rustpython-parser/ast/src/unparse.rs at main · bazeltools/rustpython-parser · GitHub

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use crate::{

Arg, ArgWithDefault, Arguments, BoolOp, Comprehension, Constant, ConversionFlag, Expr,

Identifier, Operator, PythonArguments,

};

use std::fmt;

mod precedence {

macro_rules! precedence {

($($op:ident,)*) => {

precedence!(@0, $($op,)*);

};

(@$i:expr, $op1:ident, $($op:ident,)*) => {

pub const $op1: u8 = $i;

precedence!(@$i + 1, $($op,)*);

};

(@$i:expr,) => {};

}

precedence!(

TUPLE, TEST, OR, AND, NOT, CMP, // "EXPR" =

BOR, BXOR, BAND, SHIFT, ARITH, TERM, FACTOR, POWER, AWAIT, ATOM,

);

pub const EXPR: u8 = BOR;

}

#[repr(transparent)]

struct Unparser<'a> {

f: fmt::Formatter<'a>,

}

impl<'a> Unparser<'a> {

fn new<'b>(f: &'b mut fmt::Formatter<'a>) -> &'b mut Unparser<'a> {

unsafe { &mut *(f as *mut fmt::Formatter<'a> as *mut Unparser<'a>) }

}

fn p(&mut self, s: &str) -> fmt::Result {

self.f.write_str(s)

}

fn p_id(&mut self, s: &Identifier) -> fmt::Result {

self.f.write_str(s.as_str())

}

fn p_if(&mut self, cond: bool, s: &str) -> fmt::Result {

if cond {

self.f.write_str(s)?;

}

Ok(())

}

fn p_delim(&mut self, first: &mut bool, s: &str) -> fmt::Result {

self.p_if(!std::mem::take(first), s)

}

fn write_fmt(&mut self, f: fmt::Arguments<'_>) -> fmt::Result {

self.f.write_fmt(f)

}

fn unparse_expr(&mut self, ast: &Expr, level: u8) -> fmt::Result {

macro_rules! op_prec {

($op_ty:ident, $x:expr, $enu:path, $($var:ident($op:literal, $prec:ident)),*$(,)?) => {

match $x {

$(<$enu>::$var => (op_prec!(@space $op_ty, $op), precedence::$prec),)*

}

};

(@space bin, $op:literal) => {

concat!(" ", $op, " ")

};

(@space un, $op:literal) => {

$op

};

}

macro_rules! group_if {

($lvl:expr, $body:block) => {{

let group = level > $lvl;

self.p_if(group, "(")?;

let ret = $body;

self.p_if(group, ")")?;

ret

}};

}

match &ast {

Expr::BoolOp(crate::ExprBoolOp {

op,

values,

range: _range,

}) => {

let (op, prec) = op_prec!(bin, op, BoolOp, And("and", AND), Or("or", OR));

group_if!(prec, {

let mut first = true;

for val in values {

self.p_delim(&mut first, op)?;

self.unparse_expr(val, prec + 1)?;

}

})

}

Expr::NamedExpr(crate::ExprNamedExpr {

target,

value,

range: _range,

}) => {

group_if!(precedence::TUPLE, {

self.unparse_expr(target, precedence::ATOM)?;

self.p(" := ")?;

self.unparse_expr(value, precedence::ATOM)?;

})

}

Expr::BinOp(crate::ExprBinOp {

left,

op,

right,

range: _range,

}) => {

let right_associative = matches!(op, Operator::Pow);

let (op, prec) = op_prec!(

bin,

op,

Operator,

Add("+", ARITH),

Sub("-", ARITH),

Mult("*", TERM),

MatMult("@", TERM),

Div("/", TERM),

Mod("%", TERM),

Pow("**", POWER),

LShift("<<", SHIFT),

RShift(">>", SHIFT),

BitOr("|", BOR),

BitXor("^", BXOR),

BitAnd("&", BAND),

FloorDiv("//", TERM),

);

group_if!(prec, {

self.unparse_expr(left, prec + right_associative as u8)?;

self.p(op)?;

self.unparse_expr(right, prec + !right_associative as u8)?;

})

}

Expr::UnaryOp(crate::ExprUnaryOp {

op,

operand,

range: _range,

}) => {

let (op, prec) = op_prec!(

un,

op,

crate::UnaryOp,

Invert("~", FACTOR),

Not("not ", NOT),

UAdd("+", FACTOR),

USub("-", FACTOR)

);

group_if!(prec, {

self.p(op)?;

self.unparse_expr(operand, prec)?;

})

}

Expr::Lambda(crate::ExprLambda {

args,

body,

range: _range,

}) => {

group_if!(precedence::TEST, {

let pos = args.args.len() + args.posonlyargs.len();

self.p(if pos > 0 { "lambda " } else { "lambda" })?;

self.unparse_arguments(args)?;

write!(self, ": {}", **body)?;

})

}

Expr::IfExp(crate::ExprIfExp {

test,

body,

orelse,

range: _range,

}) => {

group_if!(precedence::TEST, {

self.unparse_expr(body, precedence::TEST + 1)?;

self.p(" if ")?;

self.unparse_expr(test, precedence::TEST + 1)?;

self.p(" else ")?;

self.unparse_expr(orelse, precedence::TEST)?;

})

}

Expr::Dict(crate::ExprDict {

keys,

values,

range: _range,

}) => {

self.p("{")?;

let mut first = true;

let (packed, unpacked) = values.split_at(keys.len());

for (k, v) in keys.iter().zip(packed) {

self.p_delim(&mut first, ", ")?;

if let Some(k) = k {

write!(self, "{}: {}", *k, *v)?;

} else {

write!(self, "**{}", *v)?;

}

for d in unpacked {

self.p_delim(&mut first, ", ")?;

write!(self, "**{}", *d)?;

}

self.p("}")?;

}

Expr::Set(crate::ExprSet {

elts,

range: _range,

}) => {

self.p("{")?;

let mut first = true;

for v in elts {

self.p_delim(&mut first, ", ")?;

self.unparse_expr(v, precedence::TEST)?;

}

self.p("}")?;

}

Expr::ListComp(crate::ExprListComp {

elt,

generators,

range: _range,

}) => {

self.p("[")?;

self.unparse_expr(elt, precedence::TEST)?;

self.unparse_comp(generators)?;

self.p("]")?;

}

Expr::SetComp(crate::ExprSetComp {

elt,

generators,

range: _range,

}) => {

self.p("{")?;

self.unparse_expr(elt, precedence::TEST)?;

self.unparse_comp(generators)?;

self.p("}")?;

}

Expr::DictComp(crate::ExprDictComp {

key,

value,

generators,

range: _range,

}) => {

self.p("{")?;

self.unparse_expr(key, precedence::TEST)?;

self.p(": ")?;

self.unparse_expr(value, precedence::TEST)?;

self.unparse_comp(generators)?;

self.p("}")?;

}

Expr::GeneratorExp(crate::ExprGeneratorExp {

elt,

generators,

range: _range,

}) => {

self.p("(")?;

self.unparse_expr(elt, precedence::TEST)?;

self.unparse_comp(generators)?;

self.p(")")?;

}

Expr::Await(crate::ExprAwait {

value,

range: _range,

}) => {

group_if!(precedence::AWAIT, {

self.p("await ")?;

self.unparse_expr(value, precedence::ATOM)?;

})

}

Expr::Yield(crate::ExprYield {

value,

range: _range,

}) => {

if let Some(value) = value {

write!(self, "(yield {})", **value)?;

} else {

self.p("(yield)")?;

}

Expr::YieldFrom(crate::ExprYieldFrom {

value,

range: _range,

}) => {

write!(self, "(yield from {})", **value)?;

}

Expr::Compare(crate::ExprCompare {

left,

ops,

comparators,

range: _range,

}) => {

group_if!(precedence::CMP, {

let new_lvl = precedence::CMP + 1;

self.unparse_expr(left, new_lvl)?;

for (op, cmp) in ops.iter().zip(comparators) {

self.p(" ")?;

self.p(op.as_str())?;

self.p(" ")?;

self.unparse_expr(cmp, new_lvl)?;

}

})

}

Expr::Call(crate::ExprCall {

func,

args,

keywords,

range: _range,

}) => {

self.unparse_expr(func, precedence::ATOM)?;

self.p("(")?;

if let (

[Expr::GeneratorExp(crate::ExprGeneratorExp {

elt,

generators,

range: _range,

})],

[],

) = (&**args, &**keywords)

{

// make sure a single genexpr doesn't get double parens

self.unparse_expr(elt, precedence::TEST)?;

self.unparse_comp(generators)?;

} else {

let mut first = true;

for arg in args {

self.p_delim(&mut first, ", ")?;

self.unparse_expr(arg, precedence::TEST)?;

}

for kw in keywords {

self.p_delim(&mut first, ", ")?;

if let Some(arg) = &kw.arg {

self.p_id(arg)?;

self.p("=")?;

} else {

self.p("**")?;

}

self.unparse_expr(&kw.value, precedence::TEST)?;

}

self.p(")")?;

}

Expr::FormattedValue(crate::ExprFormattedValue {

value,

conversion,

format_spec,

range: _range,

}) => self.unparse_formatted(value, *conversion, format_spec.as_deref())?,

Expr::JoinedStr(crate::ExprJoinedStr {

values,

range: _range,

}) => self.unparse_joined_str(values, false)?,

Expr::Constant(crate::ExprConstant {

value,

kind,

range: _range,

}) => {

if let Some(kind) = kind {

self.p(kind)?;

}

assert_eq!(f64::MAX_10_EXP, 308);

let inf_str = "1e309";

match value {

Constant::Float(f) if f.is_infinite() => self.p(inf_str)?,

Constant::Complex { real, imag }

if real.is_infinite() || imag.is_infinite() =>

{

self.p(&value.to_string().replace("inf", inf_str))?

}

_ => fmt::Display::fmt(value, &mut self.f)?,

}

Expr::Attribute(crate::ExprAttribute { value, attr, .. }) => {

self.unparse_expr(value, precedence::ATOM)?;

let period = if let Expr::Constant(crate::ExprConstant {

value: Constant::Int(_),

}) = value.as_ref()

{

" ."

} else {

"."

};

self.p(period)?;

self.p_id(attr)?;

}

Expr::Subscript(crate::ExprSubscript { value, slice, .. }) => {

self.unparse_expr(value, precedence::ATOM)?;

let mut lvl = precedence::TUPLE;

if let Expr::Tuple(crate::ExprTuple { elts, .. }) = slice.as_ref() {

if elts.iter().any(|expr| expr.is_starred_expr()) {

lvl += 1

}

self.p("[")?;

self.unparse_expr(slice, lvl)?;

self.p("]")?;

}

Expr::Starred(crate::ExprStarred { value, .. }) => {

self.p("*")?;

self.unparse_expr(value, precedence::EXPR)?;

}

Expr::Name(crate::ExprName { id, .. }) => self.p_id(id)?,

Expr::List(crate::ExprList { elts, .. }) => {

self.p("[")?;

let mut first = true;

for elt in elts {

self.p_delim(&mut first, ", ")?;

self.unparse_expr(elt, precedence::TEST)?;

}

self.p("]")?;

}

Expr::Tuple(crate::ExprTuple { elts, .. }) => {

if elts.is_empty() {

self.p("()")?;

} else {

group_if!(precedence::TUPLE, {

let mut first = true;

for elt in elts {

self.p_delim(&mut first, ", ")?;

self.unparse_expr(elt, precedence::TEST)?;

}

self.p_if(elts.len() == 1, ",")?;

})

}

Expr::Slice(crate::ExprSlice {

lower,

upper,

step,

range: _range,

}) => {

if let Some(lower) = lower {

self.unparse_expr(lower, precedence::TEST)?;

}

self.p(":")?;

if let Some(upper) = upper {

self.unparse_expr(upper, precedence::TEST)?;

}

if let Some(step) = step {

self.p(":")?;

self.unparse_expr(step, precedence::TEST)?;

}

Ok(())

}

fn unparse_arguments(&mut self, args: &Arguments) -> fmt::Result {

let mut first = true;

for (i, arg) in args.posonlyargs.iter().chain(&args.args).enumerate() {

self.p_delim(&mut first, ", ")?;

self.unparse_function_arg(arg)?;

self.p_if(i + 1 == args.posonlyargs.len(), ", /")?;

}

if args.vararg.is_some() || !args.kwonlyargs.is_empty() {

self.p_delim(&mut first, ", ")?;

self.p("*")?;

}

if let Some(vararg) = &args.vararg {

self.unparse_arg(vararg)?;

}

for kwarg in args.kwonlyargs.iter() {

self.p_delim(&mut first, ", ")?;

self.unparse_function_arg(kwarg)?;

}

if let Some(kwarg) = &args.kwarg {

self.p_delim(&mut first, ", ")?;

self.p("**")?;

self.unparse_arg(kwarg)?;

}

Ok(())

}

fn unparse_function_arg(&mut self, arg: &ArgWithDefault) -> fmt::Result {

self.p_id(&arg.def.arg)?;

if let Some(ann) = &arg.def.annotation {

write!(self, ": {}", **ann)?;

}

if let Some(default) = &arg.default {

write!(self, "={}", default)?;

}

Ok(())

}

#[allow(dead_code)]

fn unparse_python_arguments(&mut self, args: &PythonArguments) -> fmt::Result {

let mut first = true;

let defaults_start = args.posonlyargs.len() + args.args.len() - args.defaults.len();

for (i, arg) in args.posonlyargs.iter().chain(&args.args).enumerate() {

self.p_delim(&mut first, ", ")?;

self.unparse_arg(arg)?;

if let Some(i) = i.checked_sub(defaults_start) {

write!(self, "={}", &args.defaults[i])?;

}

self.p_if(i + 1 == args.posonlyargs.len(), ", /")?;

}

if args.vararg.is_some() || !args.kwonlyargs.is_empty() {

self.p_delim(&mut first, ", ")?;

self.p("*")?;

}

if let Some(vararg) = &args.vararg {

self.unparse_arg(vararg)?;

}

let defaults_start = args.kwonlyargs.len() - args.kw_defaults.len();

for (i, kwarg) in args.kwonlyargs.iter().enumerate() {

self.p_delim(&mut first, ", ")?;

self.unparse_arg(kwarg)?;

if let Some(default) = i

.checked_sub(defaults_start)

.and_then(|i| args.kw_defaults.get(i))

{

write!(self, "={default}")?;

}

if let Some(kwarg) = &args.kwarg {

self.p_delim(&mut first, ", ")?;

self.p("**")?;

self.unparse_arg(kwarg)?;

}

Ok(())

}

fn unparse_arg(&mut self, arg: &Arg) -> fmt::Result {

self.p_id(&arg.arg)?;

if let Some(ann) = &arg.annotation {

write!(self, ": {}", **ann)?;

}

Ok(())

}

fn unparse_comp(&mut self, generators: &[Comprehension]) -> fmt::Result {

for comp in generators {

self.p(if comp.is_async {

" async for "

} else {

" for "

})?;

self.unparse_expr(&comp.target, precedence::TUPLE)?;

self.p(" in ")?;

self.unparse_expr(&comp.iter, precedence::TEST + 1)?;

for cond in &comp.ifs {

self.p(" if ")?;

self.unparse_expr(cond, precedence::TEST + 1)?;

}

Ok(())

}

fn unparse_fstring_body(&mut self, values: &[Expr], is_spec: bool) -> fmt::Result {

for value in values {

self.unparse_fstring_elem(value, is_spec)?;

}

Ok(())

}

fn unparse_formatted(

&mut self,

val: &Expr,

conversion: ConversionFlag,

spec: Option<&Expr>,

) -> fmt::Result {

let buffered = to_string_fmt(|f| Unparser::new(f).unparse_expr(val, precedence::TEST + 1));

let brace = if buffered.starts_with('{') {

// put a space to avoid escaping the bracket

"{ "

} else {

"{"

};

self.p(brace)?;

self.p(&buffered)?;

drop(buffered);

if conversion != ConversionFlag::None {

self.p("!")?;

let buf = &[conversion as u8];

let c = std::str::from_utf8(buf).unwrap();

self.p(c)?;

}

if let Some(spec) = spec {

self.p(":")?;

self.unparse_fstring_elem(spec, true)?;

}

self.p("}")?;

Ok(())

}

fn unparse_fstring_elem(&mut self, expr: &Expr, is_spec: bool) -> fmt::Result {

match &expr {

Expr::Constant(crate::ExprConstant { value, .. }) => {

if let Constant::Str(s) = value {

self.unparse_fstring_str(s)

} else {

unreachable!()

}

Expr::JoinedStr(crate::ExprJoinedStr {

values,

range: _range,

}) => self.unparse_joined_str(values, is_spec),

Expr::FormattedValue(crate::ExprFormattedValue {

value,

conversion,

format_spec,

range: _range,

}) => self.unparse_formatted(value, *conversion, format_spec.as_deref()),

_ => unreachable!(),

}

fn unparse_fstring_str(&mut self, s: &str) -> fmt::Result {

let s = s.replace('{', "{{").replace('}', "}}");

self.p(&s)

}

fn unparse_joined_str(&mut self, values: &[Expr], is_spec: bool) -> fmt::Result {

if is_spec {

self.unparse_fstring_body(values, is_spec)

} else {

self.p("f")?;

let body = to_string_fmt(|f| Unparser::new(f).unparse_fstring_body(values, is_spec));

rustpython_literal::escape::UnicodeEscape::new_repr(&body)

.str_repr()

.write(&mut self.f)

}

impl fmt::Display for Expr {

fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {

Unparser::new(f).unparse_expr(self, precedence::TEST)

}

fn to_string_fmt(f: impl FnOnce(&mut fmt::Formatter) -> fmt::Result) -> String {

use std::cell::Cell;

struct Fmt<F>(Cell<Option<F>>);

impl<F: FnOnce(&mut fmt::Formatter) -> fmt::Result> fmt::Display for Fmt<F> {

fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {

self.0.take().unwrap()(f)

}

Fmt(Cell::new(Some(f))).to_string()

}

rustpython-parser/ast/src/unparse.rs at main · bazeltools/rustpython-parser · GitHub

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