElementStyle;
 use crate::Level;
 
-use std::fmt;
-use std::fmt::Write;
-
 #[derive(Debug)]
 pub(crate) struct StyledBuffer {
     lines: Vec<Vec<StyledChar>>,

src/snippet.rs

@@ -1,9 +1,12 @@
 //! Structures used as an input for the library.
 
+use alloc::borrow::{Cow, ToOwned};
+use alloc::string::String;
+use alloc::{vec, vec::Vec};
+use core::ops::Range;
+
 use crate::renderer::source_map::{as_substr, TrimmedPatch};
 use crate::Level;
-use std::borrow::Cow;
-use std::ops::Range;
 
 pub(crate) const ERROR_TXT: &str = "error";
 pub(crate) const HELP_TXT: &str = "help";