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parser.y: abstract new into a function on Exprs

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so it can easily be swapped out for other implementations
This commit is contained in:
Taeer Bar-Yam 2025-11-04 15:46:47 +01:00
parent 62729ff472
commit 687dd38998
4 changed files with 111 additions and 75 deletions
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4
src/libexpr/eval.cc
View file

@ -3216,8 +3216,8 @@ Expr * EvalState::parse(
docComments = &it->second;
}
auto result = parseExprFromBuf(
text, length, origin, basePath, mem.exprs, symbols, settings, positions, *docComments, rootFS);
auto result =
parseExprFromBuf(text, length, origin, basePath, mem.exprs, symbols, settings, positions, *docComments, rootFS);
result->bindVars(*this, staticEnv);

50
src/libexpr/include/nix/expr/nixexpr.hh
View file

@ -91,13 +91,6 @@ std::string showAttrPath(const SymbolTable & symbols, std::span<const AttrName>
using UpdateQueue = SmallTemporaryValueVector<conservativeStackReservation>;
class Exprs
{
std::pmr::monotonic_buffer_resource buffer;
public:
std::pmr::polymorphic_allocator<char> alloc{&buffer};
};
/* Abstract syntax of Nix expressions. */
struct Expr
@ -810,6 +803,49 @@ struct ExprBlackHole : Expr
extern ExprBlackHole eBlackHole;
class Exprs
{
std::pmr::monotonic_buffer_resource buffer;
public:
std::pmr::polymorphic_allocator<char> alloc{&buffer};
template<class C>
[[gnu::always_inline]]
C * add(auto &&... args)
{
return new C(std::forward<decltype(args)>(args)...);
}
// we define some calls to add explicitly so that the argument can be passed in as initializer lists
template<class C>
[[gnu::always_inline]]
C * add(const PosIdx & pos, Expr * fun, std::vector<Expr *> && args)
requires(std::same_as<C, ExprCall>)
{
return new C(pos, fun, std::move(args));
}
template<class C>
[[gnu::always_inline]]
C * add(const PosIdx & pos, Expr * fun, std::vector<Expr *> && args, PosIdx && cursedOrEndPos)
requires(std::same_as<C, ExprCall>)
{
return new C(pos, fun, std::move(args), std::move(cursedOrEndPos));
}
template<class C>
[[gnu::always_inline]]
C *
add(std::pmr::polymorphic_allocator<char> & alloc,
const PosIdx & pos,
bool forceString,
const std::vector<std::pair<PosIdx, Expr *>> & es)
requires(std::same_as<C, ExprConcatStrings>)
{
return alloc.new_object<C>(alloc, pos, forceString, es);
}
};
/* Static environments are used to map variable names onto (level,
displacement) pairs used to obtain the value of the variable at
runtime. */

12
src/libexpr/include/nix/expr/parser-state.hh
View file

@ -132,11 +132,11 @@ inline void ParserState::addAttr(
dupAttr(attrPath, pos, j->second.pos);
}
} else {
nested = new ExprAttrs;
nested = exprs.add<ExprAttrs>();
attrs->attrs[i->symbol] = ExprAttrs::AttrDef(nested, pos);
}
} else {
nested = new ExprAttrs;
nested = exprs.add<ExprAttrs>();
attrs->dynamicAttrs.push_back(ExprAttrs::DynamicAttrDef(i->expr, nested, pos));
}
attrs = nested;
@ -240,7 +240,7 @@ inline Expr *
ParserState::stripIndentation(const PosIdx pos, std::vector<std::pair<PosIdx, std::variant<Expr *, StringToken>>> && es)
{
if (es.empty())
return new ExprString("");
return exprs.add<ExprString>("");
/* Figure out the minimum indentation. Note that by design
whitespace-only final lines are not taken into account. (So
@ -322,7 +322,7 @@ ParserState::stripIndentation(const PosIdx pos, std::vector<std::pair<PosIdx, st
// Ignore empty strings for a minor optimisation and AST simplification
if (s2 != "") {
es2.emplace_back(i->first, new ExprString(exprs.alloc, s2));
es2.emplace_back(i->first, exprs.add<ExprString>(exprs.alloc, s2));
}
};
for (; i != es.end(); ++i, --n) {
@ -332,7 +332,7 @@ ParserState::stripIndentation(const PosIdx pos, std::vector<std::pair<PosIdx, st
// If there is nothing at all, return the empty string directly.
// This also ensures that equivalent empty strings result in the same ast, which is helpful when testing formatters.
if (es2.size() == 0) {
auto * const result = new ExprString("");
auto * const result = exprs.add<ExprString>("");
return result;
}
@ -341,7 +341,7 @@ ParserState::stripIndentation(const PosIdx pos, std::vector<std::pair<PosIdx, st
auto * const result = (es2)[0].second;
return result;
}
return new ExprConcatStrings(exprs.alloc, pos, true, std::move(es2));
return exprs.add<ExprConcatStrings>(exprs.alloc, pos, true, std::move(es2));
}
inline PosIdx LexerState::at(const ParserLocation & loc)

120
src/libexpr/parser.y
View file

@ -113,12 +113,12 @@ static void setDocPosition(const LexerState & lexerState, ExprLambda * lambda, P
}
}
static Expr * makeCall(PosIdx pos, Expr * fn, Expr * arg) {
static Expr * makeCall(Exprs & exprs, PosIdx pos, Expr * fn, Expr * arg) {
if (auto e2 = dynamic_cast<ExprCall *>(fn)) {
e2->args.push_back(arg);
return fn;
}
return new ExprCall(pos, fn, {arg});
return exprs.add<ExprCall>(pos, fn, {arg});
}
@ -179,14 +179,14 @@ expr: expr_function;
expr_function
: ID ':' expr_function
{ auto me = new ExprLambda(CUR_POS, state->symbols.create($1), $3);
{ auto me = state->exprs.add<ExprLambda>(CUR_POS, state->symbols.create($1), $3);
$$ = me;
SET_DOC_POS(me, @1);
}
| formal_set ':' expr_function[body]
{
state->validateFormals($formal_set);
auto me = new ExprLambda(state->positions, state->exprs.alloc, CUR_POS, std::move($formal_set), $body);
auto me = state->exprs.add<ExprLambda>(state->positions, state->exprs.alloc, CUR_POS, std::move($formal_set), $body);
$$ = me;
SET_DOC_POS(me, @1);
}
@ -194,7 +194,7 @@ expr_function
{
auto arg = state->symbols.create($ID);
state->validateFormals($formal_set, CUR_POS, arg);
auto me = new ExprLambda(state->positions, state->exprs.alloc, CUR_POS, arg, std::move($formal_set), $body);
auto me = state->exprs.add<ExprLambda>(state->positions, state->exprs.alloc, CUR_POS, arg, std::move($formal_set), $body);
$$ = me;
SET_DOC_POS(me, @1);
}
@ -202,67 +202,67 @@ expr_function
{
auto arg = state->symbols.create($ID);
state->validateFormals($formal_set, CUR_POS, arg);
auto me = new ExprLambda(state->positions, state->exprs.alloc, CUR_POS, arg, std::move($formal_set), $body);
auto me = state->exprs.add<ExprLambda>(state->positions, state->exprs.alloc, CUR_POS, arg, std::move($formal_set), $body);
$$ = me;
SET_DOC_POS(me, @1);
}
| ASSERT expr ';' expr_function
{ $$ = new ExprAssert(CUR_POS, $2, $4); }
{ $$ = state->exprs.add<ExprAssert>(CUR_POS, $2, $4); }
| WITH expr ';' expr_function
{ $$ = new ExprWith(CUR_POS, $2, $4); }
{ $$ = state->exprs.add<ExprWith>(CUR_POS, $2, $4); }
| LET binds IN_KW expr_function
{ if (!$2->dynamicAttrs.empty())
throw ParseError({
.msg = HintFmt("dynamic attributes not allowed in let"),
.pos = state->positions[CUR_POS]
});
$$ = new ExprLet($2, $4);
$$ = state->exprs.add<ExprLet>($2, $4);
}
| expr_if
;
expr_if
: IF expr THEN expr ELSE expr { $$ = new ExprIf(CUR_POS, $2, $4, $6); }
: IF expr THEN expr ELSE expr { $$ = state->exprs.add<ExprIf>(CUR_POS, $2, $4, $6); }
| expr_pipe_from
| expr_pipe_into
| expr_op
;
expr_pipe_from
: expr_op PIPE_FROM expr_pipe_from { $$ = makeCall(state->at(@2), $1, $3); }
| expr_op PIPE_FROM expr_op { $$ = makeCall(state->at(@2), $1, $3); }
: expr_op PIPE_FROM expr_pipe_from { $$ = makeCall(state->exprs, state->at(@2), $1, $3); }
| expr_op PIPE_FROM expr_op { $$ = makeCall(state->exprs, state->at(@2), $1, $3); }
;
expr_pipe_into
: expr_pipe_into PIPE_INTO expr_op { $$ = makeCall(state->at(@2), $3, $1); }
| expr_op PIPE_INTO expr_op { $$ = makeCall(state->at(@2), $3, $1); }
: expr_pipe_into PIPE_INTO expr_op { $$ = makeCall(state->exprs, state->at(@2), $3, $1); }
| expr_op PIPE_INTO expr_op { $$ = makeCall(state->exprs, state->at(@2), $3, $1); }
;
expr_op
: '!' expr_op %prec NOT { $$ = new ExprOpNot($2); }
| '-' expr_op %prec NEGATE { $$ = new ExprCall(CUR_POS, new ExprVar(state->s.sub), {new ExprInt(0), $2}); }
| expr_op EQ expr_op { $$ = new ExprOpEq($1, $3); }
| expr_op NEQ expr_op { $$ = new ExprOpNEq($1, $3); }
| expr_op '<' expr_op { $$ = new ExprCall(state->at(@2), new ExprVar(state->s.lessThan), {$1, $3}); }
| expr_op LEQ expr_op { $$ = new ExprOpNot(new ExprCall(state->at(@2), new ExprVar(state->s.lessThan), {$3, $1})); }
| expr_op '>' expr_op { $$ = new ExprCall(state->at(@2), new ExprVar(state->s.lessThan), {$3, $1}); }
| expr_op GEQ expr_op { $$ = new ExprOpNot(new ExprCall(state->at(@2), new ExprVar(state->s.lessThan), {$1, $3})); }
| expr_op AND expr_op { $$ = new ExprOpAnd(state->at(@2), $1, $3); }
| expr_op OR expr_op { $$ = new ExprOpOr(state->at(@2), $1, $3); }
| expr_op IMPL expr_op { $$ = new ExprOpImpl(state->at(@2), $1, $3); }
| expr_op UPDATE expr_op { $$ = new ExprOpUpdate(state->at(@2), $1, $3); }
| expr_op '?' attrpath { $$ = new ExprOpHasAttr(state->exprs.alloc, $1, std::move($3)); }
: '!' expr_op %prec NOT { $$ = state->exprs.add<ExprOpNot>($2); }
| '-' expr_op %prec NEGATE { $$ = state->exprs.add<ExprCall>(CUR_POS, state->exprs.add<ExprVar>(state->s.sub), {state->exprs.add<ExprInt>(0), $2}); }
| expr_op EQ expr_op { $$ = state->exprs.add<ExprOpEq>($1, $3); }
| expr_op NEQ expr_op { $$ = state->exprs.add<ExprOpNEq>($1, $3); }
| expr_op '<' expr_op { $$ = state->exprs.add<ExprCall>(state->at(@2), state->exprs.add<ExprVar>(state->s.lessThan), {$1, $3}); }
| expr_op LEQ expr_op { $$ = state->exprs.add<ExprOpNot>(state->exprs.add<ExprCall>(state->at(@2), state->exprs.add<ExprVar>(state->s.lessThan), {$3, $1})); }
| expr_op '>' expr_op { $$ = state->exprs.add<ExprCall>(state->at(@2), state->exprs.add<ExprVar>(state->s.lessThan), {$3, $1}); }
| expr_op GEQ expr_op { $$ = state->exprs.add<ExprOpNot>(state->exprs.add<ExprCall>(state->at(@2), state->exprs.add<ExprVar>(state->s.lessThan), {$1, $3})); }
| expr_op AND expr_op { $$ = state->exprs.add<ExprOpAnd>(state->at(@2), $1, $3); }
| expr_op OR expr_op { $$ = state->exprs.add<ExprOpOr>(state->at(@2), $1, $3); }
| expr_op IMPL expr_op { $$ = state->exprs.add<ExprOpImpl>(state->at(@2), $1, $3); }
| expr_op UPDATE expr_op { $$ = state->exprs.add<ExprOpUpdate>(state->at(@2), $1, $3); }
| expr_op '?' attrpath { $$ = state->exprs.add<ExprOpHasAttr>(state->exprs.alloc, $1, std::move($3)); }
| expr_op '+' expr_op
{ $$ = new ExprConcatStrings(state->exprs.alloc, state->at(@2), false, {{state->at(@1), $1}, {state->at(@3), $3}}); }
| expr_op '-' expr_op { $$ = new ExprCall(state->at(@2), new ExprVar(state->s.sub), {$1, $3}); }
| expr_op '*' expr_op { $$ = new ExprCall(state->at(@2), new ExprVar(state->s.mul), {$1, $3}); }
| expr_op '/' expr_op { $$ = new ExprCall(state->at(@2), new ExprVar(state->s.div), {$1, $3}); }
| expr_op CONCAT expr_op { $$ = new ExprOpConcatLists(state->at(@2), $1, $3); }
{ $$ = state->exprs.add<ExprConcatStrings>(state->exprs.alloc, state->at(@2), false, {{state->at(@1), $1}, {state->at(@3), $3}}); }
| expr_op '-' expr_op { $$ = state->exprs.add<ExprCall>(state->at(@2), state->exprs.add<ExprVar>(state->s.sub), {$1, $3}); }
| expr_op '*' expr_op { $$ = state->exprs.add<ExprCall>(state->at(@2), state->exprs.add<ExprVar>(state->s.mul), {$1, $3}); }
| expr_op '/' expr_op { $$ = state->exprs.add<ExprCall>(state->at(@2), state->exprs.add<ExprVar>(state->s.div), {$1, $3}); }
| expr_op CONCAT expr_op { $$ = state->exprs.add<ExprOpConcatLists>(state->at(@2), $1, $3); }
| expr_app
;
expr_app
: expr_app expr_select { $$ = makeCall(CUR_POS, $1, $2); $2->warnIfCursedOr(state->symbols, state->positions); }
: expr_app expr_select { $$ = makeCall(state->exprs, CUR_POS, $1, $2); $2->warnIfCursedOr(state->symbols, state->positions); }
| /* Once a ‘cursed or’ reaches this nonterminal, it is no longer cursed,
because the uncursed parse would also produce an expr_app. But we need
to remove the cursed status in order to prevent valid things like
@ -272,9 +272,9 @@ expr_app
expr_select
: expr_simple '.' attrpath
{ $$ = new ExprSelect(state->exprs.alloc, CUR_POS, $1, std::move($3), nullptr); }
{ $$ = state->exprs.add<ExprSelect>(state->exprs.alloc, CUR_POS, $1, std::move($3), nullptr); }
| expr_simple '.' attrpath OR_KW expr_select
{ $$ = new ExprSelect(state->exprs.alloc, CUR_POS, $1, std::move($3), $5); $5->warnIfCursedOr(state->symbols, state->positions); }
{ $$ = state->exprs.add<ExprSelect>(state->exprs.alloc, CUR_POS, $1, std::move($3), $5); $5->warnIfCursedOr(state->symbols, state->positions); }
| /* Backwards compatibility: because Nixpkgs has a function named ‘or’,
allow stuff like ‘map or [...]’. This production is problematic (see
https://github.com/NixOS/nix/issues/11118) and will be refactored in the
@ -283,7 +283,7 @@ expr_select
the ExprCall with data (establishing that it is a ‘cursed or’) that can
be used to emit a warning when an affected expression is parsed. */
expr_simple OR_KW
{ $$ = new ExprCall(CUR_POS, $1, {new ExprVar(CUR_POS, state->s.or_)}, state->positions.add(state->origin, @$.endOffset)); }
{ $$ = state->exprs.add<ExprCall>(CUR_POS, $1, {state->exprs.add<ExprVar>(CUR_POS, state->s.or_)}, state->positions.add(state->origin, @$.endOffset)); }
| expr_simple
;
@ -291,15 +291,15 @@ expr_simple
: ID {
std::string_view s = "__curPos";
if ($1.l == s.size() && strncmp($1.p, s.data(), s.size()) == 0)
$$ = new ExprPos(CUR_POS);
$$ = state->exprs.add<ExprPos>(CUR_POS);
else
$$ = new ExprVar(CUR_POS, state->symbols.create($1));
$$ = state->exprs.add<ExprVar>(CUR_POS, state->symbols.create($1));
}
| INT_LIT { $$ = new ExprInt($1); }
| FLOAT_LIT { $$ = new ExprFloat($1); }
| INT_LIT { $$ = state->exprs.add<ExprInt>($1); }
| FLOAT_LIT { $$ = state->exprs.add<ExprFloat>($1); }
| '"' string_parts '"' {
std::visit(overloaded{
[&](std::string_view str) { $$ = new ExprString(state->exprs.alloc, str); },
[&](std::string_view str) { $$ = state->exprs.add<ExprString>(state->exprs.alloc, str); },
[&](Expr * expr) { $$ = expr; }},
$2);
}
@ -309,14 +309,14 @@ expr_simple
| path_start PATH_END
| path_start string_parts_interpolated PATH_END {
$2.insert($2.begin(), {state->at(@1), $1});
$$ = new ExprConcatStrings(state->exprs.alloc, CUR_POS, false, std::move($2));
$$ = state->exprs.add<ExprConcatStrings>(state->exprs.alloc, CUR_POS, false, std::move($2));
}
| SPATH {
std::string_view path($1.p + 1, $1.l - 2);
$$ = new ExprCall(CUR_POS,
new ExprVar(state->s.findFile),
{new ExprVar(state->s.nixPath),
new ExprString(state->exprs.alloc, path)});
$$ = state->exprs.add<ExprCall>(CUR_POS,
state->exprs.add<ExprVar>(state->s.findFile),
{state->exprs.add<ExprVar>(state->s.nixPath),
state->exprs.add<ExprString>(state->exprs.alloc, path)});
}
| URI {
static bool noURLLiterals = experimentalFeatureSettings.isEnabled(Xp::NoUrlLiterals);
@ -325,35 +325,35 @@ expr_simple
.msg = HintFmt("URL literals are disabled"),
.pos = state->positions[CUR_POS]
});
$$ = new ExprString(state->exprs.alloc, $1);
$$ = state->exprs.add<ExprString>(state->exprs.alloc, $1);
}
| '(' expr ')' { $$ = $2; }
/* Let expressions `let {..., body = ...}' are just desugared
into `(rec {..., body = ...}).body'. */
| LET '{' binds '}'
{ $3->recursive = true; $3->pos = CUR_POS; $$ = new ExprSelect(state->exprs.alloc, noPos, $3, state->s.body); }
{ $3->recursive = true; $3->pos = CUR_POS; $$ = state->exprs.add<ExprSelect>(state->exprs.alloc, noPos, $3, state->s.body); }
| REC '{' binds '}'
{ $3->recursive = true; $3->pos = CUR_POS; $$ = $3; }
| '{' binds1 '}'
{ $2->pos = CUR_POS; $$ = $2; }
| '{' '}'
{ $$ = new ExprAttrs(CUR_POS); }
| '[' list ']' { $$ = new ExprList(state->exprs.alloc, std::move($2)); }
{ $$ = state->exprs.add<ExprAttrs>(CUR_POS); }
| '[' list ']' { $$ = state->exprs.add<ExprList>(state->exprs.alloc, std::move($2)); }
;
string_parts
: STR { $$ = $1; }
| string_parts_interpolated { $$ = new ExprConcatStrings(state->exprs.alloc, CUR_POS, true, std::move($1)); }
| string_parts_interpolated { $$ = state->exprs.add<ExprConcatStrings>(state->exprs.alloc, CUR_POS, true, std::move($1)); }
| { $$ = std::string_view(); }
;
string_parts_interpolated
: string_parts_interpolated STR
{ $$ = std::move($1); $$.emplace_back(state->at(@2), new ExprString(state->exprs.alloc, $2)); }
{ $$ = std::move($1); $$.emplace_back(state->at(@2), state->exprs.add<ExprString>(state->exprs.alloc, $2)); }
| string_parts_interpolated DOLLAR_CURLY expr '}' { $$ = std::move($1); $$.emplace_back(state->at(@2), $3); }
| DOLLAR_CURLY expr '}' { $$.emplace_back(state->at(@1), $2); }
| STR DOLLAR_CURLY expr '}' {
$$.emplace_back(state->at(@1), new ExprString(state->exprs.alloc, $1));
$$.emplace_back(state->at(@1), state->exprs.add<ExprString>(state->exprs.alloc, $1));
$$.emplace_back(state->at(@2), $3);
}
;
@ -379,8 +379,8 @@ path_start
root filesystem accessor, rather than the accessor of the
current Nix expression. */
literal.front() == '/'
? new ExprPath(state->exprs.alloc, state->rootFS, path)
: new ExprPath(state->exprs.alloc, state->basePath.accessor, path);
? state->exprs.add<ExprPath>(state->exprs.alloc, state->rootFS, path)
: state->exprs.add<ExprPath>(state->exprs.alloc, state->basePath.accessor, path);
}
| HPATH {
if (state->settings.pureEval) {
@ -390,7 +390,7 @@ path_start
);
}
Path path(getHome() + std::string($1.p + 1, $1.l - 1));
$$ = new ExprPath(state->exprs.alloc, ref<SourceAccessor>(state->rootFS), path);
$$ = state->exprs.add<ExprPath>(state->exprs.alloc, ref<SourceAccessor>(state->rootFS), path);
}
;
@ -402,7 +402,7 @@ ind_string_parts
binds
: binds1
| { $$ = new ExprAttrs; }
| { $$ = state->exprs.add<ExprAttrs>(); }
;
binds1
@ -417,7 +417,7 @@ binds1
state->dupAttr(i.symbol, iPos, $accum->attrs[i.symbol].pos);
$accum->attrs.emplace(
i.symbol,
ExprAttrs::AttrDef(new ExprVar(iPos, i.symbol), iPos, ExprAttrs::AttrDef::Kind::Inherited));
ExprAttrs::AttrDef(state->exprs.add<ExprVar>(iPos, i.symbol), iPos, ExprAttrs::AttrDef::Kind::Inherited));
}
}
| binds[accum] INHERIT '(' expr ')' attrs ';'
@ -432,13 +432,13 @@ binds1
$accum->attrs.emplace(
i.symbol,
ExprAttrs::AttrDef(
new ExprSelect(state->exprs.alloc, iPos, from, i.symbol),
state->exprs.add<ExprSelect>(state->exprs.alloc, iPos, from, i.symbol),
iPos,
ExprAttrs::AttrDef::Kind::InheritedFrom));
}
}
| attrpath '=' expr ';'
{ $$ = new ExprAttrs;
{ $$ = state->exprs.add<ExprAttrs>();
state->addAttr($$, std::move($attrpath), @attrpath, $expr, @expr);
}
;