Merge pull request #336 from stevefan1999-personal/patch-no-std-runtime

Add no_std support for runtime crate

Author: kevinmehall

Cargo.toml

@@ -26,4 +26,7 @@ path = "tests/trybuild.rs"
 harness = false
 
 [features]
+default = ["std"]
 trace = ["peg-macros/trace"]
+std = ["peg-runtime/std"]
+unstable = ["peg-runtime/unstable"]

peg-runtime/Cargo.toml

@@ -8,4 +8,8 @@ description = "Runtime support for rust-peg grammars. To use rust-peg, see the `
 edition = "2018"
 
 [lib]
-path = "lib.rs"
+path = "lib.rs"
+
+[features]
+std = []
+unstable = []

peg-runtime/error.rs

@@ -1,13 +1,18 @@
 //! Parse error reporting
 
 use crate::{Parse, RuleResult};
-use std::collections::HashSet;
 use std::fmt::{self, Debug, Display};
 
+#[cfg(feature = "std")]
+use std::collections::BTreeSet;
+
+#[cfg(not(feature = "std"))]
+use {alloc::collections::BTreeSet, alloc::vec::Vec};
+
 /// A set of literals or names that failed to match
 #[derive(PartialEq, Eq, Debug, Clone)]
 pub struct ExpectedSet {
-    expected: HashSet<&'static str>,
+    expected: BTreeSet<&'static str>,
 }
 
 impl ExpectedSet {
@@ -58,6 +63,7 @@ impl<L: Display> Display for ParseError<L> {
     }
 }
 
+#[cfg(any(feature = "std", feature = "unstable"))]
 impl<L: Display + Debug> ::std::error::Error for ParseError<L> {
     fn description(&self) -> &str {
         "parse error"
@@ -88,7 +94,7 @@ impl ErrorState {
             suppress_fail: 0,
             reparsing_on_error: false,
             expected: ExpectedSet {
-                expected: HashSet::new(),
+                expected: BTreeSet::new(),
             },
         }
     }

peg-runtime/lib.rs

@@ -1,3 +1,6 @@
+#![cfg_attr(not(feature = "std"), no_std)]
+#![cfg_attr(feature = "unstable", feature(error_in_core))]
+
 use std::fmt::Display;
 
 pub mod error;
@@ -50,3 +53,8 @@ pub trait ParseSlice<'input>: Parse {
     /// Get a slice of input.
     fn parse_slice(&'input self, p1: usize, p2: usize) -> Self::Slice;
 }
+
+#[cfg(not(feature = "std"))]
+extern crate alloc;
+#[cfg(not(feature = "std"))]
+extern crate core as std;