lix/src/libexpr/parser.y

740 lines
22 KiB
Plaintext
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

%glr-parser
%define api.pure
%locations
%define parse.error verbose
%defines
/* %no-lines */
%parse-param { void * scanner }
%parse-param { nix::ParseData * data }
%lex-param { void * scanner }
%lex-param { nix::ParseData * data }
%expect 1
%expect-rr 1
%code requires {
#ifndef BISON_HEADER
#define BISON_HEADER
#include "util.hh"
#include "nixexpr.hh"
#include "eval.hh"
#include "globals.hh"
namespace nix {
struct ParseData
{
EvalState & state;
SymbolTable & symbols;
Expr * result;
Path basePath;
Symbol path;
ErrorInfo error;
Symbol sLetBody;
ParseData(EvalState & state)
: state(state)
, symbols(state.symbols)
, sLetBody(symbols.create("<let-body>"))
{ };
};
}
#define YY_DECL int yylex \
(YYSTYPE * yylval_param, YYLTYPE * yylloc_param, yyscan_t yyscanner, nix::ParseData * data)
#endif
}
%{
#include "parser-tab.hh"
#include "lexer-tab.hh"
YY_DECL;
using namespace nix;
namespace nix {
static void dupAttr(const AttrPath & attrPath, const Pos & pos, const Pos & prevPos)
{
throw ParseError({
.hint = hintfmt("attribute '%1%' already defined at %2%",
showAttrPath(attrPath), prevPos),
.nixCode = NixCode { .errPos = pos },
});
}
static void dupAttr(Symbol attr, const Pos & pos, const Pos & prevPos)
{
throw ParseError({
.hint = hintfmt("attribute '%1%' already defined at %2%", attr, prevPos),
.nixCode = NixCode { .errPos = pos },
});
}
static void addAttr(ExprAttrs * attrs, AttrPath & attrPath,
Expr * e, const Pos & pos)
{
AttrPath::iterator i;
// All attrpaths have at least one attr
assert(!attrPath.empty());
// Checking attrPath validity.
// ===========================
for (i = attrPath.begin(); i + 1 < attrPath.end(); i++) {
if (i->symbol.set()) {
ExprAttrs::AttrDefs::iterator j = attrs->attrs.find(i->symbol);
if (j != attrs->attrs.end()) {
if (!j->second.inherited) {
ExprAttrs * attrs2 = dynamic_cast<ExprAttrs *>(j->second.e);
if (!attrs2) dupAttr(attrPath, pos, j->second.pos);
attrs = attrs2;
} else
dupAttr(attrPath, pos, j->second.pos);
} else {
ExprAttrs * nested = new ExprAttrs;
attrs->attrs[i->symbol] = ExprAttrs::AttrDef(nested, pos);
attrs = nested;
}
} else {
ExprAttrs *nested = new ExprAttrs;
attrs->dynamicAttrs.push_back(ExprAttrs::DynamicAttrDef(i->expr, nested, pos));
attrs = nested;
}
}
// Expr insertion.
// ==========================
if (i->symbol.set()) {
ExprAttrs::AttrDefs::iterator j = attrs->attrs.find(i->symbol);
if (j != attrs->attrs.end()) {
// This attr path is already defined. However, if both
// e and the expr pointed by the attr path are two attribute sets,
// we want to merge them.
// Otherwise, throw an error.
auto ae = dynamic_cast<ExprAttrs *>(e);
auto jAttrs = dynamic_cast<ExprAttrs *>(j->second.e);
if (jAttrs && ae) {
for (auto & ad : ae->attrs) {
auto j2 = jAttrs->attrs.find(ad.first);
if (j2 != jAttrs->attrs.end()) // Attr already defined in iAttrs, error.
dupAttr(ad.first, j2->second.pos, ad.second.pos);
jAttrs->attrs[ad.first] = ad.second;
}
} else {
dupAttr(attrPath, pos, j->second.pos);
}
} else {
// This attr path is not defined. Let's create it.
attrs->attrs[i->symbol] = ExprAttrs::AttrDef(e, pos);
e->setName(i->symbol);
}
} else {
attrs->dynamicAttrs.push_back(ExprAttrs::DynamicAttrDef(i->expr, e, pos));
}
}
static void addFormal(const Pos & pos, Formals * formals, const Formal & formal)
{
if (!formals->argNames.insert(formal.name).second)
throw ParseError({
.hint = hintfmt("duplicate formal function argument '%1%'",
formal.name),
.nixCode = NixCode { .errPos = pos },
});
formals->formals.push_front(formal);
}
static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols, vector<Expr *> & es)
{
if (es.empty()) return new ExprString(symbols.create(""));
/* Figure out the minimum indentation. Note that by design
whitespace-only final lines are not taken into account. (So
the " " in "\n ''" is ignored, but the " " in "\n foo''" is.) */
bool atStartOfLine = true; /* = seen only whitespace in the current line */
size_t minIndent = 1000000;
size_t curIndent = 0;
for (auto & i : es) {
ExprIndStr * e = dynamic_cast<ExprIndStr *>(i);
if (!e) {
/* Anti-quotations end the current start-of-line whitespace. */
if (atStartOfLine) {
atStartOfLine = false;
if (curIndent < minIndent) minIndent = curIndent;
}
continue;
}
for (size_t j = 0; j < e->s.size(); ++j) {
if (atStartOfLine) {
if (e->s[j] == ' ')
curIndent++;
else if (e->s[j] == '\n') {
/* Empty line, doesn't influence minimum
indentation. */
curIndent = 0;
} else {
atStartOfLine = false;
if (curIndent < minIndent) minIndent = curIndent;
}
} else if (e->s[j] == '\n') {
atStartOfLine = true;
curIndent = 0;
}
}
}
/* Strip spaces from each line. */
vector<Expr *> * es2 = new vector<Expr *>;
atStartOfLine = true;
size_t curDropped = 0;
size_t n = es.size();
for (vector<Expr *>::iterator i = es.begin(); i != es.end(); ++i, --n) {
ExprIndStr * e = dynamic_cast<ExprIndStr *>(*i);
if (!e) {
atStartOfLine = false;
curDropped = 0;
es2->push_back(*i);
continue;
}
string s2;
for (size_t j = 0; j < e->s.size(); ++j) {
if (atStartOfLine) {
if (e->s[j] == ' ') {
if (curDropped++ >= minIndent)
s2 += e->s[j];
}
else if (e->s[j] == '\n') {
curDropped = 0;
s2 += e->s[j];
} else {
atStartOfLine = false;
curDropped = 0;
s2 += e->s[j];
}
} else {
s2 += e->s[j];
if (e->s[j] == '\n') atStartOfLine = true;
}
}
/* Remove the last line if it is empty and consists only of
spaces. */
if (n == 1) {
string::size_type p = s2.find_last_of('\n');
if (p != string::npos && s2.find_first_not_of(' ', p + 1) == string::npos)
s2 = string(s2, 0, p + 1);
}
es2->push_back(new ExprString(symbols.create(s2)));
}
/* If this is a single string, then don't do a concatenation. */
return es2->size() == 1 && dynamic_cast<ExprString *>((*es2)[0]) ? (*es2)[0] : new ExprConcatStrings(pos, true, es2);
}
static inline Pos makeCurPos(const YYLTYPE & loc, ParseData * data)
{
return Pos(data->path, loc.first_line, loc.first_column);
}
#define CUR_POS makeCurPos(*yylocp, data)
}
void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * error)
{
data->error = {
.hint = hintfmt(error),
.nixCode = NixCode { .errPos = makeCurPos(*loc, data) }
};
}
%}
%union {
// !!! We're probably leaking stuff here.
nix::Expr * e;
nix::ExprList * list;
nix::ExprAttrs * attrs;
nix::Formals * formals;
nix::Formal * formal;
nix::NixInt n;
nix::NixFloat nf;
const char * id; // !!! -> Symbol
char * path;
char * uri;
std::vector<nix::AttrName> * attrNames;
std::vector<nix::Expr *> * string_parts;
}
%type <e> start expr expr_function expr_if expr_op
%type <e> expr_app expr_select expr_simple
%type <list> expr_list
%type <attrs> binds
%type <formals> formals
%type <formal> formal
%type <attrNames> attrs attrpath
%type <string_parts> string_parts_interpolated ind_string_parts
%type <e> string_parts string_attr
%type <id> attr
%token <id> ID ATTRPATH
%token <e> STR IND_STR
%token <n> INT
%token <nf> FLOAT
%token <path> PATH HPATH SPATH
%token <uri> URI
%token IF THEN ELSE ASSERT WITH LET IN REC INHERIT EQ NEQ AND OR IMPL OR_KW
%token DOLLAR_CURLY /* == ${ */
%token IND_STRING_OPEN IND_STRING_CLOSE
%token ELLIPSIS
%right IMPL
%left OR
%left AND
%nonassoc EQ NEQ
%nonassoc '<' '>' LEQ GEQ
%right UPDATE
%left NOT
%left '+' '-'
%left '*' '/'
%right CONCAT
%nonassoc '?'
%nonassoc NEGATE
%%
start: expr { data->result = $1; };
expr: expr_function;
expr_function
: ID ':' expr_function
{ $$ = new ExprLambda(CUR_POS, data->symbols.create($1), false, 0, $3); }
| '{' formals '}' ':' expr_function
{ $$ = new ExprLambda(CUR_POS, data->symbols.create(""), true, $2, $5); }
| '{' formals '}' '@' ID ':' expr_function
{ $$ = new ExprLambda(CUR_POS, data->symbols.create($5), true, $2, $7); }
| ID '@' '{' formals '}' ':' expr_function
{ $$ = new ExprLambda(CUR_POS, data->symbols.create($1), true, $4, $7); }
| ASSERT expr ';' expr_function
{ $$ = new ExprAssert(CUR_POS, $2, $4); }
| WITH expr ';' expr_function
{ $$ = new ExprWith(CUR_POS, $2, $4); }
| LET binds IN expr_function
{ if (!$2->dynamicAttrs.empty())
throw ParseError({
.hint = hintfmt("dynamic attributes not allowed in let"),
.nixCode = NixCode { .errPos = CUR_POS },
});
$$ = new ExprLet($2, $4);
}
| expr_if
;
expr_if
: IF expr THEN expr ELSE expr { $$ = new ExprIf(CUR_POS, $2, $4, $6); }
| expr_op
;
expr_op
: '!' expr_op %prec NOT { $$ = new ExprOpNot($2); }
| '-' expr_op %prec NEGATE { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__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 { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__lessThan")), $1), $3); }
| expr_op LEQ expr_op { $$ = new ExprOpNot(new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__lessThan")), $3), $1)); }
| expr_op '>' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__lessThan")), $3), $1); }
| expr_op GEQ expr_op { $$ = new ExprOpNot(new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__lessThan")), $1), $3)); }
| expr_op AND expr_op { $$ = new ExprOpAnd(CUR_POS, $1, $3); }
| expr_op OR expr_op { $$ = new ExprOpOr(CUR_POS, $1, $3); }
| expr_op IMPL expr_op { $$ = new ExprOpImpl(CUR_POS, $1, $3); }
| expr_op UPDATE expr_op { $$ = new ExprOpUpdate(CUR_POS, $1, $3); }
| expr_op '?' attrpath { $$ = new ExprOpHasAttr($1, *$3); }
| expr_op '+' expr_op
{ $$ = new ExprConcatStrings(CUR_POS, false, new vector<Expr *>({$1, $3})); }
| expr_op '-' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__sub")), $1), $3); }
| expr_op '*' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__mul")), $1), $3); }
| expr_op '/' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__div")), $1), $3); }
| expr_op CONCAT expr_op { $$ = new ExprOpConcatLists(CUR_POS, $1, $3); }
| expr_app
;
expr_app
: expr_app expr_select
{ $$ = new ExprApp(CUR_POS, $1, $2); }
| expr_select { $$ = $1; }
;
expr_select
: expr_simple '.' attrpath
{ $$ = new ExprSelect(CUR_POS, $1, *$3, 0); }
| expr_simple '.' attrpath OR_KW expr_select
{ $$ = new ExprSelect(CUR_POS, $1, *$3, $5); }
| /* Backwards compatibility: because Nixpkgs has a rarely used
function named or, allow stuff like map or [...]. */
expr_simple OR_KW
{ $$ = new ExprApp(CUR_POS, $1, new ExprVar(CUR_POS, data->symbols.create("or"))); }
| expr_simple { $$ = $1; }
;
expr_simple
: ID {
if (strcmp($1, "__curPos") == 0)
$$ = new ExprPos(CUR_POS);
else
$$ = new ExprVar(CUR_POS, data->symbols.create($1));
}
| INT { $$ = new ExprInt($1); }
| FLOAT { $$ = new ExprFloat($1); }
| '"' string_parts '"' { $$ = $2; }
| IND_STRING_OPEN ind_string_parts IND_STRING_CLOSE {
$$ = stripIndentation(CUR_POS, data->symbols, *$2);
}
| PATH { $$ = new ExprPath(absPath($1, data->basePath)); }
| HPATH { $$ = new ExprPath(getHome() + string{$1 + 1}); }
| SPATH {
string path($1 + 1, strlen($1) - 2);
$$ = new ExprApp(CUR_POS,
new ExprApp(new ExprVar(data->symbols.create("__findFile")),
new ExprVar(data->symbols.create("__nixPath"))),
new ExprString(data->symbols.create(path)));
}
| URI {
static bool noURLLiterals = settings.isExperimentalFeatureEnabled("no-url-literals");
if (noURLLiterals)
throw ParseError({
.hint = hintfmt("URL literals are disabled"),
.nixCode = NixCode { .errPos = CUR_POS }
});
$$ = new ExprString(data->symbols.create($1));
}
| '(' expr ')' { $$ = $2; }
/* Let expressions `let {..., body = ...}' are just desugared
into `(rec {..., body = ...}).body'. */
| LET '{' binds '}'
{ $3->recursive = true; $$ = new ExprSelect(noPos, $3, data->symbols.create("body")); }
| REC '{' binds '}'
{ $3->recursive = true; $$ = $3; }
| '{' binds '}'
{ $$ = $2; }
| '[' expr_list ']' { $$ = $2; }
;
string_parts
: STR
| string_parts_interpolated { $$ = new ExprConcatStrings(CUR_POS, true, $1); }
| { $$ = new ExprString(data->symbols.create("")); }
;
string_parts_interpolated
: string_parts_interpolated STR { $$ = $1; $1->push_back($2); }
| string_parts_interpolated DOLLAR_CURLY expr '}' { $$ = $1; $1->push_back($3); }
| DOLLAR_CURLY expr '}' { $$ = new vector<Expr *>; $$->push_back($2); }
| STR DOLLAR_CURLY expr '}' {
$$ = new vector<Expr *>;
$$->push_back($1);
$$->push_back($3);
}
;
ind_string_parts
: ind_string_parts IND_STR { $$ = $1; $1->push_back($2); }
| ind_string_parts DOLLAR_CURLY expr '}' { $$ = $1; $1->push_back($3); }
| { $$ = new vector<Expr *>; }
;
binds
: binds attrpath '=' expr ';' { $$ = $1; addAttr($$, *$2, $4, makeCurPos(@2, data)); }
| binds INHERIT attrs ';'
{ $$ = $1;
for (auto & i : *$3) {
if ($$->attrs.find(i.symbol) != $$->attrs.end())
dupAttr(i.symbol, makeCurPos(@3, data), $$->attrs[i.symbol].pos);
Pos pos = makeCurPos(@3, data);
$$->attrs[i.symbol] = ExprAttrs::AttrDef(new ExprVar(CUR_POS, i.symbol), pos, true);
}
}
| binds INHERIT '(' expr ')' attrs ';'
{ $$ = $1;
/* !!! Should ensure sharing of the expression in $4. */
for (auto & i : *$6) {
if ($$->attrs.find(i.symbol) != $$->attrs.end())
dupAttr(i.symbol, makeCurPos(@6, data), $$->attrs[i.symbol].pos);
$$->attrs[i.symbol] = ExprAttrs::AttrDef(new ExprSelect(CUR_POS, $4, i.symbol), makeCurPos(@6, data));
}
}
| { $$ = new ExprAttrs; }
;
attrs
: attrs attr { $$ = $1; $1->push_back(AttrName(data->symbols.create($2))); }
| attrs string_attr
{ $$ = $1;
ExprString * str = dynamic_cast<ExprString *>($2);
if (str) {
$$->push_back(AttrName(str->s));
delete str;
} else
throw ParseError({
.hint = hintfmt("dynamic attributes not allowed in inherit"),
.nixCode = NixCode { .errPos = makeCurPos(@2, data) },
});
}
| { $$ = new AttrPath; }
;
attrpath
: attrpath '.' attr { $$ = $1; $1->push_back(AttrName(data->symbols.create($3))); }
| attrpath '.' string_attr
{ $$ = $1;
ExprString * str = dynamic_cast<ExprString *>($3);
if (str) {
$$->push_back(AttrName(str->s));
delete str;
} else
$$->push_back(AttrName($3));
}
| attr { $$ = new vector<AttrName>; $$->push_back(AttrName(data->symbols.create($1))); }
| string_attr
{ $$ = new vector<AttrName>;
ExprString *str = dynamic_cast<ExprString *>($1);
if (str) {
$$->push_back(AttrName(str->s));
delete str;
} else
$$->push_back(AttrName($1));
}
;
attr
: ID { $$ = $1; }
| OR_KW { $$ = "or"; }
;
string_attr
: '"' string_parts '"' { $$ = $2; }
| DOLLAR_CURLY expr '}' { $$ = $2; }
;
expr_list
: expr_list expr_select { $$ = $1; $1->elems.push_back($2); /* !!! dangerous */ }
| { $$ = new ExprList; }
;
formals
: formal ',' formals
{ $$ = $3; addFormal(CUR_POS, $$, *$1); }
| formal
{ $$ = new Formals; addFormal(CUR_POS, $$, *$1); $$->ellipsis = false; }
|
{ $$ = new Formals; $$->ellipsis = false; }
| ELLIPSIS
{ $$ = new Formals; $$->ellipsis = true; }
;
formal
: ID { $$ = new Formal(CUR_POS, data->symbols.create($1), 0); }
| ID '?' expr { $$ = new Formal(CUR_POS, data->symbols.create($1), $3); }
;
%%
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include "eval.hh"
#include "filetransfer.hh"
#include "fetchers.hh"
#include "store-api.hh"
namespace nix {
Expr * EvalState::parse(const char * text,
const Path & path, const Path & basePath, StaticEnv & staticEnv)
{
yyscan_t scanner;
ParseData data(*this);
data.basePath = basePath;
data.path = data.symbols.create(path);
yylex_init(&scanner);
yy_scan_string(text, scanner);
int res = yyparse(scanner, &data);
yylex_destroy(scanner);
if (res) throw ParseError(data.error);
data.result->bindVars(staticEnv);
return data.result;
}
Path resolveExprPath(Path path)
{
assert(path[0] == '/');
unsigned int followCount = 0, maxFollow = 1024;
/* If `path' is a symlink, follow it. This is so that relative
path references work. */
struct stat st;
while (true) {
// Basic cycle/depth limit to avoid infinite loops.
if (++followCount >= maxFollow)
throw Error("too many symbolic links encountered while traversing the path '%s'", path);
if (lstat(path.c_str(), &st))
throw SysError("getting status of '%s'", path);
if (!S_ISLNK(st.st_mode)) break;
path = absPath(readLink(path), dirOf(path));
}
/* If `path' refers to a directory, append `/default.nix'. */
if (S_ISDIR(st.st_mode))
path = canonPath(path + "/default.nix");
return path;
}
Expr * EvalState::parseExprFromFile(const Path & path)
{
return parseExprFromFile(path, staticBaseEnv);
}
Expr * EvalState::parseExprFromFile(const Path & path, StaticEnv & staticEnv)
{
return parse(readFile(path).c_str(), path, dirOf(path), staticEnv);
}
Expr * EvalState::parseExprFromString(std::string_view s, const Path & basePath, StaticEnv & staticEnv)
{
return parse(s.data(), "(string)", basePath, staticEnv);
}
Expr * EvalState::parseExprFromString(std::string_view s, const Path & basePath)
{
return parseExprFromString(s, basePath, staticBaseEnv);
}
Expr * EvalState::parseStdin()
{
//Activity act(*logger, Verbosity::Talkative, format("parsing standard input"));
return parseExprFromString(drainFD(0), absPath("."));
}
void EvalState::addToSearchPath(const string & s)
{
size_t pos = s.find('=');
string prefix;
Path path;
if (pos == string::npos) {
path = s;
} else {
prefix = string(s, 0, pos);
path = string(s, pos + 1);
}
searchPath.emplace_back(prefix, path);
}
Path EvalState::findFile(const string & path)
{
return findFile(searchPath, path);
}
Path EvalState::findFile(SearchPath & searchPath, const string & path, const Pos & pos)
{
for (auto & i : searchPath) {
std::string suffix;
if (i.first.empty())
suffix = "/" + path;
else {
auto s = i.first.size();
if (path.compare(0, s, i.first) != 0 ||
(path.size() > s && path[s] != '/'))
continue;
suffix = path.size() == s ? "" : "/" + string(path, s);
}
auto r = resolveSearchPathElem(i);
if (!r.first) continue;
Path res = r.second + suffix;
if (pathExists(res)) return canonPath(res);
}
throw ThrownError({
.hint = hintfmt(evalSettings.pureEval
? "cannot look up '<%s>' in pure evaluation mode (use '--impure' to override)"
: "file '%s' was not found in the Nix search path (add it using $NIX_PATH or -I)",
path),
.nixCode = NixCode { .errPos = pos }
});
}
std::pair<bool, std::string> EvalState::resolveSearchPathElem(const SearchPathElem & elem)
{
auto i = searchPathResolved.find(elem.second);
if (i != searchPathResolved.end()) return i->second;
std::pair<bool, std::string> res;
if (isUri(elem.second)) {
try {
res = { true, store->toRealPath(fetchers::downloadTarball(
store, resolveUri(elem.second), "source", false).storePath) };
} catch (FileTransferError & e) {
logWarning({
.name = "Entry download",
.hint = hintfmt("Nix search path entry '%1%' cannot be downloaded, ignoring", elem.second)
});
res = { false, "" };
}
} else {
auto path = absPath(elem.second);
if (pathExists(path))
res = { true, path };
else {
logWarning({
.name = "Entry not found",
.hint = hintfmt("warning: Nix search path entry '%1%' does not exist, ignoring", elem.second)
});
res = { false, "" };
}
}
debug(format("resolved search path element '%s' to '%s'") % elem.second % res.second);
searchPathResolved[elem.second] = res;
return res;
}
}