%glr-parser
%pure-parser
%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 <variant>
#include "libutil/util.hh"
#include "libexpr/nixexpr.hh"
#include "libexpr/eval.hh"
#include <glog/logging.h>
namespace nix {
struct ParseData
{
EvalState & state;
SymbolTable & symbols;
Expr * result;
Path basePath;
Symbol path;
std::string 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 "generated/parser-tab.hh"
#include "generated/lexer-tab.hh"
YY_DECL;
using namespace nix;
namespace nix {
static void dupAttr(const AttrPath & attrPath, const Pos & pos, const Pos & prevPos)
{
throw ParseError(format("attribute '%1%' at %2% already defined at %3%")
% showAttrPath(attrPath) % pos % prevPos);
}
static void dupAttr(Symbol attr, const Pos & pos, const Pos & prevPos)
{
throw ParseError(format("attribute '%1%' at %2% already defined at %3%")
% attr % pos % prevPos);
}
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 (const auto* sym = std::get_if<Symbol>(&(*i)); sym && sym->set()) {
ExprAttrs::AttrDefs::iterator j = attrs->attrs.find(*sym);
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[*sym] = ExprAttrs::AttrDef(nested, pos);
attrs = nested;
}
} else {
// Yes, this code does not handle all conditions
// exhaustively. We use std::get to throw if the condition
// that isn't covered happens, which is potentially a
// behaviour change from the previous default constructed
// Symbol. It should alert us about anything untoward going
// on here.
auto* expr = std::get<Expr*>(*i);
ExprAttrs *nested = new ExprAttrs;
attrs->dynamicAttrs.push_back(ExprAttrs::DynamicAttrDef(expr, nested, pos));
attrs = nested;
}
}
// Expr insertion.
// ==========================
if (auto* sym = std::get_if<Symbol>(&(*i)); sym && sym->set()) {
ExprAttrs::AttrDefs::iterator j = attrs->attrs.find(*sym);
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[*sym] = ExprAttrs::AttrDef(e, pos);
e->setName(*sym);
}
} else {
// Same caveat as the identical line above.
auto* expr = std::get<Expr*>(*i);
attrs->dynamicAttrs.push_back(ExprAttrs::DynamicAttrDef(expr, e, pos));
}
}
static void addFormal(const Pos & pos, Formals * formals, const Formal & formal)
{
if (formals->argNames.find(formal.name) != formals->argNames.end())
throw ParseError(format("duplicate formal function argument '%1%' at %2%")
% formal.name % pos);
formals->formals.push_front(formal);
formals->argNames.insert(formal.name);
}
static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols, std::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. */
std::vector<Expr *> * es2 = new std::vector<Expr *>;
atStartOfLine = true;
size_t curDropped = 0;
size_t n = es.size();
for (std::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;
}
std::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) {
std::string::size_type p = s2.find_last_of('\n');
if (p != std::string::npos && s2.find_first_not_of(' ', p + 1) == std::string::npos) {
s2 = std::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 = (format("%1%, at %2%")
% error % makeCurPos(*loc, data)).str();
}
%}
%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(format("dynamic attributes not allowed in let at %1%")
% CUR_POS);
$$ = new ExprLet($2, $4);
}
| expr_if
;
expr_if
: IF expr THEN expr ELSE expr { $$ = new ExprIf($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 std::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() + std::string{$1 + 1}); }
| SPATH {
std::string path($1 + 1, strlen($1) - 2);
$$ = new ExprApp(CUR_POS,
new ExprApp(new ExprVar(data->symbols.Create("__findFile")),
new ExprVar(data->symbols.Create("__nixPath"))),
new ExprString(data->symbols.Create(path)));
}
| URI { $$ = 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 std::vector<Expr *>; $$->push_back($2); }
| STR DOLLAR_CURLY expr '}' {
$$ = new std::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); }
| { $$ = new std::vector<Expr *>; }
;
binds
: binds attrpath '=' expr ';' { $$ = $1; addAttr($$, *$2, $4, makeCurPos(@2, data)); }
| binds INHERIT attrs ';'
{ $$ = $1;
for (auto & i : *$3) {
auto sym = std::get<Symbol>(i);
if ($$->attrs.find(sym) != $$->attrs.end()) {
dupAttr(sym, makeCurPos(@3, data), $$->attrs[sym].pos);
}
Pos pos = makeCurPos(@3, data);
$$->attrs[sym] = ExprAttrs::AttrDef(new ExprVar(CUR_POS, sym), pos, true);
}
}
| binds INHERIT '(' expr ')' attrs ';'
{ $$ = $1;
/* !!! Should ensure sharing of the expression in $4. */
for (auto & i : *$6) {
auto sym = std::get<Symbol>(i);
if ($$->attrs.find(sym) != $$->attrs.end()) {
dupAttr(sym, makeCurPos(@6, data), $$->attrs[sym].pos);
}
$$->attrs[sym] = ExprAttrs::AttrDef(new ExprSelect(CUR_POS, $4, sym), makeCurPos(@6, data));
}
}
| { $$ = 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) {
$$->push_back(AttrName(str->s));
delete str;
} else
throw ParseError(format("dynamic attributes not allowed in inherit at %1%")
% makeCurPos(@2, data));
}
| { $$ = 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 { $$ = new std::vector<AttrName>; $$->push_back(AttrName(data->symbols.Create($1))); }
| string_attr
{ $$ = new std::vector<AttrName>;
ExprString *str = dynamic_cast<ExprString *>($1);
if (str) {
$$->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 { $$ = new Formal(data->symbols.Create($1), 0); }
| ID '?' expr { $$ = new Formal(data->symbols.Create($1), $3); }
;
%%
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include "libexpr/eval.hh"
#include "libstore/download.hh"
#include "libstore/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] == '/');
/* If `path' is a symlink, follow it. This is so that relative
path references work. */
struct stat st;
while (true) {
if (lstat(path.c_str(), &st))
throw SysError(format("getting status of '%1%'") % 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(const std::string & s, const Path & basePath, StaticEnv & staticEnv)
{
return parse(s.c_str(), "(std::string)", basePath, staticEnv);
}
Expr * EvalState::parseExprFromString(const std::string & s, const Path & basePath)
{
return parseExprFromString(s, basePath, staticBaseEnv);
}
Expr * EvalState::parseStdin()
{
//Activity act(*logger, lvlTalkative, format("parsing standard input"));
return parseExprFromString(drainFD(0), absPath("."));
}
void EvalState::addToSearchPath(const std::string & s)
{
size_t pos = s.find('=');
std::string prefix;
Path path;
if (pos == std::string::npos) {
path = s;
} else {
prefix = std::string(s, 0, pos);
path = std::string(s, pos + 1);
}
searchPath.emplace_back(prefix, path);
}
Path EvalState::findFile(const std::string & path)
{
return findFile(searchPath, path);
}
Path EvalState::findFile(SearchPath & searchPath, const std::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 ? "" : "/" + std::string(path, s);
}
auto r = resolveSearchPathElem(i);
if (!r.first) { continue; }
Path res = r.second + suffix;
if (pathExists(res)) { return canonPath(res); }
}
format f = format(
"file '%1%' was not found in the Nix search path (add it using $NIX_PATH or -I)"
+ std::string(pos ? ", at %2%" : ""));
f.exceptions(boost::io::all_error_bits ^ boost::io::too_many_args_bit);
throw ThrownError(f % path % 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 {
CachedDownloadRequest request(elem.second);
request.unpack = true;
res = { true, getDownloader()->downloadCached(store, request).path };
} catch (DownloadError & e) {
LOG(WARNING) << "Nix search path entry '" << elem.second << "' cannot be downloaded, ignoring";
res = { false, "" };
}
} else {
auto path = absPath(elem.second);
if (pathExists(path)) {
res = { true, path };
} else {
LOG(WARNING) << "Nix search path entry '" << elem.second << "' does not exist, ignoring";
res = { false, "" };
}
}
DLOG(INFO) << "resolved search path element '" << elem.second << "' to '" << res.second << "'";
searchPathResolved[elem.second] = res;
return res;
}
} // namespace nix
