lix/src/libexpr/parser.y
2014-01-21 18:29:55 +01:00

651 lines
19 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
%pure-parser
%locations
%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"
namespace nix {
struct ParseData
{
EvalState & state;
SymbolTable & symbols;
Expr * result;
Path basePath;
Symbol path;
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 "parser-tab.hh"
#include "lexer-tab.hh"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
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());
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;
}
}
if (i->symbol.set()) {
ExprAttrs::AttrDefs::iterator j = attrs->attrs.find(i->symbol);
if (j != attrs->attrs.end()) {
dupAttr(attrPath, pos, j->second.pos);
} else {
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.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(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 */
unsigned int minIndent = 1000000;
unsigned int curIndent = 0;
foreach (vector<Expr *>::iterator, 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 (unsigned int 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;
unsigned int curDropped = 0;
unsigned int 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 (unsigned int 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(true, es2);
}
void backToString(yyscan_t scanner);
void backToIndString(yyscan_t scanner);
static 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;
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 <path> PATH 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
%nonassoc IMPL
%left OR
%left AND
%nonassoc EQ NEQ
%left '<' '>' LEQ GEQ
%right UPDATE
%left NOT
%left '+' '-'
%left '*' '/'
%right CONCAT
%nonassoc '?'
%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(new ExprApp(new ExprBuiltin(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 { $$ = new ExprApp(new ExprApp(new ExprBuiltin(data->symbols.create("lessThan")), $1), $3); }
| expr_op LEQ expr_op { $$ = new ExprOpNot(new ExprApp(new ExprApp(new ExprBuiltin(data->symbols.create("lessThan")), $3), $1)); }
| expr_op '>' expr_op { $$ = new ExprApp(new ExprApp(new ExprBuiltin(data->symbols.create("lessThan")), $3), $1); }
| expr_op GEQ expr_op { $$ = new ExprOpNot(new ExprApp(new ExprApp(new ExprBuiltin(data->symbols.create("lessThan")), $1), $3)); }
| expr_op AND expr_op { $$ = new ExprOpAnd($1, $3); }
| expr_op OR expr_op { $$ = new ExprOpOr($1, $3); }
| expr_op IMPL expr_op { $$ = new ExprOpImpl($1, $3); }
| expr_op UPDATE expr_op { $$ = new ExprOpUpdate($1, $3); }
| expr_op '?' attrpath { $$ = new ExprOpHasAttr($1, *$3); }
| expr_op '+' expr_op
{ vector<Expr *> * l = new vector<Expr *>;
l->push_back($1);
l->push_back($3);
$$ = new ExprConcatStrings(false, l);
}
| expr_op '-' expr_op { $$ = new ExprApp(new ExprApp(new ExprBuiltin(data->symbols.create("sub")), $1), $3); }
| expr_op '*' expr_op { $$ = new ExprApp(new ExprApp(new ExprBuiltin(data->symbols.create("mul")), $1), $3); }
| expr_op '/' expr_op { $$ = new ExprApp(new ExprApp(new ExprBuiltin(data->symbols.create("div")), $1), $3); }
| expr_op CONCAT expr_op { $$ = new ExprOpConcatLists($1, $3); }
| expr_app
;
expr_app
: expr_app expr_select
{ $$ = new ExprApp($1, $2); }
| expr_select { $$ = $1; }
;
expr_select
: expr_simple '.' attrpath
{ $$ = new ExprSelect($1, *$3, 0); }
| expr_simple '.' attrpath OR_KW expr_select
{ $$ = new ExprSelect($1, *$3, $5); }
| /* Backwards compatibility: because Nixpkgs has a rarely used
function named or, allow stuff like map or [...]. */
expr_simple OR_KW
{ $$ = new ExprApp($1, new ExprVar(CUR_POS, data->symbols.create("or"))); }
| expr_simple { $$ = $1; }
;
expr_simple
: ID {
if (strcmp($1, "__curPos") == 0)
$$ = new ExprPos(CUR_POS);
else
$$ = new ExprVar(CUR_POS, data->symbols.create($1));
}
| INT { $$ = new ExprInt($1); }
| '"' string_parts '"' { $$ = $2; }
| IND_STRING_OPEN ind_string_parts IND_STRING_CLOSE {
$$ = stripIndentation(data->symbols, *$2);
}
| PATH { $$ = new ExprPath(absPath($1, data->basePath)); }
| SPATH {
string path($1 + 1, strlen($1) - 2);
Path path2 = data->state.findFile(path);
/* The file wasn't found in the search path. However, we can't
throw an error here, because the expression might never be
evaluated. So return an expression that lazily calls
throw. */
$$ = path2 == ""
? (Expr * ) new ExprApp(
new ExprBuiltin(data->symbols.create("throw")),
new ExprString(data->symbols.create(
(format("file `%1%' was not found in the Nix search path (add it using $NIX_PATH or -I)") % path).str())))
: (Expr * ) new ExprPath(path2);
}
| URI { $$ = 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($3, data->symbols.create("body")); }
| REC '{' binds '}'
{ $3->recursive = true; $$ = $3; }
| '{' binds '}'
{ $$ = $2; }
| '[' expr_list ']' { $$ = $2; }
;
string_parts
: STR
| string_parts_interpolated { $$ = new ExprConcatStrings(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 '}' { backToString(scanner); $$ = $1; $1->push_back($3); }
| STR DOLLAR_CURLY expr '}'
{
backToString(scanner);
$$ = new vector<Expr *>;
$$->push_back($1);
$$->push_back($3);
}
| DOLLAR_CURLY expr '}'
{
backToString(scanner);
$$ = new vector<Expr *>;
$$->push_back($2);
}
;
ind_string_parts
: ind_string_parts IND_STR { $$ = $1; $1->push_back($2); }
| ind_string_parts DOLLAR_CURLY expr '}' { backToIndString(scanner); $$ = $1; $1->push_back($3); }
| { $$ = new vector<Expr *>; }
;
binds
: binds attrpath '=' expr ';' { $$ = $1; addAttr($$, *$2, $4, makeCurPos(@2, data)); }
| binds INHERIT attrs ';'
{ $$ = $1;
foreach (AttrPath::iterator, 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 ';'
{ $$ = $1;
/* !!! Should ensure sharing of the expression in $4. */
foreach (AttrPath::iterator, i, *$6) {
if ($$->attrs.find(i->symbol) != $$->attrs.end())
dupAttr(i->symbol, makeCurPos(@6, data), $$->attrs[i->symbol].pos);
$$->attrs[i->symbol] = ExprAttrs::AttrDef(new ExprSelect($4, i->symbol), makeCurPos(@6, data));
}
}
| { $$ = 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) {
$$->push_back(AttrName(str->s));
delete str;
} else
throw ParseError(format("dynamic attributes not allowed in inherit at %1%")
% makeCurPos(@2, data));
}
| { $$ = 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 { $$ = new vector<AttrName>; $$->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 '}' { $$ = new ExprConcatStrings(true, new vector<Expr*>(1, $2)); }
;
expr_list
: expr_list expr_select { $$ = $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 <eval.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 parse(readFile(path).c_str(), path, dirOf(path), staticBaseEnv);
}
Expr * EvalState::parseExprFromString(const string & s, const Path & basePath, StaticEnv & staticEnv)
{
return parse(s.c_str(), "(string)", basePath, staticEnv);
}
Expr * EvalState::parseExprFromString(const string & s, const Path & basePath)
{
return parseExprFromString(s, basePath, staticBaseEnv);
}
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);
}
path = absPath(path);
if (pathExists(path)) {
debug(format("adding path `%1%' to the search path") % path);
searchPath.insert(searchPathInsertionPoint, std::pair<string, Path>(prefix, path));
}
}
Path EvalState::findFile(const string & path)
{
foreach (SearchPath::iterator, i, searchPath) {
Path res;
if (i->first.empty())
res = i->second + "/" + path;
else {
if (path.compare(0, i->first.size(), i->first) != 0 ||
(path.size() > i->first.size() && path[i->first.size()] != '/'))
continue;
res = i->second +
(path.size() == i->first.size() ? "" : "/" + string(path, i->first.size()));
}
if (pathExists(res)) return canonPath(res);
}
return "";
}
}