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lix/src/libexpr/parser.y

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%glr-parser
%pure-parser
%locations
%error-verbose
%defines
/* %no-lines */
%parse-param { yyscan_t scanner }
%parse-param { ParseData * data }
%lex-param { yyscan_t scanner }
%{
/* Newer versions of Bison copy the declarations below to
parser-tab.hh, which sucks bigtime since lexer.l doesn't want that
stuff. So allow it to be excluded. */
#ifndef BISON_HEADER_HACK
#define BISON_HEADER_HACK
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "aterm.hh"
#include "util.hh"
#include "parser-tab.hh"
#include "lexer-tab.hh"
#include "nixexpr.hh"
#include "nixexpr-ast.hh"
using namespace nix;
namespace nix {
struct ParseData
{
Expr result;
Path basePath;
Path path;
string error;
};
static Expr fixAttrs(int recursive, ATermList as)
{
ATermList bs = ATempty, cs = ATempty;
ATermList * is = recursive ? &cs : &bs;
for (ATermIterator i(as); i; ++i) {
ATermList names;
Expr src;
ATerm pos;
if (matchInherit(*i, src, names, pos)) {
bool fromScope = matchScope(src);
for (ATermIterator j(names); j; ++j) {
Expr rhs = fromScope ? makeVar(*j) : makeSelect(src, *j);
*is = ATinsert(*is, makeBind(*j, rhs, pos));
}
} else bs = ATinsert(bs, *i);
}
if (recursive)
return makeRec(bs, cs);
else
return makeAttrs(bs);
}
static Expr stripIndentation(ATermList es)
{
if (es == ATempty) return makeStr("");
/* 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;
ATerm e;
for (ATermIterator i(es); i; ++i) {
if (!matchIndStr(*i, e)) {
/* Anti-quotations end the current start-of-line whitespace. */
if (atStartOfLine) {
atStartOfLine = false;
if (curIndent < minIndent) minIndent = curIndent;
}
continue;
}
string s = aterm2String(e);
for (unsigned int j = 0; j < s.size(); ++j) {
if (atStartOfLine) {
if (s[j] == ' ')
curIndent++;
else if (s[j] == '\n') {
/* Empty line, doesn't influence minimum
indentation. */
curIndent = 0;
} else {
atStartOfLine = false;
if (curIndent < minIndent) minIndent = curIndent;
}
} else if (s[j] == '\n') {
atStartOfLine = true;
curIndent = 0;
}
}
}
/* Strip spaces from each line. */
ATermList es2 = ATempty;
atStartOfLine = true;
unsigned int curDropped = 0;
unsigned int n = ATgetLength(es);
for (ATermIterator i(es); i; ++i, --n) {
if (!matchIndStr(*i, e)) {
atStartOfLine = false;
curDropped = 0;
es2 = ATinsert(es2, *i);
continue;
}
string s = aterm2String(e);
string s2;
for (unsigned int j = 0; j < s.size(); ++j) {
if (atStartOfLine) {
if (s[j] == ' ') {
if (curDropped++ >= minIndent)
s2 += s[j];
}
else if (s[j] == '\n') {
curDropped = 0;
s2 += s[j];
} else {
atStartOfLine = false;
curDropped = 0;
s2 += s[j];
}
} else {
s2 += s[j];
if (s[j] == '\n') atStartOfLine = true;
}
}
/* Remove the last line if it is empty and consists only of
spaces. */
if (n == 1) {
unsigned int 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 = ATinsert(es2, makeStr(s2));
}
return makeConcatStrings(ATreverse(es2));
}
void backToString(yyscan_t scanner);
void backToIndString(yyscan_t scanner);
static Pos makeCurPos(YYLTYPE * loc, ParseData * data)
{
return makePos(toATerm(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%':%3%:%4%")
% error % data->path % loc->first_line % loc->first_column).str();
}
/* Make sure that the parse stack is scanned by the ATerm garbage
collector. */
static void * mallocAndProtect(size_t size)
{
void * p = malloc(size);
if (p) ATprotectMemory(p, size);
return p;
}
static void freeAndUnprotect(void * p)
{
ATunprotectMemory(p);
free(p);
}
#define YYMALLOC mallocAndProtect
#define YYFREE freeAndUnprotect
#endif
%}
%union {
ATerm t;
ATermList ts;
}
%type <t> start expr expr_function expr_if expr_op
%type <t> expr_app expr_select expr_simple bind inheritsrc formal
%type <ts> binds ids expr_list formals string_parts ind_string_parts
%token <t> ID INT STR IND_STR PATH URI
%token IF THEN ELSE ASSERT WITH LET IN REC INHERIT EQ NEQ AND OR IMPL
%token DOLLAR_CURLY /* == ${ */
%token IND_STRING_OPEN IND_STRING_CLOSE
%nonassoc IMPL
%left OR
%left AND
%nonassoc EQ NEQ
%right UPDATE
%left NEG
%left '+'
%right CONCAT
%nonassoc '?'
%nonassoc '~'
%%
start: expr { data->result = $1; };
expr: expr_function;
expr_function
: '{' formals '}' ':' expr_function
{ $$ = makeFunction($2, $5, CUR_POS); }
| ID ':' expr_function
{ $$ = makeFunction1($1, $3, CUR_POS); }
| ASSERT expr ';' expr_function
{ $$ = makeAssert($2, $4, CUR_POS); }
| WITH expr ';' expr_function
{ $$ = makeWith($2, $4, CUR_POS); }
| LET binds IN expr_function
{ $$ = makeSelect(fixAttrs(1, ATinsert($2, makeBind(toATerm("<let-body>"), $4, CUR_POS))), toATerm("<let-body>")); }
| expr_if
;
expr_if
: IF expr THEN expr ELSE expr
{ $$ = makeIf($2, $4, $6); }
| expr_op
;
expr_op
: '!' expr_op %prec NEG { $$ = makeOpNot($2); }
| expr_op EQ expr_op { $$ = makeOpEq($1, $3); }
| expr_op NEQ expr_op { $$ = makeOpNEq($1, $3); }
| expr_op AND expr_op { $$ = makeOpAnd($1, $3); }
| expr_op OR expr_op { $$ = makeOpOr($1, $3); }
| expr_op IMPL expr_op { $$ = makeOpImpl($1, $3); }
| expr_op UPDATE expr_op { $$ = makeOpUpdate($1, $3); }
| expr_op '~' expr_op { $$ = makeSubPath($1, $3); }
| expr_op '?' ID { $$ = makeOpHasAttr($1, $3); }
| expr_op '+' expr_op { $$ = makeOpPlus($1, $3); }
| expr_op CONCAT expr_op { $$ = makeOpConcat($1, $3); }
| expr_app
;
expr_app
: expr_app expr_select
{ $$ = makeCall($1, $2); }
| expr_select { $$ = $1; }
;
expr_select
: expr_select '.' ID
{ $$ = makeSelect($1, $3); }
| expr_simple { $$ = $1; }
;
expr_simple
: ID { $$ = makeVar($1); }
| INT { $$ = makeInt(ATgetInt((ATermInt) $1)); }
| '"' string_parts '"' {
/* For efficiency, and to simplify parse trees a bit. */
if ($2 == ATempty) $$ = makeStr(toATerm(""), ATempty);
else if (ATgetNext($2) == ATempty) $$ = ATgetFirst($2);
else $$ = makeConcatStrings(ATreverse($2));
}
| IND_STRING_OPEN ind_string_parts IND_STRING_CLOSE {
$$ = stripIndentation(ATreverse($2));
}
| PATH { $$ = makePath(toATerm(absPath(aterm2String($1), data->basePath))); }
| URI { $$ = makeStr($1, ATempty); }
| '(' expr ')' { $$ = $2; }
/* Let expressions `let {..., body = ...}' are just desugared
into `(rec {..., body = ...}).body'. */
| LET '{' binds '}'
{ $$ = makeSelect(fixAttrs(1, $3), toATerm("body")); }
| REC '{' binds '}'
{ $$ = fixAttrs(1, $3); }
| '{' binds '}'
{ $$ = fixAttrs(0, $2); }
| '[' expr_list ']' { $$ = makeList($2); }
;
string_parts
: string_parts STR { $$ = ATinsert($1, $2); }
| string_parts DOLLAR_CURLY expr '}' { backToString(scanner); $$ = ATinsert($1, $3); }
| { $$ = ATempty; }
;
ind_string_parts
: ind_string_parts IND_STR { $$ = ATinsert($1, $2); }
| ind_string_parts DOLLAR_CURLY expr '}' { backToIndString(scanner); $$ = ATinsert($1, $3); }
| { $$ = ATempty; }
;
binds
: binds bind { $$ = ATinsert($1, $2); }
| { $$ = ATempty; }
;
bind
: ID '=' expr ';'
{ $$ = makeBind($1, $3, CUR_POS); }
| INHERIT inheritsrc ids ';'
{ $$ = makeInherit($2, $3, CUR_POS); }
;
inheritsrc
: '(' expr ')' { $$ = $2; }
| { $$ = makeScope(); }
;
ids: ids ID { $$ = ATinsert($1, $2); } | { $$ = ATempty; };
expr_list
: expr_select expr_list { $$ = ATinsert($2, $1); }
/* yes, this is right-recursive, but it doesn't matter since
otherwise we would need ATreverse which requires unbounded
stack space */
| { $$ = ATempty; }
;
formals
: formal ',' formals { $$ = ATinsert($3, $1); } /* idem - right recursive */
| formal { $$ = ATinsert(ATempty, $1); }
| { $$ = ATempty; }
;
formal
: ID { $$ = makeFormal($1, makeNoDefaultValue()); }
| ID '?' expr { $$ = makeFormal($1, makeDefaultValue($3)); }
;
%%
#include "eval.hh"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
namespace nix {
static void checkAttrs(ATermMap & names, ATermList bnds)
{
for (ATermIterator i(bnds); i; ++i) {
ATerm name;
Expr e;
ATerm pos;
if (!matchBind(*i, name, e, pos)) abort(); /* can't happen */
if (names.get(name))
throw EvalError(format("duplicate attribute `%1%' at %2%")
% aterm2String(name) % showPos(pos));
names.set(name, name);
}
}
static void checkAttrSets(ATerm e)
{
ATermList formals;
ATerm body, pos;
if (matchFunction(e, formals, body, pos)) {
ATermMap names(ATgetLength(formals));
for (ATermIterator i(formals); i; ++i) {
ATerm name;
ATerm d1;
if (!matchFormal(*i, name, d1)) abort();
if (names.get(name))
throw EvalError(format("duplicate formal function argument `%1%' at %2%")
% aterm2String(name) % showPos(pos));
names.set(name, name);
}
}
ATermList bnds;
if (matchAttrs(e, bnds)) {
ATermMap names(ATgetLength(bnds));
checkAttrs(names, bnds);
}
ATermList rbnds, nrbnds;
if (matchRec(e, rbnds, nrbnds)) {
ATermMap names(ATgetLength(rbnds) + ATgetLength(nrbnds));
checkAttrs(names, rbnds);
checkAttrs(names, nrbnds);
}
if (ATgetType(e) == AT_APPL) {
int arity = ATgetArity(ATgetAFun(e));
for (int i = 0; i < arity; ++i)
checkAttrSets(ATgetArgument(e, i));
}
else if (ATgetType(e) == AT_LIST)
for (ATermIterator i((ATermList) e); i; ++i)
checkAttrSets(*i);
}
static Expr parse(EvalState & state,
const char * text, const Path & path,
const Path & basePath)
{
yyscan_t scanner;
ParseData data;
data.basePath = basePath;
data.path = path;
yylex_init(&scanner);
yy_scan_string(text, scanner);
int res = yyparse(scanner, &data);
yylex_destroy(scanner);
if (res) throw EvalError(data.error);
try {
checkVarDefs(state.primOps, data.result);
} catch (Error & e) {
throw EvalError(format("%1%, in `%2%'") % e.msg() % path);
}
checkAttrSets(data.result);
return data.result;
}
Expr parseExprFromFile(EvalState & state, Path path)
{
assert(path[0] == '/');
#if 0
/* Perhaps this is already an imploded parse tree? */
Expr e = ATreadFromNamedFile(path.c_str());
if (e) return e;
#endif
/* 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 (stat(path.c_str(), &st))
throw SysError(format("getting status of `%1%'") % path);
if (S_ISDIR(st.st_mode))
path = canonPath(path + "/default.nix");
/* Read and parse the input file. */
return parse(state, readFile(path).c_str(), path, dirOf(path));
}
Expr parseExprFromString(EvalState & state,
const string & s, const Path & basePath)
{
return parse(state, s.c_str(), "(string)", basePath);
}
}
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