Implement no_std support

Turns out that supporting no_std is pretty trivial, so here are the
changes necessary for that.

scripts/gen-tag-table.py

@@ -925,8 +925,8 @@ def same_tag(bcp_47_tag, ot_tags):
 print('}')
 print()
 print('fn strncmp(s1: &str, s2: &str, n: usize) -> bool {')
-print(' let n1 = std::cmp::min(n, s1.len());')
-print(' let n2 = std::cmp::min(n, s2.len());')
+print(' let n1 = core::cmp::min(n, s1.len());')
+print(' let n2 = core::cmp::min(n, s2.len());')
 print(' &s1[..n1] == &s2[..n2]')
 print('}')
 print()

src/aat/extended_kerning.rs

@@ -1,4 +1,4 @@
-use std::convert::TryFrom;
+use core::convert::TryFrom;
 
 use crate::Face;
 use crate::buffer::{BufferScratchFlags, Buffer};

src/aat/map.rs

@@ -1,7 +1,8 @@
+use alloc::vec::Vec;
+
 use crate::{Face, Tag, Mask};
 use super::feature_mappings::FEATURE_MAPPINGS;
 
-
 #[repr(u8)]
 #[derive(Clone, Copy, PartialEq)]
 pub enum FeatureType {
@@ -123,7 +124,7 @@ impl MapBuilder {
  } else if !a.is_exclusive && (a.setting & !1) != (b.setting & !1) {
  a.setting.cmp(&b.setting)
  } else {
- std::cmp::Ordering::Equal
+ core::cmp::Ordering::Equal
  }
  });
 

src/buffer.rs

@@ -1,4 +1,5 @@
-use std::convert::TryFrom;
+use alloc::{string::String, vec::Vec};
+use core::convert::TryFrom;
 
 use ttf_parser::GlyphId;
 
@@ -756,13 +757,13 @@ impl Buffer {
 
  if self.have_separate_output {
  // Swap info and pos buffers.
- let info: Vec<GlyphPosition> = bytemuck::cast_vec(std::mem::take(&mut self.info));
- let pos: Vec<GlyphInfo> = bytemuck::cast_vec(std::mem::take(&mut self.pos));
+ let info: Vec<GlyphPosition> = bytemuck::cast_vec(core::mem::take(&mut self.info));
+ let pos: Vec<GlyphInfo> = bytemuck::cast_vec(core::mem::take(&mut self.pos));
  self.pos = info;
  self.info = pos;
  }
 
- std::mem::swap(&mut self.len, &mut self.out_len);
+ core::mem::swap(&mut self.len, &mut self.out_len);
 
  self.idx = 0;
  }
@@ -951,7 +952,7 @@ impl Buffer {
  return;
  }
 
- if cluster_start == 0 && cluster_end == std::u32::MAX {
+ if cluster_start == 0 && cluster_end == core::u32::MAX {
  for info in &mut self.info[..self.len] {
  info.mask = (info.mask & not_mask) | value;
  }
@@ -983,7 +984,7 @@ impl Buffer {
  let mut cluster = self.info[start].cluster;
 
  for i in start+1..end {
- cluster = std::cmp::min(cluster, self.info[i].cluster);
+ cluster = core::cmp::min(cluster, self.info[i].cluster);
  }
 
  // Extend end
@@ -1022,7 +1023,7 @@ impl Buffer {
  let mut cluster = self.out_info()[start].cluster;
 
  for i in start+1..end {
- cluster = std::cmp::min(cluster, self.out_info()[i].cluster);
+ cluster = core::cmp::min(cluster, self.out_info()[i].cluster);
  }
 
  // Extend start
@@ -1143,7 +1144,7 @@ impl Buffer {
  }
 
  fn unsafe_to_break_impl(&mut self, start: usize, end: usize) {
- let mut cluster = std::u32::MAX;
+ let mut cluster = core::u32::MAX;
  cluster = Self::_unsafe_to_break_find_min_cluster(&self.info, start, end, cluster);
  let unsafe_to_break = Self::_unsafe_to_break_set_mask(&mut self.info, start, end, cluster);
  if unsafe_to_break {
@@ -1160,7 +1161,7 @@ impl Buffer {
  assert!(start <= self.out_len);
  assert!(self.idx <= end);
 
- let mut cluster = std::u32::MAX;
+ let mut cluster = core::u32::MAX;
  cluster = Self::_unsafe_to_break_find_min_cluster(self.out_info(), start, self.out_len, cluster);
  cluster = Self::_unsafe_to_break_find_min_cluster(&self.info, self.idx, end, cluster);
  let idx = self.idx;
@@ -1323,7 +1324,7 @@ impl Buffer {
 
  fn _unsafe_to_break_find_min_cluster(info: &[GlyphInfo], start: usize, end: usize, mut cluster: u32) -> u32 {
  for i in start..end {
- cluster = std::cmp::min(cluster, info[i].cluster);
+ cluster = core::cmp::min(cluster, info[i].cluster);
  }
 
  cluster
@@ -1630,8 +1631,8 @@ impl UnicodeBuffer {
  }
 }
 
-impl std::fmt::Debug for UnicodeBuffer {
- fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+impl core::fmt::Debug for UnicodeBuffer {
+ fn fmt(&self, fmt: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
  fmt.debug_struct("UnicodeBuffer")
  .field("direction", &self.direction())
  .field("language", &self.language())
@@ -1693,8 +1694,8 @@ impl GlyphBuffer {
  self.serialize_impl(face, flags).unwrap_or_default()
  }
 
- fn serialize_impl(&self, face: &Face, flags: SerializeFlags) -> Result<String, std::fmt::Error> {
- use std::fmt::Write;
+ fn serialize_impl(&self, face: &Face, flags: SerializeFlags) -> Result<String, core::fmt::Error> {
+ use core::fmt::Write;
 
  let mut s = String::with_capacity(64);
 
@@ -1757,8 +1758,8 @@ impl GlyphBuffer {
  }
 }
 
-impl std::fmt::Debug for GlyphBuffer {
- fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+impl core::fmt::Debug for GlyphBuffer {
+ fn fmt(&self, fmt: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
  fmt.debug_struct("GlyphBuffer")
  .field("glyph_positions", &self.glyph_positions())
  .field("glyph_infos", &self.glyph_infos())

src/common.rs

@@ -1,4 +1,5 @@
-use std::ops::{Bound, RangeBounds};
+use alloc::string::String;
+use core::ops::{Bound, RangeBounds};
 
 use ttf_parser::Tag;
 
@@ -152,7 +153,7 @@ impl Default for Direction {
  }
 }
 
-impl std::str::FromStr for Direction {
+impl core::str::FromStr for Direction {
  type Err = &'static str;
 
  fn from_str(s: &str) -> Result<Self, Self::Err> {
@@ -184,7 +185,7 @@ impl Language {
  }
 }
 
-impl std::str::FromStr for Language {
+impl core::str::FromStr for Language {
  type Err = &'static str;
 
  fn from_str(s: &str) -> Result<Self, Self::Err> {
@@ -249,7 +250,7 @@ impl Script {
  }
 }
 
-impl std::str::FromStr for Script {
+impl core::str::FromStr for Script {
  type Err = &'static str;
 
  fn from_str(s: &str) -> Result<Self, Self::Err> {
@@ -486,7 +487,7 @@ impl Feature {
  }
 }
 
-impl std::str::FromStr for Feature {
+impl core::str::FromStr for Feature {
  type Err = &'static str;
 
  /// Parses a `Feature` form a string.
@@ -544,18 +545,18 @@ impl std::str::FromStr for Feature {
  p.advance(1);
  p.consume_i32().unwrap_or(-1) as u32 // negative value overflow is ok
  } else {
- if start_opt.is_some() && start != std::u32::MAX {
+ if start_opt.is_some() && start != core::u32::MAX {
  start + 1
  } else {
- std::u32::MAX
+ core::u32::MAX
  }
  };
 
  p.consume_byte(b']')?;
 
  (start, end)
  } else {
- (0, std::u32::MAX)
+ (0, core::u32::MAX)
  };
 
  // Parse postfix.
@@ -591,7 +592,7 @@ impl std::str::FromStr for Feature {
 #[cfg(test)]
 mod tests_features {
  use super::*;
- use std::str::FromStr;
+ use core::str::FromStr;
 
  macro_rules! test {
  ($name:ident, $text:expr, $tag:expr, $value:expr, $range:expr) => (
@@ -620,7 +621,7 @@ mod tests_features {
  test!(parse_13, "kern[3:5]=2", b"kern", 2, 3..=5);
  test!(parse_14, "kern[3;5]=2", b"kern", 2, 3..=5);
  test!(parse_15, "kern[:-1]", b"kern", 1, ..);
- test!(parse_16, "kern[-1]", b"kern", 1, std::u32::MAX as usize..);
+ test!(parse_16, "kern[-1]", b"kern", 1, core::u32::MAX as usize..);
  test!(parse_17, "kern=on", b"kern", 1, ..);
  test!(parse_18, "kern=off", b"kern", 0, ..);
  test!(parse_19, "kern=oN", b"kern", 1, ..);
@@ -637,7 +638,7 @@ pub struct Variation {
  pub value: f32,
 }
 
-impl std::str::FromStr for Variation {
+impl core::str::FromStr for Variation {
  type Err = &'static str;
 
  fn from_str(s: &str) -> Result<Self, Self::Err> {

src/complex/arabic.rs

@@ -1,3 +1,5 @@
+use alloc::boxed::Box;
+
 use crate::{script, Tag, Face, GlyphInfo, Mask, Script};
 use crate::buffer::{Buffer, BufferScratchFlags};
 use crate::ot::{feature, FeatureFlags};

src/complex/hangul.rs

@@ -1,3 +1,5 @@
+use alloc::boxed::Box;
+
 use crate::{Face, GlyphInfo, Mask};
 use crate::buffer::{Buffer, BufferFlags, BufferClusterLevel};
 use crate::ot::{feature, FeatureFlags, Map};

src/complex/indic.rs

@@ -1,6 +1,7 @@
-use std::convert::TryFrom;
-use std::cmp;
-use std::ops::Range;
+use alloc::boxed::Box;
+use core::cmp;
+use core::convert::TryFrom;
+use core::ops::Range;
 
 use ttf_parser::GlyphId;
 

src/complex/khmer.rs

@@ -1,3 +1,5 @@
+use alloc::boxed::Box;
+
 use crate::{Tag, Mask, Face, GlyphInfo};
 use crate::buffer::{Buffer, BufferFlags};
 use crate::ot::{feature, FeatureFlags};

src/complex/mod.rs

@@ -15,7 +15,8 @@ mod universal_machine;
 mod universal_table;
 mod vowel_constraints;
 
-use std::any::Any;
+use alloc::boxed::Box;
+use core::any::Any;
 
 use crate::{script, Direction, Face, Script, Tag};
 use crate::buffer::Buffer;

src/complex/myanmar.rs

@@ -402,7 +402,7 @@ fn initial_reordering_consonant_syllable(start: usize, end: usize, buffer: &mut
  }
  }
 
- buffer.sort(start, end, |a, b| a.indic_position().cmp(&b.indic_position()) == std::cmp::Ordering::Greater);
+ buffer.sort(start, end, |a, b| a.indic_position().cmp(&b.indic_position()) == core::cmp::Ordering::Greater);
 }
 
 fn override_features(planner: &mut ShapePlanner) {

src/complex/universal.rs

@@ -217,7 +217,7 @@ fn setup_rphf_mask(plan: &ShapePlan, buffer: &mut Buffer) {
  let limit = if buffer.info[start].use_category() == category::R {
  1
  } else {
- std::cmp::min(3, end - start)
+ core::cmp::min(3, end - start)
  };
 
  for i in start..start+limit {

src/face.rs

@@ -214,7 +214,7 @@ impl<'a> Face<'a> {
  pub(crate) fn glyph_extents(&self, glyph: GlyphId) -> Option<GlyphExtents> {
  let pixels_per_em = match self.pixels_per_em {
  Some(ppem) => ppem.0,
- None => std::u16::MAX,
+ None => core::u16::MAX,
  };
 
  if let Some(img) = self.ttfp_face.glyph_raster_image(glyph, pixels_per_em) {

src/glyph_set.rs

@@ -1,5 +1,6 @@
-use std::cmp::{self, Ordering};
-use std::ops::RangeInclusive;
+use alloc::vec::Vec;
+use core::cmp::{self, Ordering};
+use core::ops::RangeInclusive;
 
 use ttf_parser::GlyphId;
 
@@ -14,7 +15,7 @@ pub struct GlyphSet {
 impl GlyphSet {
  /// Create a new glyph set builder.
  pub fn builder() -> GlyphSetBuilder {
- GlyphSetBuilder { ranges: vec![] }
+ GlyphSetBuilder { ranges: Vec::new() }
  }
 
  /// Check whether the glyph is contained in the set.
@@ -93,6 +94,7 @@ impl GlyphSetBuilder {
 #[cfg(test)]
 mod tests {
  use super::*;
+ use alloc::vec;
 
  #[test]
  fn test_empty() {

src/lib.rs

@@ -2,9 +2,12 @@
 `rustybuzz` is an attempt to incrementally port [harfbuzz](https://github.com/harfbuzz/harfbuzz) to Rust.
 */
 
+#![no_std]
 #![doc(html_root_url = "https://docs.rs/rustybuzz/0.3.0")]
 #![warn(missing_docs)]
 
+extern crate alloc;
+
 #[macro_use]
 mod buffer;
 mod aat;

src/ot/layout.rs

@@ -1,6 +1,6 @@
 //! OpenType layout.
 
-use std::ops::{Index, IndexMut};
+use core::ops::{Index, IndexMut};
 
 use ttf_parser::GlyphId;