From ecded729ad935d0812d020d17f9ac19a7bdef60c Mon Sep 17 00:00:00 2001
From: Stephen Chung <Stephen.Chung@intexact.com>
Date: Wed, 18 Mar 2020 10:50:51 +0800
Subject: [PATCH] Finalize `no_std` support.

---
 Cargo.toml    | 40 +++++++++++++++++++++-------------------
 README.md     |  5 ++++-
 src/stdlib.rs |  2 ++
 3 files changed, 27 insertions(+), 20 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 11015a39..060df2f0 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,6 +18,27 @@ keywords = [ "scripting" ]
 [dependencies]
 num-traits = "0.2.11"
 
+[features]
+#default = ["no_function", "no_index", "no_float", "only_i32", "no_stdlib", "unchecked", "no_optimize"]
+default = [ "optimize_full" ]
+debug_msgs = []     # print debug messages on function registrations and calls
+unchecked = []      # unchecked arithmetic
+no_index = []       # no arrays and indexing
+no_float = []       # no floating-point
+no_function = []    # no script-defined functions
+no_optimize = []    # no script optimizer
+optimize_full = []  # set optimization level to Full (default is Simple)
+only_i32 = []       # set INT=i32 (useful for 32-bit systems)
+only_i64 = []       # set INT=i64 (default) and disable support for all other integer types
+
+# no standard library of utility functions
+no_stdlib = [ "num-traits/libm", "hashbrown", "core-error", "libm" ]
+
+[profile.release]
+lto = "fat"
+codegen-units = 1
+#opt-level = "z"     # optimize for size
+
 [dependencies.libm]
 version = "0.2.1"
 optional = true
@@ -37,22 +58,3 @@ optional = true
 version = "0.3.2"
 default-features = false
 optional = true
-
-[features]
-#default = ["no_function", "no_index", "no_float", "only_i32", "no_stdlib", "unchecked", "no_optimize"]
-default = [ "optimize_full" ]
-debug_msgs = []     # print debug messages on function registrations and calls
-unchecked = []      # unchecked arithmetic
-no_stdlib = ["num-traits/libm", "hashbrown", "core-error", "libm"]      # no standard library of utility functions
-no_index = []       # no arrays and indexing
-no_float = []       # no floating-point
-no_function = []    # no script-defined functions
-no_optimize = []    # no script optimizer
-optimize_full = []  # set optimization level to Full (default is Simple)
-only_i32 = []       # set INT=i32 (useful for 32-bit systems)
-only_i64 = []       # set INT=i64 (default) and disable support for all other integer types
-
-[profile.release]
-lto = "fat"
-codegen-units = 1
-#opt-level = "z"     # optimize for size
diff --git a/README.md b/README.md
index 5032e531..7ed77c0f 100644
--- a/README.md
+++ b/README.md
@@ -3,8 +3,9 @@ Rhai - Embedded Scripting for Rust
 
 Rhai is an embedded scripting language and evaluation engine for Rust that gives a safe and easy way to add scripting to any application.
 
-Rhai's current feature set:
+Rhai's current features set:
 
+* `no-std` support
 * Easy integration with Rust functions and data types, supporting getter/setter methods
 * Easily call a script-defined function from Rust
 * Fairly efficient (1 million iterations in 0.75 sec on my 5 year old laptop)
@@ -52,6 +53,7 @@ Optional features
 | `no_optimize` | Disable the script optimizer.                                                                                                                            |
 | `only_i32`    | Set the system integer type to `i32` and disable all other integer types. `INT` is set to `i32`.                                                         |
 | `only_i64`    | Set the system integer type to `i64` and disable all other integer types. `INT` is set to `i64`.                                                         |
+| `no_std`      | Build for `no-std`. Notice that additional dependencies will be pulled in to replace `std` features.                                                     |
 
 By default, Rhai includes all the standard functionalities in a small, tight package.  Most features are here to opt-**out** of certain functionalities that are not needed.
 Excluding unneeded functionalities can result in smaller, faster builds as well as less bugs due to a more restricted language.
@@ -1477,6 +1479,7 @@ engine.set_optimization_level(rhai::OptimizationLevel::None);
 [`no_optimize`]: #optional-features
 [`only_i32`]: #optional-features
 [`only_i64`]: #optional-features
+[`no_std`]: #optional-features
 
 [`Engine`]: #hello-world
 [`Scope`]: #initializing-and-maintaining-state
diff --git a/src/stdlib.rs b/src/stdlib.rs
index fa147c7d..2bffb4c2 100644
--- a/src/stdlib.rs
+++ b/src/stdlib.rs
@@ -1,3 +1,5 @@
+//! Helper module which defines most of the needed features from `std` for `no-std` builds.
+
 #[cfg(feature = "no_stdlib")]
 mod inner {
     pub use core::{