Add a std feature to vm

Cargo.lock

@@ -24,6 +24,12 @@ version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "aae1277d39aeec15cb388266ecc24b11c80469deae6067e17a1a7aa9e5c1f234"
 
+[[package]]
+name = "ahash"
+version = "0.4.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "739f4a8db6605981345c5654f3a85b056ce52f37a39d34da03f25bf2151ea16e"
+
 [[package]]
 name = "ahash"
 version = "0.6.2"
@@ -876,6 +882,9 @@ name = "hashbrown"
 version = "0.9.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d7afe4a420e3fe79967a00898cc1f4db7c8a49a9333a29f8a4bd76a253d5cd04"
+dependencies = [
+ "ahash 0.4.7",
+]
 
 [[package]]
 name = "hermit-abi"
@@ -1875,7 +1884,7 @@ dependencies = [
 name = "rustpython-compiler-core"
 version = "0.1.2"
 dependencies = [
- "ahash",
+ "ahash 0.6.2",
  "indexmap",
  "insta",
  "itertools",
@@ -1885,6 +1894,7 @@ dependencies = [
  "rustpython-ast",
  "rustpython-bytecode",
  "rustpython-parser",
+ "scopeguard",
 ]
 
 [[package]]
@@ -1922,7 +1932,8 @@ dependencies = [
 name = "rustpython-parser"
 version = "0.1.2"
 dependencies = [
- "ahash",
+ "ahash 0.6.2",
+ "hashbrown",
  "lalrpop",
  "lalrpop-util",
  "log",
@@ -1948,7 +1959,7 @@ name = "rustpython-vm"
 version = "0.1.2"
 dependencies = [
  "adler32",
- "ahash",
+ "ahash 0.6.2",
  "atty",
  "base64",
  "bitflags",
@@ -2233,13 +2244,12 @@ checksum = "ae524f056d7d770e174287294f562e95044c68e88dec909a00d2094805db9d75"
 
 [[package]]
 name = "socket2"
-version = "0.3.17"
+version = "0.3.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2c29947abdee2a218277abeca306f25789c938e500ea5a9d4b12a5a504466902"
+checksum = "122e570113d28d773067fab24266b66753f6ea915758651696b6e35e49f88d6e"
 dependencies = [
  "cfg-if 1.0.0",
  "libc",
- "redox_syscall",
  "winapi",
 ]
 

ast/Cargo.toml

@@ -5,4 +5,4 @@ authors = ["RustPython Team"]
 edition = "2018"
 
 [dependencies]
-num-bigint = "0.3"
+num-bigint = { version = "0.3", default-features = false }

ast/src/ast.rs

@@ -5,6 +5,7 @@
 //! location of the node.
 
 pub use crate::location::Location;
+use alloc::{boxed::Box, string::String, vec::Vec};
 use num_bigint::BigInt;
 
 #[allow(clippy::large_enum_variant)]

ast/src/lib.rs

@@ -1,3 +1,7 @@
+#![no_std]
+
+extern crate alloc;
+
 mod ast;
 mod location;
 

ast/src/location.rs

@@ -1,6 +1,6 @@
 //! Datatypes to support source location information.
 
-use std::fmt;
+use core::fmt;
 
 /// A location somewhere in the sourcecode.
 #[derive(Clone, Copy, Debug, Default, PartialEq)]

bytecode/Cargo.toml

@@ -7,13 +7,16 @@ edition = "2018"
 repository = "https://github.com/RustPython/RustPython"
 license = "MIT"
 
+[features]
+std = ["bstr/std", "itertools/use_std", "lz4_flex/std"]
+default = ["std"]
 
 [dependencies]
 bincode =  "1.1"
 bitflags = "1.1"
-lz4_flex = "0.7"
-num-bigint = { version = "0.3", features = ["serde"] }
-num-complex = { version = "0.3", features = ["serde"] }
+lz4_flex = { version = "0.7", default-features = false, features = ["safe-decode", "safe-encode"] }
+num-bigint = { version = "0.3", default-features = false, features = ["serde"] }
+num-complex = { version = "0.3", default-features = false, features = ["serde"] }
 serde = { version = "1.0", features = ["derive"] }
-itertools = "0.9"
-bstr = "0.2"
+itertools = { version = "0.9", default-features = false }
+bstr = { version = "0.2", default-features = false }

bytecode/src/lib.rs

@@ -3,15 +3,19 @@
 
 #![doc(html_logo_url = "https://raw.githubusercontent.com/RustPython/RustPython/master/logo.png")]
 #![doc(html_root_url = "https://docs.rs/rustpython-bytecode/")]
+#![cfg_attr(not(feature = "std"), no_std)]
 
+extern crate alloc;
+
+use alloc::collections::BTreeSet;
+use alloc::{borrow::ToOwned, boxed::Box, string::String, vec::Vec};
 use bitflags::bitflags;
 use bstr::ByteSlice;
+use core::fmt;
 use itertools::Itertools;
 use num_bigint::BigInt;
 use num_complex::Complex64;
 use serde::{Deserialize, Serialize};
-use std::collections::BTreeSet;
-use std::fmt;
 
 /// Sourcecode location.
 #[derive(Clone, Copy, Debug, Default, PartialEq, Serialize, Deserialize)]
@@ -722,6 +726,7 @@ impl fmt::Display for CodeDeserializeError {
         }
     }
 }
+#[cfg(feature = "std")]
 impl std::error::Error for CodeDeserializeError {}
 
 impl CodeObject<ConstantData> {

compiler/Cargo.toml

@@ -7,15 +7,20 @@ repository = "https://github.com/RustPython/RustPython"
 license = "MIT"
 edition = "2018"
 
+[features]
+std = ["rustpython-bytecode/std", "itertools/use_std"]
+default = ["std"]
+
 [dependencies]
 indexmap = "1.0"
-itertools = "0.9"
-rustpython-bytecode = { path = "../bytecode", version = "0.1.1" }
+itertools = { version = "0.9", default-features = false }
+rustpython-bytecode = { path = "../bytecode", version = "0.1.1", default-features = false }
 rustpython-ast = { path = "../ast" }
 num-complex = { version = "0.3", features = ["serde"] }
 num-traits = "0.2"
 log = "0.4"
 ahash = "0.6"
+scopeguard = "1.1"
 
 [dev-dependencies]
 rustpython-parser = { path = "../parser" }

compiler/porcelain/Cargo.toml

@@ -5,6 +5,10 @@ description = "A usability wrapper around rustpython-parser and rustpython-compi
 authors = ["RustPython Team"]
 edition = "2018"
 
+[features]
+std = ["rustpython-compiler-core/std", "rustpython-bytecode/std", "rustpython-parser/std"]
+default = ["std"]
+
 [dependencies]
 thiserror = "1.0"
 rustpython-compiler-core = { path = ".." }

compiler/src/compile.rs

@@ -10,12 +10,15 @@ use crate::ir::{self, CodeInfo};
 pub use crate::mode::Mode;
 use crate::symboltable::{make_symbol_table, statements_to_symbol_table, SymbolScope, SymbolTable};
 use crate::IndexSet;
+use alloc::{borrow::ToOwned, boxed::Box, format, string::String, vec, vec::Vec};
 use itertools::Itertools;
 use num_complex::Complex64;
 use num_traits::ToPrimitive;
 use rustpython_ast as ast;
 use rustpython_bytecode::{self as bytecode, CodeObject, ConstantData, Instruction};
 
+pub use crate::mode::Mode;
+
 type CompileResult<T> = Result<T, CompileError>;
 
 enum NameUsage {

compiler/src/error.rs

@@ -1,7 +1,9 @@
 use rustpython_ast::Location;
 
+use alloc::string::String;
+use core::fmt;
+#[cfg(feature = "std")]
 use std::error::Error;
-use std::fmt;
 
 #[derive(Debug)]
 pub struct CompileError {
@@ -78,6 +80,7 @@ impl fmt::Display for CompileErrorType {
     }
 }
 
+#[cfg(feature = "std")]
 impl Error for CompileErrorType {}
 
 impl fmt::Display for CompileError {
@@ -86,8 +89,5 @@ impl fmt::Display for CompileError {
     }
 }
 
-impl Error for CompileError {
-    fn source(&self) -> Option<&(dyn Error + 'static)> {
-        None
-    }
-}
+#[cfg(feature = "std")]
+impl Error for CompileError {}

compiler/src/lib.rs

@@ -1,6 +1,9 @@
 //! Compile a Python AST or source code into bytecode consumable by RustPython.
 #![doc(html_logo_url = "https://raw.githubusercontent.com/RustPython/RustPython/master/logo.png")]
 #![doc(html_root_url = "https://docs.rs/rustpython-compiler/")]
+#![cfg_attr(not(feature = "std"), no_std)]
+
+extern crate alloc;
 
 #[macro_use]
 extern crate log;

compiler/src/mode.rs

@@ -1,3 +1,5 @@
+use core::fmt;
+
 #[derive(Clone, Copy)]
 pub enum Mode {
     Exec,
@@ -5,7 +7,7 @@ pub enum Mode {
     Single,
 }
 
-impl std::str::FromStr for Mode {
+impl core::str::FromStr for Mode {
     type Err = ModeParseError;
     fn from_str(s: &str) -> Result<Self, ModeParseError> {
         match s {
@@ -22,8 +24,8 @@ pub struct ModeParseError {
     _priv: (),
 }
 
-impl std::fmt::Display for ModeParseError {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+impl fmt::Display for ModeParseError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, r#"mode should be "exec", "eval", or "single""#)
     }
 }

compiler/src/symboltable.rs

@@ -9,8 +9,9 @@ Inspirational file: https://github.com/python/cpython/blob/master/Python/symtabl
 
 use crate::error::{CompileError, CompileErrorType};
 use crate::IndexMap;
+use alloc::{borrow::ToOwned, format, string::String, vec, vec::Vec};
+use core::fmt;
 use rustpython_ast::{self as ast, Location};
-use std::fmt;
 
 pub fn make_symbol_table(program: &ast::Program) -> Result<SymbolTable, SymbolTableError> {
     let mut builder = SymbolTableBuilder::default();
@@ -187,8 +188,8 @@ impl SymbolTable {
     }
 }
 
-impl std::fmt::Debug for SymbolTable {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+impl fmt::Debug for SymbolTable {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(
             f,
             "SymbolTable({:?} symbols, {:?} sub scopes)",
@@ -209,8 +210,9 @@ fn analyze_symbol_table(symbol_table: &mut SymbolTable) -> SymbolTableResult {
 type SymbolMap = IndexMap<String, Symbol>;
 
 mod stack {
-    use std::panic;
-    use std::ptr::NonNull;
+    use alloc::vec::Vec;
+    use core::ptr::NonNull;
+
     pub struct StackStack<T> {
         v: Vec<NonNull<T>>,
     }
@@ -227,9 +229,10 @@ mod stack {
             F: FnOnce(&mut Self) -> R,
         {
             self.v.push(x.into());
-            let res = panic::catch_unwind(panic::AssertUnwindSafe(|| f(self)));
-            self.v.pop();
-            res.unwrap_or_else(|x| panic::resume_unwind(x))
+            let mut this = scopeguard::guard(self, |this| {
+                this.v.pop();
+            });
+            f(&mut this)
         }
 
         pub fn iter(&self) -> impl Iterator<Item = &T> + DoubleEndedIterator + '_ {
@@ -273,7 +276,7 @@ struct SymbolTableAnalyzer {
 
 impl SymbolTableAnalyzer {
     fn analyze_symbol_table(&mut self, symbol_table: &mut SymbolTable) -> SymbolTableResult {
-        let symbols = std::mem::take(&mut symbol_table.symbols);
+        let symbols = core::mem::take(&mut symbol_table.symbols);
         let sub_tables = &mut *symbol_table.sub_tables;
 
         let mut info = (symbols, symbol_table.typ);
@@ -469,7 +472,7 @@ impl SymbolTableAnalyzer {
             SymbolTableType::Class => {
                 // named expressions are forbidden in comprehensions on class scope
                 return Err(SymbolTableError {
-                    error: "assignment expression within a comprehension cannot be used in a class body".to_string(),
+                    error: "assignment expression within a comprehension cannot be used in a class body".to_owned(),
                     // TODO: accurate location info, somehow
                     location: Location::default(),
                 });
@@ -999,7 +1002,7 @@ impl SymbolTableBuilder {
                 // comprehension iterator definitions
                 if let ExpressionContext::IterDefinitionExp = context {
                     return Err(SymbolTableError {
-                        error: "assignment expression cannot be used in a comprehension iterable expression".to_string(),
+                        error: "assignment expression cannot be used in a comprehension iterable expression".to_owned(),
                         // TODO: accurate location info, somehow
                         location: Location::default(),
                     });
@@ -1218,7 +1221,7 @@ impl SymbolTableBuilder {
             return Err(SymbolTableError {
                 error:
                     "assignment expression cannot be used in a comprehension iterable expression"
-                        .to_string(),
+                        .to_owned(),
                 location,
             });
         }

parser/Cargo.toml

@@ -8,17 +8,22 @@ repository = "https://github.com/RustPython/RustPython"
 license = "MIT"
 edition = "2018"
 
+[features]
+std = []
+default = ["std", "lalrpop-util/std", "num-bigint/std"]
+
 [build-dependencies]
-lalrpop = "0.19"
+lalrpop = "0.19.4"
 
 [dependencies]
 rustpython-ast = { path = "../ast" }
-lalrpop-util = "0.19.1"
+lalrpop-util = { version = "0.19.4", default-features = false }
 log = "0.4.1"
-num-bigint = "0.3"
-num-traits = "0.2"
+num-bigint = { version = "0.3", default-features = false }
+num-traits = { version = "0.2", default-features = false }
 unic-emoji-char = "0.9"
 unic-ucd-ident  = "0.9"
 unicode_names2 = "0.4"
 phf = { version = "0.8", features = ["macros"] }
 ahash = "0.6"
+hashbrown = "0.9"

parser/src/error.rs

@@ -5,8 +5,10 @@ use lalrpop_util::ParseError as LalrpopError;
 use crate::ast::Location;
 use crate::token::Tok;
 
+use alloc::{boxed::Box, string::String};
+use core::fmt;
+#[cfg(feature = "std")]
 use std::error::Error;
-use std::fmt;
 
 /// Represents an error during lexical scanning.
 #[derive(Debug, PartialEq)]
@@ -70,6 +72,16 @@ impl fmt::Display for LexicalErrorType {
     }
 }
 
+#[cfg(feature = "std")]
+impl Error for LexicalErrorType {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        match self {
+            LexicalErrorType::FStringError(e) => Some(e),
+            _ => None,
+        }
+    }
+}
+
 // TODO: consolidate these with ParseError
 #[derive(Debug, PartialEq)]
 pub struct FStringError {
@@ -119,6 +131,16 @@ impl From<FStringError> for LalrpopError<Location, Tok, LexicalError> {
     }
 }
 
+#[cfg(feature = "std")]
+impl Error for FStringErrorType {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        match self {
+            FStringErrorType::InvalidExpression(e) => Some(e.as_ref()),
+            _ => None,
+        }
+    }
+}
+
 /// Represents an error during parsing
 #[derive(Debug, PartialEq)]
 pub struct ParseError {
@@ -204,14 +226,22 @@ impl fmt::Display for ParseErrorType {
     }
 }
 
-impl Error for ParseErrorType {}
+#[cfg(feature = "std")]
+impl Error for ParseErrorType {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        match self {
+            ParseErrorType::Lexical(e) => Some(e),
+            _ => None,
+        }
+    }
+}
 
 impl ParseErrorType {
     pub fn is_indentation_error(&self) -> bool {
         match self {
             ParseErrorType::Lexical(LexicalErrorType::IndentationError) => true,
             ParseErrorType::UnrecognizedToken(token, expected) => {
-                *token == Tok::Indent || expected.clone() == Some("Indent".to_owned())
+                *token == Tok::Indent || expected.as_ref().map_or(false, |s| s == "Indent")
             }
             _ => false,
         }
@@ -225,15 +255,16 @@ impl ParseErrorType {
     }
 }
 
-impl std::ops::Deref for ParseError {
+impl core::ops::Deref for ParseError {
     type Target = ParseErrorType;
     fn deref(&self) -> &Self::Target {
         &self.error
     }
 }
 
+#[cfg(feature = "std")]
 impl Error for ParseError {
     fn source(&self) -> Option<&(dyn Error + 'static)> {
-        None
+        self.error.source()
     }
 }

parser/src/fstring.rs

@@ -1,6 +1,5 @@
-use std::iter;
-use std::mem;
-use std::str;
+use alloc::{borrow::ToOwned, boxed::Box, format, string::String, vec, vec::Vec};
+use core::{iter, mem, str};
 
 use crate::ast::{ConversionFlag, Expression, Location, StringGroup};
 use crate::error::{FStringError, FStringErrorType, ParseError};
@@ -81,7 +80,7 @@ impl<'a> FStringParser<'a> {
                 // match a python 3.8 self documenting expression
                 // format '{' PYTHON_EXPRESSION '=' FORMAT_SPECIFIER? '}'
                 '=' if self.chars.peek() != Some(&'=') && delims.is_empty() => {
-                    pred_expression_text = expression.to_string(); // safe expression before = to print it
+                    pred_expression_text = expression.to_owned(); // safe expression before = to print it
                 }
 
                 ':' if delims.is_empty() => {

parser/src/function.rs

@@ -1,5 +1,5 @@
-use ahash::RandomState;
-use std::collections::HashSet;
+use alloc::{string::String, vec, vec::Vec};
+use hashbrown::HashSet;
 
 use crate::ast;
 use crate::error::{LexicalError, LexicalErrorType};
@@ -46,7 +46,8 @@ pub fn parse_args(func_args: Vec<FunctionArgument>) -> Result<ast::ArgumentList,
     let mut args = vec![];
     let mut keywords = vec![];
 
-    let mut keyword_names = HashSet::with_capacity_and_hasher(func_args.len(), RandomState::new());
+    let mut keyword_names =
+        HashSet::with_capacity_and_hasher(func_args.len(), ahash::RandomState::default());
     for (name, value) in func_args {
         match name {
             Some(n) => {

parser/src/lexer.rs

@@ -5,12 +5,19 @@
 pub use super::token::Tok;
 use crate::ast::Location;
 use crate::error::{LexicalError, LexicalErrorType};
+use alloc::{
+    borrow::ToOwned,
+    format,
+    string::{String, ToString},
+    vec,
+    vec::Vec,
+};
+use core::char;
+use core::cmp::Ordering;
+use core::str::FromStr;
 use num_bigint::BigInt;
 use num_traits::identities::Zero;
 use num_traits::Num;
-use std::char;
-use std::cmp::Ordering;
-use std::str::FromStr;
 use unic_emoji_char::is_emoji_presentation;
 use unic_ucd_ident::{is_xid_continue, is_xid_start};
 
@@ -436,8 +443,8 @@ where
             }
         }
         match p {
-            0xD800..=0xDFFF => Ok(std::char::REPLACEMENT_CHARACTER),
-            _ => std::char::from_u32(p).ok_or(unicode_error),
+            0xD800..=0xDFFF => Ok(char::REPLACEMENT_CHARACTER),
+            _ => char::from_u32(p).ok_or(unicode_error),
         }
     }
 

parser/src/lib.rs

@@ -17,6 +17,13 @@
 
 #![doc(html_logo_url = "https://raw.githubusercontent.com/RustPython/RustPython/master/logo.png")]
 #![doc(html_root_url = "https://docs.rs/rustpython-parser/")]
+#![cfg_attr(not(feature = "std"), no_std)]
+
+extern crate alloc;
+
+// hack to get around lalrpop hardcoding ::std::* paths
+#[cfg(not(feature = "std"))]
+extern crate self as std;
 
 #[macro_use]
 extern crate log;

parser/src/mode.rs

@@ -1,10 +1,12 @@
+use core::fmt;
+
 #[derive(Clone, Copy)]
 pub enum Mode {
     Program,
     Statement,
 }
 
-impl std::str::FromStr for Mode {
+impl core::str::FromStr for Mode {
     type Err = ModeParseError;
     fn from_str(s: &str) -> Result<Self, ModeParseError> {
         match s {
@@ -20,8 +22,8 @@ pub struct ModeParseError {
     _priv: (),
 }
 
-impl std::fmt::Display for ModeParseError {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+impl fmt::Display for ModeParseError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, r#"mode should be "exec", "eval", or "single""#)
     }
 }

parser/src/parser.rs

@@ -5,7 +5,8 @@
 //! parse a whole program, a single statement, or a single
 //! expression.
 
-use std::iter;
+use alloc::vec::Vec;
+use core::iter;
 
 use crate::ast;
 use crate::error::ParseError;
@@ -106,6 +107,7 @@ mod tests {
     use super::parse_expression;
     use super::parse_program;
     use super::parse_statement;
+    use alloc::borrow::ToOwned;
     use num_bigint::BigInt;
 
     fn mk_ident(name: &str, row: usize, col: usize) -> ast::Expression {
@@ -136,7 +138,7 @@ mod tests {
             custom: (),
             node: ast::ExpressionType::String {
                 value: ast::StringGroup::Constant {
-                    value: String::from(value),
+                    value: value.to_owned(),
                 },
             },
         }
@@ -158,8 +160,8 @@ mod tests {
 
     #[test]
     fn test_parse_print_hello() {
-        let source = String::from("print('Hello world')");
-        let parse_ast = parse_program(&source).unwrap();
+        let source = "print('Hello world')";
+        let parse_ast = parse_program(source).unwrap();
         assert_eq!(
             parse_ast,
             ast::Program {
@@ -184,8 +186,8 @@ mod tests {
 
     #[test]
     fn test_parse_print_2() {
-        let source = String::from("print('Hello world', 2)");
-        let parse_ast = parse_program(&source).unwrap();
+        let source = "print('Hello world', 2)";
+        let parse_ast = parse_program(source).unwrap();
         assert_eq!(
             parse_ast,
             ast::Program {
@@ -210,8 +212,8 @@ mod tests {
 
     #[test]
     fn test_parse_kwargs() {
-        let source = String::from("my_func('positional', keyword=2)");
-        let parse_ast = parse_program(&source).unwrap();
+        let source = "my_func('positional', keyword=2)";
+        let parse_ast = parse_program(source).unwrap();
         assert_eq!(
             parse_ast,
             ast::Program {
@@ -239,8 +241,8 @@ mod tests {
 
     #[test]
     fn test_parse_if_elif_else() {
-        let source = String::from("if 1: 10\nelif 2: 20\nelse: 30");
-        let parse_ast = parse_statement(&source).unwrap();
+        let source = "if 1: 10\nelif 2: 20\nelse: 30";
+        let parse_ast = parse_statement(source).unwrap();
         assert_eq!(
             parse_ast,
             vec![ast::Statement {
@@ -265,8 +267,8 @@ mod tests {
 
     #[test]
     fn test_parse_lambda() {
-        let source = String::from("lambda x, y: x * y"); // lambda(x, y): x * y");
-        let parse_ast = parse_statement(&source);
+        let source = "lambda x, y: x * y"; // lambda(x, y): x * y");
+        let parse_ast = parse_statement(source);
         assert_eq!(
             parse_ast,
             Ok(vec![as_statement(ast::Expression {
@@ -278,12 +280,12 @@ mod tests {
                         args: vec![
                             ast::Parameter {
                                 location: ast::Location::new(1, 8),
-                                arg: String::from("x"),
+                                arg: "x".to_owned(),
                                 annotation: None,
                             },
                             ast::Parameter {
                                 location: ast::Location::new(1, 11),
-                                arg: String::from("y"),
+                                arg: "y".to_owned(),
                                 annotation: None,
                             }
                         ],
@@ -309,10 +311,10 @@ mod tests {
 
     #[test]
     fn test_parse_tuples() {
-        let source = String::from("a, b = 4, 5");
+        let source = "a, b = 4, 5";
 
         assert_eq!(
-            parse_statement(&source),
+            parse_statement(source),
             Ok(vec![ast::Statement {
                 location: ast::Location::new(1, 1),
                 custom: (),
@@ -338,16 +340,19 @@ mod tests {
 
     #[test]
     fn test_parse_class() {
-        let source = String::from(
-            "class Foo(A, B):\n def __init__(self):\n  pass\n def method_with_default(self, arg='default'):\n  pass",
-        );
+        let source = "\
+class Foo(A, B):
+ def __init__(self):
+  pass
+ def method_with_default(self, arg='default'):
+   pass";
         assert_eq!(
-            parse_statement(&source),
+            parse_statement(source),
             Ok(vec![ast::Statement {
                 location: ast::Location::new(1, 1),
                 custom: (),
                 node: ast::StatementType::ClassDef {
-                    name: String::from("Foo"),
+                    name: "Foo".to_owned(),
                     bases: vec![mk_ident("A", 1, 11), mk_ident("B", 1, 14)],
                     keywords: vec![],
                     body: vec![
@@ -356,12 +361,12 @@ mod tests {
                             custom: (),
                             node: ast::StatementType::FunctionDef {
                                 is_async: false,
-                                name: String::from("__init__"),
+                                name: "__init__".to_owned(),
                                 args: Box::new(ast::Parameters {
                                     posonlyargs_count: 0,
                                     args: vec![ast::Parameter {
                                         location: ast::Location::new(2, 15),
-                                        arg: String::from("self"),
+                                        arg: "self".to_owned(),
                                         annotation: None,
                                     }],
                                     kwonlyargs: vec![],
@@ -384,18 +389,18 @@ mod tests {
                             custom: (),
                             node: ast::StatementType::FunctionDef {
                                 is_async: false,
-                                name: String::from("method_with_default"),
+                                name: "method_with_default".to_owned(),
                                 args: Box::new(ast::Parameters {
                                     posonlyargs_count: 0,
                                     args: vec![
                                         ast::Parameter {
                                             location: ast::Location::new(4, 26),
-                                            arg: String::from("self"),
+                                            arg: "self".to_owned(),
                                             annotation: None,
                                         },
                                         ast::Parameter {
                                             location: ast::Location::new(4, 32),
-                                            arg: String::from("arg"),
+                                            arg: "arg".to_owned(),
                                             annotation: None,
                                         }
                                     ],
@@ -423,8 +428,8 @@ mod tests {
 
     #[test]
     fn test_parse_dict_comprehension() {
-        let source = String::from("{x1: x2 for y in z}");
-        let parse_ast = parse_expression(&source).unwrap();
+        let source = "{x1: x2 for y in z}";
+        let parse_ast = parse_expression(source).unwrap();
         assert_eq!(
             parse_ast,
             ast::Expression {
@@ -449,8 +454,8 @@ mod tests {
 
     #[test]
     fn test_parse_list_comprehension() {
-        let source = String::from("[x for y in z]");
-        let parse_ast = parse_expression(&source).unwrap();
+        let source = "[x for y in z]";
+        let parse_ast = parse_expression(source).unwrap();
         assert_eq!(
             parse_ast,
             ast::Expression {
@@ -474,8 +479,8 @@ mod tests {
 
     #[test]
     fn test_parse_double_list_comprehension() {
-        let source = String::from("[x for y, y2 in z for a in b if a < 5 if a > 10]");
-        let parse_ast = parse_expression(&source).unwrap();
+        let source = "[x for y, y2 in z for a in b if a < 5 if a > 10]";
+        let parse_ast = parse_expression(source).unwrap();
         assert_eq!(
             parse_ast,
             ast::Expression {

parser/src/python.lalrpop

@@ -3,13 +3,12 @@
 // See also: file:///usr/share/doc/python/html/reference/compound_stmts.html#function-definitions
 // See also: https://greentreesnakes.readthedocs.io/en/latest/nodes.html#keyword
 
-use std::iter::FromIterator;
-
 use crate::ast;
 use crate::fstring::parse_located_fstring;
 use crate::function::{parse_args, parse_params};
 use crate::error::LexicalError;
 use crate::lexer;
+use alloc::{boxed::Box, string::{String, ToString}, vec, vec::Vec};
 
 use num_bigint::BigInt;
 
@@ -26,7 +25,7 @@ pub Top: ast::Top = {
 
 Program: ast::Program = {
     <lines:FileLine*> => ast::Program {
-        statements: Vec::from_iter(lines.into_iter().flatten())
+        statements: lines.into_iter().flatten().collect(),
     },
 };
 

parser/src/token.rs

@@ -1,7 +1,8 @@
 //! Different token definitions.
 //! Loosely based on token.h from CPython source:
+use alloc::{string::String, vec::Vec};
+use core::fmt::{self, Write};
 use num_bigint::BigInt;
-use std::fmt::{self, Write};
 
 /// Python source code can be tokenized in a sequence of these tokens.
 #[derive(Clone, Debug, PartialEq)]

vm/Cargo.toml

@@ -9,13 +9,14 @@ edition = "2018"
 include = ["src/**/*.rs", "Cargo.toml", "build.rs", "Lib/**/*.py"]
 
 [features]
-default = ["compile-parse", "threading"]
+default = ["compile-parse", "threading", "std"]
 vm-tracing-logging = []
 flame-it = ["flame", "flamer"]
 freeze-stdlib = ["rustpython-pylib"]
 jit = ["rustpython-jit"]
 threading = ["rustpython-common/threading"]
 compile-parse = ["rustpython-parser", "rustpython-compiler"]
+std = ["rustpython-compiler/std"] # enables compiler-core/std, parser/std, etc
 
 ssl = ["openssl", "openssl-sys", "openssl-probe"]
 

vm/src/lib.rs

@@ -12,6 +12,7 @@
 #![allow(clippy::module_inception)]
 #![doc(html_logo_url = "https://raw.githubusercontent.com/RustPython/RustPython/master/logo.png")]
 #![doc(html_root_url = "https://docs.rs/rustpython-vm/")]
+#![cfg_attr(not(feature = "std"), no_std)]
 
 #[cfg(feature = "flame-it")]
 #[macro_use]